title: Phosphorylation of mismatch repair proteins MSH2 and MSH6 affecting MutSalpha mismatch-binding activity.
abstract: Mismatch repair (MMR) is involved in the removal of mispaired bases from DNA and thus plays an important role in the maintenance of genomic stability and the prevention of mutations and cancer. Moreover, MMR triggers genotoxicity and apoptosis upon processing of DNA lesions such as O6-methylguanine. Whereas the enzymology of MMR has been elucidated in great detail, only limited data are available concerning its regulation. Here we show that the major mismatch-binding proteins MSH2 and MSH6, forming the MutSalpha complex, are phosphorylated in vitro by protein kinase C and casein kinase II, but not by protein kinase A. Phosphorylation of MSH2 and MSH6 was also found within the cell, with MSH6 being more extensively phosphorylated than MSH2. Lack of MSH2 and MSH6 phosphorylation in vivo due to phosphate depletion, kinase inhibition (by H7 and quercetin) and treatment with phosphatases (CIP, SAP and lambda-PPase) significantly reduced mismatch-binding activity of MutSalpha. It also prevented methylation-induced nuclear translocation of the repair complex, indicating that nuclear translocation of MutSalpha upon mutagen treatment is dependent on protein phosphorylation. The finding that MSH2 and MSH6 are subject to phosphorylation resulting in increased mismatch binding by MutSalpha indicates a novel type of post-translational regulation of MMR which might be involved in the response of cells to genotoxic stress.
authors.affiliation: Division of Applied Toxicology, Institute of Toxicology, University of Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Christmann
authors.forename: Maja T
authors.initials: MT
authors.lastname: Tomicic
authors.forename: Bernd
authors.initials: B
authors.lastname: Kaina
mesh_terms: D021581:Active Transport, Cell Nucleus; D020137:Base Pair Mismatch; D047390:Casein Kinase II; D002467:Cell Nucleus / Q000378:metabolism; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D051718:MutS Homolog 2 Protein; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D046911:Macromolecular Substances; D011518:Proto-Oncogene Proteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein