Developmental Signals - Pax

From Embryology
(Redirected from Pax)
Jump to: navigation, search



Phylogenetic tree of Pax genes[1]

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.

Factor Links: BMP | Sonic hedgehog | Homeobox | FGF | Nanog | Notch | Pax | Retinoic acid | Sox | Tbx | TGF-beta | VEGF | Wnt | hCG

Some Recent Findings

  • Downstream genes of Pax6 in the developing rat hindbrain [2] "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."



Mouse- early Pax8 and Pax2 expression[3]
  • Hoxd4 gene a direct target of Pax6[4]
    • 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.[5]
  • Pax2 and Pax5 in midbrain and cerebellum development.[6]


Pax6 eye phenotypes.jpg

Pax6 mutation eye phenotypes[7]


  • 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.[8]


Pax1 mouse KO thymus size reduction and impaired thymocyte maturation.


  • 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)[9]

Mouse Expression

The following gallery is from a recent paper using a Pax7-cre/reporter mouse.[10]

Mouse palate gene expression 01.jpg

Mouse Palatal Shelf Wnt5a, Osr2 and Pax9 Expression.[11]

Links: Mouse Development | Neural Crest Development


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


  • renal-coloboma syndrome (RCS)


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


  • acute lymphoblastic leukemia


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)


  • rhabdomyosarcoma type 2 (RMS2)


  • congenital hypothyroidism non-goitrous type 2 (CHNG2)


  1. H Sun, A Rodin, Y Zhou, D P Dickinson, D E Harper, D Hewett-Emmett, W H Li Evolution of paired domains: isolation and sequencing of jellyfish and hydra Pax genes related to Pax-5 and Pax-6. Proc. Natl. Acad. Sci. U.S.A.: 1997, 94(10);5156-61 PMID:9144207
  2. Keiko Numayama-Tsuruta, Yoko Arai, Masanori Takahashi, Makiko Sasaki-Hoshino, Nobuo Funatsu, Shun Nakamura, Noriko Osumi Downstream genes of Pax6 revealed by comprehensive transcriptome profiling in the developing rat hindbrain. BMC Dev. Biol.: 2010, 10();6 PMID:20082710 | BMC Dev. Biol.
  3. Maxime Bouchard, Dominique de Caprona, Meinrad Busslinger, Pinxian Xu, Bernd Fritzsch Pax2 and Pax8 cooperate in mouse inner ear morphogenesis and innervation. BMC Dev. Biol.: 2010, 10();89 PMID:20727173 | PMC2939565 | BMC Dev Biol.
  4. Christof Nolte, Mojgan Rastegar, Angel Amores, Maxime Bouchard, David Grote, Richard Maas, Erzsebet Nagy Kovacs, John Postlethwait, Isabel Rambaldi, Sheldon Rowan, Yi-Lin Yan, Feng Zhang, Mark Featherstone Stereospecificity and PAX6 function direct Hoxd4 neural enhancer activity along the antero-posterior axis. Dev. Biol.: 2006, 299(2);582-93 PMID:17010333
  5. D Lang, F Chen, R Milewski, J Li, M M Lu, J A Epstein Pax3 is required for enteric ganglia formation and functions with Sox10 to modulate expression of c-ret. J. Clin. Invest.: 2000, 106(8);963-71 PMID:11032856
  6. M Schwarz, G Alvarez-Bolado, P Urbánek, M Busslinger, P Gruss Conserved biological function between Pax-2 and Pax-5 in midbrain and cerebellum development: evidence from targeted mutations. Proc. Natl. Acad. Sci. U.S.A.: 1997, 94(26);14518-23 PMID:9405645
  7. Nicole L Washington, Melissa A Haendel, Christopher J Mungall, Michael Ashburner, Monte Westerfield, Suzanna E Lewis Linking human diseases to animal models using ontology-based phenotype annotation. PLoS Biol.: 2009, 7(11);e1000247 PMID:19956802 | PLoS Biol.
  8. Beatriz Sosa-Pineda The gene Pax4 is an essential regulator of pancreatic beta-cell development. Mol. Cells: 2004, 18(3);289-94 PMID:15650323
  9. K A Balczarek, Z C Lai, S Kumar Evolution of functional diversification of the paired box (Pax) DNA-binding domains. Mol. Biol. Evol.: 1997, 14(8);829-42 PMID:9254921
  10. Barbara Murdoch, Casey DelConte, Martín I García-Castro Pax7 lineage contributions to the mammalian neural crest. PLoS ONE: 2012, 7(7);e41089 PMID:22848431 | PMC2634972 | PLoS One.
  11. Asma Almaidhan, Jeffry Cesario, Andre Landin Malt, Yangu Zhao, Neeti Sharma, Veronica Choi, Juhee Jeong Neural crest-specific deletion of Ldb1 leads to cleft secondary palate with impaired palatal shelf elevation. BMC Dev. Biol.: 2014, 14(1);3 PMID:24433583 | BMC Dev Biol.

Search Bookshelf Pax


Margaret Buckingham, Frédéric Relaix The role of Pax genes in the development of tissues and organs: Pax3 and Pax7 regulate muscle progenitor cell functions. Annu. Rev. Cell Dev. Biol.: 2007, 23();645-73 PMID:17506689

A Mansouri, G Goudreau, P Gruss Pax genes and their role in organogenesis. Cancer Res.: 1999, 59(7 Suppl);1707s-1709s; discussion 1709s-1710s PMID:10197584

Search Pubmed

Search Pubmed Now: Pax

External Links

Glossary Links

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols

Cite this page: Hill, M.A. (2014) Embryology Developmental Signals - Pax. Retrieved April 23, 2014, from

What Links Here?
Dr Mark Hill 2014, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
Personal tools

Human Embryo