title: Phosphorylation-dependent degradation of p300 by doxorubicin-activated p38 mitogen-activated protein kinase in cardiac cells.
abstract: p300 and CBP are general transcriptional coactivators implicated in different cellular processes, including regulation of the cell cycle, differentiation, tumorigenesis, and apoptosis. Posttranslational modifications such as phosphorylation are predicted to select a specific function of p300/CBP in these processes; however, the identification of the kinases that regulate p300/CBP activity in response to individual stimuli and the physiological significance of p300 phosphorylation have not been elucidated. Here we demonstrate that the cardiotoxic anticancer agent doxorubicin (adriamycin) induces the phosphorylation of p300 in primary neonatal cardiomyocytes. Hyperphosphorylation precedes the degradation of p300 and parallels apoptosis in response to doxorubicin. Doxorubicin-activated p38 kinases alpha and beta associate with p300 and are implicated in the phosphorylation-mediated degradation of p300, as pharmacological blockade of p38 prevents p300 degradation. p38 phosphorylates p300 in vitro at both the N and C termini of the protein, and enforced activation of p38 by the constitutively active form of its upstream kinase (MKK6EE) triggers p300 degradation. These data support the conclusion that p38 mitogen-activated protein kinase regulates p300 protein stability and function in cardiomyocytes undergoing apoptosis in response to doxorubicin.
authors.affiliation: Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, 2250 Alcazar St., CSC 245, Los Angeles, CA 90033, USA. poizat@usc.edu
authors.forename: Coralie
authors.initials: C
authors.lastname: Poizat
authors.forename: Pier Lorenzo
authors.initials: PL
authors.lastname: Puri
authors.forename: Yan
authors.initials: Y
authors.lastname: Bai
authors.forename: Larry
authors.initials: L
authors.lastname: Kedes
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology*; D050881:E1A-Associated p300 Protein; D004789:Enzyme Activation / Q000187:drug effects; D050991:GATA4 Transcription Factor; D020935:MAP Kinase Signaling System; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013912:Threonine / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; C084365:Gata4 protein, rat; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D016159:Tumor Suppressor Protein p53; D013912:Threonine; D004317:Doxorubicin; D050881:E1A-Associated p300 Protein; C494362:Ep300 protein, rat; D048051:p38 Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases