PINK1 phosphorylates ubiquitin predominantly in astrocytes
PINK1 phosphorylates ubiquitin predominantly in astrocytes
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DOI：
10.1038/s41531-019-0101-9
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发表时间：
2019-12-11
影响因子：
8.7
通讯作者：
Goldberg, Matthew S.
中科院分区：
文献类型：
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作者：
Barodia, Sandeep K.;McMeekin, Laura J.;Goldberg, Matthew S.
PINK1的功能丧失突变与隐性遗传性帕金森病(PD)有关，黑质中正常运动所需的多巴胺能神经元显著丧失。PINK1是一种核编码的线粒体靶向激酶，它磷酸化泛素和Parkin基因中65位氨基酸(PS65)的保守丝氨酸，Parkin是另一个与隐性帕金森病相关的功能丧失突变的基因。PINK1蛋白的稳态水平非常低，即使在表达PINK1的细胞中也是如此，因为PINK1通常是线粒体输入后通过依赖于线粒体膜电位的过程而被降解的目标。线粒体膜电位随着离子载体(如CCCP和呋喃霉素)的消散，导致线粒体膜外膜上PINK1的聚集，pS65-泛素的显著增加和Parkin的募集，Parkin以功能障碍的线粒体为靶点，通过自噬进行降解。虽然PINK1突变的高外显性确立了其维持神经元的关键功能，但PINK1在原代神经元中的活性一直难以检测到。越来越多的证据表明，包括星形胶质细胞和小胶质细胞在内的非神经细胞参与了特发性和遗传性帕金森病的发病机制。在这篇论文中，我们使用蛋白质分析和pS65-泛素免疫荧光的方法，直接比较了野生型(WT)和PINK1基因敲除(KO)大鼠脑内原代神经元、星形胶质细胞、小胶质细胞和少突胶质前体细胞中PINK1的活性。我们的研究结果表明，PINK1依赖的泛素磷酸化主要存在于星形胶质细胞中，这支持了对PINK1在星形胶质细胞中的功能以及星形胶质细胞功能障碍在帕金森病发病机制中的作用的研究。
Loss-of-function mutations in PINK1 are causally linked to recessively inherited Parkinson's disease (PD), with marked loss of dopaminergic neurons in the substantia nigra that are required for normal movement. PINK1 is a nuclear-encoded mitochondrial-targeted kinase that phosphorylates a conserved serine at amino acid 65 (pS65) in ubiquitin as well as Parkin, another gene with loss-of-function mutations linked to recessive parkinsonism. The steady-state levels of PINK1 protein are very low, even in cells that express PINK1, because PINK1 is normally targeted for degradation after mitochondrial import by a process that is dependent upon mitochondrial membrane potential. Dissipation of the mitochondrial membrane potential with ionophores, such as CCCP and valinomycin, causes the accumulation of PINK1 on the outer mitochondrial membrane, a marked increase of pS65-ubiquitin and the recruitment of Parkin, which targets dysfunctional mitochondria for degradation by autophagy. While the high penetrance of PINK1 mutations establish its critical function for maintaining neurons, the activity of PINK1 in primary neurons has been difficult to detect. Mounting evidence implicates non-neuronal cells, including astrocytes and microglia, in the pathogenesis of both idiopathic and inherited PD. Herein we used both western analysis and immunofluorescence of pS65-ubiquitin to directly compare the activity of PINK1 in primary neurons, astrocytes, microglia, and oligodendrocyte progenitor cells cultured from the brains of wild-type (WT) and PINK1 knockout (KO) rat pups. Our findings that PINK1-dependent ubiquitin phosphorylation is predominantly in astrocytes supports increased priority for research on the function of PINK1 in astrocytes and the contribution of astrocyte dysfunction to PD pathogenesis.