de Souza-Pinto Nadja C, Maynard Scott, Hashiguchi Kazunari, Hu Jingping, Muftuoglu Meltem, Bohr Vilhelm A
Laboratory of Molecular Gerontology, NIA-IRP, National Institutes of Health, Baltimore, MD 21224, USA.
Mol Cell Biol. 2009 Aug;29(16):4441-54. doi: 10.1128/MCB.00265-09. Epub 2009 Jun 8.
Oxidized bases are common types of DNA modifications. Their accumulation in the genome is linked to aging and degenerative diseases. These modifications are commonly repaired by the base excision repair (BER) pathway. Oxoguanine DNA glycosylase (OGG1) initiates BER of oxidized purine bases. A small number of protein interactions have been identified for OGG1, while very few appear to have functional consequences. We report here that OGG1 interacts with the recombination protein RAD52 in vitro and in vivo. This interaction has reciprocal functional consequences as OGG1 inhibits RAD52 catalytic activities and RAD52 stimulates OGG1 incision activity, likely increasing its turnover rate. RAD52 colocalizes with OGG1 after oxidative stress to cultured cells, but not after the direct induction of double-strand breaks by ionizing radiation. Human cells depleted of RAD52 via small interfering RNA knockdown, and mouse cells lacking the protein via gene knockout showed increased sensitivity to oxidative stress. Moreover, cells depleted of RAD52 show higher accumulation of oxidized bases in their genome than cells with normal levels of RAD52. Our results indicate that RAD52 cooperates with OGG1 to repair oxidative DNA damage and enhances the cellular resistance to oxidative stress. Our observations suggest a coordinated action between these proteins that may be relevant when oxidative lesions positioned close to strand breaks impose a hindrance to RAD52 catalytic activities.
氧化碱基是常见的DNA修饰类型。它们在基因组中的积累与衰老和退行性疾病有关。这些修饰通常由碱基切除修复（BER）途径修复。氧鸟嘌呤DNA糖基化酶（OGG1）启动氧化嘌呤碱基的BER。已确定OGG1存在少量蛋白质相互作用，而似乎很少有具有功能后果的相互作用。我们在此报告，OGG1在体外和体内均与重组蛋白RAD52相互作用。这种相互作用具有相互的功能后果，因为OGG1抑制RAD52的催化活性，而RAD52刺激OGG1的切割活性，可能会提高其周转速率。氧化应激后，RAD52与培养细胞中的OGG1共定位，但在电离辐射直接诱导双链断裂后则不会。通过小干扰RNA敲低使RAD52缺失的人类细胞，以及通过基因敲除缺失该蛋白的小鼠细胞，对氧化应激表现出更高的敏感性。此外，与RAD52水平正常的细胞相比，RAD52缺失的细胞在其基因组中氧化碱基的积累更高。我们的结果表明，RAD52与OGG1协同作用以修复氧化性DNA损伤，并增强细胞对氧化应激的抗性。我们的观察结果表明，当靠近链断裂处的氧化损伤对RAD52催化活性造成阻碍时，这些蛋白质之间可能存在协调作用。
