Base Excision Repair Is Impaired in Mammalian Cells Lacking Poly(ADP-ribose) Polymerase-1

Publisher Website
Google Scholar
Abstract
In mammalian cells, damaged bases in DNA are corrected by the base excision repair pathway which is divided into two distinct pathways depending on the length of the resynthesized patch, replacement of one nucleotide for short-patch repair, and resynthesis of several nucleotides for long-patch repair. The involvement of poly(ADP-ribose) polymerase-1 (PARP-1) in both pathways has been investigated by using PARP-1-deficient cell extracts to repair single abasic sites derived from uracil or 8-oxoguanine located in a double-stranded circular plasmid. For both lesions, PARP-1-deficient cell extracts were about half as efficient as wild-type cells at the polymerization step of the short-patch repair synthesis, but were highly inefficient at the long-patch repair. We provided evidence that PARP-1 constitutively interacts with DNA polymerase β. Using cell-free extracts from mouse embryonic cells deficient in DNA polymerase β, we demonstrated that DNA polymerase β is involved in the repair of uracil-derived AP sites via both the short and the long-patch repair pathways. When both PARP-1 and DNA polymerase β were absent, the two repair pathways were dramatically affected, indicating that base excision repair was highly inefficient. These results show that PARP-1 is an active player in DNA base excision repair.