Tsai Pei-I, Course Meredith M, Lovas Jonathan R, Hsieh Chung-Han, Babic Milos, Zinsmaier Konrad E, Wang Xinnan
Department of Neurosurgery, Stanford University School of Medicine, Stanford. CA94304.
1] Department of Neurosurgery, Stanford University School of Medicine, Stanford. CA94304 [2] Neurosciences Program, Stanford University, Stanford. CA94304.
Sci Rep. 2014 Nov 7;4:6962. doi: 10.1038/srep06962.
Mutations in the mitochondrial Ser/Thr kinase PINK1 cause Parkinson's disease. One of the substrates of PINK1 is the outer mitochondrial membrane protein Miro, which regulates mitochondrial transport. In this study, we uncovered novel physiological functions of PINK1-mediated phosphorylation of Miro, using Drosophila as a model. We replaced endogenous Drosophila Miro (DMiro) with transgenically expressed wildtype, or mutant DMiro predicted to resist PINK1-mediated phosphorylation. We found that the expression of phospho-resistant DMiro in a DMiro null mutant background phenocopied a subset of phenotypes of PINK1 null. Specifically, phospho-resistant DMiro increased mitochondrial movement and synaptic growth at larval neuromuscular junctions, and decreased the number of dopaminergic neurons in adult brains. Therefore, PINK1 may inhibit synaptic growth and protect dopaminergic neurons by phosphorylating DMiro. Furthermore, muscle degeneration, swollen mitochondria and locomotor defects found in PINK1 null flies were not observed in phospho-resistant DMiro flies. Thus, our study established an in vivo platform to define functional consequences of PINK1-mediated phosphorylation of its substrates.
线粒体丝氨酸/苏氨酸激酶PINK1的突变会导致帕金森病。PINK1的底物之一是线粒体外膜蛋白Miro，它调节线粒体运输。在本研究中，我们以果蝇为模型，揭示了PINK1介导的Miro磷酸化的新生理功能。我们用转基因表达的野生型或预测可抵抗PINK1介导磷酸化的突变型果蝇Miro（DMiro）替代内源性果蝇Miro。我们发现在DMiro缺失突变背景中表达抗磷酸化的DMiro模拟了PINK1缺失的一部分表型。具体而言，抗磷酸化的DMiro增加了幼虫神经肌肉接头处的线粒体运动和突触生长，并减少了成体大脑中多巴胺能神经元的数量。因此，PINK1可能通过磷酸化DMiro来抑制突触生长并保护多巴胺能神经元。此外，在抗磷酸化的DMiro果蝇中未观察到PINK1缺失果蝇中出现的肌肉退化、线粒体肿胀和运动缺陷。因此，我们的研究建立了一个体内平台来确定PINK1介导的其底物磷酸化的功能后果。
