Involvement of SPRTN in DNA protein cross-link damage repair

DNA-protein cross links (DPCs) are caused by covalently linking DNA and DNA-associated proteins and by intermediates of DNA-metabolizing enzymes. Current studies showed that SPRTN, metalloprotease, is a critical factor in proteolytic cleavage of DPCs. However, it has not been clarified which proteins are targets for SPRTN. In this study, we examined the contribution of SPRTN to cleave DPCs using a reverse genetic strategy with human lymphocytes, TK6. Cells deficient in SPRTN were not sensitive to formaldehyde (FA) producing DPCs with various proteins. In contrast, these cells showed hyper-sensitive to aza-deoxycytidine (azadC) which specifically trapped methyltransferase (Dnmt1) to DNA (Dnmt1-DPCs). AzadC treatment resulted in the accumulation of Dnmt1-DPCs in purified genomic DNA. The rate of removal of Dnmt1-DPCs was slower in sprtn-deficient cells than in wild type cells. Our data suggest that SPRTN plays critical role in the resolution of Dnmt1-DPCs in human cells.第43回 日本分子生物学