LRRK2 impairs autophagy by mediating phosphorylation of leucyl-tRNA synthetase
LRRK2 impairs autophagy by mediating phosphorylation of leucyl-tRNA synthetase
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DOI：
10.1002/cbf.3364
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发表时间：
2018-12-01
影响因子：
3.6
通讯作者：
Seol, Wongi
中科院分区：
文献类型：
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作者：
Ho, Dong Hwan;Kim, Hyejung;Seol, Wongi
富含亮氨酸重复序列激酶2（LRRK 2）是帕金森病的致病基因。G2019 S致病突变增加了其激酶活性。LRRK 2调节各种表型，包括自噬、神经突生长和囊泡运输。亮氨酰-tRNA合成酶（LRS）将亮氨酸连接到tRNA（Leu）并激活mTORC 1。LRS的下调诱导自噬。我们研究了LRRK 2和LRS在调节自噬中的关系，并观察了内源性LRRK 2和LRS蛋白之间的相互作用以及LRRK 2对LRS的磷酸化。突变研究表明LRS编辑结构域中的T293是一个假定的磷酸化位点。在过表达G2019 S的细胞和从G2019 S载体的诱导多能干细胞（iPS）分化的多巴胺能神经元中，LRS中的磷酸化Thr增加。通过LRRK 2激酶抑制剂（GSK 2578215 A）治疗降低。拟磷酸化T293 D显示比野生型（WT）更低的亮氨酸结合，表明其有缺陷的编辑功能。T293 D的细胞表达增加了GRP 78/BiP、LC 3B-II和p62蛋白的表达以及LC 3斑点的数量。GRP 78和磷酸化LRS的增加通过用GSK 2578215 A处理而减少。在G2019 S转基因（TG）小鼠中，LC 3B、GRP 78/BiP、p62和α-突触核蛋白的水平也增加。这些数据表明LRRK 2介导的LRS磷酸化通过增加由LRS编辑缺陷介导的蛋白质错误折叠和内质网应激来损害自噬。富含亮氨酸的重复序列激酶2（LRRK 2）是帕金森病（PD）最常见的遗传原因，最常见的致病突变G2019 S增加了其激酶活性。在这项研究中，我们阐明亮氨酰-tRNA合成酶（LRS）是LRRK 2激酶底物，并确定T293作为LRRK 2磷酸化位点。LRRK 2介导的LRS磷酸化或G2019 S可导致LRS编辑受损、ER应激增加和自噬标志物积累。这些结果表明，LRRK 2激酶活性可以促进错误折叠蛋白的积累，这表明LRRK 2激酶可能是一个潜在的PD治疗靶点，沿着先前的研究。
Leucine-rich repeat kinase 2 (LRRK2) is a causal gene of Parkinson disease. G2019S pathogenic mutation increases its kinase activity. LRRK2 regulates various phenotypes including autophagy, neurite outgrowth, and vesicle trafficking. Leucyl-tRNA synthetase (LRS) attaches leucine to tRNA(Leu) and activates mTORC1. Down-regulation of LRS induces autophagy. We investigated the relationship between LRRK2 and LRS in regulating autophagy and observed interaction between endogenous LRRK2 and LRS proteins and LRS phosphorylation by LRRK2. Mutation studies implicated that T293 in the LRS editing domain was a putative phosphorylation site. Phospho-Thr in LRS was increased in cells overexpressing G2019S and dopaminergic neurons differentiated from induced pluripotent stem (iPS) cells of a G2019S carrier. It was decreased by treatment with an LRRK2 kinase inhibitor (GSK2578215A). Phosphomimetic T293D displayed lower leucine bindings than wild type (WT), suggesting its defective editing function. Cellular expression of T293D increased expression of GRP78/BiP, LC3B-II, and p62 proteins and number of LC3 puncta. Increase of GRP78 and phosphorylated LRS was diminished by treatment with GSK2578215A. Levels of LC3B, GRP78/BiP, p62, and alpha-synuclein proteins were also increased in G2019S transgenic (TG) mice. These data suggest that LRRK2-mediated LRS phosphorylation impairs autophagy by increasing protein misfolding and endoplasmic reticulum stress mediated by LRS editing defect. Significance of the study Leucine-rich repeat kinase 2 (LRRK2) is the most common genetic cause of Parkinson disease (PD), and the most prevalent pathogenic mutation, G2019S, increases its kinase activity. In this study, we elucidated that leucyl-tRNA synthetase (LRS) was an LRRK2 kinase substrate and identified T293 as an LRRK2 phosphorylation site. LRRK2-meidated LRS phosphorylation or G2019S can lead to impairment of LRS editing, increased ER stress, and accumulation of autophagy markers. These results demonstrate that LRRK2 kinase activity can facilitate accumulation of misfolded protein, suggesting that LRRK2 kinase might be a potential PD therapeutic target along with previous studies.