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

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 ␤, 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 N-nitroso-N-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.In response to DNA interruptions, PARP-1, 1 the founding member of the poly(ADP-ribose) polymerase superfamily, catalyzes the successive covalent addition of ADP-ribose units from NAD to a limited number of nuclear acceptors to form a branched anionic polymer. PARP-1 is a nuclear enzyme involved in the detection and signaling of DNA strand breaks introduced either directly by ionizing radiation or indirectly following enzymatic incision of a DNA lesion (abasic sites or oxidized or alkylated bases) repaired by the base excision repair (BER) pathway (see for review Ref. 1). The discovery of numerous PARP-1 protein partners and/or poly(ADP-ribose) acceptors involved in DNA architecture (histones H1 and H2B, lamin B, and high mobility group proteins) or in DNA metabolism (DNA replication factors, DNA repair proteins, i.e. XRCC1, transcription factors, topoisomerases, and PARP-1 itself) has shed light onto the implication of PARP-1 in these processes (see for review Ref. 1).The function of PARP-1 in BER has long been assumed, until direct evidence demonstrated the presence of PARP-1 in the BER complex, associated to XRCC1 (2, 3) and DNA polymerase (pol) ␤ (4). The polymer produced by PARP-1 upon activation by DNA breaks triggers the recruitment of XRCC1, which shows high affinity for oligo(ADP-ribosyl)ated PARP-1 (3-5). The requirement of PARP-1 in BER was established in vivo, because PARP-1 knock-out cells displayed a severe defect in strand breaks resealing following genotoxic treatment (6, 7). The preferential role of PARP-1 in long patch BER was observed using extracts from these PARP-1 knock-out cells (4). Photoaffinity labeling experiments revealed that PARP-1 binds to BER intermediates (8). In reconstituted in vitro systems containing purified human B...

The macroPARP genes parp‐9 and parp‐14 are developmentally and differentially regulated in mouse tissues

“…Parp-1 was also expressed in specific brain regions (olfactory bulb, cerebellar and cerebral cortex, shown for E14.5 and 17.5 in Fig. 1D,G), as well as in the genital ridge, cranial and spinal ganglia (see Schreiber et al, 2002). Parp-9 was expressed in some craniofacial tissues, namely the telencephalic vesicles, hypothalamus, pituitary, olfactory bulb and nasal cavity, illustrated at E14.5 and E17.5, Fig.…”

“…In situ hybridization experiments were performed to analyze the expression patterns of Parp-9 and Parp-14 in comparison with the previously described Parp-1 pattern (Schreiber et al, 2002) at various stages of mouse development. As expected, control sense probes for each gene only showed background labeling ( Fig.…”

“…The Parp-1 template has been previously described (Schreiber et al, 2002). Digoxigenin-labeled (DIG-RNA labeling Mix, Roche) riboprobes were transcribed in vitro in antisense or sense orientations using T7, Sp6, or T3 RNA polymerases as indicated above.…”

Poly(ADP-ribose) polymerase-2: emerging transcriptional roles of a DNA-repair protein

“…Liver expression of PARP-2 was high at fetal age 12.5 days, decreased at 18.5 days fetal age and was even lower in newborn mice [8,18]. In adult mice the expression of PARP-2 is low in the liver (the lowest among the metabolic tissues; Bai P, unpublished data).…”

PARP1 is activated at telomeres upon G4 stabilization: possible target for telomere-based therapy

“…The intervention of PARP1 and PARP2 takes place early in the steps of the DNA repair process, as these enzymes bind to and are activated by DNA nicks (Pleschke et al, 2000). Upon poly-ADP ribosylation, PARPs recruit to the damaged site components of BER and NER machineries (Schreiber et al, 2002;Malanga and Althaus, 2005). Therefore, inhibition of PARP activity would prevent recruitment of repair enzymes to DNA breaks, hampering strand rejoining and consequent generation of permanent single/double-strand breaks, which in turn triggers cell death.…”