Im Eunju, Chung Kwang Chul
Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul, Korea.
J Neurochem. 2015 Aug;134(4):756-68. doi: 10.1111/jnc.13164. Epub 2015 Jun 3.
Mutations of parkin are associated with the occurrence of autosomal recessive familial Parkinson's disease (PD). Parkin acts an E3 ubiquitin ligase, which ubiquitinates target proteins and subsequently regulates either their steady-state levels through the ubiquitin-proteasome system or biochemical properties. In this study, we identify a novel regulatory mechanism of parkin by searching for new regulatory factors. After screening human fetal brain using a yeast two hybrid assay, we found dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 1A (Dyrk1A) as a novel binding partner of parkin. We also observed that parkin interacts and co-localizes with Dyrk1A in mammalian cells. In addition, Dyrk1A directly phosphorylated parkin at Ser-131, causing the inhibition of its E3 ubiquitin ligase activity. Moreover, Dyrk1A-mediated phosphorylation reduced the binding affinity of parkin to its ubiquitin-conjugating E2 enzyme and substrate, which could be the underlying inhibitory mechanism of parkin activity. Furthermore, Dyrk1A-mediated phosphorylation inhibited the neuroprotective action of parkin against 6-hydroxydopamine toxicity in dopaminergic SH-SY5Y cells. These findings suggest that Dyrk1A acts as a novel functional modulator of parkin. Parkin phosphorylation by Dyrk1A suppresses its E3 ubiquitin ligase activity potentially contributing to the pathogenesis of PD under PD-inducing pathological conditions. Mutations of parkin are linked to autosomal recessive forms of familial Parkinson's disease (PD). According to its functional relevance in abnormal protein aggregation and neuronal cell death, a number of post-translational modifications regulate the ubiquitin E3 ligase activity of parkin. Here we propose a novel inhibitory mechanism of parkin E3 ubiquitin ligase through dual-specificity tyrosine-phosphorylation-regulated kinase 1A (Dyrk1A)-mediated phosphorylation as well as its neuroprotective action against 6-hydroxydopamine (6-OHDA)-induced cell death. The present work suggests that parkin phosphorylation by Dyrk1A may affect the pathogenesis of PD under PD-inducing pathological conditions.
帕金森病蛋白（parkin）的突变与常染色体隐性遗传性帕金森病（PD）的发生有关。帕金森病蛋白作为一种E3泛素连接酶，可使靶蛋白泛素化，随后通过泛素-蛋白酶体系统调节其稳态水平或生化特性。在本研究中，我们通过寻找新的调节因子来确定帕金森病蛋白的一种新的调节机制。在用酵母双杂交试验筛选人类胎儿脑之后，我们发现双特异性酪氨酸（Y）磷酸化调节激酶1A（Dyrk1A）是帕金森病蛋白的一种新的结合伴侣。我们还观察到帕金森病蛋白在哺乳动物细胞中与Dyrk1A相互作用并共定位。此外，Dyrk1A直接在丝氨酸131位点磷酸化帕金森病蛋白，导致其E3泛素连接酶活性受到抑制。而且，Dyrk1A介导的磷酸化降低了帕金森病蛋白与其泛素结合E2酶和底物的结合亲和力，这可能是帕金森病蛋白活性的潜在抑制机制。此外，Dyrk1A介导的磷酸化抑制了帕金森病蛋白对多巴胺能SH-SY5Y细胞中6-羟基多巴胺毒性的神经保护作用。这些发现表明Dyrk1A作为帕金森病蛋白的一种新的功能调节剂。Dyrk1A对帕金森病蛋白的磷酸化抑制其E3泛素连接酶活性，这可能在帕金森病诱发的病理条件下导致帕金森病的发病机制。帕金森病蛋白的突变与家族性帕金森病（PD）的常染色体隐性形式有关。根据其在异常蛋白质聚集和神经元细胞死亡中的功能相关性，一些翻译后修饰调节帕金森病蛋白的泛素E3连接酶活性。在此，我们提出一种通过双特异性酪氨酸磷酸化调节激酶1A（Dyrk1A）介导的磷酸化对帕金森病蛋白E3泛素连接酶的新的抑制机制，以及其对6-羟基多巴胺（6-OHDA）诱导的细胞死亡的神经保护作用。目前的研究表明，在帕金森病诱发的病理条件下，Dyrk1A对帕金森病蛋白的磷酸化可能影响帕金森病的发病机制。
