View source for Biology:Pax genes

{{short description|Family of transcription factors}}
{{Pfam box
|Name=Paired domain
|image=PDB 1mdm EBI.jpg
|caption=[[Biology:PAX5|PAX5]] bound to DNA ({{PDB|1mdm}}).
|Symbol=PAX
|InterPro=IPR001523
|Pfam=PF00292
|PROSITE=PDOC00034
|SCOP=1pdn
|CATH=1pdn
|CDD=cd00131
}}
In [[Biology:Evolutionary developmental biology|evolutionary developmental biology]], '''Paired box''' ('''Pax''') '''genes''' are a family of [[Biology:Gene|gene]]s coding for tissue specific transcription factors containing an N-terminal '''paired domain''' and usually a partial, or in the case of four family members (PAX3, PAX4, PAX6 and PAX7),<ref>{{cite journal |last1=Chi |first1=N |last2=Epstein |first2=JA |title=Getting your Pax straight: Pax proteins in development and disease |journal=Trends in Genetics |date=January 2002|volume=18 |issue=1 |pages=41–7 |pmid=11750700 |doi=10.1016/s0168-9525(01)02594-x}}</ref> a complete homeodomain to the C-terminus. An octapeptide as well as a Pro-Ser-Thr-rich C terminus may also be present.<ref name="pmid10811620">{{cite journal |last1=Eberhard |first1=D |last2=Jiménez |first2=G |last3=Heavey |first3=B |last4=Busslinger |first4=M |title=Transcriptional repression by Pax5 (BSAP) through interaction with corepressors of the Groucho family. |journal=The EMBO Journal |date=15 May 2000 |volume=19 |issue=10 |pages=2292–303 |doi=10.1093/emboj/19.10.2292 |pmid=10811620|pmc=384353 }}</ref> Pax [[Biology:Protein|protein]]s are important in early animal development for the specification of specific tissues, as well as during epimorphic limb regeneration in animals capable of such.

The paired domain was initially described in 1987 as the "paired box" in the ''Drosophila'' protein paired (prd; {{UniProt|P06601}}).<ref name="pmid2877747">{{cite journal |last1=Bopp |first1=D |last2=Burri |first2=M |last3=Baumgartner |first3=S |last4=Frigerio |first4=G |last5=Noll |first5=M |title=Conservation of a large protein domain in the segmentation gene paired and in functionally related genes of Drosophila. |journal=Cell |date=26 December 1986 |volume=47 |issue=6 |pages=1033–40 |pmid=2877747|doi=10.1016/0092-8674(86)90818-4 |s2cid=21943167 }}</ref><ref name="pmid3123319">{{cite journal |last1=Baumgartner |first1=S |last2=Bopp |first2=D |last3=Burri |first3=M |last4=Noll |first4=M |title=Structure of two genes at the gooseberry locus related to the paired gene and their spatial expression during Drosophila embryogenesis. |journal=Genes & Development |date=December 1987 |volume=1 |issue=10 |pages=1247–67 |doi=10.1101/gad.1.10.1247 |pmid=3123319|doi-access=free }}</ref>

==Groups==
Within the mammalian family, there are four well defined groups of Pax genes. 
*Pax group 1 (Pax 1 and 9),
*Pax group 2 (Pax 2, 5 and 8),
*Pax group 3 (Pax 3 and 7) and
*Pax group 4 (Pax 4 and 6).

Two more families, Pox-neuro and Pax-α/β, exist in basal bilaterian species.<ref>{{cite journal |last1=Navet |first1=S |last2=Buresi |first2=A |last3=Baratte |first3=S |last4=Andouche |first4=A |last5=Bonnaud-Ponticelli |first5=L |last6=Bassaglia |first6=Y |title=The Pax gene family: Highlights from cephalopods. |journal=PLOS ONE |date=2017 |volume=12 |issue=3 |pages=e0172719 |doi=10.1371/journal.pone.0172719 |pmid=28253300 |pmc=5333810 |doi-access=free|bibcode=2017PLoSO..1272719N }}</ref><ref name="pmid25627710">{{cite journal |last1=Franke |first1=FA |last2=Schumann |first2=I |last3=Hering |first3=L |last4=Mayer |first4=G |title=Phylogenetic analysis and expression patterns of Pax genes in the onychophoran Euperipatoides rowelli reveal a novel bilaterian Pax subfamily. |journal=Evolution & Development |date=2015 |volume=17 |issue=1 |pages=3–20 |doi=10.1111/ede.12110 |pmid=25627710|s2cid=205095304 }}</ref> Orthologous genes exist throughout the Metazoa, including extensive study of the [[Biology:Ectopic expression|ectopic expression]] in Drosophila using murine Pax6.<ref name="pmid10461206">{{cite journal | vauthors = Gehring WJ, Ikeo K | title = Pax 6: mastering eye morphogenesis and eye evolution | journal = Trends in Genetics | volume = 15 | issue = 9 | pages = 371–7 | date = September 1999 | pmid = 10461206 | doi = 10.1016/S0168-9525(99)01776-X }}</ref> The two rounds of whole-genome duplications in vertebrate evolution is responsible for the creation of as many as 4 paralogs for each Pax protein.<ref name="shark">{{cite journal | vauthors = Ravi V, Bhatia S, Gautier P, Loosli F, Tay BH, Tay A, Murdoch E, Coutinho P, van Heyningen V, Brenner S, Venkatesh B, Kleinjan DA | title = Sequencing of Pax6 loci from the elephant shark reveals a family of Pax6 genes in vertebrate genomes, forged by ancient duplications and divergences | journal = PLOS Genetics | volume = 9 | issue = 1 | pages = e1003177 | date = 2013 | pmid = 23359656 | pmc = 3554528 | doi = 10.1371/journal.pgen.1003177 | doi-access = free }}</ref>

==Members==
* [[Biology:PAX1|PAX1]] has been identified in mice with the development of vertebrate and embryo segmentation, and some evidence this is also true in humans. It transcribes a 440 [[Chemistry:Amino acid|amino acid]] protein from 4 [[Biology:Exon|exon]]s and 1,323{{Not a typo|bps}} in humans. In the mouse Pax1 mutation has been linked to undulated mutant suffering from skeletal malformations.<ref>Balling et al., 1988</ref>
* [[Biology:PAX2|PAX2]] has been identified with kidney and optic nerve development. It transcribes a 417 amino acid protein from 11 exons and 4,261 {{Not a typo|bps}} in humans. Mutation of PAX2 in humans has been associated with renal-coloboma syndrome as well as oligomeganephronia.<ref>{{OMIM|167409}}</ref>
* [[Biology:PAX3|PAX3]] has been identified with ear, eye and facial development. It transcribes a 479 amino acid protein in humans. Mutations in it can cause [[Medicine:Waardenburg syndrome|Waardenburg syndrome]]. [[Biology:PAX3|PAX3]] is frequently expressed in [[Medicine:Melanoma|melanoma]]s<ref name="pmid20421967">{{cite journal | author = Medic S, Ziman M | editor1-last = Soyer | editor1-first = H. Peter | title = PAX3 Expression in Normal Skin Melanocytes and Melanocytic Lesions (Naevi and Melanomas) | journal = PLOS ONE | volume = 5 | issue = 4 | page = e9977 | date = April 2010| pmid = 20421967 | pmc = 2858648 | doi =  10.1371/journal.pone.0009977| bibcode = 2010PLoSO...5.9977M | doi-access = free }}</ref> and contributes to tumor cell survival.<ref name="pmid11221862">{{cite journal |vauthors=Scholl FA, Kamarashev J, Murmann OV, Geertsen R, Dummer R, Schäfer BW | title = PAX3 is expressed in human melanomas and contributes to tumor cell survival | journal = Cancer Res | volume = 61 | issue = 3 | pages = 823–6 | date = Feb 2001| pmid = 11221862}}</ref>
* [[Biology:PAX4|PAX4]] has been identified with pancreatic islet beta cells. It transcribes a 350 amino acid protein from 9 exons and 2,010 {{Not a typo|bps}} in humans. Knockout mice lacking Pax4 expression fail to develop insulin-producing cells.<ref>Sosa-Pineda et al., 1997</ref> Pax4 undergoes mutual reciprocal interaction with the transcription factor Arx to endow pancreatic endocrine cells with insulin and glucagon cells respectively<ref>Collombat et al, 2003</ref>
* [[Biology:PAX5|PAX5]] has been identified with neural and spermatogenesis development and b-cell differentiation. It transcribes a 391 amino acid protein from 10 exons and 3,644{{Not a typo|bps}} in humans.
* [[Biology:PAX6|PAX6]] (eyeless) is the most researched and appears throughout the literature as a "master control" gene for the development of eyes and sensory organs, certain neural and epidermal tissues as well as other [[Biology:Homology|homologous]] structures, usually derived from [[Biology:Ectoderm|ectoderm]]al tissues.<ref>Walter and Gruss, 1991</ref>
* [[Biology:PAX7|PAX7]] has been possibly associated with [[Biology:Myogenesis|myogenesis]]. It transcribes a protein of 520 amino acids from 8 exons and 2,260{{Not a typo|bps}} in humans.  PAX7 directs postnatal renewal  and propagation of myogenic satellite cells but not for the specification.<ref>{{cite journal | last1 = Oustanina | first1 = S | display-authors = etal   | year = 2004 | title = PAX7 directs postnatal renewal and propagation of myogenic satellite cells but not their specification | journal = The EMBO Journal | volume = 23 | issue = 16| pages = 3430–3439 | doi=10.1038/sj.emboj.7600346 | pmid=15282552 | pmc=514519}}</ref>
* [[Biology:PAX8|PAX8]] has been associated with [[Biology:Thyroid|thyroid]] specific expression. It transcribes a protein of 451 amino acids from 11 exons and 2,526{{Not a typo|bps}} in humans. Pax8 loss-of-function mutant mice lack follicular cells of the thyroid gland.<ref>Mansouri et al.,1998</ref>
* [[Biology:PAX9|PAX9]] has found to be associated with a number of organ and other skeletal developments, particularly teeth. It transcribes a protein of 341 amino acids from 4 exons and 1,644{{Not a typo|bps}} in humans.

==See also==
* [[Biology:Homeobox|Homeobox]]
* [[Biology:Evolutionary developmental biology|Evolutionary developmental biology]]
* [[Biology:Body plan|Body plan]]
* SOX genes

==References==
{{reflist}}

<ref>Mansouri A et al. 1996</ref>==Further reading==
{{refbegin}}
*{{cite journal|
last=Zuker|
first=Charles S.|
authorlink=Charles Zuker|
title=On the evolution of eyes: would you like it simple or compound?|
journal=Science|
volume=265|
issue=5173|date=August 1994|
pmid=8047881|
doi=10.1126/science.8047881|
pages=742–3
|
bibcode=1994Sci...265..742Z}}
*{{cite journal|
last=Quiring|
first=Rebecca|author2=Walldorf, Uwe |author3=Kloter U |author4= Gehring WJ |
title=Homology of the eyeless gene of Drosophila to the small eye gene in mice and Aniridia in humans.|
journal=Science|
volume=265|
issue=5173|date=August 1994|
pmid=7914031|
doi=10.1126/science.7914031|
pages=785–9
|
bibcode=1994Sci...265..785Q}}
{{refend}}

==External links==
*[https://web.archive.org/web/20120827093742/http://www.jyi.org/volumes/volume1/issue1/articles/friedman.html A Review of the Highly Conserved PAX6 Gene in Eye Development Regulation]
* [http://www.expasy.org/cgi-bin/nicedoc.pl?PDOC00034 Paired domain] in [[Biology:PROSITE|PROSITE]]
* {{MeshName|Pax+Transcription+Factors}}

{{Transcription factors|g3}}
{{genarch}}
{{InterPro content|IPR001523}}

[[Category:Developmental genes and proteins]]
[[Category:Transcription factors]]

{{Sourceattribution|Pax genes}}