title: c-Abl phosphorylates Hdm2 at tyrosine 276 in response to DNA damage and regulates interaction with ARF.
abstract: The p53 tumour-suppressor protein is tightly regulated through its association with the Hdm2 E3 ligase. Activation of p53 by DNA strand breaks is orchestrated by the ataxia-telangiectasia mutated (ATM) protein kinase and involves interruption of Hdm2-mediated p53 degradation. As part of this mechanism ATM itself, and the ATM-activated protein tyrosine kinase, c-Abl, inhibit Hdm2 function through phosphorylation of serine 395 and tyrosine 394 (Y394), respectively. In the present study, we have identified a novel target of c-Abl in the Hdm2 protein, tyrosine 276 (Y276). We show that c-Abl phosphorylates this residue in vitro and confirm that Y394 is a target of c-Abl. We also show that Y276 is phosphorylated in a c-Abl-dependent manner in cultured cells and provide evidence that Y276 is phosphorylated in response to DNA damage coincident with the activation of c-Abl. Finally, we show that Y276 phosphorylation stimulates interaction with ARF, leading to increased levels of nucleolar Hdm2 and decreased turnover of p53. These data establish Y276 as a physiological target of c-Abl that contributes functionally to the induction of p53.
authors.affiliation: Molecular Signalling Group, Biomedical Research Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK.
authors.forename: S S
authors.initials: SS
authors.lastname: Dias
authors.forename: D M
authors.initials: DM
authors.lastname: Milne
authors.forename: D W
authors.initials: DW
authors.lastname: Meek
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D019556:COS Cells; D018797:Cell Cycle Proteins / Q000378:metabolism; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000737:chemistry* / Q000378:metabolism*; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: C417743:Cdkn2a protein, mouse; D018797:Cell Cycle Proteins; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D016315:Proto-Oncogene Proteins c-abl; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases