HGNC Approved Gene Symbol: E2F4
Cytogenetic location: 16q22.1 Genomic coordinates (GRCh38): 16:67,192,155-67,198,918 (from NCBI)
The transcription factor E2F (see E2F1, 189971) was identified as a DNA-binding protein required for transcription of the adenovirus E2A promoter. The E2F binding site is also present in many growth-responsive and growth-promoting genes. E2F family members, such as E2F4, regulate these genes, in part, through their interaction with other cellular proteins, including the nuclear pocket proteins RB1 (614041), p107 (116957), and p130 (180203) (Ginsberg et al., 1994).
Ginsberg et al. (1994) isolated a distinct E2F-related PCR product that was used as a probe to screen cDNA libraries. The cDNA identified encodes a 2.2-kb RNA and has a predicted protein of 411 to 416 amino acids depending on the number of serine-encoding CAG repeats present in the transcript. The protein, designated E2F4, has many of the structural domains present in other E2F family members. Northern blot analysis showed that the gene was expressed in all tissues examined.
Ginsberg et al. (1994) localized the E2F4 gene to chromosome 16q22.1 by fluorescence in situ hybridization.
Ginsberg et al. (1994) noted that a member of the E2F family, DP-1 (189902), forms heterodimers with E2F1 that stimulate the DNA-binding and RB1-binding action of E2F1. They found that E2F4, like E2F1, formed heterodimers with DP-1. Coexpression of E2F1 and E2F4 gave markedly higher levels of transcription from an E2-CAT reporter gene. However, Ginsberg et al. (1994) showed that, unlike other members of the E2F family, E2F4 interacted with p107 in vivo and that the interaction diminished E2F4's transactivating capacity. This interaction also diminished E2F4's transforming activity in U2OS cells. Like other E2F family members, E2F4 also interacted with RB1 in vivo, although with lower affinity than it did with p107.
Sardet et al. (1995) cloned E2F4 from a human fibroblast library using the 2 hybrid system with p130 as bait. Unlike E2F1, E2F4 and E2F5 (600967) did not bind with the retinoblastoma gene product, RB1. In synchronized keratinocytes, E2F4 and E2F5 transcription was highest in mid-G1 phase and prior to that of E2F1.
MYC (190080) induces transcription of the E2F1, E2F2 (600426), and E2F3 (600427) genes. Using primary mouse embryo fibroblasts deleted for individual E2f genes, Leone et al. (2001) showed that MYC-induced S phase and apoptosis required distinct E2F activities. The ability of Myc to induce S phase was impaired in the absence of either E2f2 or E2f3, but not E2f1 or E2f4. In contrast, the ability of Myc to induce apoptosis was markedly reduced in cells deleted for E2f1, but not E2f2 or E2f3. The authors proposed that the induction of specific E2F activities is an essential component in the MYC pathways that control cell proliferation and cell fate decisions.
SMAD3 (603109) is a direct mediator of transcriptional activation by the TGF-beta (190180) receptor (see 190181). Its target genes in epithelial cells include cyclin-dependent kinase (CDK; see 116953) inhibitors that generate a cytostatic response. Chen et al. (2002) defined how, in the same context, SMAD3 can mediate transcriptional repression of the growth-promoting gene MYC. A complex containing SMAD3, the transcription factors E2F4, E2F5, and DP1, and the corepressor p107 preexists in the cytoplasm. In response to TGF-beta, this complex moves into the nucleus and associates with SMAD4 (600993), recognizing a composite SMAD-E2F site on MYC for repression. Previously known as the ultimate recipients of CDK regulatory signals, E2F4/E2F5 and p107 act here as transducers of TGF-beta receptor signals upstream of CDK. SMAD proteins therefore mediate transcriptional activation or repression depending on their associated partners.
Fajas et al. (2002) concluded that the E2F1 and E2F4 proteins play a direct role in the regulation of early adipocyte differentiation. Using electrophoretic mobility shift assays and immunoprecipitation experiments, Fajas et al. (2002) demonstrated that E2F family members bind in vitro and in vivo to the PPARG (601487) promoter. Using a combination of in vitro experiments and in vivo experiments with knockout and chimeric mice, Fajas et al. (2002) demonstrated that depletion of E2F4 stimulated adipogenesis. They concluded that E2F4 represses PPARG expression during terminal adipocyte differentiation.
By analyzing data from chromatin immunoprecipitation-sequencing and -microarray analyses in mouse embryonic stem cells, Gokhman et al. (2013) identified E2f1 and E2f4 as master regulators of histone gene expression. These 2 factors bound all histone genes examined.
Humbert et al. (2000) generated a mutant mouse model to assess the in vivo role of the predominant E2F family member, E2F4. Loss of E2f4 had no detectable effect on either cell cycle arrest or proliferation. However, E2f4 was essential for normal development. E2f4 -/- mice died of an increased susceptibility to opportunistic infections that appeared to result from craniofacial defects. They also displayed a variety of erythroid abnormalities that arose from a cell-autonomous defect in late-stage maturation. These findings suggested that E2F4 makes a major contribution to the control of erythrocyte development by the RB tumor suppressor.
Rempel et al. (2000) also generated mice deficient in E2f4 activity. Analysis of newborn pups deficient in E2f4 revealed abnormalities in hematopoietic lineage development as well as defects in the development of the gut epithelium. Specifically, the authors observed a deficiency of various mature hematopoietic cell types together with an increased number of immature cells in several lineages. This was associated with an increased frequency of apoptotic cells. Rempel et al. (2000) also found a substantial reduction in the thickness of the gut epithelium that normally gives rise to crypts as well as a reduction in the density of villi.
Gaubatz et al. (2000) reported that simultaneous inactivation of E2f4 and E2f5 in mice resulted in neonatal lethality, suggesting that E2f4 and E2f5 perform overlapping functions during mouse development. Embryonic fibroblasts isolated from these mice proliferated normally and reentered from G0 with normal kinetics compared to wildtype cells; however, they failed to arrest in G1 in response to p16INK4A (CDKN2A; 600160). Thus, the authors concluded that E2F4 and E2F5 are dispensable for cell cycle progression but necessary for pocket protein-mediated G1 arrest of cycling cells.
Chen, C.-R., Kang, Y., Siegel, P. M., Massague, J. E2F4/5 and p107 as Smad cofactors linking the TGF-beta receptor to c-myc repression. Cell 110: 19-32, 2002. [PubMed: 12150994] [Full Text: https://doi.org/10.1016/s0092-8674(02)00801-2]
Fajas, L., Landsberg, R. L., Huss-Garcia, Y., Sardet, C., Lees, J. A., Auwerx, J. E2Fs regulate adipocyte differentiation. Dev. Cell 3: 39-49, 2002. [PubMed: 12110166] [Full Text: https://doi.org/10.1016/s1534-5807(02)00190-9]
Gaubatz, S., Lindeman, G. J., Ishida, S., Jakoi, L., Nevins, J. R., Livingston, D. M., Rempel, R. E. E2F4 and E2F5 play an essential role in pocket protein-mediated G1 control. Molec. Cell 6: 729-735, 2000. [PubMed: 11030352] [Full Text: https://doi.org/10.1016/s1097-2765(00)00071-x]
Ginsberg, D., Vairo, G., Chittenden, T., Xiao, Z.-X., Xu, G., Wydner, K. L., DeCaprio, J. A., Lawrence, J. B., Livingston, D. M. E2F-4, a new member of the E2F transcription factor family, interacts with p107. Genes Dev. 8: 2665-2679, 1994. [PubMed: 7958924] [Full Text: https://doi.org/10.1101/gad.8.22.2665]
Gokhman, D., Livyatan, I., Sailaja, B. S., Melcer, S., Meshorer, E. Multilayered chromatin analysis reveals E2f, Smad and Zfx as transcriptional regulators of histones. Nature Struct. Molec. Biol. 20: 119-126, 2013. [PubMed: 23222641] [Full Text: https://doi.org/10.1038/nsmb.2448]
Humbert, P. O., Rogers, C., Ganiatsas, S., Landsberg, R. L., Trimarchi, J. M., Dandapani, S., Brugnara, C., Erdman, S., Schrenzel, M., Bronson, R. T., Lees, J. A. E2F4 is essential for normal erythrocyte maturation and neonatal viability. Molec. Cell 6: 281-291, 2000. [PubMed: 10983976] [Full Text: https://doi.org/10.1016/s1097-2765(00)00029-0]
Leone, G., Sears, R., Huang, E., Rempel, R., Nuckolls, F., Park, C.-H., Giangrande, P., Wu, L., Saavedra, H. I., Field, S. J., Thompson, M. A., Yang, H., Fujiwara, Y., Greenberg, M. E., Orkin, S., Smith, C., Nevins, J. R. Myc requires distinct E2F activities to induce S phase and apoptosis. Molec. Cell 8: 105-113, 2001. [PubMed: 11511364] [Full Text: https://doi.org/10.1016/s1097-2765(01)00275-1]
Rempel, R. E., Saenz-Robles, M. T., Storms, R., Morham, S., Ishida, S., Engel, A., Jakoi, L., Melhem, M. F., Pipas, J. M., Smith, C., Nevins, J. R. Loss of E2F4 activity leads to abnormal development of multiple cellular lineages. Molec. Cell 6: 293-306, 2000. [PubMed: 10983977] [Full Text: https://doi.org/10.1016/s1097-2765(00)00030-7]
Sardet, C., Vidal, M., Cobrinik, D., Geng, Y., Onufryk, C., Chen, A., Weinberg, R. A. E2F-4 and E2F-5, two members of the E2F family, are expressed in the early phases of the cell cycle. Proc. Nat. Acad. Sci. 92: 2403-2407, 1995. [PubMed: 7892279] [Full Text: https://doi.org/10.1073/pnas.92.6.2403]