Regulation of plant MSH2 and MSH6 genes in the UV-B-induced DNA damage response

LARIO L.; ELENA RAMIREZ-PARRA; CRISANTO GUTIERREZ; PAULA CASATI; CLAUDIA P. SPAMPINATO

JOURNAL OF EXPERIMENTAL BOTANY

OXFORD UNIV PRESS

Año: 2011 p. 230 - 243

0022-0957

Deleterious effects of UV-B radiation on DNA include the formation of cyclobutane pyrimidine dimers (CPDs) andpyrimidine (6–4) pyrimidone photoproducts (6–4PPs). These lesions must be repaired to maintain the integrity of DNAand provide genetic stability. Of the several repair systems involved in the recognition and removal of UV-B-inducedlesions in DNA, the focus in the present study was on the mismatch repair system (MMR). The contribution of MutSa(MSH2–MSH6) to UV-induced DNA lesion repair and cell cycle regulation was investigated. MSH2 and MSH6 genes inArabidopsis and maize are up-regulated by UV-B, indicating that MMR may have a role in UV-B-induced DNAdamage responses. Analysis of promoter sequences identified MSH6 as a target of the E2F transcription factors.Using electrophoretic mobility shift assays, MSH6 was experimentally validated as an E2F target gene, suggestingan interaction between MMR genes and the cell cycle control. Mutations in MSH2 or MSH6 caused an increasedaccumulation of CPDs relative to wild-type plants. In addition, msh2 mutant plants showed a different expressionpattern of cell cycle marker genes after the UV-B treatment when compared with wild-type plants. Taken together,these data provide evidence that plant MutSa is involved in a UV-B-induced DNA damage response pathway.