title: Novel link between E2F and p53: proapoptotic cofactors of p53 are transcriptionally upregulated by E2F.
abstract: The E2F1 transcription factor is a critical downstream target of the tumor suppressor RB. When activated, E2F1 induces cell proliferation. In addition, E2F1 can induce apoptosis via both p53-dependent and p53-independent pathways. A number of E2F-regulated genes, including ARF, ATM and Chk2, contribute to E2F-induced p53 stabilization. However, it is not known how E2F directs p53 activity towards apoptosis rather than growth arrest. We show that E2F1 upregulates the expression of four proapoptotic cofactors of p53--ASPP1, ASPP2, JMY and TP53INP1--through a direct transcriptional mechanism. Adenovirus E1A protein also induces upregulation of these genes, implicating endogenous E2F in this effect. TP53INP1 was shown to mediate phosphorylation of p53 on serine 46. We demonstrate that activation of E2F1 leads to phosphorylation of p53 on serine 46 and this modification is important for E2F1-p53 cooperation in apoptosis. Overall, these data provide novel functional links between RB/E2F pathway and p53-induced apoptosis.
authors.affiliation: Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: T
authors.initials: T
authors.lastname: Hershko
authors.forename: M
authors.initials: M
authors.lastname: Chaussepied
authors.forename: M
authors.initials: M
authors.lastname: Oren
authors.forename: D
authors.initials: D
authors.lastname: Ginsberg
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D005786:Gene Expression Regulation / Q000502:physiology; D006360:Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; D006360:Heat-Shock Proteins; C121977:JMY protein, human; D009687:Nuclear Proteins; C498406:PPP1R13B protein, human; C090468:TP53BP2 protein, human; C429767:TP53INP1 protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53