1. Regulation of Chk2 phosphorylation by interaction with protein phosphatase 2A via its B' regulatory subunit
- Author
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Laurent Baricault, Jean-Marie Darbon, Christine Dozier, Mortaza Bonyadi, Laure Tonasso, Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Centre de Biologie Intégrative (CBI), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Identité et plasticité tumorale, and Université Montpellier 1 (UM1)-CRLCC Val d'Aurelle - Paul Lamarque-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
MESH: Signal Transduction ,animal structures ,macromolecular substances ,[SDV.BC]Life Sciences [q-bio]/Cellular Biology ,Mitogen-activated protein kinase kinase ,Protein Serine-Threonine Kinases ,MESH: Two-Hybrid System Techniques ,environment and public health ,MESH: Protein-Serine-Threonine Kinases ,MAP2K7 ,Cell Line ,03 medical and health sciences ,MESH: Protein Structure, Tertiary ,Two-Hybrid System Techniques ,MESH: Phosphoprotein Phosphatases ,Phosphoprotein Phosphatases ,MESH: Protein Binding ,Humans ,c-Raf ,Protein Phosphatase 2 ,Phosphorylation ,030304 developmental biology ,0303 health sciences ,MESH: Humans ,MAP kinase kinase kinase ,biology ,MESH: Phosphorylation ,MESH: Protein Phosphatase 2 ,030302 biochemistry & molecular biology ,Cyclin-dependent kinase 2 ,Cell Biology ,General Medicine ,Protein phosphatase 2 ,MESH: Protein Subunits ,3. Good health ,Cell biology ,MESH: Cell Line ,Protein Structure, Tertiary ,enzymes and coenzymes (carbohydrates) ,Checkpoint Kinase 2 ,Protein Subunits ,Biochemistry ,Cyclin-dependent kinase complex ,biology.protein ,Casein kinase 2 ,biological phenomena, cell phenomena, and immunity ,Protein Binding ,Signal Transduction - Abstract
Chk2 is a key player of the DNA damage signalling pathway. To identify new regulators of this kinase, we performed a yeast two-hybrid screen and found that Chk2 associated with the B′ regulatory subunit of protein phosphatase PP2A. In vitro GST-Chk2 pulldowns demonstrated that B′γ isoforms bound to Chk2 with the strongest apparent affinity. This was confirmed in cellulo by co-immunoprecipitation after overexpression of the respective partners in HEK293 cells. The A and C subunits of PP2A were present in the complexes, suggesting that Chk2 was associated with a functionnal PP2A. In vitro kinase assays showed that B′γ3 was a potent Chk2 substrate. This phosphorylation increased the catalytic phosphatase activity of PP2A measured on MAP kinase-phosphorylated myelin basic protein as well as on autophosphorylated Chk2. Finally, we demonstrated that overexpressing B′γ3 in HEK293 suppressed the phosphorylation of Chk2 induced by a genotoxic treatment, suggesting that PP2A may counteract the action of the checkpoint kinase in living cells.
- Published
- 2004
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