Disulfide cross-linked protein represents a significant fraction of ALS-associated Cu, Zn-superoxide dismutase aggregates in spinal cords of model mice
Disulfide cross-linked protein represents a significant fraction of ALS-associated Cu, Zn-superoxide dismutase aggregates in spinal cords of model mice
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DOI：
10.1073/pnas.0602048103
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发表时间：
2006-05-02
影响因子：
11.1
通讯作者：
O'Halloran, TV
中科院分区：
文献类型：
--
作者：
Furukawa, Y;Fu, RG;O'Halloran, TV
铜锌超氧化物歧化酶（SOD 1）的点突变导致神经退行性疾病肌萎缩侧索硬化症（ALS）的家族形式。在组织病理学中观察到突变体SOD 1蛋白的聚集体，并且在几种提出的运动神经元死亡机制中被调用;然而，在这种模型中不容易解释成熟突变体蛋白的显著稳定性和活性。最近的生物化学研究表明，它是不成熟的二硫键还原形式的家族性ALS突变体SOD 1蛋白，发挥关键作用，这些形式往往错误折叠，寡聚化，并容易发生不正确的二硫键形成后，温和的体外氧化应激。在这里，我们提供了这种机制的聚集体形成的生理支持，并表明，在ALS模型转基因小鼠的脊髓中的不溶性SOD 1聚集体的一个显着的分数包含通过分子间二硫键交联的多聚体。这些不可溶的二硫键连接的SOD 1多聚体仅在有症状的转基因动物的脊髓中发现，在脑皮质和肝脏等未受累组织中未观察到，并且可以掺入WT SOD 1蛋白。这些发现为这种疾病的病理标志提供了生化基础;即，不成熟的错误折叠的突变蛋白的不正确的二硫键交联导致不溶性聚集体。
Point mutations in Cu, Zn-superoxide dismutase (SOD1) cause a familial form of the neurodegenerative disease amyotrophic lateral sclerosis (ALS). Aggregates of mutant SOD1 proteins are observed in histopathology and are invoked in several proposed mechanisms for motor neuronal death; however, the significant stability and activity of the mature mutant proteins are not readily explained in such models. Recent biochemical studies suggest that it is the immature disulfide-reduced forms of the familial ALS mutant SOD1 proteins that play a critical role; these forms tend to misfold, oligomerize, and readily undergo incorrect disulfide formation upon mild oxidative stress in vitro. Here we provide physiological support for this mechanism of aggregate formation and show that a significant fraction of the insoluble SOD1 aggregates in spinal cord of the ALS-model transgenic mice contain multimers cross-linked via intermolecular disulfide bonds. These insoluble disulfide-linked SOD1 multimers are found only in the spinal cord of symptomatic transgenic animals, are not observed in unafflicted tissue such as brain cortex and liver, and can incorporate WT SOD1 protein. The findings provide a biochemical basis for a pathological hallmark of this disease; namely, incorrect disulfide cross-linking of the immature, misfolded mutant proteins leads to insoluble aggregates.