title: Regulation of E2F transcription by cyclin E-Cdk2 kinase mediated through p300/CBP co-activators.
abstract: The E2F proteins form a family of transcription factors that regulate the transition from the G1 to the S phase in the cell cycle. E2F activity is regulated by members of the retinoblastoma protein (pRb) family, ensuring the tight control of E2F-responsive genes. During the G1 phase, phosphorylation of pRb by cyclin-dependent kinases (CDKs), most notably cyclin D-CDK complexes, releases pRb from E2F, facilitating cell-cycle progression by the timely induction of E2F-targeted genes such as cyclin E. However, it is not known whether E2F proteins are directly targeted by CDKs. Here we show that E2F-5 is phosphorylated by the cyclin E-Cdk2 complex, which functions in the late G1 phase, but not by the early-G1-phase-acting cyclin D-CDK complex. A phosphorylation site in the trans-activation domain of E2F-5 stimulates transcription and cell-cycle progression by the recruitment of the p300/CBP family of co-activators, whose binding to E2F-5 is stabilized upon phosphorylation by cyclin E-Cdk2. These results indicate that E2F activity may be directly regulated by cyclin E-Cdk2, and imply an autoregulatory mechanism for cell-cycle-dependent transcription through the CDK-stimulated interaction of E2F with p300/CBP co-activators.
authors.affiliation: Division of Biochemistry and Molecular Biology, Davidson Building, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: L
authors.initials: L
authors.lastname: Morris
authors.forename: K E
authors.initials: KE
authors.lastname: Allen
authors.forename: N B
authors.initials: NB
authors.lastname: La Thangue
mesh_terms: D000818:Animals; D042846:CDC2-CDC28 Kinases; D050882:CREB-Binding Protein; D002352:Carrier Proteins; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D019927:Cyclin E / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050700:E2F5 Transcription Factor; D016193:G1 Phase / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006706:Homeostasis / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D056465:Retinoblastoma-Binding Protein 1; D016196:S Phase / Q000235:genetics; D013912:Threonine; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D019927:Cyclin E; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050700:E2F5 Transcription Factor; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D056465:Retinoblastoma-Binding Protein 1; D015534:Trans-Activators; D014157:Transcription Factors; D013912:Threonine; D050882:CREB-Binding Protein; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases