Talk:Endoderm

Vertebrate Endoderm Development and Organ Formation

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2861293/?tool=pubmed

1. Development. 2010 Jan;137(2):223-35.

Nodal and BMP2/4 pattern the mesoderm and endoderm during development of the sea urchin embryo.

Duboc V, Lapraz F, Saudemont A, Bessodes N, Mekpoh F, Haillot E, Quirin M, Lepage T.

UPMC Univ Paris 06-CNRS, UMR 7009 Biologie du D√©veloppement Observatoire Oc√©anologique, 06230 Villefranche-sur-mer, France.

Nodal factors play fundamental roles in induction and patterning of the mesoderm and endoderm in vertebrates, but whether this reflects an ancient role or one that evolved recently in vertebrates is not known. Here, we report that in addition to its primary role in patterning the ectoderm, sea urchin Nodal is crucial for patterning of the endoderm and skeletogenic mesoderm through the regulation of the expression of key transcription factors and signalling molecules, including BMP2/4 and FGFA. In addition, we uncovered an essential role for Nodal and BMP2/4 in the formation and patterning of the non-skeletogenic mesoderm. By comparing the effects of misexpressing Nodal or an activated Nodal receptor in clones of cells, we provide evidence that Nodal acts over a long range in the endomesoderm and that its effects on the blastocoelar cell precursors are likely to be direct. The activity of Nodal and BMP2/4 are antagonistic, and although bmp2/4 is transcribed in the ventral ectoderm downstream of Nodal, the BMP2/4 ligand is translocated to the dorsal side, where it activates signalling in the dorsal primary mesenchyme cells, the dorsal endoderm and in pigment cell precursors. Therefore, correct patterning of the endomesoderm depends on a balance between ventralising Nodal signals and dorsalising BMP2/4 signals. These experiments confirm that Nodal is a key regulator of dorsal-ventral polarity in the sea urchin and support the idea that the ventral ectoderm, like the Spemann organiser in vertebrates, is an organising centre that is required for patterning all three germ layers of the embryo.

PMID: 20040489 [PubMed - indexed for MEDLINE]

2. Dev Biol. 2010 Jan 1;337(1):63-73. Epub 2009 Oct 20.

Gata4 directs development of cardiac-inducing endoderm from ES cells.

Holtzinger A, Rosenfeld GE, Evans T.

Department of Surgery, Weill Cornell Medical School, New York, NY 10021, USA.

The transcription factor Gata4 is essential for normal heart morphogenesis and regulates the survival, growth, and proliferation of cardiomyocytes. We tested if Gata4 can specify cardiomyocyte fate from an uncommitted stem or progenitor cell population, by developing a system for conditional expression of Gata4 in embryonic stem cells. We find that in embryoid body cultures containing even a low ratio of these cells, expression of Gata4 is sufficient to enhance significantly the generation of cardiomyocytes, via a non-cell-autonomous mechanism. The Gata4-expressing cells do not generate cardiac or other mesoderm derivatives. Rather, Gata4 expression directs the development of two types of Sox17+ endoderm. This includes an epCam+Dpp4+ subtype of visceral endoderm. In addition, Gata4 generates similar amounts of epCam+Dpp4- definitive endoderm enriched for Cxcr4, FoxA2, FoxA3, Dlx5 and other characteristic transcripts. Both types of endoderm express cardiac-inducing factors, including WNT antagonists Dkk1 and Sfrp5, although the visceral endoderm subtype has much higher cardiac-inducing activity correlating with relatively enhanced levels of transcripts encoding BMPs. The Gata4-expressing cells eventually express differentiation markers showing commitment to liver development, even under conditions that normally support mesoderm development. The results suggest that Gata4 is capable of specifying endoderm fates that facilitate, with temporal and spatial specificity, the generation of cardiomyocyte progenitors from associated mesoderm.

PMCID: PMC2799892 [Available on 2011/1/1] PMID: 19850025 [PubMed - indexed for MEDLINE]

3. Annu Rev Cell Dev Biol. 2009;25:221-51.

Vertebrate endoderm development and organ formation.

Zorn AM, Wells JM.

Division of Developmental Biology, Cincinnati Children's Research Foundation and Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45229, USA. aaron.zorn@cchmc.org

The endoderm germ layer contributes to the respiratory and gastrointestinal tracts and to all of their associated organs. Over the past decade, studies in vertebrate model organisms, including frog, fish, chick, and mouse, have greatly enhanced our understanding of the molecular basis of endoderm organ development. We review this progress with a focus on early stages of endoderm organogenesis including endoderm formation, gut tube morphogenesis and patterning, and organ specification. Lastly, we discuss how developmental mechanisms that regulate endoderm organogenesis are used to direct differentiation of embryonic stem cells into specific adult cell types, which function to alleviate disease symptoms in animal models.

PMCID: PMC2861293 PMID: 19575677 [PubMed - indexed for MEDLINE]

4. Dev Dyn. 2009 Mar;238(3):514-23.

C-Fos elimination compensates for disabled-2 requirement in mouse extraembryonic endoderm development.

Yang DH, Smith ER, Cai KQ, Xu XX.

Ovarian Cancer Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA.

Disabled-2 (Dab2) is expressed in primitive endoderm cells as they are differentiating from the inner cell mass and dab2 deficiency in mice results in lethality at E5.5-E6.5 due to the disorganization of the endoderm layers. Here we show that Dab2 suppresses c-Fos expression in endoderm cells. A morphological normal primitive endoderm layer was observed in putative E5.5 dab2 (-/-):c-fos (-/-) embryos, indicating that the primitive endoderm defect due to the loss of Dab2 is rescued by deletion of the c-fos gene. The lethality of the double knockout embryos was delayed until E9.5-E10.5 and the defective embryos failed to undergo organogenesis. We conclude that Dab2 plays a role in epithelial organization by suppression of c-Fos expression and suggest that unsuppressed c-Fos can lead to disruption of primitive endoderm epithelial organization, yet an additional dab2 function is required for later organogenesis. (c) 2009 Wiley-Liss, Inc.

PMCID: PMC2743073 PMID: 19191218 [PubMed - indexed for MEDLINE]

5. Cytotechnology. 2008 Jun;57(2):151-9. Epub 2008 Feb 12.

Cephalic hedgehog expression is regulated directly by Sox17 in endoderm development of Xenopus laevis.

Yagi Y, Ito Y, Kuhara S, Tashiro K.

Graduate School of Systems Life Sciences, Kyushu University, Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.

In early development of animals, hedgehog (Hh) genes function as morphogen in the axis determination and the organ formation. In Xenopus, three hedgehog genes, sonic (shh), banded (bhh), and cephalic (chh), were identified and might organize various tissues and organs in embryogenesis. Here, we report the spatial and temporal regulation of Xchh which is expressed in endoderm cells differentiating to digestive organs. Xchh expression in endoderm was inhibited by ectopic expression of the dominant-negative activin receptor, tAR. Moreover, a maternally inherited transcription factor VegT and its downstream regulators activated Xchh expression. These indicates that Xchh is regulated by the factor involved in the cascade originated from VegT via activin/nodal signals. Using the Sox17alpha-VP16-GR construct, we showed that Xchh expression might be induced directly by transcription factor Sox17.

PMCID: PMC2553669 PMID: 19003160 [PubMed - in process]

6. Dev Growth Differ. 2008 Sep;50(7):615-21.

Bone morphogenetic protein 4 signaling regulates development of the anterior visceral endoderm in the mouse embryo.

Soares ML, Torres-Padilla ME, Zernicka-Goetz M.

The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.

The extraembryonic ectoderm (ExE) of the mouse conceptus is known to play a role in embryo patterning by signaling to the underlying epiblast and surrounding visceral endoderm. Bmp4 is one of the key ExE signaling molecules and has been recently implicated to participate in regulating development and migration of the anterior visceral endoderm (AVE). However, it remains unclear when exactly BMP4 signaling starts to regulate AVE positioning. To examine this, we have chosen to affect BMP4 function at two different time points, at embryonic day 5.25 (E5.25), thus before AVE migration, and E5.75, just after AVE migration. To this end, an RNAi technique was used, which consisted of the injection of Bmp4 dsRNA into the proamniotic cavity of the egg cylinder followed by its targeted electroporation into the ExE. This resulted in specific knockdown of Bmp4. It was found that Bmp4 RNAi at E5.25, but not at E5.75, led to an abnormal pattern of expression of the AVE marker Cerberus-like. Thus, BMP4 signaling appears to affect the expression of Cer1 at a specific time window. This RNAi approach provides a convenient means to study spatial and temporal function of genes shortly after embryo implantation.

PMID: 18657169 [PubMed - indexed for MEDLINE]

7. Dev Biol. 2008 Jun 1;318(1):52-64. Epub 2008 Mar 20.

Endoderm-derived Sonic hedgehog and mesoderm Hand2 expression are required for enteric nervous system development in zebrafish.

Reichenbach B, Delalande JM, Kolmogorova E, Prier A, Nguyen T, Smith CM, Holzschuh J, Shepherd IT.

Department of Developmental Biology, University of Freiburg, Biology I, Hauptstrasse 1, 79104 Freiburg, Germany.

The zebrafish enteric nervous system (ENS), like those of all other vertebrate species, is principally derived from the vagal neural crest cells (NCC). The developmental controls that govern the migration, proliferation and patterning of the ENS precursors are not well understood. We have investigated the roles of endoderm and Sonic hedgehog (SHH) in the development of the ENS. We show that endoderm is required for the migration of ENS NCC from the vagal region to the anterior end of the intestine. We show that the expression of shh and its receptor ptc-1 correlate with the development of the ENS and demonstrate that hedgehog (HH) signaling is required in two phases, a pre-enteric and an enteric phase, for normal ENS development. We show that HH signaling regulates the proliferation of vagal NCC and ENS precursors in vivo. We also show the zebrafish hand2 is required for the normal development of the intestinal smooth muscle and the ENS. Furthermore we show that endoderm and HH signaling, but not hand2, regulate gdnf expression in the intestine, highlighting a central role of endoderm and SHH in patterning the intestine and the ENS.

PMCID: PMC2435286 PMID: 18436202 [PubMed - indexed for MEDLINE]

8. Dev Biol. 2008 May 15;317(2):467-79. Epub 2008 Mar 4.

Multiple roles for Med12 in vertebrate endoderm development.

Shin CH, Chung WS, Hong SK, Ober EA, Verkade H, Field HA, Huisken J, Stainier DY.

Department of Biochemistry and Biophysics, Liver Center, University of California, San Francisco, CA 94158, USA. chong.shin@ucsf.edu

In zebrafish, the endoderm originates at the blastula stage from the most marginal blastomeres. Through a series of complex morphogenetic movements and differentiation events, the endodermal germ layer gives rise to the epithelial lining of the digestive tract as well as its associated organs such as the liver, pancreas, and swim bladder. How endodermal cells differentiate into distinct cell types such as hepatocytes or endocrine and exocrine pancreatic cells remains a major question. In a forward genetic screen for genes regulating endodermal organ development, we identified mutations at the shiri locus that cause defects in the development of a number of endodermal organs including the liver and pancreas. Detailed phenotypic analyses indicate that these defects are partially due to a reduction in endodermal expression of the hairy/enhancer of split-related gene, her5, at mid to late gastrulation stages. Using the Tg(0.7her5:EGFP)(ne2067) line, we show that her5 is expressed in the endodermal precursors that populate the pharyngeal region as well as the organ-forming region. We also find that knocking down her5 recapitulates some of the endodermal phenotypes of shiri mutants, further revealing the role of her5 in endoderm development. Positional cloning reveals that shiri encodes Med12, a regulatory subunit of the transcriptional Mediator complex recently associated with two human syndromes. Additional studies indicate that Med12 modulates the ability of Casanova/Sox32 to induce sox17 expression. Thus, detailed phenotypic analyses of embryos defective in a component of the Mediator complex have revealed new insights into discrete aspects of vertebrate endoderm development, and provide possible explanations for the craniofacial and digestive system defects observed in humans with mutations in MED12.

PMCID: PMC2435012 PMID: 18394596 [PubMed - indexed for MEDLINE]

9. Mech Dev. 2008 May-Jun;125(5-6):377-95. Epub 2008 Feb 20.

Foregut endoderm is specified early in avian development through signal(s) emanating from Hensen's node or its derivatives.

Matsushita S, Urase K, Komatsu A, Scotting PJ, Kuroiwa A, Yasugi S.

Department of Biology, School of Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan. matsus@research.twmu.ac.jp

In this study, the initial specification of foregut endoderm in the chick embryo was analyzed. A fate map constructed for the area pellucida endoderm at definitive streak-stage showed centrally-located presumptive cells of foregut-derived organs around Hensen's node. Intracoelomic cultivation of the area pellucida endoderm at this stage combined with somatic mesoderm resulted in the differentiation predominantly into intestinal epithelium, suggesting that this endoderm may not yet be regionally specified. In vitro cultivation of this endoderm for 1-1.5 day combined with Hensen's node or its derivatives but not with other embryonic structures/tissues elicited endodermal expression of cSox2 but not of cHoxb9, which is characteristic of specified foregut endoderm. When the anteriormost or posteriormost part of the area pellucida endoderm at this stage, whose fate is extraembryonic, was combined with Hensen's node or its derivatives for 1 day, then enwrapped with somatic mesoderm and cultivated for a long period intracoelomically, differentiation of various foregut organ epithelia was observed. Such epithelia never appeared in the endoderm associated with other embryonic structures/tissues and cultured similarly. Thus, Hensen's node and its derivatives that lie centrally in the presumptive endodermal area of the foregut are likely to play an important role in the initial specification of the foregut. Chordin-expressing COS cells or noggin-producing CHO cells transplanted into the anteriormost area pellucida of the definitve streak-stage embryo could induce endodermal expression of cSox2 but not of cHoxb9, suggesting that chordin and noggin that emanate from Hensen's node and its derivatives, may be involved in this process.

PMID: 18374547 [PubMed - indexed for MEDLINE]

10. Dev Dyn. 2008 Jan;237(1):216-21.

Myocardin expression during avian embryonic heart development requires the endoderm but is independent of BMP signaling.

Warkman AS, Yatskievych TA, Hardy KM, Krieg PA, Antin PB.

Department of Cell Biology and Anatomy, University of Arizona, Tucson, Arizona, USA.

Myocardin, a serum response factor cofactor, plays an important role in regulating heart and smooth muscle development. To investigate myocardin function during early stages of heart development, we isolated the chicken orthologue of myocardin and characterized its expression between Hamburger and Hamilton stages 3 and 15. At stage 4, myocardin transcripts are detected in the lateral and extraembryonic mesoderm, become progressively localized to the precardiac mesoderm and the differentiated myocardium and are also seen in smooth muscle cells of the developing vascular plexus. Surprisingly, myocardin expression within the developing chicken embryo precedes that of the homeodomain transcription factor Nkx2.5. Embryonic dissection studies demonstrate that signals from the endoderm are required for myocardin expression within the precardiac mesoderm. However, unlike Nkx2.5, myocardin expression is not regulated by bone morphogenetic protein (BMP) signaling. These results suggest that initial expression of myocardin in the precardiac mesoderm is regulated by a signaling pathway that is parallel to, and independent of, Nkx2.5 expression.

PMID: 18069699 [PubMed - indexed for MEDLINE]

11. Development. 2007 Nov;134(22):4011-21. Epub 2007 Oct 17.

Reciprocal endoderm-mesoderm interactions mediated by fgf24 and fgf10 govern pancreas development.

Manfroid I, Delporte F, Baudhuin A, Motte P, Neumann CJ, Voz ML, Martial JA, Peers B.

GIGA-Research-Unit√© de Biologie Mol√©culaire et G√©nie G√©n√©tique, Tour B34, Universit√© de Li√®ge, B-4000 Sart Tilman, Belgium. isabelle.manfroid@ulg.ac.be

In amniotes, the pancreatic mesenchyme plays a crucial role in pancreatic epithelium growth, notably through the secretion of fibroblast growth factors. However, the factors involved in the formation of the pancreatic mesenchyme are still largely unknown. In this study, we characterize, in zebrafish embryos, the pancreatic lateral plate mesoderm, which is located adjacent to the ventral pancreatic bud and is essential for its specification and growth. We firstly show that the endoderm, by expressing the fgf24 gene at early stages, triggers the patterning of the pancreatic lateral plate mesoderm. Based on the expression of isl1, fgf10 and meis genes, this tissue is analogous to the murine pancreatic mesenchyme. Secondly, Fgf10 acts redundantly with Fgf24 in the pancreatic lateral plate mesoderm and they are both required to specify the ventral pancreas. Our results unveil sequential signaling between the endoderm and mesoderm that is critical for the specification and growth of the ventral pancreas, and explain why the zebrafish ventral pancreatic bud generates the whole exocrine tissue.

PMID: 17942484 [PubMed - indexed for MEDLINE]

12. Development. 2007 Jun;134(12):2207-17. Epub 2007 May 16.

Repression of Wnt/beta-catenin signaling in the anterior endoderm is essential for liver and pancreas development.

McLin VA, Rankin SA, Zorn AM.

Cincinnati Children's Research Foundation, Department of Pediatrics, College of Medicine, University of Cincinnati, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.

The liver and pancreas are specified from the foregut endoderm through an interaction with the adjacent mesoderm. However, the earlier molecular mechanisms that establish the foregut precursors are largely unknown. In this study, we have identified a molecular pathway linking gastrula-stage endoderm patterning to organ specification. We show that in gastrula and early-somite stage Xenopus embryos, Wnt/beta-catenin activity must be repressed in the anterior endoderm to maintain foregut identity and to allow liver and pancreas development. By contrast, high beta-catenin activity in the posterior endoderm inhibits foregut fate while promoting intestinal development. Experimentally repressing beta-catenin activity in the posterior endoderm was sufficient to induce ectopic organ buds that express early liver and pancreas markers. beta-catenin acts in part by inhibiting expression of the homeobox gene hhex, which is one of the earliest foregut markers and is essential for liver and pancreas development. Promoter analysis indicates that beta-catenin represses hhex transcription indirectly via the homeodomain repressor Vent2. Later in development, beta-catenin activity has the opposite effect and enhances liver development. These results illustrate that turning Wnt signaling off and on in the correct temporal sequence is essential for organ formation, a finding that might directly impact efforts to differentiate liver and pancreas tissue from stem cells.

PMID: 17507400 [PubMed - indexed for MEDLINE]

13. Int Rev Cytol. 2007;259:49-111.

Molecular basis of vertebrate endoderm development.

Zorn AM, Wells JM.

Division of Developmental Biology, Cincinnati Children's Hospital Research, Foundation and University of Cincinnati College of Medicine, Cincinnati, Ohio 45229, USA.

The embryonic endoderm gives rise to the epithelial lining of the digestive and respiratory systems and organs such as the thyroid, lungs, liver, gallbladder, and pancreas. Studies in Xenopus, zebrafish, and mice have revealed a conserved molecular pathway controlling vertebrate endoderm development. The TGFbeta/Nodal signaling pathway is at the top of this molecular hierarchy and controls the expression of a number of key transcription factors including Mix-like homeodomain proteins, Gata zinc finger factors, Sox HMG domain proteins, and Fox forkhead factors. Here we review the function of these molecules comparing and contrasting their roles in each model organism. Finally, we will describe how our understanding of the molecular pathway governing endoderm development in embryos is being used to differentiate embryonic stem cells in vitro along endodermal lineages, with the ultimate goal of making therapeutically useful tissue.

PMID: 17425939 [PubMed - indexed for MEDLINE]

14. Stem Cells Dev. 2007 Feb;16(1):3-5.

Heart development: the battle between mesoderm and endoderm.

Pal R, Khanna A.

Embryonic Stem Cell Group, Reliance Life Sciences Pvt. Ltd. Dhirubhai Ambani Life Sciences Center, Navi Mumbai, India.

Recent years have seen a surge of scientific research examining the interdependence of one germ layer in the development of the other, both in vivo and in vitro. For example, the endoderm is believed to play a crucial role in the formation of mesoderm and subsequent maturation of cells belonging to the mesodermal lineage. Our understanding of this complex relationship is continuously growing with reinterpretation of earlier concepts and apprehension of newer hypotheses into the biology of embryonic development. Here we discuss some of the events governing the cooperative control of endoderm over mesoderm, and propose a perspective based on the existing literature and our own experience.

PMID: 17348801 [PubMed - indexed for MEDLINE]

15. Proc Natl Acad Sci U S A. 2006 Aug 1;103(31):11607-12. Epub 2006 Jul 25.

An early role for sonic hedgehog from foregut endoderm in jaw development: ensuring neural crest cell survival.

Brito JM, Teillet MA, Le Douarin NM.

Laboratoire de D√©veloppement, Evolution et Plasticit√© du Syst√®me Nerveux, Unit√© Propre de Recherche 2197, Centre National de la Recherche Scientifique, Institut de Neurobiologie Alfred Fessard, F-91198 Gif-sur-Yvette, France.

We have investigated the role of Sonic hedgehog (Shh) in the development of facial structures by depriving chicken embryos of the most anterior sources of this morphogen, including the prechordal plate and the anterior ventral endoderm of the foregut, before the onset of neural crest cell (NCC) migration to the first branchial arch (BA1). The entire forehead, including the foregut endoderm, was removed at 5- to 10-somite stage (ss), which led to the absence of the lower jaw when the operation was performed before 7-ss. If the embryos were deprived of their forehead at 8- to 10-ss, they were later on endowed with a lower beak. In embryos that were operated on early, the NCCs migrated normally to BA1 but were subjected to massive apoptosis a few hours later. Cell death did not occur when forehead excision was performed at a later stage. In this case, onward expression of Shh in the ventral foregut endoderm extended caudally over the excision limit, and we hypothesized that absence of Shh production by the endoderm in embryos that were operated on early could be responsible for the NCC apoptosis and the failure of BA1 development. We thus provided exogenous Shh to the embryos that were operated on before 7-ss. In this case, the development of the lower jaw was rescued. Therefore, Shh derived from the ventral foregut endoderm ensures the survival of NCCs at a critical stage of BA1 development.

PMCID: PMC1544217 PMID: 16868080 [PubMed - indexed for MEDLINE]

16. Dev Growth Differ. 2006 Jun;48(5):283-95.

Development of the endoderm and gut in medaka, Oryzias latipes.

Kobayashi D, Jindo T, Naruse K, Takeda H.

Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.

We performed an extensive analysis of endodermal development and gut tube morphogenesis in the medaka embryo by histology and in situ hybridization. The markers used in these analyses included sox17, sox32, foxA2, gata-4, -5, -6 and shh. sox17, sox32, foxA2, and gata-5 and -6 are expressed in the early endoderm to the onset of gut tube formation. Sections of medaka embryos hybridized with foxA2, a pan-endodermal marker during gut morphogenesis, demonstrated that gut tube formation is initiated in the anterior portion and that the anterior and mid/posterior gut undergo distinct morphogenetic processes. Tube formation in the anterior endoderm that is fated to the pharynx and esophagus is much delayed and appears to be independent of gut morphogenesis. The overall aspects of medaka gut development are similar to those of zebrafish, except that zebrafish tube formation initiates at both the anterior and posterior portions. Our results therefore describe both molecular and morphological aspects of medaka digestive system development that will be necessary for the characterization of medaka mutants.

PMID: 16759279 [PubMed - indexed for MEDLINE]

17. Dev Dyn. 2006 Sep;235(9):2549-58.

Tg(Afp-GFP) expression marks primitive and definitive endoderm lineages during mouse development.

Kwon GS, Fraser ST, Eakin GS, Mangano M, Isern J, Sahr KE, Hadjantonakis AK, Baron MH.

Developmental Biology Program, Sloan-Kettering Institute, New York, New York 10021, USA.

Alpha-fetoprotein (Afp) is the most abundant serum protein in the developing embryo. It is secreted by the visceral endoderm, its derivative yolk sac endoderm, fetal liver hepatocytes, and the developing gut epithelium. The abundance of this protein suggested that Afp gene regulatory elements might serve to effectively drive reporter gene expression in developing endodermal tissues. To this end, we generated transgenic mouse lines Tg(Afp-GFP) using an Afp promoter/enhancer to drive expression of green fluorescent protein (GFP). Bright GFP fluorescence allowed the visualization, in real time, of visceral endoderm, yolk sac endoderm, fetal liver hepatocytes, and the epithelium of the gut and pancreas. Comparison of the localization of green fluorescence with that of endogenous Afp transcripts and protein indicated that the regulatory elements used to generate these mouse lines directed transgene expression in what appeared to be all Afp-expressing cells of the embryo, but only in a subset of fetal liver cells. The bright GFP signal permitted flow cytometric analysis of fetal liver hepatocytes. These mice represent a valuable resource for live imaging as well as identification, quantitation, and isolation of cells from the primitive and definitive endoderm lineages of the developing mouse embryo. Copyright 2006 Wiley-Liss, Inc.

PMCID: PMC1850385 PMID: 16708394 [PubMed - indexed for MEDLINE]

18. Biochem Biophys Res Commun. 2006 Jun 9;344(3):852-8. Epub 2006 Apr 19.

Changes in S1P1 and S1P2 expression during embryonal development and primitive endoderm differentiation of F9 cells.

Hiraga Y, Kihara A, Sano T, Igarashi Y.

Department of Biomembrane and Biofunctional Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12-jo, Nishi 6-choume, Kita-ku, Sapporo 060-0812, Japan.

Sphingosine 1-phosphate (S1P) is a ligand for S1P family receptors (S1P(1)-S1P(5)). Of these receptors, S1P(1), S1P(2), and S1P(3) are ubiquitously expressed in adult mice, while S1P(4) and S1P(5) are tissue specific. However, little is known of their expression during embryonal development. We performed Northern blot analyses in mouse embryonal tissue and found that such expression is developmentally regulated. We also examined the expression of these receptors during primitive endoderm (PrE) differentiation of mouse F9 embryonal carcinoma (EC) cells, a well-known in vitro endoderm differentiation system. S1P(2) mRNA was abundantly expressed in F9 EC cells, but little S1P(1) and no S1P(3), S1P(4), or S1P(5) mRNA was detectable. However, S1P(1) mRNA expression was induced during EC-to-PrE differentiation. Studies using small interference RNA of S1P(1) indicated that increased S1P(1) expression is required for PrE differentiation. Thus, S1P(1) may play an important function in PrE differentiation that is not substituted for by S1P(2).

PMID: 16631609 [PubMed - indexed for MEDLINE]

19. Genesis. 2006 Feb;44(2):93-104.

Visceral endoderm function is regulated by quaking and required for vascular development.

Bohnsack BL, Lai L, Northrop JL, Justice MJ, Hirschi KK.

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.

The quaking (qkI) gene produces three major alternatively spliced variants (qkI-5,-6,-7) that encode for proteins that share the RNA binding, KH domain. Previous studies utilizing the qk(k2) allele, which contains an N-ethyl-N-nitrosourea (ENU)-induced point mutation in the KH domain, demonstrate that this functional region of qkI is required for embryonic vascular development. In the current studies we demonstrate that qk(l-1)/qk(l-1) mutants, which lack the QKI-5 splice variant, also died at midgestation due to vascular remodeling defects. In addition, although all three QKI isoforms were expressed in the visceral endoderm of wildtype yolk sacs, qkI-6 and qkI-7 transcript and protein expression were suppressed in qk(k2)/qk(k2) and qk(l-1)/qk(l-1) mutant yolk sacs, suggesting that the KH-domain of QKI-5 was required for qkI-6 and qkI-7 expression. Further studies revealed that the cellular role of qkI is to regulate visceral endoderm function, including the local synthesis of retinoic acid (RA) and the subsequent control of endothelial cell proliferation, matrix production, and visceral endoderm survival. Although these defects were rescued by exogenous RA, visceral endoderm function or vascular remodeling were not restored. Thus, we conclude that qkI regulates visceral endoderm function, which is critical for vascular remodeling.

PMID: 16470614 [PubMed - indexed for MEDLINE]

20. Dev Biol. 2006 Feb 1;290(1):44-56. Epub 2005 Dec 20.

Hex homeobox gene controls the transition of the endoderm to a pseudostratified, cell emergent epithelium for liver bud development.

Bort R, Signore M, Tremblay K, Martinez Barbera JP, Zaret KS.

Cell and Developmental Biology Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.

Little is known about the mechanism by which embryonic liver, lung, and pancreas progenitor cells emerge from the endodermal epithelium to initiate organogenesis. Understanding this process and its genetic control provides insight into ontogeny, developmental abnormalities, and tissue regeneration. We find that shortly after hepatic endoderm cells are specified, they undergo a transition from a columnar, gut morphology to a pseudostratified morphology, with concomitant "interkinetic nuclear migration" (INM) during cell division. INM is a hallmark of pseudostratified epithelia and the process used by neural progenitors to emerge from the neural epithelium. We find that the transition of the hepatic endoderm, but not the neural epithelium, to a pseudostratified epithelium is dependent upon the cell-autonomous activity of the homeobox gene Hex. In the absence of Hex, hepatic endoderm cells survive but maintain a columnar, simple epithelial phenotype and ectopically express Shh and other genes characteristic of the midgut epithelium. Thus, Hex promotes endoderm organogenesis by promoting the transition to a pseudostratified epithelium, which in turn allows hepatoblasts to emerge into the stromal environment and continue differentiating.

PMID: 16364283 [PubMed - indexed for MEDLINE]

21. Mech Dev. 2006 Jan;123(1):56-66. Epub 2005 Dec 5.

Determination of the minimal domains of Mix.3/Mixer required for endoderm development.

Doherty JR, Zhu H, Kuliyev E, Mead PE.

Department of Pathology, St Jude Children's Research Hospital, 332 North Lauderdale Street, Memphis, TN 38105, USA.

The Mix/Bix family of Pax-like homeodomain transcription factors is expressed early in vertebrate development and play important roles in endoderm and mesoderm formation. Like other Pax-related homeodomain proteins, the Mix/Bix family binds DNA as monomers or dimers and dimerization is mediated by the homeodomain. While the Mix/Bix family shares extensive sequence homology within the DNA-binding homeodomain, ectopic expression of these proteins has profoundly different outcomes. Expression of Xenopus Mix.3/Mixer in explanted ectoderm results in endoderm differentiation, whereas Mix.1 expression does not. In this study we sought to define the domains of Mix.3/Mixer that are responsible for this endoderm inducing activity. We generated domain swap mutants between Mix.3/Mixer and Mix.1 and tested their ability to induce endoderm in explanted ectoderm. We demonstrate that the homeodomain and sixty-two amino acids in the carboxyl terminus are required to induce endoderm and that these domains must be on the same polypeptide and can not act in trans as a heterodimer. A Smad2 interaction motif in Mix.3/Mixer is involved in endoderm differentiation but is not essential. Thus, we have defined the regions of Mix.3/Mixer that confer endoderm-inducing activity. These studies reveal a novel co-operation between the homeodomain and a small domain in the carboxyl terminal region that is essential for Mix.3/Mixer function.

PMID: 16330190 [PubMed - indexed for MEDLINE]

22. Dev Growth Differ. 2005 Dec;47(9):581-9.

GATA factors as key regulatory molecules in the development of Drosophila endoderm.

Murakami R, Okumura T, Uchiyama H.

Department of Physics, Biology, and Informatics, Yamaguchi University, Yamaguchi 753-8512, Japan. ryu@yamaguchi-u.ac.jp

Essential roles for GATA factors in the development of endoderm have been reported in various animals. A Drosophila GATA factor gene, serpent (srp, dGATAb, ABF), is expressed in the prospective endoderm, and loss of srp activity causes transformation of the prospective endoderm into ectodermal foregut and hindgut, indicating that srp acts as a selector gene to specify the developmental fate of the endoderm. While srp is expressed in the endoderm only during early stages, it activates a subsequent GATA factor gene, dGATAe, and the latter continues to be expressed specifically in the endoderm throughout life. dGATAe activates various functional genes in the differentiated endodermal midgut. An analogous mode of regulation has been reported in Caenorhabditis elegans, in which a pair of GATA genes, end-1/3, specifies endodermal fate, and a downstream pair of GATA genes, elt-2/7, activates genes in the differentiated endoderm. Functional homology of GATA genes in nature is apparently extendable to vertebrates, because endodermal GATA genes of C. elegans and Drosophila induce endoderm development in Xenopus ectoderm. These findings strongly imply evolutionary conservation of the roles of GATA factors in the endoderm across the protostomes and the deuterostomes.

PMID: 16316403 [PubMed - indexed for MEDLINE]

23. J Anat. 2005 Nov;207(5):479-87.

The role of the endoderm in the development and evolution of the pharyngeal arches.

Graham A, Okabe M, Quinlan R.

MRC Centre for Developmental Neurobiology, Guys Campus, Kings College London, London, UK. anthony.graham@kcl.ac.uk

The oro-pharyngeal apparatus has its origin in a series of bulges found on the lateral surface of the embryonic head, the pharyngeal arches. Significantly, the development of these structures is extremely complex, involving interactions between a number of disparate embryonic cell types: ectoderm, endoderm, mesoderm and neural crest, each of which generates particular components of the arches, and whose development must be co-ordinated to generate the functional adult oro-pharyngeal apparatus. In the past most studies have emphasized the role played by the neural crest, which generates the skeletal elements of the arches, in directing pharyngeal arch development. However, it is now apparent that the pharyngeal endoderm plays an important role in directing arch development. Here we discuss the role of the pharyngeal endoderm in organizing the development of the pharyngeal arches, and the mechanisms that act to pattern the endoderm itself and those which direct its morphogenesis. Finally, we discuss the importance of modification to the pharyngeal endoderm during vertebrate evolution. In particular, we focus on the emergence of the parathyroid gland, which we have recently shown to be the result of the internalization of the gills.

PMCID: PMC1571564 PMID: 16313389 [PubMed - indexed for MEDLINE]

24. Dev Dyn. 2006 Feb;235(2):368-81.

Genomic profiling of mixer and Sox17beta targets during Xenopus endoderm development.

Dickinson K, Leonard J, Baker JC.

Department of Genetics, Stanford University Medical School, Stanford, California 94062, USA.

The transcription factors Mixer and Sox17beta have well-characterized roles in endoderm specification during Xenopus embryogenesis. In order to more thoroughly understand the mechanisms by which these endodermal regulators act, we expressed Mixer and Sox17beta in na√Øve ectodermal tissue and, using oligonucleotide-based microarrays, compared their genomic transcriptional profile to that of unaffected tissue. Using this approach, we identified 71 transcripts that are upregulated by Mixer or Sox17beta, 63 of which have previously uncharacterized roles in endoderm development. Furthermore, an in situ hybridization screen using antisense probes for several of these clones identified six targets of Mixer and/or Sox17beta that are expressed in the endoderm during gastrula stages, providing new and regional markers of the endoderm. Our results contribute further insight into the functions of Mixer and Sox17beta and bring us closer to understanding at the molecular level the pathways that regulate endoderm development. Copyright 2005 Wiley-Liss, Inc.

PMID: 16278889 [PubMed - indexed for MEDLINE]

25. Stem Cells. 2006 Mar;24(3):624-30. Epub 2005 Oct 6.

Crucial transcription factors in endoderm and embryonic gut development are expressed in gut-like structures from mouse ES cells.

Matsuura R, Kogo H, Ogaeri T, Miwa T, Kuwahara M, Kanai Y, Nakagawa T, Kuroiwa A, Fujimoto T, Torihashi S.

Department of Anatomy and Molecular Cell Biology, Graduate School of Medicine, Nagoya University, Japan.

Mouse embryonic stem (ES) cells are pluripotent and retain the potential to form an organ similar to the gut showing spontaneous contractions in vitro. The morphological features of these structures and their formation, as assessed using the hanging drop method to produce embryoid bodies (EBs), seem to be similar to those in vivo. To determine whether the same molecular mechanisms are involved in the formation process, the expression pattern of transcription factors regulating endoderm and gut development in the mouse embryo was examined by in situ hybridization and compared with in vivo expression. Expression of gene products was also examined by immunohistochemistry, and expression colocalization was analyzed with double staining. The results showed that all factors examined, that is, Sox17, Id2, HNF3beta/Foxa2, and GATA4, were expressed in both EBs and gut-like structures. Moreover, their expression patterns were similar to those in the mouse embryo. EBs after the hanging drop period and before outgrowth already expressed all factors that were colocalized with each other in EB epithelial structures. These findings suggest that the origin of the gut-like structure is determined during the hanging drop period and that the gut-like structure is formed as the epithelial structure in EBs during the hanging drop period. They also indicate that the in vitro system using mouse ES cells mimics in vivo development and should prove useful in the study of molecular mechanisms for endoderm and gut development.

PMID: 16210401 [PubMed - indexed for MEDLINE]

26. Dev Growth Differ. 2005 Aug;47(6):343-55.

Endoderm development in vertebrates: fate mapping, induction and regional specification.

Fukuda K, Kikuchi Y.

Department of Biological Sciences, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.

The formation of the vertebrate body plan begins with the differentiation of cells into three germ layers: ectoderm, mesoderm and endoderm. Cells in the endoderm give rise to the epithelial lining of the digestive tract, associated glands and respiratory system. One of the fundamental problems in developmental biology is to elucidate how these three primary germ layers are established from the homologous population of cells in the early blastomere. To address this question, ectoderm and mesoderm development have been extensively analyzed, but study of endoderm development has only begun relatively recently. In this review, we focus on the 'where', 'when' and 'how' of endoderm development in four vertebrate model organisms: the zebrafish, Xenopus, chick and mouse. We discuss the classical fate mapping of the endoderm and the more recent progress in characterizing its induction, segregation and regional specification.

PMID: 16109032 [PubMed - indexed for MEDLINE]

27. Dev Biol. 2005 Sep 15;285(2):510-23.

The Wnt effector POP-1 and the PAL-1/Caudal homeoprotein collaborate with SKN-1 to activate C. elegans endoderm development.

Maduro MF, Kasmir JJ, Zhu J, Rothman JH.

Department of MCD Biology and Neuroscience Research Institute, University of California at Santa Barbara, Santa Barbara, CA 93106, USA.

POP-1, a Tcf/Lef-1-like target of the convergent Wnt and MAP kinase (MAPK) signaling pathways, functions throughout Caenorhabditis elegans development to generate unequal daughters during asymmetric cell divisions. A particularly prominent such asymmetric division occurs when the EMS blastomere divides to produce MS, a mesoderm precursor, and E, the sole endoderm progenitor. POP-1 allows mesoderm development in the MS lineage by repressing the endoderm-promoting end-1 and end-3 genes. This repression is relieved in the E lineage by Wnt/MAPK signaling, which results in phosphorylation and export of POP-1 from the E nucleus. Here, we report that, in addition to repressing E development in MS, POP-1 also functions positively in endoderm development, in conjunction with the well-characterized endoderm-promoting SKN-1-->MED regulatory cascade. While removal of POP-1 alone results in derepression of endoderm development in the MS lineage, mutations in several genes that result in impenetrant loss of endoderm are strongly enhanced by loss of pop-1 function. A Lef-1-like binding site is essential for activation of an end-1 promoter fusion, suggesting that POP-1 may act directly on end-1. Thus, POP-1 may generate developmental asymmetry during many cell divisions in C. elegans by reiteratively switching from repressive and activating states. Furthermore, we report that the Caudal-like homeodomain protein PAL-1, whose role in early embryogenesis was thought to be exclusive specification of mesectodermal development in the lineage of the C blastomere, can act with POP-1 to activate endoderm specification in the absence of the SKN-1-->MED transcriptional input, accounting for the impenetrance of mutants lacking SKN-1 or MED-1,2 activity. We conclude that the combined action of several separate transcriptional regulatory inputs, including SKN-1, the MEDs, PAL-1, and the Wnt/MAPK-activated form of POP-1, are responsible for activating end gene transcription and endoderm development.

PMID: 16084508 [PubMed - indexed for MEDLINE]

28. PLoS Biol. 2004 Sep;2(9):E244. Epub 2004 Jul 20.

An integrin-dependent role of pouch endoderm in hyoid cartilage development.

Crump JG, Swartz ME, Kimmel CB.

Institute of Neuroscience, University of Oregon, Eugene, Oregon, USA. gage@uoneuro.uoregon.edu

Pharyngeal endoderm is essential for and can reprogram development of the head skeleton. Here we investigate the roles of specific endodermal structures in regulating craniofacial development. We have isolated an integrinalpha5 mutant in zebrafish that has region-specific losses of facial cartilages derived from hyoid neural crest cells. In addition, the cranial muscles that normally attach to the affected cartilage region and their associated nerve are secondarily reduced in integrinalpha5- animals. Earlier in development, integrinalpha5 mutants also have specific defects in the formation of the first pouch, an outpocketing of the pharyngeal endoderm. By fate mapping, we show that the cartilage regions that are lost in integrinalpha5 mutants develop from neural crest cells directly adjacent to the first pouch in wild-type animals. Furthermore, we demonstrate that Integrinalpha5 functions in the endoderm to control pouch formation and cartilage development. Time-lapse recordings suggest that the first pouch promotes region-specific cartilage development by regulating the local compaction and survival of skeletogenic neural crest cells. Thus, our results reveal a hierarchy of tissue interactions, at the top of which is the first endodermal pouch, which locally coordinates the development of multiple tissues in a specific region of the vertebrate face. Lastly, we discuss the implications of a mosaic assembly of the facial skeleton for the evolution of ray-finned fish.

PMCID: PMC479042 PMID: 15269787 [PubMed - indexed for MEDLINE]

29. Development. 2004 Apr;131(7):1651-62. Epub 2004 Mar 3.

Development of definitive endoderm from embryonic stem cells in culture.

Kubo A, Shinozaki K, Shannon JM, Kouskoff V, Kennedy M, Woo S, Fehling HJ, Keller G.

The Carl C. Icahn Center for Gene Therapy and Molecular Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA.

The cellular and molecular events regulating the induction and tissue-specific differentiation of endoderm are central to our understanding of the development and function of many organ systems. To define and characterize key components in this process, we have investigated the potential of embryonic stem (ES) cells to generate endoderm following their differentiation to embryoid bodies (EBs) in culture. We found that endoderm can be induced in EBs, either by limited exposure to serum or by culturing in the presence of activin A (activin) under serum-free conditions. By using an ES cell line with the green fluorescent protein (GFP) cDNA targeted to the brachyury locus, we demonstrate that endoderm develops from a brachyury(+) population that also displays mesoderm potential. Transplantation of cells generated from activin-induced brachyury(+) cells to the kidney capsule of recipient mice resulted in the development of endoderm-derived structures. These findings demonstrate that ES cells can generate endoderm in culture and, as such, establish this differentiation system as a unique murine model for studying the development and specification of this germ layer.

PMID: 14998924 [PubMed - indexed for MEDLINE]

30. EMBO Rep. 2004 Jan;5(1):78-84.

Vegfc is required for vascular development and endoderm morphogenesis in zebrafish.

Ober EA, Olofsson B, M√§kinen T, Jin SW, Shoji W, Koh GY, Alitalo K, Stainier DY.

Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics and Human Genetics, University of California, San Francisco, California 94143-0448, USA.

During embryogenesis, complex morphogenetic events lead endodermal cells to coalesce at the midline and form the primitive gut tube and associated organs. While several genes have recently been implicated in endoderm differentiation, we know little about the genes that regulate endodermal morphogenesis. Here, we show that vascular endothelial growth factor C (Vegfc), an angiogenic as well as a lymphangiogenic factor, is unexpectedly involved in this process in zebrafish. Reducing Vegfc levels using morpholino antisense oligonucleotides, or through overexpression of a soluble form of the VEGFC receptor, VEGFR-3, affects the coalescence of endodermal cells in the anterior midline, leading to the formation of a forked gut tube and the duplication of the liver and pancreatic buds. Further analyses indicate that Vegfc is additionally required for the initial formation of the dorsal endoderm. We also demonstrate that Vegfc is required for vasculogenesis as well as angiogenesis in the zebrafish embryo. These data argue for a requirement of Vegfc in the developing vasculature and, more surprisingly, implicate Vegfc signalling in two distinct steps during endoderm development, first during the initial differentiation of the dorsal endoderm, and second in the coalescence of the anterior endoderm to the midline.

PMCID: PMC1298958 PMID: 14710191 [PubMed - indexed for MEDLINE]

31. Anat Embryol (Berl). 2003 Dec;207(4-5):283-8. Epub 2003 Nov 25.

Loss of beta1-integrin-deficient cells during the development of endoderm-derived epithelia.

Berger TM, Hirsch E, Djonov V, Schittny JC.

Institute of Anatomy, University of Bern, Buehlstrasse 26, 3000 Bern 9, Switzerland.

Beta1-integrins (beta1) represent cell surface receptors which mediate cell-matrix and cell-cell interactions. F√§ssler and Meyer described chimeric mice containing transgenic cells that express the LacZ gene instead of the beta1 gene. They observed beta1-negative cells in all germ layers at embryonic day E 8.5. Later in development, using a glucose phosphate isomerase assay of homogenized tissue samples, high levels of transgenic cells were found in skeletal muscle and gut, low levels in lung, heart, and kidney and none in the liver and spleen (F√§ssler and Meyer 1995). In order to study which cell types require beta1 during development of the primitive gut including its derivatives, chimeric fetuses containing 15 to 25% transgenic cells were obtained at days E 14.5 and E 15.5. They were LacZ (beta-galactosidase) stained "en bloc" and cross-sectioned head to tail. In esophagus, trachea, lung, stomach, hindgut, and the future urinary bladder, we observed various mesoderm-derived beta1-negative cells (e.g. fibroblasts, chondrocytes, endothelial cells, and smooth muscle cells) but no beta1-negative epithelial cells. Since the epithelia of lung, esophagus, trachea, stomach, hindgut, and urinary bladder are derived from the endodermal gut tube, we hypothesize that beta1 is essential for the development and/or survival of the epithelia of the fore- and hindgut and its derivatives.

PMID: 14648219 [PubMed - indexed for MEDLINE]

32. Development. 2003 Dec;130(25):6361-74.

Ablation of specific expression domains reveals discrete functions of ectoderm- and endoderm-derived FGF8 during cardiovascular and pharyngeal development.

Macatee TL, Hammond BP, Arenkiel BR, Francis L, Frank DU, Moon AM.

Program in Human Molecular Biology and Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.

Fibroblast growth factor 8 (Fgf8) is expressed in many domains of the developing embryo. Globally decreased FGF8 signaling during murine embryogenesis results in a hypomorphic phenotype with a constellation of heart, outflow tract, great vessel and pharyngeal gland defects that phenocopies human deletion 22q11 syndromes, such as DiGeorge. We postulate that these Fgf8 hypomorphic phenotypes result from disruption of local FGF8 signaling from pharyngeal arch epithelia to mesenchymal cells populating and migrating through the third and fourth pharyngeal arches. To test our hypothesis, and to determine whether the pharyngeal ectoderm and endoderm Fgf8 expression domains have discrete functional roles, we performed conditional mutagenesis of Fgf8 using novel Crerecombinase drivers to achieve domain-specific ablation of Fgf8 gene function in the pharyngeal arch ectoderm and endoderm. Remarkably, ablating FGF8 protein in the pharyngeal arch ectoderm causes failure of formation of the fourth pharyngeal arch artery that results in aortic arch and subclavian artery anomalies in 95% of mutants; these defects recapitulate the spectrum and frequency of vascular defects reported in Fgf8 hypomorphs. Surprisingly, no cardiac, outflow tract or glandular defects were found in ectodermal-domain mutants, indicating that ectodermally derived FGF8 has essential roles during pharyngeal arch vascular development distinct from those in cardiac, outflow tract and pharyngeal gland morphogenesis. By contrast, ablation of FGF8 in the third and fourth pharyngeal endoderm and ectoderm caused glandular defects and bicuspid aortic valve, which indicates that the FGF8 endodermal domain has discrete roles in pharyngeal and valvar development. These results support our hypotheses that local FGF8 signaling from the pharyngeal epithelia is required for pharyngeal vascular and glandular development, and that the pharyngeal ectodermal and endodermal domains of FGF8 have separate functions.

PMCID: PMC1876660 PMID: 14623825 [PubMed - indexed for MEDLINE]

33. Mech Dev. 2003 Oct;120(10):1165-76.

Expression and function of a starfish Otx ortholog, AmOtx: a conserved role for Otx proteins in endoderm development that predates divergence of the eleutherozoa.

Hinman VF, Nguyen AT, Davidson EH.

Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA.

The sea urchin orthodenticle (Otx)-related transcription factor is an early activator of other endomesodermally expressed transcription factors. Its normal function is required for the development of the archenteron and to lock cells into endomesodermal fate. To determine if this is a basal Otx function in echinoderms we have studied the role of an Otx ortholog in a starfish, Asterina miniata. The patterns of AmOtx expression are found to be similar, in many details, to those reported for other indirectly developing echinoderms and hemichordates, suggestive of a conserved function both in endoderm development and ciliary band formation in these two phyla. When downstream targets of the AmOtx protein are suppressed using a dominant engrailed repressor strategy, embryos fail to develop the endodermal component of the archenteron, though initial phases of mesoderm development proceed normally. The function of Otx proteins in endodermal development at least predated the evolution of the free-living echinoderms (Eleutherozoa).

PMID: 14568105 [PubMed - indexed for MEDLINE]

34. Gene Expr Patterns. 2003 Oct;3(5):681-4.

The mouse secreted frizzled-related protein 5 gene is expressed in the anterior visceral endoderm and foregut endoderm during early post-implantation development.

Finley KR, Tennessen J, Shawlot W.

Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA.

The anterior visceral endoderm (AVE) plays an important role in anterior-posterior axis formation in the mouse. The AVE functions in part by expressing secreted factors that antagonize growth factor signaling in the proximal epiblast. Here we report that the Secreted frizzled-related protein 5 (Sfrp5) gene, which encodes a secreted factor that can antagonize Wnt signaling, is expressed in the AVE and foregut endoderm during early mouse development. At embryonic day (E) 5.5, Sfrp5 is expressed in the visceral endoderm at the distal tip region of the embryo and at E6.5 in the AVE opposite the primitive streak. In Lim1 embryos, which lack anterior neural tissue and sometimes form a secondary body axis, Sfrp5-expressing cells fail to move towards the anterior and remain at the distal tip of E6.5 embryos. When compared with Dkk1, which encodes another secreted Wnt antagonist molecule present in the visceral endoderm, Sfrp5 and Dkk1 expression overlap but Sfrp5 is expressed more broadly in the AVE. Between E7.5 and 8, Sfrp5 is expressed in the foregut endoderm underlying the cardiac mesoderm. At E8.5, Sfrp5 is expressed in the ventral foregut endoderm that gives rise to the liver. Additional domains of Sfrp5 expression occur in the dorsal neural tube and in the forebrain anterior to the optic placode. These findings identify a gene encoding a secreted Wnt antagonist that is expressed in the extraembryonic visceral endoderm and anterior definitive endoderm during axis formation and organogenesis in the mouse.

PMID: 12972006 [PubMed - indexed for MEDLINE]

35. Curr Opin Genet Dev. 2003 Aug;13(4):393-400.

Early endoderm development in vertebrates: lineage differentiation and morphogenetic function.

Tam PP, Kanai-Azuma M, Kanai Y.

Embryology Unit, Children's Medical Research Institute, Locked Bag 23, Wentworthville, New South Wales 2145, Australia. ptam@cmri.usyd.edu.au

Gastrulation of the vertebrate embryo culminates in the formation of three primary germ layers: ectoderm, mesoderm and endoderm. The endoderm contributes to the lining of the gut and the associated organs. New components of the molecular pathway for endoderm specification have been identified in the zebrafish and Xenopus. In the mouse, the activity of orthologous factors is involved with the allocation and differentiation of the definitive endoderm. Morphogenetic interactions between the endoderm and the other germ layer derivatives are critical for the morphogenesis of head structures and organogenesis of gut derivatives.

PMID: 12888013 [PubMed - indexed for MEDLINE]

36. Genesis. 2003 May;36(1):40-7.

Paracrine action of FGF4 during periimplantation development maintains trophectoderm and primitive endoderm.

Goldin SN, Papaioannou VE.

FGF4, a member of the fibroblast growth factor (FGF) family, is absolutely required for periimplantation mouse development, although its precise role at this stage remains unknown. The nature of the defect leading to postimplantation lethality of embryos lacking zygotic FGF4 is unclear and little is known about downstream targets of FGF4-initiated signaling within the various cellular compartments of the blastocyst. Here we report that postimplantation lethality of Fgf4(-/-) embryos is unlikely to reflect strictly mitogenic requirements for FGF4. Rather, our results suggest that FGF4 is required to maintain trophectoderm and primitive endoderm identity at embryonic day 4.5. This result is consistent with the reported in vitro activity of FGF4 in maintaining trophoblast stem cells and with the requirement for receptor tyrosine kinase signaling in primitive endoderm formation. Thus, postimplantation lethality of Fgf4(-/-) embryos likely results from the failure of proper differentiation and function of extraembryonic cell types. Copyright 2003 Wiley-Liss, Inc.

PMID: 12748966 [PubMed - indexed for MEDLINE]

37. Gene Expr Patterns. 2003 May;3(2):147-52.

Darmin is a novel secreted protein expressed during endoderm development in Xenopus.

Pera EM, Martinez SL, Flanagan JJ, Brechner M, Wessely O, De Robertis EM.

Howard Hughes Medical Institute and Department of Biological Chemistry, University of California, Los Angeles, CA 90095-1662, USA.

Endoderm development is an area of intense interest in developmental biology, but progress has been hampered by the lack of specific markers for differentiated endodermal cells. In an unbiased secretion cloning screen of Xenopus gastrula embryos we isolated a novel gene, designated Darmin. Darmin encodes a secreted protein of 56 kDa containing a peptidase M20 domain characteristic of the glutamate carboxypeptidase group of zinc metalloproteases. We also identified homologous Darmin genes in other eukaryotes and in prokaryotes suggesting that Darmin is the founding member of a family of evolutionarily conserved proteins. Xenopus Darmin showed zygotic expression in the early endoderm and later became restricted to the midgut. By secretion cloning of Xenopus cleavage-stage embryos we isolated another novel protein, designated Darmin-related (Darmin-r) due to its sequence similarity with Darmin. Darmin-r was maternally expressed and showed at later stages expression in the lens and pronephric glomus. The endoderm-specific expression of Darmin makes this gene a useful marker for the study of endoderm development.

PMID: 12711541 [PubMed - indexed for MEDLINE]

38. Mech Dev. 2003 Mar;120(3):337-48.

Redundant early and overlapping larval roles of Xsox17 subgroup genes in Xenopus endoderm development.

Clements D, Cameleyre I, Woodland HR.

Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.

We have used antisense morpholino oligos to establish the developmental roles of three Xsox17 proteins in Xenopus development (Xsox17alpha(1), alpha(2) and beta). We show that their synthesis can be inhibited with modest amounts of oligo. The inhibition of each individually produces defects in late midgut development. Loss of activity of the Xsox17alpha proteins additionally inhibits hindgut formation, and inhibiting Xsox17alpha(1) disrupts foregut development with variable penetrance. When all Xsox17 activity is inhibited cell movements are halted during late gastrulation and the transcription of several endodermally expressed genes is reduced. Thus the Xsox17 proteins have redundant roles in early development of the endoderm and partly distinct roles during later organogenesis.

PMID: 12591603 [PubMed - indexed for MEDLINE]

39. Mech Dev. 2003 Jan;120(1):5-18.

From endoderm formation to liver and pancreas development in zebrafish.

Ober EA, Field HA, Stainier DY.

Department of Biochemistry and Biophysics, Programs in Developmental Biology, Genetics and Human Genetics, University of California, San Francisco, CA 94143-0448, USA.

Recent studies in zebrafish have contributed to our understanding of early endoderm formation in vertebrates. Specifically, they have illustrated the importance of Nodal signaling as well as three transcription factors, Faust/Gata5, Bonnie and Clyde, and Casanova, in this process. Ongoing genetic and embryological studies in zebrafish are also contributing to our understanding of later aspects of endoderm development, including the formation of the gut and its associated organs, the liver and pancreas. The generation of transgenic lines expressing GFP in these organs promises to be particularly helpful in such studies.

PMID: 12490292 [PubMed - indexed for MEDLINE]

40. Dev Biol. 2002 Sep 15;249(2):191-203.

Molecular regulation of vertebrate early endoderm development.

Shivdasani RA.

Department of Adult Oncology and Cancer Biology, Dana-Faber Cancer Institute, Boston, MA 02115, USA. ramesh_shivdasani@dcfi.harvard.edu

Detailed study of the ectoderm and mesoderm has led to increasingly refined understanding of molecular mechanisms that operate early in development to generate cellular diversity. More recently, a number of powerful studies have begun to characterize the molecular determinants of the endoderm, a germ layer previously neglected in developmental biology. Work in diverse model systems has converged on an integrated transcriptional and signaling pathway that serves to establish the vertebrate endoderm. A T-box transcription factor identified in Xenopus embryos, VegT, appears to function near the top of an endoderm-specifying transcriptional hierarchy. VegT activates and reinforces Nodal-related TGFbeta signaling and also induces expression of essential downstream transcriptional regulators, Mix-like paired-homeodomain and GATA factors. These proteins cooperate to regulate expression of a relay of HMG-box Sox-family transcription factors culminating with Sox 17, which may be an obligate mediator of vertebrate endoderm development. This review synthesizes findings in three vertebrate model organisms and discusses these genetic interactions in the context of the progressive acquisition of endodermal identity early in vertebrate development.

PMID: 12221001 [PubMed - indexed for MEDLINE]

41. Dev Dyn. 2002 Aug;224(4):450-6.

Distribution of the titf2/foxe1 gene product is consistent with an important role in the development of foregut endoderm, palate, and hair.

Dathan N, Parlato R, Rosica A, De Felice M, Di Lauro R.

Centro di Studi di Biocristallografia del CNR, via Mezzocannone, Naples, Italy.

Titf2/foxe1 is a forkhead domain-containing gene expressed in the foregut, in the thyroid, and in the cranial ectoderm of the developing mouse. Titf2 null mice exhibit cleft palate and either a sublingual or completely absent thyroid gland. In humans, mutations of the gene encoding for thyroid transcription factor-2 (TTF-2) result in the Bamforth syndrome, characterized by thyroid agenesis, cleft palate, spiky hair, and choanal atresia. Here, we report a detailed expression pattern of TTF-2 protein during mouse embryogenesis and show its presence in structures where it has not been described yet. At embryonic day (E) 10.5, TTF-2 is expressed in Rathke's pouch, in thyroid, and in the epithelium of the pharyngeal wall and arches, whereas it is absent in the epithelium of the pharyngeal pouches. According to this expression, at E13.5, TTF-2 is present in endoderm derivatives, such as tongue, palate, epiglottis, pharynx, and oesophagus. Later in embryogenesis, we detect TTF-2 in the choanae and whiskers. This pattern of expression helps to define the complex phenotype displayed by human patients. Finally, we show that TTF-2 is a phosphorylated protein. These results help to characterize the domains of TTF-2 expression, from early embryogenesis throughout organogenesis, providing more detail on the potential role of TTF-2 in the development of endoderm and ectoderm derived structures. Copyright 2002 Wiley-Liss, Inc.

PMID: 12203737 [PubMed - indexed for MEDLINE]

42. Development. 2002 Feb;129(3):551-61.

Tail gut endoderm and gut/genitourinary/tail development: a new tissue-specific role for Hoxa13.

de Santa Barbara P, Roberts DJ.

Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.

Hoxa13 is expressed early in the caudal mesoderm and endoderm of the developing hindgut. The tissue-specific roles of Hoxa13 function have not been described. Hand-foot-genital syndrome, a rare dominantly inherited human malformation syndrome characterized by distal extremity and genitourinary anomalies, is caused by mutations in the HOXA13 gene. We show evidence that one specific HOXA13 mutation likely acts as a dominant negative in vivo. When chick HFGa13 is overexpressed in the chick caudal endoderm early in development, caudal structural malformations occur. The phenotype is specific to HFGa13 expression in the posterior endoderm, and includes taillessness and severe gut/genitourinary (GGU) malformations. Finally, we show that chick HFGa13 negatively regulates expression of Hoxd13 and antagonizes functions of both endogenous Hoxa13 and Hoxd13 proteins. We suggest a fundamental role for epithelial specific expression of Hoxa13 in the epithelial-mesenchymal interaction necessary for tail growth and posterior GGU patterning.

PMCID: PMC2435615 PMID: 11830557 [PubMed - indexed for MEDLINE]

43. Dev Dyn. 2002 Jan;223(1):33-47.

Pre-gut endoderm of chick embryos is regionalized by 1.5 days of development.

Matsushita S, Ishii Y, Scotting PJ, Kuroiwa A, Yasugi S.

Department of Biology, School of Medicine, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan. matsus@research.twmu.ac.jp

In this study, we set out to test the ability of endoderm from 1.5-day-old chick embryos (just before digestive tube formation) to develop region-specific characteristics when cultured heterotopically. Various parts of the 1.5-day endoderm were cultured in combination with the flank somatic mesoderm of 3- to 3.5-day chick embryos, and these cultures were analyzed for the expression of several transcription factors and the differentiation of the endoderm. By 1.5 days of normal development, the transcription factors, which are expressed in specific digestive organs, cSox2, CdxA, and cHoxb9/a13 were already expressed in the endodermal cells of the presumptive areas of their later expression domains. When 1.5-day pre-gut endoderm was cultured for 14-15 days, it showed specific differentiation into appropriate organ structures. In general, the more anterior part of the pre-gut endoderm formed the more rostral digestive organ structures while the posterior part became the caudal gut. The differentiation of these regions of endoderm matches their normal fate as recently elucidated (Matsushita [1996a] Rouxs Arch. Dev. Biol. 205:225-231; Matsushita [1999] Dev. Growth Differ. 41:313-319). Expression of cSox2, CdxA, and cHoxb9/a13 in endoderm cultured for 4-5 days is also consistent with their normal fate. Thus, each part of the pre-gut endoderm appears to be already regionally committed to some extent, in accordance with its fate by 1.5 days of development. Copyright 2001 Wiley-Liss, Inc.

PMID: 11803568 [PubMed - indexed for MEDLINE]

44. Science. 2001 Oct 19;294(5542):530-1. Epub 2001 Sep 27.

Development. Endothelium--chicken soup for the endoderm.

Bahary N, Zon LI.

Department of Adult Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.

Comment on:

   Science. 2001 Oct 19;294(5542):559-63.
   Science. 2001 Oct 19;294(5542):564-7.

Endothelial cells in blood vessels are known to be important during the later stages of organ development in the embryo. However, their involvement at the induction stage of organ formation has not been previously documented. As Bahary and Zon explain in their Perspective, new work demonstrates that endothelial cells secrete factors early in development that induce embryonic endoderm to become liver or pancreas (Matsumoto et al., Lammert et al.).

PMID: 11577202 [PubMed - indexed for MEDLINE]

45. EMBO J. 2001 Mar 1;20(5):1114-22.

The transcription factors MTF-1 and USF1 cooperate to regulate mouse metallothionein-I expression in response to the essential metal zinc in visceral endoderm cells during early development.

Andrews GK, Lee DK, Ravindra R, Lichtlen P, Sirito M, Sawadogo M, Schaffner W.

Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7421, USA. gandrews@kumc.edu

During early development of the mouse embryo, expression of the metallothionein-I (MT-I) gene is heightened specifically in the endoderm cells of the visceral yolk sac. The mechanisms of regulation of this cell-specific pattern of expression of metallothionein-I are unknown. However, it has recently been shown that MTF-1, functioning as a metalloregulatory transcription factor, activates metallothionein genes in response to the essential metal zinc. In contrast with the metallothionein genes, MTF-1 is essential for development; null mutant embryos die due to liver degeneration. We report here that MTF-1 is absolutely essential for upregulation of MT-I gene expression in visceral endoderm cells and that optimal expression also involves interactions of the basic helix-loop-helix upstream stimulatory factor-1 (USF1) with an E-box1-containing sequence at -223 bp in the MT-I promoter. Expression of MT-I in visceral endoderm cells was dependent on maternal dietary zinc. Thus, the essential metal, zinc, apparently provides the signaling ligand that activates cell-specific MT-I expression in visceral endoderm cells.

PMCID: PMC145491 PMID: 11230134 [PubMed - indexed for MEDLINE]

46. Zygote. 2000;8 Suppl 1:S35-6.

Gene expression in the endoderm during sea urchin development.

Livingston B, David ES, Thurm C.

School of Biological Sciences, University of Missouri-Kansas City, 64110, USA.

PMID: 11191300 [PubMed - indexed for MEDLINE]

47. Dev Biol. 2000 Sep 15;225(2):304-21.

Visceral endoderm mediates forebrain development by suppressing posteriorizing signals.

Kimura C, Yoshinaga K, Tian E, Suzuki M, Aizawa S, Matsuo I.

Department of Morphogenesis, Institute of Molecular Embryology and Genetics, Kumamoto University, Honjo 2-2-1, Kumamoto, 860-0811, Japan.

The anterior visceral endoderm (AVE) has attracted recent attention as a critical player in mouse forebrain development and has been proposed to act as "head organizer" in mammals. However, the precise role of the AVE in induction and patterning of the anterior neuroectoderm is not yet known. Here we identified a 5'-flanking region of the mouse Otx2 gene (VEcis) that governs the transgene expression in the visceral endoderm. In transgenic embryos, VEcis-active cells were found in the distal visceral endoderm at 5.5 days postcoitus (dpc), had begun to move anteriorly at 5.75 dpc, and then became restricted to the AVE prior to gastrulation. The VEcis-active visceral endoderm cells exhibited ectodermal morphology distinct from that of the other endoderm cells and consisted of two cell layers at 5.75 dpc. In the Otx2(-/-) background, the VEcis-active endoderm cells remained distal even at 6.5 dpc when a primitive streak was formed; anterior definitive endoderm was not formed nor were any markers of anterior neuroectoderm ever induced. The Otx2 cDNA transgene under the control of the VEcis restored these Otx2(-/-) defects, demonstrating that Otx2 is essential to the anterior movement of distal visceral endoderm cells. In germ-layer explant assays between ectoderm and visceral endoderm, the AVE did not induce anterior neuroectoderm markers, but instead suppressed posterior markers in the ectoderm; Otx2(-/-) visceral endoderm lacked this activity. Thus Otx2 is also essential for the AVE to repress the posterior character. These results suggest that distal visceral endoderm cells move to the future anterior side to generate a prospective forebrain territory indirectly, by preventing posteriorizing signals. Copyright 2000 Academic Press.

PMID: 10985852 [PubMed - indexed for MEDLINE]

48. Dev Dyn. 2000 Sep;219(1):84-9.

Hex expression suggests a role in the development and function of organs derived from foregut endoderm.

Bogue CW, Ganea GR, Sturm E, Ianucci R, Jacobs HC.

Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut 06520-8064, USA. clifford.bogue@yale.edu

Hex is a divergent homeobox gene expressed as early as E4.5 in the mouse and in a pattern that suggests a role in anterior-posterior patterning. Later in embryogenesis, Hex is expressed in the developing thyroid, lung, and liver. We now show Hex expression during thymus, gallbladder, and pancreas development and in the adult thyroid, lung, and liver. At E10.0, Hex is expressed in the 3rd pharyngeal pouch, from which the thymus originates, the endodermal cells of liver that are invading the septum transversum, the thyroid, the dorsal pancreatic bud, and gallbladder primoridum. At E13.5, expression is maintained at high levels in the thyroid, liver, epithelial cells lining the pancreatic and extrahepatic biliary ducts and is present in both the epithelial and mesenchymal cells of the lung. Expression in the thymus at this age is less than in the other organs. In the E16.5 embryo, expression persists in the thyroid, pancreatic, and bile duct epithelium, lung, and liver, with thymic expression dropping to barely detectable levels. By E18.5, expression in the thyroid and bile ducts remains high, whereas lung expression is markedly decreased. At this age, expression in the pancreas and thymus is no longer present. Finally, we show the cell types in the adult thyroid, lung, and liver that express Hex in the mature animal. Our results provide more detail on the potential role of Hex in the development of several organs derived from foregut endoderm and in the maintenance of function of several of these organs in the mature animal. Copyright 2000 Wiley-Liss, Inc.

PMID: 10974674 [PubMed - indexed for MEDLINE]

49. Development. 2000 Jul;127(13):2795-809.

Development of chick axial mesoderm: specification of prechordal mesoderm by anterior endoderm-derived TGFbeta family signalling.

Vesque C, Ellis S, Lee A, Szabo M, Thomas P, Beddington R, Placzek M.

Developmental Genetics Programme, Krebs Institute, Firth Court, Sheffield S10 2TN, UK. m.placzek@sheffield.ac.uk

Two populations of axial mesoderm cells can be recognised in the chick embryo, posterior notochord and anterior prechordal mesoderm. We have examined the cellular and molecular events that govern the specification of prechordal mesoderm. We report that notochord and prechordal mesoderm cells are intermingled and share expression of many markers as they initially extend out of Hensen's node. In vitro culture studies, together with in vivo grafting experiments, reveal that early extending axial mesoderm cells are labile and that their character may be defined subsequently through signals that derive from anterior endodermal tissues. Anterior endoderm elicits aspects of prechordal mesoderm identity in extending axial mesoderm by repressing notochord characteristics, briefly maintaining gsc expression and inducing BMP7 expression. Together these experiments suggest that, in vivo, signalling by anterior endoderm may determine the extent of prechordal mesoderm. The transforming growth factor (beta) (TGFbeta) superfamily members BMP2, BMP4, BMP7 and activin, all of which are transiently expressed in anterior endoderm mimic distinct aspects of its patterning actions. Together our results suggest that anterior endoderm-derived TGFbetas may specify prechordal mesoderm character in chick axial mesoderm.

PMID: 10851126 [PubMed - indexed for MEDLINE]

50. Dev Dyn. 2000 Apr;217(4):327-42.

Endoderm and heart development.

Lough J, Sugi Y.

Department of Cell Biology, Neurobiology, and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA. jlough@mcw.edu

Since the first half of the 20th century, experimental embryologists have noted a relationship between endoderm cells and the development of cardiac tissue from mesoderm. During the past decade, the accumulation of evidence for an obligatory interaction between endoderm and mesoderm during the specification and terminal differentiation of myocardial, and more recently endocardial, cells has markedly accelerated. Moreover, the endoderm-derived molecules that may regulate these processes are being identified. It now appears that endoderm-derived growth factors regulate the formation of both myocardial and endocardial cells during specification, terminal differentiation, and perhaps morphogenesis of cells in the developing embryonic heart.

PMID: 10767078 [PubMed - indexed for MEDLINE]

51. Proc Natl Acad Sci U S A. 2000 Apr 11;97(8):4076-81.

Action of the Caenorhabditis elegans GATA factor END-1 in Xenopus suggests that similar mechanisms initiate endoderm development in ecdysozoa and vertebrates.

Shoichet SA, Malik TH, Rothman JH, Shivdasani RA.

Department of Adult Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.

In ecdysozoan protostomes, including arthropods and nematodes, transcription factors of the GATA family specify the endoderm: Drosophila dGATAb (ABF/Serpent) and Caenorhabditis elegans END-1 play important roles in generating this primary germ layer. end-1 is the earliest expressed endoderm-specific gene known in C. elegans and appears to initiate the program of gene expression required for endoderm differentiation, including a cascade of GATA factors required for development and maintenance of the intestine. Among vertebrate GATA proteins, the GATA-4/5/6 subfamily regulates aspects of late endoderm development, but a role for GATA factors in establishing the endoderm is unknown. We show here that END-1 binds to the canonical target DNA sequence WGATAR with specificity similar to that of vertebrate GATA-1 and GATA-4, and that it functions as a transcriptional activator. We exploited this activity of END-1 to demonstrate that establishment of the vertebrate endoderm, like that of invertebrate species, also appears to involve GATA transcriptional activity. Like the known vertebrate endoderm regulators Mixer and Sox17, END-1 is a potent activator of endoderm differentiation in isolated Xenopus ectoderm. Moreover, a dominant inhibitory GATA-binding fusion protein abrogates endoderm differentiation in intact embryos. By examining these effects in conjunction with those of Mixer- and Sox17beta-activating and dominant inhibitory constructs, we further establish the likely relationships between GATA activity and these regulators in early development of the vertebrate endoderm. These results suggest that GATA factors may function sequentially to regulate endoderm differentiation in both protostomes and deuterostomes.

PMCID: PMC18153 PMID: 10760276 [PubMed - indexed for MEDLINE]

52. Trends Genet. 2000 Mar;16(3):124-30.

Endoderm development: from patterning to organogenesis.

Grapin-Botton A, Melton DA.

Department of Molecular and Cellular Biology, and Howard Hughes Medical Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA. grapin@fas.harvard.edu

Although the ectoderm and mesoderm have been the focus of intensive work in the recent era of studies on the molecular control of vertebrate development, the endoderm has received less attention. Because signaling must occur between germ layers in order to achieve a properly organized body, our understanding of the coordinated development of all organs requires a more thorough consideration of the endoderm and its derivatives. This review focuses on present knowledge and perspectives concerning endoderm patterning and organogenesis. Some of the classical embryology of the endoderm is discussed and the progress and deficiencies in cellular and molecular studies are noted.

PMID: 10689353 [PubMed - indexed for MEDLINE]

53. Int J Dev Biol. 1999;43(7):605-13.

Pieter Nieuwkoop's contributions to the understanding of meso-endoderm induction and neural induction in chordate development.

Gerhart J.

Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA. gerhart@socrates.berkeley.edu

Pieter Nieuwkoop, who died September 18, 1996, at age 79 in Utrecht, The Netherlands, is remembered by developmental biologists for his numerous research contributions and integrative hypotheses over the past 50 years, especially in the areas of neural induction, meso-endoderm induction, and germ cell induction in chordates. Most of his experimentation was done on the embryos of amphibia, the preferred vertebrate embryo of the early years of the 20th century. One of his last publications contains a comparison of the experimental advantages and disadvantages of anuran and urodele amphibians (Nieuwkoop, 1996). The significance of his findings and interpretations for developmental biology can be estimated from the fact that researchers of many laboratories worldwide continue to work on the phenomena he first described and to extend the hypotheses he first formulated. The aim of this article is to review Nieuwkoop's main contributions and to cite the recent extensions by others.

PMID: 10668970 [PubMed - indexed for MEDLINE]

54. Development. 2000 Feb;127(4):869-79.

Endoderm patterning by the notochord: development of the hypochord in Xenopus.

Cleaver O, Seufert DW, Krieg PA.

Division of Molecular Cell and Developmental Biology, School of Biological Sciences, University of Texas at Austin, Austin, TX 78712, USA.

The patterning and differentiation of the vertebrate endoderm requires signaling from adjacent tissues. In this report, we demonstrate that signals from the notochord are critical for the development of the hypochord, which is a transient, endodermally derived structure that lies immediately ventral to the notochord in the amphibian and fish embryo. It appears likely that the hypochord is required for the formation of the dorsal aorta in these organisms. We show that removal of the notochord during early neurulation leads to the complete failure of hypochord development and to the elimination of expression of the hypochord marker, VEGF. Removal of the notochord during late neurulation, however, does not interfere with hypochord formation. These results suggest that signals arising in the notochord instruct cells in the underlying endoderm to take on a hypochord fate during early neural stages, and that the hypochord does not depend on further notochord signals for maintenance. In reciprocal experiments, when the endoderm receives excess notochord signaling, a significantly enlarged hypochord develops. Overall, these results demonstrate that, in addition to patterning neural and mesodermal tissues, the notochord plays an important role in patterning of the endoderm.

PMID: 10648245 [PubMed - indexed for MEDLINE]

55. Annu Rev Cell Dev Biol. 1999;15:393-410.

Vertebrate endoderm development.

Wells JM, Melton DA.

Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA. wells@biohp.harvard.edu

Endoderm, one of the three principal germ layers, contributes to all organs of the alimentary tract. For simplicity, this review divides formation of endodermal organs into four fundamental steps: (a) formation of endoderm during gastrulation, (b) morphogenesis of a gut tube from a sheet of cells, (c) budding of organ domains from the tube, and (d) differentiation of organ-specific cell types within the growing buds. We discuss possible mechanisms that regulate how undifferentiated endoderm becomes specified into a myriad of cell types that populate the respiratory and gastrointestinal tracts.

PMID: 10611967 [PubMed - indexed for MEDLINE]

56. Genes Dev. 1999 Nov 15;13(22):2983-95.

Gata5 is required for the development of the heart and endoderm in zebrafish.

Reiter JF, Alexander J, Rodaway A, Yelon D, Patient R, Holder N, Stainier DY.

Department of Biochemistry and Biophysics, Programs in Human Genetics and Developmental Biology, University of California at San Francisco, San Francisco, California 94143-0448 USA.

The mechanisms regulating vertebrate heart and endoderm development have recently become the focus of intense study. Here we present evidence from both loss- and gain-of-function experiments that the zinc finger transcription factor Gata5 is an essential regulator of multiple aspects of heart and endoderm development. We demonstrate that zebrafish Gata5 is encoded by the faust locus. Analysis of faust mutants indicates that early in embryogenesis Gata5 is required for the production of normal numbers of developing myocardial precursors and the expression of normal levels of several myocardial genes including nkx2.5. Later, Gata5 is necessary for the elaboration of ventricular tissue. We further demonstrate that Gata5 is required for the migration of the cardiac primordia to the embryonic midline and for endodermal morphogenesis. Significantly, overexpression of gata5 induces the ectopic expression of several myocardial genes including nkx2.5 and can produce ectopic foci of beating myocardial tissue. Together, these results implicate zebrafish Gata5 in controlling the growth, morphogenesis, and differentiation of the heart and endoderm and indicate that Gata5 regulates the expression of the early myocardial gene nkx2.5.

PMCID: PMC317161 PMID: 10580005 [PubMed - indexed for MEDLINE]

57. Curr Biol. 1999 Nov 4;9(21):R812-5.

Vertebrate development: Multiple phases to endoderm formation.

Dale L.

Department of Anatomy and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK. l.dale@ucl.ac.uk

Recent results support a two-step model for endoderm formation in amphibian embryos, in which endoderm is initially specified by localised maternal factors, including the transcription factor VegT, but is then maintained by extracellular signalling molecules of the transforming growth factor-beta family.

PMID: 10556077 [PubMed - indexed for MEDLINE]

58. Development. 1999 Nov;126(22):5149-59.

Expression and functional analysis of Cititf1, an ascidian NK-2 class gene, suggest its role in endoderm development.

Ristoratore F, Spagnuolo A, Aniello F, Branno M, Fabbrini F, Di Lauro R.

Laboratory of Biochemistry and Molecular Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Italy.

In solitary ascidians the fate of endoderm is determined at a very early stage of development and depends on cytoplasmic factors whose nature has not been determined. We have isolated a member of the NK-2 gene family, Cititf1, from the ascidian Ciona intestinalis, showing high sequence homology to mammalian TITF1. The Cititf1 gene was expressed in all endodermal precursors at the pregastrula and gastrula stages, and is thus the first specific regulatory endodermal marker to be isolated from an ascidian. Cititf1 expression was downregulated at the end of gastrulation to reappear at middle tailbud and larval stages in the most anterior and ventral parts of head endoderm, regions which give rise, after metamorphosis, to the adult endostyle, where Cititf1 mRNA was still present. Microinjection of Cititf1 mRNA into fertilized eggs resulted in tadpole larvae with abnormalities in head-trunk development consequent to the formation of excess endoderm, perhaps due to recruitment of notochord precursors to an endodermal fate. These data suggest that Cititf1 plays an important role in normal endoderm differentiation during ascidian embryogenesis.

PMID: 10529431 [PubMed - indexed for MEDLINE]

59. Development. 1999 Oct;126(19):4193-200.

Bix4 is activated directly by VegT and mediates endoderm formation in Xenopus development.

Casey ES, Tada M, Fairclough L, Wylie CC, Heasman J, Smith JC.

Division of Developmental Biology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK. jim@nimr.mrc. ac.uk

The maternal T-box gene VegT, whose transcripts are restricted to the vegetal hemisphere of the Xenopus embryo, plays an essential role in early development. Depletion of maternal VegT transcripts causes embryos to develop with no endoderm, while vegetal blastomeres lose the ability to induce mesoderm (Zhang, J., Houston, D. W., King, M. L., Payne, C., Wylie, C. and Heasman, J. (1998) Cell 94, 515-524). The targets of VegT, a transcription activator, must therefore include genes involved both in the specification of endoderm and in the production of mesoderm-inducing signals. We recently reported that the upstream regulatory region of the homeobox-containing gene Bix4 contains T-box binding sites. Here we show that expression of Bix4 requires maternal VegT and that two T-box binding sites are necessary and sufficient for mesodermal and endodermal expression of reporter genes driven by the Bix4 promoter in transgenic Xenopus embryos. Remarkably, a single T-box binding site is able to act as a mesoderm-specific enhancer when placed upstream of a minimal promoter. Finally, we show that Bix4 rescues the formation of endodermal markers in embryos in which VegT transcripts have been ablated but does not restore the ability of vegetal pole blastomeres to induce mesoderm. These results demonstrate that Bix4 acts directly downstream of VegT to specify endodermal differentiation in Xenopus embryos.

PMID: 10477288 [PubMed - indexed for MEDLINE]

60. Development. 1999 Sep;126(18):4005-15.

Bmp signaling regulates proximal-distal differentiation of endoderm in mouse lung development.

Weaver M, Yingling JM, Dunn NR, Bellusci S, Hogan BL.

Howard Hughes Medical Institute, Department of Cell Biology, Nashville, TN, USA.

In the mature mouse lung, the proximal-distal (P-D) axis is delineated by two distinct epithelial subpopulations: the proximal bronchiolar epithelium and the distal respiratory epithelium. Little is known about the signaling molecules that pattern the lung along the P-D axis. One candidate is Bone Morphogenetic Protein 4 (Bmp4), which is expressed in a dynamic pattern in the epithelial cells in the tips of growing lung buds. Previous studies in which Bmp4 was overexpressed in the lung endoderm (Bellusci, S., Henderson, R., Winnier, G., Oikawa, T. and Hogan, B. L. M. (1996) Development 122, 1693-1702) suggested that this factor plays an important role in lung morphogenesis. To further investigate this question, two complementary approaches were utilized to inhibit Bmp signaling in vivo. The Bmp antagonist Xnoggin and, independently, a dominant negative Bmp receptor (dnAlk6), were overexpressed using the surfactant protein C (Sp-C) promoter/enhancer. Inhibiting Bmp signaling results in a severe reduction in distal epithelial cell types and a concurrent increase in proximal cell types, as indicated by morphology and expression of marker genes, including the proximally expressed hepatocyte nuclear factor/forkhead homologue 4 (Hfh4) and Clara cell marker CC10, and the distal marker Sp-C. In addition, electron microscopy demonstrates the presence of ciliated cells, a proximal cell type, in the most peripheral regions of the transgenic lungs. We propose a model in which Bmp4 is a component of an apical signaling center controlling P-D patterning. Endodermal cells at the periphery of the lung, which are exposed to high levels of Bmp4, maintain or adopt a distal character, while cells receiving little or no Bmp4 signal initiate a proximal differentiation program.

PMID: 10457010 [PubMed - indexed for MEDLINE]

61. Int J Dev Biol. 1999 May;43(3):183-205.

Distinct roles for visceral endoderm during embryonic mouse development.

Bielinska M, Narita N, Wilson DB.

Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA.

The murine visceral endoderm is an extraembryonic cell layer that appears prior to gastrulation and performs critical functions during embryogenesis. The traditional role ascribed to the visceral endoderm entails nutrient uptake and transport. Besides synthesizing a number of specialized proteins that facilitate uptake, digestion, and secretion of nutrients, the extraembryonic visceral endoderm coordinates blood cell differentiation and vessel formation in the adjoining mesoderm, thereby facilitating efficient exchange of nutrients and gases between the mother and embryo. Recent studies suggest that in addition to this nutrient exchange function the visceral endoderm overlying the egg cylinder stage embryo plays an active role in guiding early development. Cells in the anterior visceral endoderm function as an early organizer. Prior to formation of the primitive streak, these cells express specific gene products that specify the fate of underlying embryonic tissues. In this review we highlight recent investigations demonstrating this dual role for visceral endoderm as a provider of both nutrients and developmental cues for the early embryo.

PMID: 10410899 [PubMed - indexed for MEDLINE]

62. Science. 1999 Jun 18;284(5422):1998-2003.

Initiation of mammalian liver development from endoderm by fibroblast growth factors.

Jung J, Zheng M, Goldfarb M, Zaret KS.

Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Box G-J363, Providence, RI 02912, USA.

The signaling molecules that elicit embryonic induction of the liver from the mammalian gut endoderm or induction of other gut-derived organs are unknown. Close proximity of cardiac mesoderm, which expresses fibroblast growth factors (FGFs) 1, 2, and 8, causes the foregut endoderm to develop into the liver. Treatment of isolated foregut endoderm from mouse embryos with FGF1 or FGF2, but not FGF8, was sufficient to replace cardiac mesoderm as an inducer of the liver gene expression program, the latter being the first step of hepatogenesis. The hepatogenic response was restricted to endoderm tissue, which selectively coexpresses FGF receptors 1 and 4. Further studies with FGFs and their specific inhibitors showed that FGF8 contributes to the morphogenetic outgrowth of the hepatic endoderm. Thus, different FGF signals appear to initiate distinct phases of liver development during mammalian organogenesis.

PMID: 10373120 [PubMed - indexed for MEDLINE]

63. Mech Ageing Dev. 1999 Apr 1;108(1):77-85.

Evidence that FGF receptor signaling is necessary for endoderm-regulated development of precardiac mesoderm.

Zhu X, Sasse J, Lough J.

Department of Cell Biology, Neurobiology and Anatomy and Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee 53226, USA.

Endoderm cells in the heart forming region (HFR endoderm) of stage 6 chicken embryos are required to support the proliferation and terminal differentiation of precardiac mesoderm cells in vitro. The endoderm's effect can be substituted by growth factors, including members of the fibroblast growth factor (FGF) family. However, direct implication of FGFs in this process requires evidence that inhibition of FGF signaling interferes with proliferation and/or terminal differentiation. This report examines the consequences of treating endoderm/precardiac mesoderm co-explants with agents that inactivate FGF receptors. Using sodium chlorate, which prevents FGF ligand-receptor interaction, it was observed that the percentage of S-phase precardiac mesoderm cells was markedly reduced, suggesting that cell proliferation was inhibited. To more specifically affect FGF signaling, the explants were treated with an antibody that recognizes an extracellular domain of FGF receptor-1 (FGFR-1). This treatment similarly inhibited cell proliferation. Although both agents modestly delayed cardiac myocyte differentiation as indicated by the contractile function, expression of alpha-sarcomeric actin was not affected. These findings provide additional evidence that an intact FGF signaling pathway is required during heart development.

PMID: 10366041 [PubMed - indexed for MEDLINE]

64. Mech Dev. 1998 Dec;79(1-2):83-97.

Drosophila endoderm development requires a novel homeobox gene which is a target of Wingless and Dpp signalling.

Fuss B, Hoch M.

Max-Planck-Institut f√ºr biophysikalische Chemie, Abt. Molekulare Entwicklungsbiologie, G√∂ttingen, Germany.

We have identified and cloned a novel type of homeobox gene that is composed of two homeodomains and is expressed in the Drosophila endoderm. Mutant analysis reveals that its activity is required at the foregut/midgut boundary for the development of the proventriculus. This organ regulates food passage from the foregut into the midgut and forms by the infolding of ectoderm and endoderm-derived tissues. The endodermal outer wall structure of the proventriculus is collapsed in the mutants leading to a failure of the ectodermal part to invaginate and build a functional multilayered organ. Lack-of-function and gain-of-function experiments show that the expression of this homeobox gene in the proventriculus endoderm is induced in response to Wingless activity emanating from the ectoderm/endoderm boundary whereas its expression in the central midgut is controlled by Dpp and Wingless signalling emanating from the overlying visceral mesoderm.

PMID: 10349623 [PubMed - indexed for MEDLINE]

65. Development. 1999 Feb;126(4):827-38.

Origin and development of the zebrafish endoderm.

Warga RM, N√ºsslein-Volhard C.

Max-Planck-Institut f√ºr Entwicklungsbiologie, Abteilung Genetik, Spemannstrasse 35, Germany. rachel_warga@urmc.rochester.edu

The segregation of cells into germ layers is one of the earliest events in the establishment of cell fate in the embryo. In the zebrafish, endoderm and mesoderm are derived from cells that involute into an internal layer, the hypoblast, whereas ectoderm is derived from cells that remain in the outer layer, the epiblast. In this study, we examine the origin of the zebrafish endoderm and its separation from the mesoderm. By labeling individual cells located at the margin of the blastula, we demonstrate that all structures that are endodermal in origin are derived predominantly from the more dorsal and lateral cells of the blastoderm margin. Frequently marginal cells give rise to both endodermal and mesodermal derivatives, demonstrating that these two lineages have not yet separated. Cells located farther than 4 cell diameters from the margin give rise exclusively to mesoderm, and not to endoderm. Following involution, we see a variety of cellular changes indicating the differentiation of the two germ layers. Endodermal cells gradually flatten and extend filopodial processes forming a noncontiguous inner layer of cells against the yolk. At this time, they also begin to express Forkhead-domain 2 protein. Mesodermal cells form a coherent layer of round cells separating the endoderm and ectoderm. In cyclops-mutant embryos that have reduced mesodermal anlage, we demonstrate that by late gastrulation not only mesodermal but also endodermal cells are fewer in number. This suggests that a common pathway initially specifies germ layers together before a progressive sequence of determinative events segregate endoderm and mesoderm into morphologically distinct germ layers.

PMID: 9895329 [PubMed - indexed for MEDLINE]

66. Science. 1998 Jul 3;281(5373):91-6.

Mixer, a homeobox gene required for endoderm development.

Henry GL, Melton DA.

Howard Hughes Medical Institute, Department of Molecular and Cellular Biology, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA.

An expression cloning strategy in Xenopus laevis was used to isolate a homeobox-containing gene, Mixer, that can cause embryonic cells to form endoderm. Mixer transcripts are found specifically in the prospective endoderm of gastrula, which coincides with the time and place that endodermal cells become histologically distinct and irreversibly determined. Loss-of-function studies with a dominant inhibitory mutant demonstrate that Mixer activity is required for endoderm development. In particular, the expression of Sox17alpha and Sox17beta, two previously identified endodermal determinants, require Mixer function. Together, these data suggest that Mixer is an embryonic transcription factor involved in specifying the endodermal germ layer.

PMID: 9651252 [PubMed - indexed for MEDLINE]

67. Development. 1997 Nov;124(21):4243-52.

Notochord to endoderm signaling is required for pancreas development.

Kim SK, Hebrok M, Melton DA.

Department of Molecular and Cellular Biology, and Howard Hughes Medical Institute, Harvard University, Cambridge, Massachusetts 02138, USA.

The role of the notochord in inducing and patterning adjacent neural and mesodermal tissues is well established. We provide evidence that the notochord is also required for one of the earliest known steps in the development of the pancreas, an endodermally derived organ. At a developmental stage in chick embryos when the notochord touches the endoderm, removal of notochord eliminates subsequent expression of several markers of dorsal pancreas bud development, including insulin, glucagon and carboxypeptidase A. Pancreatic gene expression can be initiated and maintained in prepancreatic chick endoderm grown in vitro with notochord. Non-pancreatic endoderm, however, does not express pancreatic genes when recombined with the same notochord. The results suggest that the notochord provides a permissive signal to endoderm to specify pancreatic fate in a stepwise manner.

PMID: 9334273 [PubMed - indexed for MEDLINE]

68. EMBO J. 1997 Jul 1;16(13):3995-4006.

Transcriptional regulation in endoderm development: characterization of an enhancer controlling Hnf3g expression by transgenesis and targeted mutagenesis.

Hiemisch H, Sch√ºtz G, Kaestner KH.

Molecular Biology of the Cell I Division, German Cancer Research Center, Heidelberg.

The hepatic nuclear factor 3gamma (Hnf3g) is a member of the winged helix gene family of transcription factors and is thought to be involved in anterior-posterior regionalization of the primitive gut. In this study, cis-regulatory elements essential for the expression of Hnf3g in vivo have been characterized. To this end, a 170 kb yeast artificial chromosome (YAC) carrying the entire Hnf3g locus was isolated and modified with a lacZ reporter gene. The two mouse lines carrying the unfragmented Hnf3g-lacZ YAC showed tissue-specific, copy number-dependent and position-independent expression, proving that 170 kb of the Hnf3g locus contain all elements important in the regulation of Hnf3g. Cis-regulatory elements necessary for expression of Hnf3g were identified in a three-step procedure. First, DNase I hypersensitive site mapping was used to delineate important chromatin regions around the gene required for tissue-specific activation of Hnf3g. Second, plasmid-derived transgenes and gene targeting of the endogenous Hnf3g gene locus were used to demonstrate that the 3'-flanking region of the gene is necessary and sufficient to direct reporter gene expression in liver, pancreas, stomach and small intestine. Third, a binding site for HNF-1alpha and beta, factors expressed in organs derived from the endoderm such as liver, gut and pancreas, was identified in this 3'-enhancer and shown to be crucial for enhancer function in vitro. Based on its expression pattern we inferred that HNF-1beta is a likely candidate for directly activating Hnf3g gene expression during development.

PMCID: PMC1170023 PMID: 9233809 [PubMed - indexed for MEDLINE]

69. Dev Growth Differ. 1997 Apr;39(2):199-205.

Analysis of the temporal expression of endoderm-specific alkaline phosphatase during development of the ascidian Halocynthia roretzi.

Nishida H, Kumano G.

Department of Life Sciences, Tokyo Institute of Technology, Midori-ku, Yokohama, Japan.

During embryogenesis of ascidians, endoderm cells initiate certain processes associated with differentiation and produce a tissue-specific enzyme, alkaline phosphatase (ALP). ALP has been used as a histochemical marker of endoderm differentiation. In the present study, the temporal profile of ALP expression during embryogenesis was investigated. In Halocynthia roretzi, endoderm-specific ALP is a membrane bound protein and is distinguishable from maternal cytoplasmic ALP by molecular mass. The activity of endodermal ALP first appeared at the early tail-bud stage. Treatment of developing embryos with inhibitors of translation and transcription was started at various stages. The results suggested that the synthesis of endodermal ALP protein started at the early tail-bud stage, and that the transcription of mRNA was initiated in the gastrula. In other ascidians, Ciona and Styela, it has been suggested that a significant amount of maternal ALP mRNA exists in eggs. The present study revealed that there are significant species differences in ALP expression during ascidian embryogenesis.

PMID: 9108333 [PubMed - indexed for MEDLINE]

70. Development. 1996 Dec;122(12):4023-31.

A molecular aspect of hematopoiesis and endoderm development common to vertebrates and Drosophila.

Rehorn KP, Thelen H, Michelson AM, Reuter R.

Institut f√ºr Genetik, Universit√§t zu K√∂ln, Germany.

In vertebrates, transcriptional regulators of the GATA family appear to have a conserved function in differentiation and organ development. GATA-1, -2 and -3 are required for different aspects of hematopoiesis, while GATA-4, -5 and -6 are expressed in various organs of endodermal origin, such as intestine and liver, and are implicated in endodermal differentiation. Here we report that the Drosophila gene serpent (srp) encodes the previously described GATA factor ABF. The multiple functions of srp in Drosophila suggest that it is an ortholog of the entire vertebrate Gata family. srp is required for the differentiation and morphogenesis of the endodermal gut. Here we show that it is also essential for Drosophila hematopoiesis and for the formation of the fat body, the insect organ analogous to the liver. These findings imply that some aspects of the molecular mechanisms underlying blood cell development as well as endodermal differentiation are early acquisitions of metazoan evolution and may be common to most higher animals.

PMID: 9012522 [PubMed - indexed for MEDLINE]

71. Anat Rec. 1996 Oct;246(2):293-304.

Unusual aspects of inner cell mass formation, endoderm differentiation, Reichert's membrane development, and amniogenesis in the lesser bulldog bat, Noctilio albiventris.

Rasweiler JJ 4th, Badwaik NK.

Department of Obstetrics and Gynecology, Cornell University Medical College, New York, NY 10021, USA.

BACKGROUND AND METHODS: The early embryogenesis of the lesser bulldog bat, Noctilio albiventris (family Noctilionidae), was examined histologically in 59 pregnant females collected from a reproductively synchronized population in Colombia. RESULTS: Early blastocysts of Noctilio are unusual in lacking a typical inner cell mass. Instead, cells inside of the trophoblast are dispersed for a period as a monolayer. A typical inner cell mass (ICM) only forms and becomes properly oriented after the initiation of implantation. Several features of Reichert's membrane in this species are also noteworthy: it develops between the ICM and trophoblast and between the parietal endoderm and trophoblast; it becomes linked to a meshwork of basal laminalike material that extends into the ICM; and it appears to be continuous, or fused, with prominent basal laminae that develop within the cytotrophoblastic villi that radiate throughout the preplacenta. Amniogenesis occurs by cavitation and converts the ICM into a hollow epiblastic vesicle. Gastrulation commences before this vesicle exhibits obvious differentiation into an embryonic shield and amniotic ectoderm. CONCLUSIONS: Because development and proper orientation of a typical ICM in Noctilio occur after the initiation of implantation, these may involve the migration of cells on the interior of the blastocyst and/or an unusual method of early endoderm differentiation. The possibility exists that epiblast, endoderm, and cytotrophoblast may all contribute to the secretion of Reichert's membrane in this bat. Although the early embryogenesis of Noctilio exhibits many similarities to that in phyllostomid bats, substantial differences also exist between these closely related species.

PMID: 8888970 [PubMed - indexed for MEDLINE]

72. J Cell Biol. 1994 Jul;126(1):211-21.

Fetal endoderm primarily holds the temporal and positional information required for mammalian intestinal development.

Duluc I, Freund JN, Leberquier C, Kedinger M.

INSERM U381, Strasbourg, France.

In rodents, the intestinal tract progressively acquires a functional regionalization during postnatal development. Using lactase-phlorizin hydrolase as a marker, we have analyzed in a xenograft model the ontogenic potencies of fetal rat intestinal segments taken prior to endoderm cytodifferentiation. Segments from the presumptive proximal jejunum and distal ileum grafted in nude mice developed correct spatial and temporal patterns of lactase protein and mRNA expression, which reproduced the normal pre- and post-weaning conditions. Segments from the fetal colon showed a faint lactase immunostaining 8-10 d after transplantation in chick embryos but not in mice; it is consistent with the transient expression of this enzyme in the colon of rat neonates. Heterotopic cross-associations comprising endoderm and mesenchyme from the presumptive proximal jejunum and distal ileum developed as xenografts in nude mice, and they exhibited lactase mRNA and protein expression patterns that were typical of the origin of the endodermal moiety. Endoderm from the distal ileum also expressed a normal lactase pattern when it was associated to fetal skin fibroblasts, while the fibroblasts differentiated into muscle layers containing alpha-smooth-muscle actin. Noteworthy, associations comprising colon endoderm and small intestinal mesenchyme showed a typical small intestinal morphology and expressed the digestive enzyme sucrase-isomaltase normally absent in the colon. However, in heterologous associations comprising lung or stomach endoderm and small intestinal mesenchyme, the epithelial compartment expressed markers in accordance to their tissue of origin but neither intestinal lactase nor sucrase-isomaltase. A thick intestinal muscle coat in which cells expressed alpha-smooth-muscle actin surrounded the grafts. The results demonstrate that: (a) the temporal and positional information needed for intestinal ontogeny up to the post-weaning stage results from an intrinsic program that is fixed in mammalian fetuses prior to endoderm cytodifferentiation; (b) this temporal and positional information is primarily carried by the endodermal moiety which is also able to change the fate of heterologous mesodermal cells to form intestinal mesenchyme; and (c) the small intestinal mesenchyme in turn may deliver instructive information as shown in association with colonic endoderm; yet this effect is not obvious with nonintestinal endoderms.

PMCID: PMC2120088 PMID: 8027179 [PubMed - indexed for MEDLINE]

73. Genet Res. 1990 Oct-Dec;56(2-3):209-22.

Use of triple tissue blastocyst reconstitution to study the development of diploid parthenogenetic primitive ectoderm in combination with fertilization-derived trophectoderm and primitive endoderm.

Gardner RL, Barton SC, Surani MA.

Imperial Cancer Research Fund, Department of Zoology, Oxford.

Diploid mouse conceptuses lacking a paternal genome can form morphologically normal but small fetuses of up to 25 somites, but they invariably fail to develop beyond mid-gestation. Such conceptuses differ from normal most notably in the poor development of extra-embryonic tissues which are largely of trophectodermal and primitive endodermal origin. However, it is not clear whether the demise of diploid parthenogenetic (P) or gynogenetic (G) conceptuses is attributable entirely to the defective development of these two tissues or whether differentiation of the primitive ectoderm, the precursor of the foetus, extra-embryonic mesoderm and amnion, is also impaired by the absence of a paternal genome. Therefore, a new blastocyst reconstitution technique was used which enabled primitive ectoderm from P blastocysts to be combined with primitive endoderm and trophectoderm from fertilization-derived (F) blastocysts. One third of the 'triple tissue' reconstituted blastocysts that implanted yielded foetuses. However, all foetuses recovered on the 11th or 12th day of gestation were small and, with one exception, either obviously retarded or arrested in development. The exception was a living 44 somite specimen which is the most advanced P foetus yet recorded. Foetuses were invariably degenerating in conceptuses recovered on the 13th day. In contrast, at least 16% of control reconstituted blastocysts with primitive ectoderm as well as primitive endoderm and trophectoderm of F origin developed normally on the 13th day of gestation or to term. Hence, the presence of a paternal genome seems to be essential for normal differentiation of all 3 primary tissues of the mouse blastocyst. The P foetuses that developed from reconstituted blastocysts were so closely invested by their membranes that they often showed abnormal flexure of the posterior region of the body. Several also showed a deficiency of allantoic tissue. Therefore, the possibility that the defect in development of P primitive ectoderms resided in their extra-embryonic tissues was investigated by analysing a series of chimaeras produced by injecting them into intact F blastocysts. The foregoing anomalies were not discernible even when P cells made a large contribution to the extra-embryonic mesoderm or amnion plus umbilical cord. Furthermore, selection against P cells was no greater in extra-embryonic derivatives of the primitive ectoderm than in the foetus itself.

PMID: 2272512 [PubMed - indexed for MEDLINE]

74. Development. 1989 Jun;106(2):407-19.

Differential localization of villin and fimbrin during development of the mouse visceral endoderm and intestinal epithelium.

Ezzell RM, Chafel MM, Matsudaira PT.

Whitehead Institute for Biomedical Research, Cambridge, Massachusetts.

The apical surface of transporting epithelia is specially modified to absorb nutrients efficiently by amplifying its surface area as microvilli. Each microvillus is supported by an underlying core of bundled actin filaments. Villin and fimbrin are two actin-binding proteins that bundle actin filaments in the intestine and kidney brush border epithelium. To better understand their function in the assembly of the cytoskeleton during epithelial differentiation, we examined the pattern of villin and fimbrin expression in the developing mouse using immunofluorescence and immunoelectron microscopy. Villin is first detected at day 5 in the primitive endoderm of the postimplantation embryo and is later restricted to the visceral endoderm. By day 8.5, villin becomes redistributed to the apical surface in the visceral endoderm, appearing in the gut at day 10 and concentrating in the apical cytoplasm of the differentiating intestinal epithelium 2-3 days later. In contrast, fimbrin is found in the oocyte and in all tissues of the early embryo. In both the visceral endoderm and gut epithelium, fimbrin concentrates at the apical surface 2-3 days after villin; this redistribution occurs when the visceral endoderm microvilli first contain organized microfilament bundles and when microvilli first begin to appear in the gut. These results suggest a common mechanism of assembly of the absorptive surface of two different tissues in the embryo and identify villin as a useful marker for the visceral endoderm.

PMID: 2686960 [PubMed - indexed for MEDLINE]

75. Shi Yan Sheng Wu Xue Bao. 1989 Mar;22(1):43-55.

An extensive increase of junctional communication capacity in endoderm development of the Xenopus embryo.

Chen DL.

The present result shows that in blastula and gastrula stages although endoderm cells of the Xenopus embryo may be electrically coupled with each other, most of them can not detectably transfer the 376 dalton molecular weight tracer, the carboxyfluorescein, to their contiguous neighbor cells. They become capable of such junctional dye transfer at the end of gastrulation. This transition reflects temporally well ordered development of junctional communication capacity from low to high level, which may be related to the developmental program of endodermal cellular differentiation. The time course of this transition provides a measure for study of the effects of various factors on the development of junctional communication capacity in this embryo.

PMID: 2763765 [PubMed - indexed for MEDLINE]

76. Dev Biol. 1985 Apr;108(2):513-21.

Cell surface glycoproteins mediate compaction, trophoblast attachment, and endoderm formation during early mouse development.

Richa J, Damsky CH, Buck CA, Knowles BB, Solter D.

Early mouse embryos undergo several morphogenetic processes, such as compaction, trophoblast attachment, and endoderm formation that can be studied in vitro. Several polyspecific and monospecific antisera have been used to perturb these processes in a nontoxic, reversible fashion. One of the antibody-defined molecules, cell CAM 120/80, promotes epithelial cell adhesion, embryo compaction, and endoderm formation. The results suggest the presence of another such molecule(s) involved in these same processes. Evidence is also presented that another set of antibody-defined molecules, GP 140, involved in attachment of somatic cells to the substrate, mediates trophoblast attachment of the mouse blastocyst. The possible role of these molecules in governing the processes leading to cell lineages in the mouse embryo is discussed.

PMID: 4076542 [PubMed - indexed for MEDLINE]

77. Dev Biol. 1985 Feb;107(2):432-41.

Abnormal embryonic development induced by antibodies to rat visceral yolk-sac endoderm: isolation of the antigen and localization to microvillar membrane.

Leung CC, Lee C, Cheewatrakoolpong B, Hilton D.

An antigenic substance was isolated from rat visceral yolk-sac endoderm of the 18th-20th days of gestation by extraction with the nonionic detergent Nonidet P-40, Sephacryl S-300 gel filtration, and Ricinus communis agglutinin affinity chromatography. The rabbit antiserum directed against this antigenic substance when injected into pregnant rats during the period of organogenesis caused abnormal embryonic development, fetal growth retardation, and embryonic death. Ouchterlony gel diffusion analysis demonstrated that the antiserum formed one immunoprecipitin band against the crude detergent extract and a complete identity between the present visceral yolk-sac antigen and the renal glycoprotein antigen previously isolated (C. C. K. Leung, (1982) J. Exp. Med. 156, 372-384). The antigen eluted from the antibody affinity column appeared to consist of two major peptides of 60 and 30 kDa when analyzed by SDS-polyacrylamide gel electrophoresis. Indirect immunofluorescent and immunoperoxidase localization studies at the light microscopic level demonstrated that both rat renal proximal tubule and embryonic visceral yolk-sac endoderm at various gestational stages (including the organogenetic period) shared the same antigen. Indirect immunoperoxidase localization studies at the electron microscopic level demonstrated that the antigen was a part of (or associated with) the microvillar membrane and membrane invaginations at the base of the microvilli of the renal proximal tubule and visceral yolk-sac endoderm. In vivo immunoperoxidase localization studies demonstrated that the teratogenic antibodies localized within the large phagolysosomes and the apical vesicles of the visceral yolk-sac endoderm. It is postulated that visceral yolk-sac pathology was induced by the antibodies.

PMID: 3972164 [PubMed - indexed for MEDLINE]

78. J Embryol Exp Morphol. 1984 Apr;80:251-88.

An in situ cell marker for clonal analysis of development of the extraembryonic endoderm in the mouse.

Gardner RL.

Conditions were found for staining whole mid-gestation capsular parietal endoderms and visceral yolk sacs for malic enzyme activity that gave excellent discrimination between wild-type (Mod-1+/Mod-1+) cells and mutant (Mod-1n/Mod-1n) cells that lack the cytoplasmic form of the enzyme. Reciprocal blastocyst injection experiments were undertaken in which single primitive endoderm cells of one genotype were transplanted into embryos of the other genotype. In addition, Mod-1+/Mod-1+ early inner cell mass (ICM) cells were injected into Mod-1n/Mod-1n blastocysts, either in groups of two or three singletons or as daughter cell pairs. A substantial proportion of the resulting conceptuses showed mosaic histochemical staining in the parietal endoderm, visceral yolk sac, or in both these membranes. Stained cells were invariably intimately intermixed with unstained cells in the mosaic parietal endoderms. In contrast, one or both of two distinct patterns of staining could be discerned in mosaic visceral yolk sacs. The first, a conspicuously 'coherent' pattern, was found to be due to endodermal chimaerism; the second, a more diffuse pattern, was attributable to chimaerism in the mesodermal layer of this membrane. The overall distribution of cells with donor staining characteristics resulting from primitive endoderm versus early ICM cell injections was consistent with findings in earlier experiments in which allozymes of glucosephosphate isomerase were used as markers. The conspicuous lack of phenotypically intermediate cells in predominantly stained areas of mosaic membranes suggested that the histochemical difference between Mod-1+/Mod-1+ and Mod-1n/Mod-1n genotypes was cell-autonomous. This conclusion was strengthened by the results of staining mixed in vitro cultures of parietal endoderm in which presence or absence of phagocytosed melanin granules was used as an independent means of distinguishing wild type from null cells. By substituting tetranitro blue tetrazolium for nitro blue tetrazolium in the incubation medium, satisfactory differential staining was obtained for both the extraembryonic endoderm and other tissues of earlier postimplantation wild type versus null embryos. Finally, absence of cytoplasmic malic enzyme activity does not appear to have a significant effect on the viability or behaviour of mutant cells.

PMID: 6205114 [PubMed - indexed for MEDLINE]

79. Pediatr Res. 1983 May;17(5):313-8.

Antiserum to rat visceral yolk sac endoderm induced abnormal embryonic development.

Leung CC.

The induction of abnormal embryonic development by heterologous tissue antisera has been well established. The underlying mechanism whereby such teratogenesis occurs is not known. There were implications that visceral yolk sac endoderm might be involved. Endoderm was isolated from rat visceral yolk sac of 14th day of gestation using a nonenzymic procedure. The purity of the endoderm preparation was examined by electron microscopy. The preparation contained sheets of single layer of endodermal cells with no apparent contamination by the underlying mesenchyme or basal lamina. The specificity of the antiserum was examined by in vitro immunofluorescent localization studies. The antibodies against the endoderm localized only in the endodermal cells and some of the renal tubular cells. Intraperitoneal injection of the endoderm antiserum into 9-day pregnant rats resulted in congenital malformation, embryonic death, and fetal growth retardation. The effects of the antiserum were dose-dependent. The most frequently observed defects were anophthalmia and microphthalmia. Retarding effect of the antiserum on the growth of the embryo at the egg cylinder stage was also observed. In vivo immunofluorescent localization studies indicated that the endoderm antibodies localized only in the endodermal cells of the visceral yolk sac placenta; no localization was observed in the visceral yolk sac mesenchyme, basal lamina. Reichert's membrane, maternal kidney tissue or the embryo proper.

PMID: 6343995 [PubMed - indexed for MEDLINE]

80. C R Seances Acad Sci III. 1982 Sep 20;295(2):89-92.

[Development of the adenylate cyclase activity of the embryonic chorda-mesoderm and endoderm during the migration of primordial germ cells in Xenopus laevis (anuran amphibian)]

[Article in French]

Brustis JJ, Galante M, Peyret D.

In the embryo of Xenopus laevis, adenylate cyclase activity is higher in the chorda-mesoderm than in the endoderm. The peak of activity in the chorda-mesoderm is observed at the beginning of the migration of the primordial germ cells (PGC). There could be a correlation between the adenylate cyclase activity of the chorda-mesoderm and the intraendodermic migration of the PGC.

PMID: 6816405 [PubMed - indexed for MEDLINE]

81. J Embryol Exp Morphol. 1979 Aug;52:49-62.

The development of hepatogenic potency in the endoderm of quail embryos.

Fukuda S.

Hepatogenic potency of the endoderm is detectable in the anterior half of the endoderm of quail embryos older than 2-somite stage when endodermal fragments are cultured with or without heterologous chick mesenchymes, in the coelomic cavity of 3-day chick embryos. On the other hand, the posterior half of the endoderm never has hepatogenic potency. The hepatogenic potency of the endoderm is gradually stabilised with increasing age. However, expression of hepatogenesis can be affected when the endoderm is associated with inductively active digestive tract mesenchymes. Mesenchyme taken from the presumptive cardiac region ('cardiac' mesenchyme) of chick embryos is necessary for the uncommitted anterior endoderm to acquire hepatogenic potency, and this effect is specific for the 'cardiac' mesenchyme. The 'cardiac' mesenchyme, however, fails to induce hepatic epithelium in the allantoic endoderm, which can differentiate heterotypically when cultured in combination with digestive tract mesenchymes. The evidence presented in this study suggests that the effect of 'cardiac' mesenchyme on the acquisition of hepatogenic potency in the endoderm is limited.

PMID: 521753 [PubMed - indexed for MEDLINE]

82. Anat Embryol (Berl). 1978 Jun 2;153(2):167-78.

Development of the chick embryo endoderm studied by S.E.M.

Wakely J, England MA.

PMID: 677469 [PubMed - indexed for MEDLINE]

83. C R Acad Sci Hebd Seances Acad Sci D. 1977 May 2;284(17):1713-6.

[Induction of the mesoderm and primordial germ cells by the endoderm of Pleurodeles waltlii (Amphibia, Urodele): development during gastrulation]

[Article in French]

Maufroid JP, Capuron A.

Blastulae ectoderm is combined with dorsal or ventral endoderm from blastulae, gastrulae and early neurulae. In vitro culture reveals the presence of different mesodermal structures whose nature is connected with the endoderm origin site. Primordial germ cells differentiate essentially in the recombinates including ventral endoderm. The inducing capacity of this latter concerning germ cells is maximum at the beginning of gastrulation, then decreases during it and finally disappears at the onset of neurulation.

PMID: 406093 [PubMed - indexed for MEDLINE]

84. Am J Anat. 1976 May;146(1):1-30.

Cytological development of yolk sac endoderm and protein-absorptive mesothelium in the little brown bat, Myotis lucifugus.

Enders AC, Wimsatt WA, King BF.

The yolk sac of the little brown bat is unusual in that during the course of gestation both the inner endodermal cells (bordering the yolk sac cavity) and outer mesothelium (facing the exocelom) form simple columnar epithelia which persist throughout gestation. These endodermal cells develop an extensive system of agranular endoplasmic reticulum, numerous lipid droplets and unusual "giant" mitochondria. During development the Golgi apparatus changes position from the apical to the basal side of the nucleus, reversing the polarity of the cells. In general, the endodermal cells have cytological features suggestive of synthetic or secretory activity. The mesothelial cells develop an extensive "absorptive apparatus" in their apices, while large crystalloid-containing granules become numerous in their basal cytoplasm. The mesothelial cells have large deposits of glycogen, especially during mid-gestation, but few mitochondria and little granular endoplasmic reticulum. Endodermal cells do not absorb exogenous protein (peroxidase) even if it is injected directly into the yolk sac cavity. However, placement of peroxidase either in the exocelom or in the maternal vascular system results in the appearance of this protein in the "absorptive apparatus" of mesothelial cells as well as in macrophages in the stroma of the yolk sac. While evidence of absorption was clear, no direct evidence of transport of tracer to fetal blood vascular system was obtained. It is postulated that a major function of the hypertrophied mesothelial cells during gestation is the absorption of proteins and possibly other substances from the exocelomic fluid. The major function of the hypertrophied endodermal cells may be synthesis and secretion of substances into the fetal circulation.

PMID: 945685 [PubMed - indexed for MEDLINE]

85. Dev Biol. 1971 Dec;26(4):547-59.

Differentiation of parietal endoderm cells of the guinea pig yolk sac, with particular reference to the development of endoplasmic reticulum.

King BF.

PMID: 5134612 [PubMed - indexed for MEDLINE]

86. C R Seances Soc Biol Fil. 1971;165(9):1972-5.

[Attempt at in vitro analysis of the inhibitor effect exerted by the somitic mesenchyme on the development of the hepatic endoderm]

[Article in French]

Fontaine J, Le Dougarin N.

PMID: 4263135 [PubMed - indexed for MEDLINE]

87. C R Acad Sci Hebd Seances Acad Sci D. 1968 Dec 16;267(25):2174-7.

[Development of differentiation capacities of chick embryo thyroid endoderm after the determination stage]

[Article in French]

Le Li√®vre C, Le Douarin N.

PMID: 4973827 [PubMed - indexed for MEDLINE]

88. J Embryol Exp Morphol. 1964 Sep;12:551-62.

AN INHERITED ABNORMALITY AFFECTING THE DEVELOPMENT OF THE YOLK PLASMODIUM AND ENDODERM IN DERMESTES MACULATUS (COLEOPTERA).

EDE DA.

PMID: 14207039 [PubMed - indexed for MEDLINE]

89. C R Hebd Seances Acad Sci. 1952 Mar 31;234(14):1480-2.

[Development of the endoderm in bird eggs.]

[Article in Undetermined Language]

LUTZ H, REYROLLES J.

PMID: 12979285 [PubMed - indexed for MEDLINE]