Poly(ADP-ribose) Polymerase-2 (PARP-2) Is Required for Efficient Base Excision DNA Repair in Association with PARP-1 and XRCC1

TLDR

PARP‑2 activity is triggered by DNA damage, suggesting a role in genome surveillance and protection. The study aims to clarify PARP‑2’s physiological role in genotoxic stress by generating PARP‑2 knockout mice. PARP‑2 knockout mice were produced via gene disruption to investigate its function. PARP‑2‑deficient cells display a pronounced delay in DNA strand‑break resealing after alkylation, similar to PARP‑1 deficiency, confirming PARP‑2’s active participation in base‑excision repair despite its low ADP‑ribosylation capacity.

Abstract

The DNA damage dependence of poly(ADP-ribose) polymerase-2 (PARP-2) activity is suggestive of its implication in genome surveillance and protection. Here we show that the PARP-2 gene, mainly expressed in actively dividing tissues follows, but to a smaller extent, that of PARP-1 during mouse development. We found that PARP-2 and PARP-1 homo- and heterodimerize; the interacting interfaces, sites of reciprocal modification, have been mapped. PARP-2 was also found to interact with three other proteins involved in the base excision repair pathway: x-ray cross complementing factor 1 (XRCC1), DNA polymerase β, and DNA ligase III, already known as partners of PARP-1. XRCC1 negatively regulates PARP-2 activity, as it does for PARP-1, while being a polymer acceptor for both PARP-1 and PARP-2. To gain insight into the physiological role of PARP-2 in response to genotoxic stress, we developed by gene disruption mice deficient in PARP-2. Following treatment by the alkylating agent<i>N</i>-nitroso-<i>N</i>-methylurea (MNU), PARP-2-deficient cells displayed an important delay in DNA strand breaks resealing, similar to that observed in PARP-1 deficient cells, thus confirming that PARP-2 is also an active player in base excision repair despite its low capacity to synthesize ADP-ribose polymers.