title: Regulation of the cyclin D3 promoter by E2F1.
abstract: We have previously demonstrated that ectopic expression of E2F1 is sufficient to drive quiescent cells into S phase and that E2F1 expression can contribute to oncogenic transformation. Key target genes in this process include master regulators of the cell cycle, such as cyclin E, which regulates G(1) progression, and cyclin A, which is required for the initiation of DNA synthesis. In the present work, we present novel evidence that a second G(1) cyclin, cyclin D3, is also potently activated by E2F1. First, an estrogen receptor-E2F1 fusion protein (ER-E2F1) potently activates the endogenous cyclin D3 mRNA upon treatment with 4-hydroxytamoxifen, which induces nuclear accumulation of the otherwise cytosolic fusion protein. Furthermore, trans-activation of cyclin D3 by ER-E2F1 occurs even in the presence of the protein synthesis inhibitor cycloheximide and thus appears direct. Second, all of the growth-stimulatory members of the E2F family (E2F1, -2, and -3A) potently activate a cyclin D3 promoter reporter, whereas growth-restraining members of the family (E2F4, -5, and -6) have little effect. Third, recombinant E2F1 binds with high affinity to the cyclin D3 promoter in vitro. Fourth, chromatin immunoprecipitation assays demonstrate that endogenous E2F1 is associated with the cyclin D3 promoter in vivo. Finally, mapping experiments localize the essential E2F regulatory element of the cyclin D3 promoter to a noncanonical E2F site in the promoter between nucleotides -143 and -135 relative to the initiating methionine codon. We conclude that in addition to cyclins E and A, E2F family members can also activate one member of the D-type cyclins, further contributing to the ability of the stimulatory E2F family members to drive cellular proliferation.
authors.affiliation: Program in Molecular Oncology, H. Lee Moffitt Comprehensive Cancer Center, Tampa, Florida 33612, USA.
authors.forename: Yihong
authors.initials: Y
authors.lastname: Ma
authors.forename: Jing
authors.initials: J
authors.lastname: Yuan
authors.forename: Mei
authors.initials: M
authors.lastname: Huang
authors.forename: Richard
authors.initials: R
authors.lastname: Jove
authors.forename: W Douglas
authors.initials: WD
authors.lastname: Cress
mesh_terms: D018797:Cell Cycle Proteins; D002460:Cell Line; D056743:Cyclin D3; D016213:Cyclins / Q000235:genetics*; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D050704:E2F4 Transcription Factor; D016193:G1 Phase / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D011401:Promoter Regions, Genetic / Q000235:genetics*; D016196:S Phase / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*
chemical_list: C534696:CCND3 protein, human; D018797:Cell Cycle Proteins; D056743:Cyclin D3; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D050704:E2F4 Transcription Factor; C493762:E2F4 protein, human; D014157:Transcription Factors