Loss of PINK1 function decreases PP2A activity and promotes autophagy in dopaminergic cells and a murine model
Loss of PINK1 function decreases PP2A activity and promotes autophagy in dopaminergic cells and a murine model
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PINK1 功能丧失会降低 PP2A 活性并促进多巴胺能细胞和小鼠模型中的自噬
DOI：
10.1016/j.neuint.2011.03.023
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发表时间：
2011-10-01
影响因子：
4.2
通讯作者：
Yang, Hui
中科院分区：
文献类型：
--
作者：
Qi, Zhifeng;Yang, Weiwei;Yang, Hui
帕金森病（PD）是最常见的神经退行性运动障碍。PTEN诱导的激酶1（PINK 1）突变是隐性PD的常见原因。自噬是一种清除蛋白质聚集体或受损细胞器的途径，是PD发展的一种新机制。然而，目前还不清楚是什么分子调节PINK 1沉默细胞中的自噬。在这里，我们报告说，自体吞噬体的形成是促进在早期阶段响应于PINK 1基因沉默的慢病毒转移载体在小鼠纹状体中表达。在PINK 1敲低的多巴胺能细胞和纹状体组织中观察到PP 2A活性降低和PP 2A在Y307（PP 2A的失活形式）处的磷酸化增加。用C2-神经酰胺（PP 2A的激动剂）处理降低了PINK 1沉默的MN 9D细胞中的自噬水平，这表明PP 2A在PINK 1敲低诱导的自噬途径中起重要作用。此外，在PINK 1沉默的细胞中，Bcl-2在S87处的磷酸化增加，并且通过用C2-神经酰胺的额外处理而负调节，这表明Bcl-2可能是响应于PINK 1功能障碍的PP 2A失活的下游。免疫沉淀还显示PINK 1沉默细胞中Bcl-2/Beclin 1复合物的解离，其通过用C2-神经酰胺的额外处理而逆转，并且与自噬水平和Bcl-2的587磷酸化的变化相关。最后，蛋白质印迹法切割的caspase-9和流式细胞术的活性caspase-3的结果表明，PP 2A失活参与了自噬对PINK 1沉默细胞的保护作用。我们的研究结果表明，PINK 1沉默细胞中PP 2A活性的下调通过Bcl-2在587处的磷酸化和caspase途径的阻断促进了自噬的保护作用。这些结果可能对确定PD的机制具有意义。(C)2011爱思唯尔有限公司版权所有。
Parkinson's disease (PD) is the most common neurodegenerative movement disorder. Mutations in PTEN-induced kinase 1 (PINK1) are a frequent cause of recessive PD. Autophagy, a pathway for clearance of protein aggregates or impaired organelles, is a newly identified mechanism for PD development. However, it is still unclear what molecules regulate autophagy in PINK1-silenced cells. Here we report that auto-phagosome formation is promoted in the early phase in response to PINK1 gene silencing by lentivirus transfer vectors expressed in mouse striatum. Reduced PP2A activity and increased phosphorylation of PP2A at Y307 (inactive form of PP2A) were observed in PINK1-knockdown dopaminergic cells and striatum tissues. Treatment with C2-ceramide (an agonist of PP2A) reduced autophagy levels in PINK1-silenced MN9D cells, which suggests that PP2A plays an important role in the PINK1-knockdown-induced autophagic pathway. Furthermore, phosphorylation of Bcl-2 at S87 increased in PINK1-silenced cells and was negatively regulated by additional treatment with C2-ceramide, which indicates that Bcl-2 may be downstream of PP2A inactivation in response to PINK1 dysfunction. Immunoprecipitation also revealed dissociation of the Bcl-2/Beclin1 complex in PINK1-silenced cells, which was reversed by additional treatment with C2-ceramide, and correlated with changes in level of autophagy and 587 phosphorylation of Bcl-2. Finally, Western blots for cleaved caspase-9 and flow cytometry results for active caspase-3 revealed that PP2A inactivation is involved in the protective effect of autophagy on PINK1-silenced cells. Our findings show that downregulation of PP2A activity in PINK1-silenced cells promotes the protective effect of autophagy through phosphorylation of Bcl-2 at 587 and blockage of the caspase pathway. These results may have implications for identifying the mechanism of PD. (C) 2011 Elsevier B.V. All rights reserved.