Sanford-Burnham Medical Research Institute, Del E, Webb Center for Neuroscience, Aging, and Stem Cell Research, 10901, North Torrey Pines Road, La Jolla, CA 92037, USA.
Mol Neurodegener. 2013 Aug 28;8:29. doi: 10.1186/1750-1326-8-29.
Mutations in the gene encoding parkin, a neuroprotective protein with dual functions as an E3 ubiquitin ligase and transcriptional repressor of p53, are linked to familial forms of Parkinson's disease (PD). We hypothesized that oxidative posttranslational modification of parkin by environmental toxins may contribute to sporadic PD.
We first demonstrated that S-nitrosylation of parkin decreased its activity as a repressor of p53 gene expression, leading to upregulation of p53. Chromatin immunoprecipitation as well as gel-shift assays showed that parkin bound to the p53 promoter, and this binding was inhibited by S-nitrosylation of parkin. Additionally, nitrosative stress induced apoptosis in cells expressing parkin, and this death was, at least in part, dependent upon p53. In primary mesencephalic cultures, pesticide-induced apoptosis was prevented by inhibition of nitric oxide synthase (NOS). In a mouse model of pesticide-induced PD, both S-nitrosylated (SNO-)parkin and p53 protein levels were increased, while administration of a NOS inhibitor mitigated neuronal death in these mice. Moreover, the levels of SNO-parkin and p53 were simultaneously elevated in postmortem human PD brain compared to controls.
Taken together, our data indicate that S-nitrosylation of parkin, leading to p53-mediated neuronal cell death, contributes to the pathophysiology of sporadic PD.
Parkin 基因编码的蛋白具有 E3 泛素连接酶和转录抑制因子 p53 的双重功能，其基因突变与家族性帕金森病（PD）有关。我们假设环境毒素对 Parkin 的氧化后翻译修饰可能导致散发性 PD。
我们首先证明 Parkin 的 S-亚硝基化降低了其作为 p53 基因表达抑制剂的活性，导致 p53 的上调。染色质免疫沉淀和凝胶迁移实验表明 Parkin 与 p53 启动子结合，而 Parkin 的 S-亚硝基化抑制了这种结合。此外，表达 Parkin 的细胞中的硝化应激诱导细胞凋亡，这种死亡至少部分依赖于 p53。在原代中脑培养物中，一氧化氮合酶（NOS）抑制剂可预防农药诱导的细胞凋亡。在农药诱导的 PD 小鼠模型中，S-亚硝基化（SNO-）Parkin 和 p53 蛋白水平均升高，而给予 NOS 抑制剂可减轻这些小鼠的神经元死亡。此外，与对照组相比，帕金森病患者死后大脑中的 SNO-Parkin 和 p53 水平同时升高。
综上所述，我们的数据表明，Parkin 的 S-亚硝基化导致 p53 介导的神经元细胞死亡，导致散发性 PD 的病理生理学变化。
