Developmental Signals - Pax

Embryology - 19 Apr 2024        Expand to Translate
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Introduction

Phylogenetic tree of Pax genes

The name derived from Drosophila gene "paired" (prd) with a box (homeodomain) domain. A transcription factor of the helix-turn-helix structural family, DNA binding, and activating gene expression. In human, there are nine member proteins from Pax1 to Pax9.

Pax6 has been identified as regulating development of the central nervous system, eyes, nose, pancreas and pituitary gland.

Some Recent Findings

Review - Pax genes: regulators of lineage specification and progenitor cell maintenance "These results indicate that Unc5h1 and Cyp26b1 are novel candidates for target genes transactivated by Pax6. Furthermore, our results suggest the interesting possibility that Pax6 regulates anterior-posterior patterning of the hindbrain via activation of Cyp26b1, an enzyme that metabolizes retinoic acid."

More recent papers

This table allows an automated computer search of the external PubMed database using the listed "Search term" text link. This search now requires a manual link as the original PubMed extension has been disabled. The displayed list of references do not reflect any editorial selection of material based on content or relevance. References also appear on this list based upon the date of the actual page viewing. References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability. More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Development Pax <pubmed limit=5>Development Pax</pubmed>

Functions

Neural

Mouse- early Pax8 and Pax2 expression

• Hoxd4 gene a direct target of Pax6
  • mouse embryo - Hoxd4 expression in rhombomere 7 and the spinal cord is reduced to some extent in the Pax6 mutant
  • zebrafish embryo - double knockdown of pax6a and pax6b with MOs resulted in malformed rhombomere boundaries and an anteriorized hoxd4a expression border

• Pax3 is expressed in the somite, neural tube, and neural crest.
• Pax3 is required for enteric ganglia formation.
• Pax2 and Pax5 in midbrain and cerebellum development.

Vision

Pax6 mutation eye phenotypes

Pancreas

• Pax6 acts in endocrine development in the pancreas as a glucagon gene transactivator role in alpha (α) cell development.
• Pax2 is also expressed in the pancreas.
• Pax4 is a regulator of pancreatic beta cell development.

Thymus

Pax1 mouse KO thymus size reduction and impaired thymocyte maturation.

Structure

• tissue-specific transcriptional regulators
• contain a highly conserved DNA-binding domain with six alpha-helices (paired domain)
• a complete or residual homeodomain.
• 4 Groups: group I (Pax-1, 9), II (Pax-2, 5, 8), III (Pax-3, 7), and IV (Pax-4, 6)

Mouse Expression

The following gallery is from a recent paper using a Pax7-cre/reporter mouse.

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  E7.5 E8.5 neural fold

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  E9.5 Pax7 heart

• 

  E11.5 Trunk neural crest 1

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  E11.5 Trunk neural crest 2

• 

  E15.5 Pax7 limb

Mouse Palatal Shelf Wnt5a, Osr2 and Pax9 Expression.

Links: Mouse Development | Neural Crest Development

Abnormalities

Associated with defects in each Pax protein or their signaling pathway.

PAX2

• renal-coloboma syndrome (RCS)

Pax3

• Waardenburg syndrome type 1 (WS1)
• Waardenburg syndrome type 3 (WS3)
• craniofacial-deafness-hand syndrome (CDHS)
• rhabdomyosarcoma type 2 (RMS2)

Pax5

• acute lymphoblastic leukemia

PAX6

A series of vision associated defects.

• aniridia (AN)
• Peters anomaly
• ectopia pupillae
• foveal hypoplasia
• autosomal dominant keratitis
• ocular coloboma
• coloboma of optic nerve
• bilateral optic nerve hypoplasia
• aniridia cerebellar ataxia and mental deficiency (ACAMD)

Pax7

• rhabdomyosarcoma type 2 (RMS2)

PAX8

• congenital hypothyroidism non-goitrous type 2 (CHNG2)

References

Search Bookshelf Pax

Reviews

<pubmed>17506689</pubmed> <pubmed>10197584</pubmed>

Search Pubmed

Search Pubmed Now: Pax

http://www.ncbi.nlm.nih.gov/omim

External Links

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• OMIM - Pax6

Glossary Links

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Cite this page: Hill, M.A. (2024, April 19) Embryology Developmental Signals - Pax. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Developmental_Signals_-_Pax

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G