肌萎缩侧索硬化症相关突变 SOD1 通过降低 Miro1 水平抑制线粒体顺行轴突运输。

Amyotrophic lateral sclerosis-associated mutant SOD1 inhibits anterograde axonal transport of mitochondria by reducing Miro1 levels.

机构信息

Sheffield Institute for Translational Neuroscience (SITraN), Department of Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK.

出版信息

Hum Mol Genet. 2017 Dec 1;26(23):4668-4679. doi: 10.1093/hmg/ddx348.

Abstract

Defective axonal transport is an early neuropathological feature of amyotrophic lateral sclerosis (ALS). We have previously shown that ALS-associated mutations in Cu/Zn superoxide dismutase 1 (SOD1) impair axonal transport of mitochondria in motor neurons isolated from SOD1 G93A transgenic mice and in ALS mutant SOD1 transfected cortical neurons, but the underlying mechanisms remained unresolved. The outer mitochondrial membrane protein mitochondrial Rho GTPase 1 (Miro1) is a master regulator of mitochondrial axonal transport in response to cytosolic calcium (Ca2+) levels ([Ca2+]c) and mitochondrial damage. Ca2+ binding to Miro1 halts mitochondrial transport by modifying its interaction with kinesin-1 whereas mitochondrial damage induces Phosphatase and Tensin Homolog (PTEN)-induced Putative Kinase 1 (PINK1) and Parkin-dependent degradation of Miro1 and consequently stops transport. To identify the mechanism underlying impaired axonal transport of mitochondria in mutant SOD1-related ALS we investigated [Ca2+]c and Miro1 levels in ALS mutant SOD1 expressing neurons. We found that expression of ALS mutant SOD1 reduced the level of endogenous Miro1 but did not affect [Ca2+]c. ALS mutant SOD1 induced reductions in Miro1 levels were Parkin dependent. Moreover, both overexpression of Miro1 and ablation of PINK1 rescued the mitochondrial axonal transport deficit in ALS mutant SOD1-expressing cortical and motor neurons. Together these results provide evidence that ALS mutant SOD1 inhibits axonal transport of mitochondria by inducing PINK1/Parkin-dependent Miro1 degradation.

摘要

轴突运输缺陷是肌萎缩侧索硬化症(ALS)的早期神经病理学特征。我们之前已经表明,铜/锌超氧化物歧化酶 1(SOD1)中的 ALS 相关突变会损害 SOD1 G93A 转基因小鼠分离的运动神经元中和 ALS 突变 SOD1 转染的皮质神经元中线粒体的轴突运输,但潜在机制仍未解决。外线粒体膜蛋白线粒体 Rho GTP 酶 1(Miro1)是线粒体轴突运输对细胞浆钙离子(Ca2+)水平([Ca2+]c)和线粒体损伤反应的主要调节因子。Ca2+与 Miro1 结合通过改变其与驱动蛋白-1的相互作用来阻止线粒体运输,而线粒体损伤诱导磷酸酶和张力蛋白同源物(PTEN)诱导的假定激酶 1(PINK1)和 Parkin 依赖性 Miro1 降解,并因此停止运输。为了确定与突变 SOD1 相关的 ALS 中线粒体轴突运输受损的机制,我们研究了表达 ALS 突变 SOD1 的神经元中的 [Ca2+]c 和 Miro1 水平。我们发现,表达 ALS 突变 SOD1 会降低内源性 Miro1 的水平,但不会影响 [Ca2+]c。ALS 突变 SOD1 诱导的 Miro1 水平降低依赖于 Parkin。此外,Miro1 的过表达和 PINK1 的缺失均挽救了 ALS 突变 SOD1 表达的皮质和运动神经元中线粒体的轴突运输缺陷。这些结果共同表明,ALS 突变 SOD1 通过诱导 PINK1/Parkin 依赖性 Miro1 降解来抑制线粒体的轴突运输。

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