Down-regulation of SMU1 Expression Influence Cell Proliferation and Cellular Response to DNA Double-Strand Breaks

Abstract: SMU1 is a novel gene， which implicated in both DNA replication and RNA splicing events. In this study， in order to investigate the role of SMU1 in cellular proliferation and response to DNA double-strand breaks (DSBs)， SMU1-specific siRNA was designed and synthesized， and SMU1 siRNA or control siRNA (scramble) was transfected into HEK 293T or U2OS cells， respectively. Western blot was used to assess the expression level of SMU1 and γH2AX; the cellular proliferation ability was determined by cell counting after trypan blue stains. After treating cells with X-ray， the recruitment of γH2AX to DNA damage site was determined by immunofluorescence (IF). The results showed that the expression of SMU1 protein was remarkably decreased in SMU1 siRNAtransfected cells， and knockdown of SMU1 in 293T cells caused obvious growth inhibition. The results also showed that down-regulation of SMU1 led to elevated endogenous DSBs (increased γH2AX foci and protein level) and prolonged DSBs repair kinetics (prolonged existence of the γH2AX foci and protein level) after treating cells with X-ray. Together， these results show that SMU1 plays an important role in the response of cells to DSBs damage and actively participates in the protection of genomic integrity.

CSTR: 32200.14.cjcb.2014.01.0011