Role of Purα in the cellular response to ultraviolet-C radiation

Abstract

Puraα is a nucleic acid-binding protein with DNA-unwinding activity, which has recently been shown to have a role in the cellular response to DNA damage. We have investigated the function of Puraα in Ultraviolet-C (UVC) radiation-induced DNA damage and nucleotide excision repair (NER). Mouse embryo fibroblasts from PURA-/- knockout mice, which lack Puraα, showed enhanced sensitivity to UVC irradiation as assessed by assays for cell viability and clonogenicity compared to Puraα positive control cultures. In reporter plasmid reactivation assays to measure the removal of DNA adducts induced in vitro by UVC, the Puraα-negative cells were less efficient in DNA damage repair. Puraα-negative cells were also more sensitive to UVC-induced DNA damage measured by Comet assay and showed a decreased ability to remove UVC-induced cyclobutane pyrimidine dimers. In wild-type mouse fibroblasts, expression of Puraα is induced following S-phase checkpoint activation by UVC in a similar manner to the NER factor TFIIH. Moreover, co-immunoprecipitation experiments showed that Puraα physically associates with TFIIH. Thus, Puraα has a role in NER and the repair of UVC-induced DNA damage. © 2010 Landes Bioscience.