Talk:Developmental Signals - Homeobox
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Cite this page: Hill, M.A. (2019, December 13) Embryology Developmental Signals - Homeobox. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Developmental_Signals_-_Homeobox
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Hoxb1b controls oriented cell division, cell shape and microtubule dynamics in neural tube morphogenesis
Development. 2014 Feb;141(3):639-49. doi: 10.1242/dev.098731.
Zigman M1, Laumann-Lipp N, Titus T, Postlethwait J, Moens CB. Author information
Hox genes are classically ascribed to function in patterning the anterior-posterior axis of bilaterian animals; however, their role in directing molecular mechanisms underlying morphogenesis at the cellular level remains largely unstudied. We unveil a non-classical role for the zebrafish hoxb1b gene, which shares ancestral functions with mammalian Hoxa1, in controlling progenitor cell shape and oriented cell division during zebrafish anterior hindbrain neural tube morphogenesis. This is likely distinct from its role in cell fate acquisition and segment boundary formation. We show that, without affecting major components of apico-basal or planar cell polarity, Hoxb1b regulates mitotic spindle rotation during the oriented neural keel symmetric mitoses that are required for normal neural tube lumen formation in the zebrafish. This function correlates with a non-cell-autonomous requirement for Hoxb1b in regulating microtubule plus-end dynamics in progenitor cells in interphase. We propose that Hox genes can influence global tissue morphogenesis by control of microtubule dynamics in individual cells in vivo. KEYWORDS: Cell polarity, Hoxa1, Hoxb1b, In vivo tissue morphogenesis, Neural tube formation, Oriented cell division, Zebrafish
Evolution of anterior Hox regulatory elements among chordates
BMC Evol Biol. 2011 Nov 15;11:330.
Natale A, Sims C, Chiusano ML, Amoroso A, D'Aniello E, Fucci L, Krumlauf R, Branno M, Locascio A. Source Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy. Abstract BACKGROUND: The Hox family of transcription factors has a fundamental role in segmentation pathways and axial patterning of embryonic development and their clustered organization is linked with the regulatory mechanisms governing their coordinated expression along embryonic axes. Among chordates, of particular interest are the Hox paralogous genes in groups 1-4 since their expression is coupled to the control of regional identity in the anterior nervous system, where the highest structural diversity is observed. RESULTS: To investigate the degree of conservation in cis-regulatory components that form the basis of Hox expression in the anterior nervous system, we have used assays for transcriptional activity in ascidians and vertebrates to compare and contrast regulatory potential. We identified four regulatory sequences located near the CiHox1, CiHox2 and CiHox4 genes of the ascidian Ciona intestinalis which direct neural specific domains of expression. Using functional assays in Ciona and vertebrate embryos in combination with sequence analyses of enhancer fragments located in similar positions adjacent to Hox paralogy group genes, we compared the activity of these four Ciona cis-elements with a series of neural specific enhancers from the amphioxus Hox1-3 genes and from mouse Hox paralogous groups 1-4. CONCLUSIONS: This analysis revealed that Kreisler and Krox20 dependent enhancers critical in segmental regulation of the hindbrain appear to be specific for the vertebrate lineage. In contrast, neural enhancers that function as Hox response elements through the action of Hox/Pbx binding motifs have been conserved during chordate evolution. The functional assays reveal that these Hox response cis-elements are recognized by the regulatory components of different and extant species. Together, our results indicate that during chordate evolution, cis-elements dependent upon Hox/Pbx regulatory complexes, are responsible for key aspects of segmental Hox expression in neural tissue and appeared with urochordates after cephalochordate divergence.
Hedgehog signaling is dispensable for adult murine hematopoietic stem cell function and hematopoiesis
Cell Stem Cell. 2009 Jun 5;4(6):559-67.
Hofmann I, Stover EH, Cullen DE, Mao J, Morgan KJ, Lee BH, Kharas MG, Miller PG, Cornejo MG, Okabe R, Armstrong SA, Ghilardi N, Gould S, de Sauvage FJ, McMahon AP, Gilliland DG. Source Division of Hematology, Department of Medicine, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
We report the unexpected finding that loss of Hh signaling through conditional deletion of Smoothened (Smo) in the adult hematopoietic compartment has no apparent effect on adult hematopoiesis, including peripheral blood count, number or cell-cycle status of stem or progenitor cells, hematopoietic colony-forming potential, long-term repopulating activity in competitive repopulation assays, or stress response to serial 5-fluorouracil treatment. Furthermore, pharmacologic inhibition of Hh signaling with a potent and selective small molecule antagonist has no substantive effect on hematopoiesis in the mouse. In addition, Hh signaling is not required for the development of MLL-AF9-mediated acute myeloid leukemia (AML). Taken together, these data demonstrate that Hh signaling is dispensable for normal hematopoietic development and hematopoietic stem cell function, indicating that targeting of Hh signaling in solid tumors is not likely to result in hematopoietic toxicity. Furthermore, the Hh pathway may not be a compelling target in certain hematopoietic malignancies.
Comment in Cell Stem Cell. 2009 Jun 5;4(6):470-1.
Hox transcription factors and their elusive mammalian gene targets
Heredity. 2006 Aug;97(2):88-96. Epub 2006 May 24.
Svingen T, Tonissen KF. Source Cell Biology Group, Eskitis Institute for Cell and Molecular Therapies and School of Biomolecular and Biomedical Science, Griffith University, Nathan, Queensland 4111, Australia.
The Hox family of homeodomain transcription factors regulate numerous pathways during developmental and normal cellular processes. All Hox proteins recognise similar sequences in vitro yet display functional diversity in an in vivo environment. This review focuses on the transcriptional and functional specificity elicited by Hox proteins, giving an overview of homeodomain-DNA interactions and the gain of binding specificity through cooperative binding with cofactors. Furthermore, currently identified mammalian Hox target genes are presented, of which the most striking feature is that very few direct Hox targets have been identified. The direct targets participate in an array of cellular functions including organogenesis and cellular differentiation, cell adhesion and migration and cell cycle and apoptotic pathways. A further assessment of identified mammalian promoter targets and the contribution of bases outside the canonical recognition motif is given, highlighting roles they may play in either trans-activation or repression by Hox proteins.
The list contains likely Hox gene targets and the Hox protein responsible for the trans-regulatory effect. The (+/-) symbols represent either a positive or negative regulatory effect on the target gene and (?) symbol indicates an unknown effect. Also, note that although there is some experimental evidence to suggest all are likely direct gene targets, not all have been exclusively verified of being so through in vivo experiments. The corresponding reference(s) for each gene target is also shown.</thead><tbody valign="top"></tbody>
Kutejova et al (2005)
Raman et al (2000a)
Raman et al (2000b)
Chen et al (2005)
Foucher et al (2002); Gao et al (2002)
Shi et al (1999, 2001)
Bruhl et al (2004)
Bromleigh and Freedman (2000)
Daftary et al (2002)
Troy et al (2003)
Kim et al (2003)
Salsi and Zappavigna (2006)
Penkov et al (2000)
Guazzi et al (1994)
Wu et al (2003)
Carè et al (1996)
Jones et al (1992)
Jones et al (1992)
Tomotsune et al (1993)
Tkatchenko et al (2001)
|Hoxd10, b6, b7, b9, c8||+||Renin||Mouse||
Pan et al (2004)
Developmental regulation of the Hox genes during axial morphogenesis in the mouse
Development. 2005 Jul;132(13):2931-42.
Deschamps J, van Nes J. Source Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands. email@example.com
The Hox genes confer positional information to the axial and paraxial tissues as they emerge gradually from the posterior aspect of the vertebrate embryo. Hox genes are sequentially activated in time and space, in a way that reflects their organisation into clusters in the genome. Although this co-linearity of expression of the Hox genes has been conserved during evolution, it is a phenomenon that is still not understood at the molecular level. This review aims to bring together recent findings that have advanced our understanding of the regulation of the Hox genes during mouse embryonic development. In particular, we highlight the integration of these transducers of anteroposterior positional information into the genetic network that drives tissue generation and patterning during axial elongation.