Laboratoire Lésions des Acides Nucléiques, Grenoble Cedex 9, France.
Mech Ageing Dev. 2010 Nov-Dec;131(11-12):661-5. doi: 10.1016/j.mad.2010.09.002. Epub 2010 Sep 18.
Base Excision Repair (BER) is the predominant repair pathway responsible for removal of so-called small DNA lesions such as abasic sites (AP site), uracil (U), 8-oxo-7,8-dihydroguanine (8oxoG), thymine glycol (Tg). In this study, we investigated effect of aging on excision efficacy of several endogenous base lesions and AP sites using an in vitro multiplexed fluorescent approach on support (parallelized oligonucleotide cleavage assay). Human fibroblasts nuclear extracts from 29 donors of different ages were characterized in their ability to simultaneously excise the different lesions. Clearly, three different groups of lesions emerged according to the efficiency of their cleavage: one exhibited very high cleavage efficiency (AP sites and U paired with G), one showed intermediate cleavage efficiency (U paired with A and Tg). The third group included 8oxoG, A paired with 8oxoG, T at CpG site and hypoxanthine (Hx) and displayed poor repair. Aging was significantly associated with modification of excision efficiency for AP sites, uracil, Tg and 8oxoG. Repair rate decreased for the first three lesions and the most drastic effects were observed for repair of U:A. Surprisingly, excision of 8oxoG increased with aging suggesting a completely different regulation or adaptation for the initiation step of this related specific repair pathway.
碱基切除修复（BER）是负责清除所谓的小 DNA 损伤的主要修复途径，例如脱碱基位点（AP 位点）、尿嘧啶（U）、8-氧-7,8-二氢鸟嘌呤（8oxoG）、胸腺嘧啶二醇（Tg）。在这项研究中，我们使用体外多重荧光方法（平行寡核苷酸切割测定法）研究了衰老对几种内源性碱基损伤和 AP 位点切除效率的影响。我们研究了来自不同年龄的 29 名供体的人类成纤维细胞核提取物，以研究它们同时切除不同损伤的能力。显然，根据切割效率，出现了三种不同的损伤组：一组显示出非常高的切割效率（AP 位点和与 G 配对的 U），一组显示出中等切割效率（与 A 和 Tg 配对的 U）。第三组包括 8oxoG、与 8oxoG 配对的 A、CpG 位点的 T 和次黄嘌呤（Hx），修复效果较差。衰老与 AP 位点、尿嘧啶、Tg 和 8oxoG 的切除效率的改变显著相关。前三种损伤的修复率下降，而 U:A 的修复效果最为明显。令人惊讶的是，8oxoG 的切除效率随着衰老而增加，这表明该相关特定修复途径的起始步骤存在完全不同的调控或适应。
