Interaction with OGG1 Is Required for Efficient Recruitment of XRCC1 to Base Excision Repair and Maintenance of Genetic Stability after Exposure to Oxidative Stress

Abstract

XRCC1 is an essential protein required for the maintenance of genomic stability through its implication in DNA repair. The main function of XRCC1 is associated with its role in the single-strand break (SSB) and base excision repair (BER) pathways that share several enzymatic steps. We show here that the polymorphic XRCC1 variant R194W presents a defect in its interaction with the DNA glycosylase OGG1 after oxidative stress. While proficient for single-strand break repair (SSBR), this variant does not colocalize with OGG1, reflecting a defect in its involvement in BER. Consistent with a role of XRCC1 in the coordination of the BER pathway, induction of oxidative base damage in XRCC1-deficient cells complemented with the R194W variant results in increased genetic instability as revealed by the accumulation of micronuclei. These data identify a specific molecular role for the XRCC1-OGG1 interaction in BER and provide a model for the effects of the R194W variant identified in molecular cancer epidemiology studies. C ellular DNA is continuously exposed to oxidative stress arising from both endogenous and exogenous sources. As a consequence, lesions such as modified bases, abasic (AP) sites, and single-strand breaks (SSBs) are generated (1). One of the major base lesions induced by oxidative stress is 8-oxoguanine (8-oxoG), which is recognized and excised by a specific DNA glycosylase, OGG1, initiating the base excision repair (BER) pathway (2). The AP site produced by OGG1 DNA glycosylase activity is then cleaved by the AP endonuclease APE1, resulting in a SSB. The subsequent synthesis and ligation steps are carried out by polymerase ␤ (POL␤) and ligase 3 (LIG3), respectively, to restore an intact DNA molecule (3). SSBs can also be directly induced in genomic DNA, and most of the enzymatic steps required for their repair are common to the single-strand break repair (SSBR) and BER pathways. Besides the enzymes mentioned above, other proteins participate in the efficient repair of modified bases and SSBs. Of these proteins, XRCC1, which is essential for embryonic development in mice (4), is a protein with no known enzymatic activity that acts as a scaffolding platform for SSBR and BER activities (5, 6). Cells deficient in XRCC1 exhibit increased frequencies of sister chromatid exchanges and chromosomal rearrangements. XRCC1 function is based in its capacity to interact with multiple enzymes and DNA intermediates in various DNA repair pathways (7,8), coordinating the rate and sequence of the enzymatic activities and thus avoiding the exposure of toxic DNA intermediates to the cellular milieu (9). The various XRCC1 domains responsible for the interactions with BER or SSBR enzymes have been identified. XRCC1 is composed of three structured domains, interspaced by two flexible/nonstructured linkers (10) (see Fig. 1A). The NTD (N-terminal domain) is responsible for the interaction with POL␤ (11, 12), the BRCT1 (BRCA1 carboxyl-terminal protein interaction domain 1) is involved in the interaction with poly(ADP-ribose) polymer...

Oxidized nucleotide insertion by pol β confounds ligation during base excision repair

“…We believe the difference is likely due to the nature of the oxidizing agent-mediated DNA damage in cells. H 2 O 2 has been widely utilized as a representative ROS for studies of oxidative stress in mammalian cells and is considered to induce single-strand breaks and various forms of base damage363738. Thus, we considered H 2 O 2 as less likely than KBrO 3 to specifically oxidize guanine in the nucleotide pool.…”

Association Studies Between XRCC1, XRCC2, XRCC3 Polymorphisms and Differentiated Thyroid Carcinoma

“…XRCC1 protein is involved in the BER pathway to repair DNA single-strand breaks combined with three DNA repair enzymes (DNA ligase III, DNA polymerase and PARP) [22,24,35,36]. Recently, evidence has attempted to reveal the underlying biological meaning of common XRCC1 polymorphisms (rs25487, rs25489, rs1799782), but the results of genetic studies are still inconclusive [22,24].…”

FOXO3 Transcription Factor Is Essential for Protecting Hematopoietic Stem and Progenitor Cells from Oxidative DNA Damage

“…Loss of FOXO3 may lead to discrepancies between mRNA and protein expressions (41,42). Given the critical OGG1-XRCC1 interaction for BER, it is likely that reduced expression of XRRC1 mediates the defective OGG1 activity (43)(44)(45) Ϫ/Ϫ mice and kept in vitro displayed similar numbers of ␥H2AX nuclear foci 2 h after 10 Gy IR (Fig. 7A).…”