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Forkhead box O4
Protein MLLT7 PDB 1e17.png
PDB rendering based on 1e17.
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols FOXO4 ; AFX; AFX1; MLLT7
External IDs OMIM300033 MGI1891915 HomoloGene4342 GeneCards: FOXO4 Gene
RNA expression pattern
PBB GE MLLT7 205451 at tn.png
More reference expression data
Species Human Mouse
Entrez 4303 54601
Ensembl ENSG00000184481 ENSMUSG00000042903
UniProt P98177 Q9WVH3
RefSeq (mRNA) NM_001170931 NM_018789
RefSeq (protein) NP_001164402 NP_061259
Location (UCSC) Chr X:
71.1 – 71.1 Mb
Chr X:
101.25 – 101.26 Mb
PubMed search [1] [2]

Forkhead box protein O4 is a protein that in humans is encoded by the FOXO4 gene.[1][2] It is located on the long arm of the X chromosome from base pair 71,096,148 to 71,103,533.[3]

Structure and function[edit]

FOXO4 is a member of the forkhead family transciption factors O subclass, which is characterized by a winged helix domain used for DNA binding.[4][5] There are 4 members of the FOXO family, including FOXO1, FOXO3, and FOXO6. Their activity is modified by many post translational activities, such as phosphorylation, ubiquitination, and acetylation.[6] Depending on this modified state, FOXO4 binding affinity for DNA is altered, allowing for FOXO4 to regulate many cellular pathways including oxidative stress signaling, longevity, insulin signaling, cell cycle progression, and apoptosis.[7][8][9][10][11] Two of the main upstream regulators of FOXO4 activity are phosphoinositide 3- kinase (PI3K) and serine/threonine kinase AKT/PKB.[12][13] Both PI3K and AKT modify FOXO4 and prevent it from translocating to the nucleus, effectively preventing the transcription of the downstream FOXO targets.

Clinical significance[edit]

Associations with longevity[edit]

FOXO transcription factors have been shown to be the down downstream effector molecules of insulin-like growth factor (IGF) signaling pathway. In the absence of insulin, PI3K is inactive, so the FOXO homolog daf-16 is able to translocate to the nucleus and turn on many genetic pathways associated with longevity in the roundworm Caenorhabditis elegans.[14] FOXO’s ability to restrict this pathway produces an increase in lifespan for worms, flies, mice; similar variants of FOXO3a have been associated with longer human lives as well.[15][16]


Many different kinds of cancers have been observed to contain mutations that promote AKT phosphorylation, and thus the inactivation of FOXOs, effectively preventing proper cell cycle regulation.[17][18][19] FOXO4 activates the cell cycle dependent kinase inhibitor, P27, which in turn prevents tumors from progressing into G1.[20] In HER-2 positive tumor cells, increasing FOXO4 activity reduces tumor size.[20] Chromosomal translocations of FOXO4 have been shown to be a cause of acute leukemia.[21] The fusion proteins formed by these translocations lack the DNA-binding domain, causing the protein to lose function.[21]

In gastric cancers (GC), it has been observed that there were lower levels of FOXO4 mRNA in cancers that had already progressed to invading lymph nodes compared to cancers that remained in situ.[22] When compared to normal tissue, all GC epithelia had lower levels of FOXO4 located in the nucleus, consistent with less FOXO4 effector activity and FOXO4’s function as a suppressor of carcinogenic properties. It does this by causing cell cycle arrest between the Go and S phases, preventing cell proliferation, as well as by inhibiting metastasis by downregulating vimentin.[23] These results are consistent with FOXO4 providing a role in inhibiting the epithelia to mesenchymal transition (EMT).

In non-small cell lung carcinoma, there are varying levels of FOXO4 expressed that correspond to how the cancer was staged; worse cases had the lowest amount of FOXO4 while less severe cases had higher levels of FOXO4.[24] As with gastric cancer, these cancers with the lowest levels of FOXO4 also had the lowest levels of E-cadherin and highest levels of vimentin, consistent with FOXO4 acting as a suppressor of the EMT phenotype.[24]


FOXO4 has been shown to interact with PIN1[25] and Mdm2.[26]

See also[edit]


  1. ^ Parry P, Wei Y, Evans G (Feb 1995). "Cloning and characterization of the t(X;11) breakpoint from a leukemic cell line identify a new member of the forkhead gene family". Genes Chromosomes Cancer 11 (2): 79–84. doi:10.1002/gcc.2870110203. PMID 7529552. 
  2. ^ "Entrez Gene: MLLT7 myeloid/lymphoid or mixed-lineage leukemia (trithorax homolog, Drosophila); translocated to, 7". 
  3. ^
  4. ^ Weigel D, Jäckle H (Nov 1990). "The fork head domain: a novel DNA binding motif of eukaryotic transcription factors?". Cell 63 (3): 455–456. PMID 2225060. 
  5. ^ Kaestner KH, Knochel W, Martinez DE (Jan 2000). "Unified nomenclature for the winged helix/forkhead transcription factors". Genes & Development 14 (2): 142–146. PMID 10702024. 
  6. ^ van der Horst A, Burgering BM (Jun 2007). "Stressing the role of FoxO proteins in lifespan and disease". Nature Reviews. Molecular Cell Biology 8 (6): 440–450. doi:10.1038/nrm2190. PMID 17522590. 
  7. ^ van der Heide LP, Jacobs FM, Burbach JP, Hoekman MF, Smidt MP (Nov 2005). "FoxO6 transcriptional activity is regulated by Thr26 and Ser184, independent of nucleo-cytoplasmic shuttling". The Biochemical Journal 391 (Pt 3): 623–629. doi:10.1042/BJ20050525. PMID 15987244. 
  8. ^ Matsuzaki H, Daitoku H, Hatta M, Aoyama H, Yoshimochi K, Fukamizu A (Aug 2005). "Acetylation of Foxo1 alters its DNA-binding ability and sensitivity to phosphorylation". Proceedings of the National Academy of Sciences of the United States of America 102 (32): 11278–11283. doi:10.1073/pnas.0502738102. PMID 16076959. 
  9. ^ Boura E, Silhan J, Herman P, Vecer J, Sulc M, Teisinger J, Obsilova V, Obsil T (Mar 2007). "Both the N-terminal loop and wing W2 of the forkhead domain of transcription factor Foxo4 are important for DNA binding". The Journal of Biological Chemistry 282 (11): 8265–8275. doi:10.1074/jbc.M605682200. PMID 17244620. 
  10. ^ Tsai KL, Sun YJ, Huang CY, Yang JY, Hung MC, Hsiao CD. "Crystal structure of the human FOXO3a-DBD/DNA complex suggests the effects of post-translational modification". Nucleic Acids Research 35 (20): 6984–6994. doi:10.1093/nar/gkm703. PMID 17940099. 
  11. ^ Brent MM, Anand R, Marmorstein R (Sep 2008). "Structural basis for DNA recognition by FoxO1 and its regulation by posttranslational modification". Structure 16 (9): 1407–16. doi:10.1016/j.str.2008.06.013. PMID 18786403. 
  12. ^ Manning BD, Cantley LC (Jun 2007). "AKT/PKB signaling: navigating downstream". Cell 129 (7): 261–1274. doi:10.1016/j.cell.2007.06.009. PMID 17604717. 
  13. ^ Calnan DR, Brunet A (Apr 2008). "The FoxO code". Oncogene 27 (16): 2276–2288. doi:10.1038/onc.2008.21. PMID 18391970. 
  14. ^ Neumann-Haefelin E, Qi W, Finkbeiner E, Walz G, Baumeister R, Hertweck M (Oct 2008). "SHC-1/p52Shc targets the insulin/IGF-1 and JNK signaling pathways to modulate life span and stress response in C. elegans". Genes & Development 22 (19): 2721–2735. doi:10.1101/gad.478408. PMID 18832074. 
  15. ^ Kenyon C, Chang J, Gensch E, Rudner A, Tabtiang R (Dec 1993). "A C. elegans mutant that lives twice as long as wild type". Nature 366 (6454): 461–464. doi:10.1038/366461a0. PMID 8247153. 
  16. ^ Willcox BJ, Donlon TA, He Q, Chen R, Grove JS, Yano K, Masaki KH, Willcox DC, Rodriguez B, Curb JD (Sep 2008). "FOXO3A genotype is strongly associated with human longevity". Proceedings of the National Academy of Sciences of the United States of America 105 (37): 13987–13992. doi:10.1073/pnas.0801030105. PMID 18765803. 
  17. ^ Li J, Yen C, Liaw D, Podsypanina K, Bose S, Wang SI, Puc J, Miliaresis C, Rodgers L, McCombie R, Bigner SH, Giovanella BC, Ittmann M, Tycko B, Hibshoosh H, Wigler MH, Parsons R (Mar 1997). "PTEN, a putative protein tyrosine phosphatase gene mutated in human brain, breast, and prostate cancer". Science 275 (5308): 1943–1947. PMID 9072974. 
  18. ^ Samuels Y, Wang Z, Bardelli A, Silliman N, Ptak J, Szabo S, Yan H, Gazdar A, Powell SM, Riggins GJ, Willson JK, Markowitz S, Kinzler KW, Vogelstein B, Velculescu VE (Apr 2004). "High frequency of mutations of the PIK3CA gene in human cancers". Science 304 (5670): 554. doi:10.1126/science.1096502. PMID 15016963. 
  19. ^ Saal LH, Holm K, Maurer M, Memeo L, Su T, Wang X, Yu JS, Malmström PO, Mansukhani M, Enoksson J, Hibshoosh H, Borg A, Parsons R (Apr 2005). "PIK3CA mutations correlate with hormone receptors, node metastasis, and ERBB2, and are mutually exclusive with PTEN loss in human breast carcinoma". Cancer Research 65 (7): 2554– 2559. doi:10.1158/0008-5472-CAN-04-3913. PMID 15805248. 
  20. ^ a b Yang H, Zhao R, Yang HY, Lee MH (Mar 2005). "Constitutively active FOXO4 inhibits Akt activity, regulates p27 Kip1 stability, and suppresses HER2-mediated tumorigenicity". Oncogene 24 (11): 1924–35. doi:10.1038/sj.onc.1208352. PMID 15688030. 
  21. ^ a b Paik JH, Kollipara R, Chu G, Ji H, Xiao Y, Ding Z, Miao L, Tothova Z, Horner JW, Carrasco DR, Jiang S, Gilliland DG, Chin L, Wong WH, Castrillon DH, DePinho RA (Jan 2007). "FoxOs are lineage-restricted redundant tumor suppressors and regulate endothelial cell homeostasis". Cell 128 (2): 309–323. doi:10.1016/j.cell.2006.12.029. PMID 17254969. 
  22. ^ Liu X, Zhang Z, Sun L, Chai N, Tang S, Jin J, Hu H, Nie Y, Wang X, Wu K, Jin H, Fan D (Dec 2011). "MicroRNA-499-5p promotes cellular invasion and tumor metastasis in colorectal cancer by targeting FOXO4 and PDCD4". Carcinogenesis 32 (12): 1798–1805. doi:10.1093/carcin/bgr213. PMID 21934092. 
  23. ^ Su L, Liu X, Chai N, Lv L, Wang R, Li X, Nie Y, Shi Y, Fan D. "The transcription factor FOXO4 is down-regulated and inhibits tumor proliferation and metastasis in gastric cancer". BMC Cancer 14: 378. doi:10.1186/1471-2407-14-378. PMID 24886657. 
  24. ^ a b Xu MM, Mao GX, Liu J, Li JC, Huang H, Liu YF, Liu JH. "Low expression of the FoxO4 gene may contribute to the phenomenon of EMT in non-small cell lung cancer". Asian Pacific Journal of Cancer Prevention 15 (9): 4013–4018. PMID 24935588. 
  25. ^ Brenkman AB, de Keizer PL, van den Broek NJ, van der Groep P, van Diest PJ, van der Horst A, Smits AM, Burgering BM (Sep 2008). "The peptidyl-isomerase Pin1 regulates p27kip1 expression through inhibition of Forkhead box O tumor suppressors". Cancer Res. 68 (18): 7597–605. doi:10.1158/0008-5472.CAN-08-1059. PMID 18794148. 
  26. ^ Brenkman AB, de Keizer PL, van den Broek NJ, Jochemsen AG, Burgering BM (2008). Cookson MR, ed. "Mdm2 induces mono-ubiquitination of FOXO4". PLoS ONE 3 (7): e2819. doi:10.1371/journal.pone.0002819. PMC 2475507. PMID 18665269. 

Further reading[edit]

External links[edit]

This article incorporates text from the United States National Library of Medicine, which is in the public domain.