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Phosphorylation‐dependent signaling controls degradation of DNA mismatch repair protein PMS2
Author(s) -
Hinrichsen Inga,
Weßbecher Isabel M.,
Huhn Meik,
Passmann Sandra,
Zeuzem Stefan,
Plotz Guido,
Biondi Ricardo M.,
Brieger Angela
Publication year - 2017
Publication title -
molecular carcinogenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 97
eISSN - 1098-2744
pISSN - 0899-1987
DOI - 10.1002/mc.22709
Subject(s) - pms2 , biology , phosphorylation , microbiology and biotechnology , dna repair , biochemistry , dna mismatch repair , dna
MutLα, a heterodimer consisting of MLH1 and PMS2, plays an important role in DNA mismatch repair and has been shown to be additionally involved in several other important cellular mechanisms. Previous work indicated that AKT could modulate PMS2 stability by phosphorylation. Still, the mechanisms of regulation of MutLα remain unclear. The stability of MutLα subunits was investigated by transiently overexpression of wild type and mutant forms of MLH1 and PMS2 using immunoblotting for measuring the protein levels after treatment. We found that treatment with the cell‐permeable serine/threonine phosphatase inhibitor, Calyculin, leads to degradation of PMS2 when MLH1 or its C‐terminal domain is missing or if amino acids of MLH1 essential for PMS2 interaction are mutated. In addition, we discovered that the C‐terminal tail of PMS2 is relevant for this Calyculin‐dependent degradation. A direct involvement of AKT, which was previously described to be responsible for PMS2 degradation, could not be detected. The multi‐kinase inhibitor Sorafenib, in contrast, was able to avoid the degradation of PMS2 which postulates that cellular phosphorylation is involved in this process. Together, we show that pharmacologically induced phosphorylation by Calyculin can induce the selective proteasome‐dependent degradation of PMS2 but not of MLH1 and that the PMS2 degradation could be blocked by Sorafenib treatment. Curiously, the C‐terminal Lynch Syndrome‐variants MLH1 L749P and MLH1 Y750X make PMS2 prone to Calyculin induced degradation. Therefore, we conclude that the specific degradation of PMS2 may represent a new mechanism to regulate MutLα.