Paired box (Pax) genes are a family of tissue specific transcription factors containing a PAIRED domain and usually a partial or complete homeodomain. An octapeptide may also be present. Pax proteins are important in early animal development for the specification of specific tissues, as well as during epimorphic limb regeneration in animals capable of such.
Additional recommended knowledge
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).
Orthologous genes exist throughout the Metazoa, including extensive study of the ectopic expression in Drosophila using murine Pax6.
Members
- 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 amino acid protein from 4 exons and 1,323bps in humans.
- PAX2 has been identified with kidney and optic nerve development. It transcribes a 417 amino acid protein from 11 exons and 4,261 bps in humans. Mutation of PAX2 in humans has been associated with renal-coloboma syndrome as well as oligomeganephronia.[1]
- PAX3 has been identified with ear, eye and facial development. It transcribes a 479 amino acid protein in humans. Mutations in it can cause Waardenburg syndrome.
- PAX4 has been identified with pancreatic islet beta cells. It transcribes a 350 amino acid protein from 9 exons and 2,010 bps in humans.
- PAX5 has been identified with neural and spermatogenesis development and b-cell differentiation. It transcribes a 391 amino acid protein from 10 exons and 3,644bps in humans.
- PAX6 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 homologous structures, usually derived from ectodermal tissues.
- PAX7 has been possibly associated with myogenesis. It transcribes a protein of 520 amino acids from 8 exons and 2,260bps in humans. PAX7 is required for the developmental specification of satellite cells in skeletal muscle.
- PAX8 has been associated with thyroid specific expression. It transcribes a protein of 451 amino acids from 11 exons and 2,526bps in humans.
- 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 1,644bps in humans.
See also
References
Further reading
- Zuker, Charles S. (Aug 1994). "On the evolution of eyes: would you like it simple or compound?". Science 265 (5173). PMID 8047881.
- Quiring, Rebecca; Walldorf, Uwe; Kloter U; Gehring WJ (Aug 1994). "Homology of the eyeless gene of Drosophila to the small eye gene in mice and Aniridia in humans.". Science 265 (5173). PMID 7914031.
| Transcription factors and intracellular receptors |
|---|
| (1) Basic domains |
| (1.1) Basic leucine zipper (bZIP) |
Activating transcription factor (1, 2, 3, 4, 5, 6) • AP-1 (c-Fos, FOSB, FOSL1, FOSL2, c-Jun, JUNB, JUND) • BACH (1, 2) • C/EBP (α, β, γ, δ, ε, ζ) • CREB (1, 3) • GABPA • MAF (B, F, G, K) • NRL • NRF1 • XBP1 |
| (1.2) Basic helix-loop-helix (bHLH) |
ATOH1 • AhR • AHRR • ARNT • ASCL1 • BMAL (ARNTL, ARNTL2) • CLOCK • HIF (1A, 3A) • Myogenic regulatory factors (MyoD, Myogenin, MYF5, MYF6) • NEUROD1 • Twist • USF1 |
| (1.3) bHLH-ZIP |
Myc • MITF • SREBP (1, 2) |
| (1.6) Basic helix-span-helix (bHSH) |
AP-2 |
|
|---|
(2) Zinc finger
DNA-binding domains |
| (2.1) Nuclear receptor (Cys4) |
subfamily 1 (Thyroid hormone (α, β), CAR, FXR, LXR (α, β), PPAR (α, β/δ, γ), PXR, RAR (α, β, γ), ROR (α, β, γ), Rev-ErbA (α, β), VDR) • subfamily 2 (COUP-TF (I, II), Ear-2, HNF4 (α, γ), PNR, RXR (α, β, γ), Testicular receptor (2, 4), TLX) • subfamily 3 (Steroid hormone (Estrogen (α, β), Estrogen related (α, β, γ), Androgen, Glucocorticoid, Mineralocorticoid, Progesterone)) • subfamily 4 NUR (NGFIB, NOR1, NURR1) • subfamily 5 (LRH-1, SF1) • subfamily 6 (GCNF) • subfamily 0 (DAX1, SHP) |
| (2.2) Other Cys4 |
GATA (1, 2, 3, 4, 5, 6) |
| (2.3) Cys2His2 |
General transcription factors (TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH: 1, 2) • GLI-Krüppel family (1, 2, 3, YY1) • KLF (2, 4, 5, 6, 10, 11, 12, 13) • Sp1 • zinc finger (3, 35, 43, 146, 148, 165, 217, 268, 281, 350) • Zbtb7 (7A) • ZBT (16, 17, 33) |
| (2.4) Cys6 |
HIVEP1 |
|
|---|
(3) Helix-turn-helix
domains |
| (3.1) Homeo domain |
ARX • Homeobox (A1, A3, A4, A5, A7, A9, A10, A11, A13, B1, B2, B3, B4, B5, B6, B7, B8, B9, B13, C4, C6, C8, C9, C13, D1, D3, D4, D9, D10, D11, D12, D13) • NANOG • NKX (2-1, 2-5, 3-1) • POU domain (PIT-1, BRN-3: 1, 2, Octamer transcription factor: 1, 2, 3/4, 6, 7) |
| (3.2) Paired box |
PAX (1, 2, 3, 4, 5, 6, 7, 8, 9) |
| (3.3) Fork head / winged helix |
E2F (1, 2, 3, 4, 5) • FOX proteins (C1, C2, E1, G1, H1, L2, M1, N3, O3, O4, P1, P2, P3) |
| (3.4) Heat Shock Factors |
HSF1 |
| (3.5) Tryptophan clusters |
ELF (4, 5) • Interferon regulatory factors (1, 2, 3, 4, 5, 6, 7, 8) • MYB |
| (3.6) TEA domain |
transcriptional enhancer factor 1, 2 |
|
|---|
(4) β-Scaffold factors with
minor groove contacts |
| (4.1) Rel homology region |
NF-κB (NFKB1, NFKB2, REL, RELA, RELB) • NFAT (5, C1, C2, C3, C4) |
| (4.2) STAT |
STAT (1, 2, 3, 4, 5, 6) |
| (4.3) p53 |
p53 |
| (4.4) MADS box |
Mef2 (A, B, C, D) • SRF |
| (4.7) High mobility group |
HNF (1A, 1B) • LEF1 • SOX (3, 4, 6, 9, 10, 13, 18) • SRY • SSRP1 |
| (4.10) Cold-shock domain |
CSDA |
| (4.11) Runt |
CBF (RUNX1, RUNX2, RUNX3) |
|
|---|
(0) Other
transcription factors |
| (0.2) HMGI(Y) |
HMGA (1, 2) |
| (0.3) Pocket domain |
Rb • RBL1 • RBL2 |
| (0.6) Miscellaneous |
ARID (1A, 1B, 2, 3A, 3B, 4A) • CAP • Rho/Sigma • R-SMAD |
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