Human POLD1 modulates cell cycle progression and DNA damage repair

BACKGROUND: The activity of eukaryotic DNA polymerase delta (Pol δ) plays an essential role in genome stability through its effects on DNA replication and repair. The p125 catalytic subunit of Pol δ is encoded by POLD1 gene in human cells. To clarify biological functions of POLD1, we investigated the effects of POLD1 overexpression or downregulation on cell proliferation, cell cycle progression, DNA synthesis and oxidative DNA damage induced by H(2)O(2). METHODS: HEK293 cells were transfected with POLD1 expression plasmid or shRNA, cell proliferation, cell cycle progression, and DNA synthesis in HEK293 cells were analyzed. RESULTS: HEK293 cells were transfected with POLD1 expression plasmid or shRNA. POLD1 downregulation by shRNA suppressed cell proliferation, cell cycle progression, and DNA synthesis in HEK293 cells. However, POLD1 overexpression had no significant effects on these processes. Finally, comet assay showed that POLD1 downregulation led to increased DNA damage. CONCLUSIONS: Our results suggest that human POLD1 plays important role in the regulation of cell cycle progression and DNA damage repair.