Regulation of Chk2 phosphorylation by interaction with protein phosphatase 2A via its B' regulatory subunit.
Biol Cell
; 96(7): 509-17, 2004 Sep.
Article
em En
| MEDLINE
| ID: mdl-15380617
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'gamma 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'gamma3 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'gamma3 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.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas Serina-Treonina Quinases
/
Fosfoproteínas Fosfatases
/
Subunidades Proteicas
Limite:
Humans
Idioma:
En
Ano de publicação:
2004
Tipo de documento:
Article