Disulfide bond mediates aggregation, toxicity, and ubiquitylation of familial amyotrophic lateral sclerosis-linked mutant SOD1
Disulfide bond mediates aggregation, toxicity, and ubiquitylation of familial amyotrophic lateral sclerosis-linked mutant SOD1
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DOI：
10.1074/jbc.m704465200
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发表时间：
2007-09-21
影响因子：
4.8
通讯作者：
Sobue, Gen
中科院分区：
文献类型：
--
作者：
Niwa, Jun-ichi;Yamada, Shin-ichi;Sobue, Gen
铜/锌-超氧化物歧化酶（SOD 1）基因突变通过获得毒性功能导致家族性肌萎缩侧索硬化症（ALS）;然而，这种毒性功能的性质在很大程度上仍然未知。受影响的脑病变中的突变SOD 1蛋白的泛素化聚集体是该疾病的病理标志，并被认为参与了几种提出的运动神经元死亡机制。最近的研究表明，突变型SODI在体外轻度氧化应激时容易形成不正确的二硫键，ALS模型小鼠脊髓中不溶性的SOD 1聚集体含有通过分子间二硫键交联的多聚体。在这里，我们表明，突变SOD 1的位置6和111的半胱氨酸之间的非生理性分子间二硫键是重要的高分子量聚集体的形成，ubliquitylation，和神经毒性，所有这些都显着减少时，相关的半胱氨酸被替换在突变SOD 1在神经细胞-2a细胞中表达。Dorfin是一种遍在基连接酶，可特异性结合家族性ALS相关突变体SOD 1并使其遍在化，从而促进其降解。我们发现Dorfin通过识别CYS 6-和Cys（111）-二硫键交联形式泛素化突变体SOD 1，并靶向其进行蛋白酶体降解。
Mutations in the Cu/Zn-superoxide dismutase (SOD1) gene cause familial amyotrophic lateral sclerosis (ALS) through the gain of a toxic function; however, the nature of this toxic function remains largely unknown. Ubiquitylated aggregates of mutant SOD 1 proteins in affected brain lesions are pathological hallmarks of the disease and are suggested to be involved in several proposed mechanisms of motor neuron death. Recent studies suggest that mutant SODI readily forms an incorrect disulfide bond upon mild oxidative stress in vitro, and the insoluble SOD 1 aggregates in spinal cord of ALS model mice contain multimers cross-linked via intermolecular disulfide bonds. Here we show that a non-physiological intermolecular disulfide bond between cysteines at positions 6 and 111 of mutant SOD 1 is important for high molecular weight aggregate formation, ubliquitylation, and neurotoxicity, all of which were dramatically reduced when the pertinent cysteines were replaced in mutant SOD 1 expressed in Neuro-2a cells. Dorfin is a ubiquityl ligase that specifically binds familial ALS-linked mutant SOD 1 and ubiquitylates it, thereby promoting its degradation. We found that Dorfin ubiquitylated mutant SOD1 by recognizing the CYS6- and Cys(111)-disulfide cross-linked form and targeted it for proteasomal degradation.