title: Role of pRB-family/E2F complex in the inhibition of IL-3-dependent lymphoid cell proliferation.
abstract: Interleukin 3 (IL-3)-dependent proliferation of haematopoietic cells is specifically inhibited by p130, a member of the pRB-family proteins. p130 interacts with the cell-cycle regulatory E2F transcription factors, notably E2F-4 and E2F-5, and affects promoters containing E2F-binding sites through two distinct mechanisms. First, upon complex formation with E2F, it blocks transcriptional activation by E2F. Second, the formed p130-E2F complex binds to E2F sites and actively represses transcription by inhibiting the activity of surrounding enhancer elements on the promoter. To pursue the relative contributions of each mechanism in the p130-mediated inhibition of IL-3-dependent cell proliferation, we employed a dominant-negative DP-1, which suppresses both E2F-dependent transactivation and the formation of active transcriptional repressors. Ectopic expression of the dominant negative DP-1 in the IL-3-dependent BaF3 lymphoid cells gave rise to an inhibition of cell proliferation, which was concomitantly associated with a decrease in levels of cyclin E, an indispensable molecule for G1 to S-phase cell-cycle progression. Our results indicate that blocking E2F-dependent transactivation, but not the formation of p130-E2F transcriptional repressor complexes, is responsible for the inhibition of IL-3-dependent cell growth by p130.
authors.affiliation: Division of Molecular Oncology, Institute for Genetic Medicine, Hokkaido University, Kita-15, Nishi-7, Kita-ku, Sapporo 060-0815, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yamada
authors.forename: Takuma
authors.initials: T
authors.lastname: Kondo
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ashizawa
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Takebayashi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Higashi
authors.forename: Masanori
authors.initials: M
authors.lastname: Hatakeyama
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002455:Cell Division; D002460:Cell Line; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050704:E2F4 Transcription Factor; D050700:E2F5 Transcription Factor; D015870:Gene Expression; D007377:Interleukin-3 / Q000378:metabolism*; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects; D051379:Mice; D016296:Mutagenesis; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011506:Proteins; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050717:Retinoblastoma-Like Protein p130; D013752:Tetracycline / Q000494:pharmacology; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation
chemical_list: D018797:Cell Cycle Proteins; D019927:Cyclin E; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050704:E2F4 Transcription Factor; D050700:E2F5 Transcription Factor; C493763:E2f4 protein, mouse; D007377:Interleukin-3; D010750:Phosphoproteins; D011506:Proteins; C493838:Rbl2 protein, mouse; D016160:Retinoblastoma Protein; D050717:Retinoblastoma-Like Protein p130; C493736:Tfdp1 protein, mouse; D050680:Transcription Factor DP1; D014157:Transcription Factors; D007544:Isopropyl Thiogalactoside; D013752:Tetracycline