High levels of oxidatively generated DNA damage 8,5′-cyclo-2′-deoxyadenosine accumulate in the brain tissues of xeroderma pigmentosum group A gene-knockout mice
High levels of oxidatively generated DNA damage 8,5′-cyclo-2′-deoxyadenosine accumulate in the brain tissues of xeroderma pigmentosum group A gene-knockout mice
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DOI：
10.1016/j.dnarep.2019.04.004
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发表时间：
2019-08-01
期刊：
影响因子：
3.8
通讯作者：
Sugiura, Shigeki
中科院分区：
文献类型：
--
作者：
Mori, Toshio;Nakane, Hironobu;Sugiura, Shigeki
着色性干皮病（XP）是一种与核苷酸切除修复缺陷相关的遗传性疾病，核苷酸切除修复是一种消除各种螺旋扭曲DNA损伤（包括紫外线诱导的嘧啶二聚体）的途径。除了暴露在阳光下的皮肤病，大约25%的XP患者发展为进行性神经系统疾病，这被假设为与称为嘌呤8，5 '-环-2'-脱氧核苷（环嘌呤）的氧化产生的DNA损伤类型的积累有关。然而，这一假设尚未得到证实。在这项研究中，我们通过使用XP A组基因敲除（Xpa（-/-））小鼠模型来验证这一假设。为了定量该模型中的环嘌呤损伤，我们先前使用特异性识别8，5 '-环-2'-脱氧腺苷（cyclo-dA）的单克隆抗体（CdA-1）建立了酶联免疫吸附测定（ELISA）。通过优化条件，我们将ELISA灵敏度提高到（类似于）一个环-dA损伤/10（6）个核苷的检测限。改进的ELISA显示，在Xpa（-/-）和野生型（wt）小鼠的脑组织中，cyclo-dA损伤随着年龄的增长而积累，但在6、24和29月龄时，Xpa（-/-）小鼠中的cyclo-dA损伤显著多于wt小鼠。这些发现与长期存在的假设一致，即内源性环嘌呤病变在大脑中的年龄依赖性积累可能是XP神经系统异常的关键。
Xeroderma pigmentosum (XP) is a genetic disorder associated with defects in nucleotide excision repair, a pathway that eliminates a wide variety of helix-distorting DNA lesions, including ultraviolet-induced pyrimidine dimers. In addition to skin diseases in sun-exposed areas, approximately 25% of XP patients develop progressive neurological disease, which has been hypothesized to be associated with the accumulation of an oxidatively generated type of DNA damage called purine 8,5'-cyclo-2'-deoxynucleoside (cyclopurine). However, that hypothesis has not been verified. In this study, we tested that hypothesis by using the XP group A gene-knockout (Xpa(-/-)) mouse model. To quantify cyclopurine lesions in this model, we previously established an enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody (CdA-1) that specifically recognizes 8,5'-cyclo-2'-deoxyadenosine (cyclo-dA). By optimizing conditions, we increased the ELISA sensitivity to a detection limit of (similar to)one cyclo-dA lesion/10(6) nucleosides. The improved ELISA revealed that cyclo-dA lesions accumulate with age in the brain tissues of Xpa(-/-) and of wild-type (wt) mice, but there were significantly more cyclo-dA lesions in Xpa(-/-) mice than in wt mice at 6, 24 and 29 months of age. These findings are consistent with the long-standing hypothesis that the age-dependent accumulation of endogenous cyclopurine lesions in the brain may be critical for XP neurological abnormalities.