Forkhead box proteins (FOX proteins) are a family of transcription factors that play important roles in regulating the expression of genes involved in cell growth, proliferation, differentiation, and longevity. Many FOX proteins are important to embryonic development.
The defining feature of FOX proteins is the forkhead box, a sequence of 80 to 100 amino acids forming a motif that binds to DNA. This forkhead motif is also known as the winged helix due to the butterfly-like appearance of the loops in the protein structure of the domain.[1] Forkhead genes are a subgroup of the helix-turn-helix class of proteins.
Additional recommended knowledge
Biological roles
Many other genes encoding FOX proteins have been identified. For example,
the FOXF2 gene encodes forkhead box F2, one of many human homologues of the Drosophila melanogaster transcription factor forkhead. FOXF2 is expressed in lung and placenta.
Some FOX genes are downstream targets of the hedgehog signaling pathway, which plays a role in the development of basal cell carcinomas.
History
The first protein in the FOX family that was discovered was the fork head transcription factor in Drosophila (thus the name). Since then a large number of family members have been discovered, especially in vertebrates. Originally they were given vastly different names (such as HFH, FREAC, and fkh), but in 2000 a unified nomenclature was introduced that grouped the FOX proteins into subclasses (FOXA-FOXS) based on sequence conservation.[2]
Genes
- FOXA1, FOXA2, FOXA3 (See also Hepatocyte nuclear factors)
- FOXB1, FOXB2
- FOXC1, FOXC2
- FOXD1, FOXD2, FOXD3, FOXD4, FOXD5, FOXPD6
- FOXE1, FOXE2, FOXE3
- FOXF1, FOXF2
- FOXG1
- FOXH1
- FOXI1, FOXI2
- FOXJ1, FOXJ2, FOXJ3
- FOXK1, FOXK2
- FOXL1, FOXL2
- FOXM1
- FOXN1, FOXN2, FOXN3, FOXN4
- FOXO1, FOXO2, FOXO3, FOXO4
- FOXP1, FOXP2, FOXP3, FOXP4
- FOXQ1
- FOXR1, FOXR2
References
- ^ Lehmann OJ, Sowden JC, Carlsson P, Jordan T, Bhattacharya SS (2003). "Fox's in development and disease". TRENDS in Genetics 19 (6): 339-344. PMID 12801727.
- ^ Kaestner KH, Knochel W, Martinez DE (2000). "Unified nomenclature for the winged helix/forkhead transcription factors.". Genes and Development 14: 142-146. PMID 10702024.
Further reading
- Tuteja G, Kaestner KH (2007). "SnapShot: Forkhead Transcription Factors I.". Cell 130: 1160-1160e1.
- Tuteja G, Kaestner KH (2007). "SnapShot: Forkhead Transcription Factors II.". Cell 131: 192-192e1.
Transcription factors and intracellular receptors |
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(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 |
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(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 |
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(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 |
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(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) |
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(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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