title: Interaction of E2F-Rb family members with corepressors binding to the adjacent E2F site.
abstract: Cell cycle-dependent transcriptional repression of the E2F1 and B-myb promoters is mediated through E2F-binding sites and adjacent corepressor site (cell cycle gene homology region (CHR)/downstream repression site (DRS)). Here, we show that a factor binding to the B-myb CHR is co-purified with E2F DNA-binding activity, and coimmunoprecipitated with components of E2F/Rb-family repressor complexes, E2F4 and retinoblastoma (Rb) family proteins. In spite of structural and functional similarities, however, the E2F1 and B-myb CHRs exhibited distinct factor-binding specificities. Furthermore, substitution of E2F1 CHR with the B-myb CHR in the E2F1 promoter revealed that the B-myb CHR was unable to repress the E2F1 promoter completely in the G0 phase. These results suggest that transcriptional repression of the E2F1 and B-myb promoters is mediated by physical interaction of E2F/Rb-family repressor complexes with promoter-specific corepressors.
authors.affiliation: Section of Oral and Maxillofacial Surgery, Graduate School, Tokyo Medical and Dental University, Tokyo 113-8549, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Shumpei
authors.initials: S
authors.lastname: Yamada
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kamata
authors.forename: Masa-aki
authors.initials: MA
authors.lastname: Ikeda
mesh_terms: D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D050684:E2F Transcription Factors / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D051379:Mice; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: D050684:E2F Transcription Factors; D012097:Repressor Proteins; D016160:Retinoblastoma Protein