title: The Establishment of a Hyperactive Structure Allows the Tumour Suppressor Protein p53 to Function through P-TEFb during Limited CDK9 Kinase Inhibition.
abstract: CDK9 is the catalytic subunit of positive elongation factor b (P-TEFb) that controls the transition of RNA polymerase II (RNAPII) into elongation. CDK9 inhibitors block mRNA synthesis and trigger activation of the stress-sensitive p53 protein. This in turn induces transcription of CDKN1A (p21) and other cell cycle control genes. It is presently unclear if and how p53 circumvents a general P-TEFb-requirement when it activates its target genes. Our investigations using a panel of specific inhibitors reason for a critical role of CDK9 also in the case of direct inhibition of the kinase. At the prototypic p21 gene, the activator p53 initially accumulates at the pre-bound upstream enhancer followed-with significant delay-by de novo binding to a secondary enhancer site within the first intron of p21. This is accompanied by recruitment of the RNAPII initiation machinery to both elements. ChIP and functional analyses reason for a prominent role of CDK9 itself and elongation factor complexes PAF1c and SEC involved in pause and elongation control. It appears that the strong activation potential of p53 facilitates gene activation in the situation of global repression of RNAPII transcription. The data further underline the fundamental importance of CDK9 for class II gene transcription.
authors.affiliation: Institute of Molecular Tumor Biology (IMTB), Faculty of Medicine, University Muenster, 48149, Muenster, Germany.
authors.forename: Thomas K
authors.initials: TK
authors.lastname: Albert
authors.affiliation: Institute of Molecular Tumor Biology (IMTB), Faculty of Medicine, University Muenster, 48149, Muenster, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Antrecht
authors.affiliation: Institute of Molecular Immunology (IMI), Helmholtz Research Center for Environment and Health, 81377, Munich, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Kremmer
authors.affiliation: Institute of Molecular Tumor Biology (IMTB), Faculty of Medicine, University Muenster, 48149, Muenster, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Meisterernst
mesh_terms: D001483:Base Sequence; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D042863:Cyclin-Dependent Kinase 9 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D042925:Positive Transcriptional Elongation Factor B / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D012319:RNA Polymerase II / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D016415:Sequence Alignment; D014157:Transcription Factors; D015533:Transcriptional Activation; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D009687:Nuclear Proteins; C501972:PAF1 protein, human; D034741:RNA, Small Interfering; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D042925:Positive Transcriptional Elongation Factor B; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II