Laboratory for Skin Cancer Research, Hospital Research Centre of Laval University (CHUL) and Centre Hospitalier Universitaire du Quebec (CHUQ), Laval University, Quebec, QC, Canada G1V 4G2.
Proc Natl Acad Sci U S A. 2013 Jan 29;110(5):1658-63. doi: 10.1073/pnas.1209507110. Epub 2013 Jan 14.
Among the earliest responses of mammalian cells to DNA damage is catalytic activation of a nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1). Activated PARP-1 forms the polymers of ADP-ribose (pADPr or PAR) that posttranslationally modify its target proteins, such as PARP-1 and DNA repair-related proteins. Although this metabolism is known to be implicated in other repair pathways, here we show its role in the versatile nucleotide excision repair pathway (NER) that removes a variety of DNA damages including those induced by UV. We show that PARP inhibition or specific depletion of PARP-1 decreases the efficiency of removal of UV-induced DNA damage from human skin fibroblasts or mouse epidermis. Using NER-proficient and -deficient cells and in vitro PARP-1 assays, we show that damaged DNA-binding protein 2 (DDB2), a key lesion recognition protein of the global genomic subpathway of NER (GG-NER), associates with PARP-1 in the vicinity of UV-damaged chromatin, stimulates its catalytic activity, and is modified by pADPr. PARP inhibition abolishes UV-induced interaction of DDB2 with PARP-1 or xeroderma pigmentosum group C (XPC) and also decreases localization of XPC to UV-damaged DNA, which is a key step that leads to downstream events in GG-NER. Thus, PARP-1 collaborates with DDB2 to increase the efficiency of the lesion recognition step of GG-NER.
哺乳动物细胞对 DNA 损伤的最早反应之一是催化激活核酶多聚（ADP-核糖）聚合酶 1（PARP-1）。激活的 PARP-1 形成 ADP-核糖（pADPr 或 PAR）的聚合物，这些聚合物可以对其靶蛋白进行翻译后修饰，如 PARP-1 和与 DNA 修复相关的蛋白质。尽管这种代谢已知与其他修复途径有关，但在这里我们表明它在各种核苷酸切除修复途径（NER）中的作用，该途径可去除多种 DNA 损伤，包括由 UV 诱导的损伤。我们表明，PARP 抑制或 PARP-1 的特异性耗竭会降低人皮肤成纤维细胞或小鼠表皮中 UV 诱导的 DNA 损伤的去除效率。使用 NER 功能正常和缺陷的细胞以及体外 PARP-1 测定，我们表明受损 DNA 结合蛋白 2（DDB2），即全球基因组亚途径（GG-NER）的关键损伤识别蛋白，与 PARP-1 在 UV 损伤染色质附近结合，刺激其催化活性，并被 pADPr 修饰。PARP 抑制会破坏 UV 诱导的 DDB2 与 PARP-1 或着色性干皮病组 C（XPC）的相互作用，也会减少 XPC 向 UV 损伤 DNA 的定位，这是导致 GG-NER 下游事件的关键步骤。因此，PARP-1 与 DDB2 合作，提高 GG-NER 损伤识别步骤的效率。
