Overexpression of PLK3 Mediates the Degradation of Abnormal Prion Proteins Dependent on Chaperone-Mediated Autophagy
Overexpression of PLK3 Mediates the Degradation of Abnormal Prion Proteins Dependent on Chaperone-Mediated Autophagy
复制标题
PLK3 的过度表达介导依赖于分子伴侣介导的自噬的异常朊病毒蛋白的降解
DOI：
10.1007/s12035-016-9985-0
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发表时间：
2017-08-01
影响因子：
5.1
通讯作者：
Dong, Xiao-Ping
中科院分区：
文献类型：
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作者：
Wang, Hui;Tian, Chan;Dong, Xiao-Ping
Polo样激酶3（PLK 3）是细胞周期折返相关的神经元凋亡的主要原因，与朊病毒病的发病机制有关。以前的工作也表明外源PLK 3对PrP（朊蛋白）突变体和致病性PrPSc的降解具有调节活性;然而，确切的机制仍然未知。在这项研究中，我们发现PLK 3介导的PrP突变体和PrPSc降解的过表达被溶酶体抑制，而不是被蛋白酶体和大自噬抑制剂抑制。在表达PrP突变体的HEK 293 T细胞和羊瘙痒病感染的细胞系SMB-S15中，伴侣蛋白介导的自噬（CMA）效应子的核心组分、溶酶体相关膜蛋白2A型（LAMP 2a）和热休克同源蛋白70（Hsc 70）显著减少。同时，PrP突变体显示出与LAMP 2a和Hsc 70相互作用的能力。PLK 3的过表达显著增加了细胞内LAMP 2a和Hsc 70的表达水平，同时降低了PrP突变体和PrPSc的积累。PLK 3的激酶结构域（KD）负责升高LAMP 2a和Hsc 70。内源性PLK 3的敲低增强了培养细胞中的大自噬活性。此外，在仓鼠适应性羊瘙痒症因子263 K感染的仓鼠的脑组织中也观察到LAMP 2a和Hsc 70的时间依赖性减少，表明在朊病毒感染期间CMA受损。这些数据表明PLK 3介导的异常PrP降解的过表达在很大程度上依赖于CMA途径。
Polo-like kinase 3 (PLK3) is the main cause of cell cycle reentry-related neuronal apoptosis which has been implicated in the pathogenesis of prion diseases. Previous work also showed the regulatory activity of exogenous PLK3 on the degradation of PrP (prion protein) mutants and pathogenic PrPSc; however, the precise mechanisms remain unknown. In this study, we identified that the overexpression of PLK3-mediated degradation of PrP mutant and PrPScwas repressed by lysosome rather than by proteasomal and macroautophagy inhibitors. Core components of chaperone-mediated autophagy (CMA) effectors, lysosome-associated membrane protein type 2A (LAMP2a), and heat shock cognate protein 70 (Hsc70) are markedly decreased in the HEK293T cells expressing PrP mutant and scrapie-infected cell line SMB-S15. Meanwhile, PrP mutant showed ability to interact with LAMP2a and Hsc70. Overexpression of PLK3 sufficiently increased the cellular levels of LAMP2a and Hsc70, accompanying with declining the accumulations of PrP mutant and PrPSc. The kinase domain (KD) of PLK3 was responsible for elevating LAMP2a and Hsc70. Knockdown of endogenous PLK3 enhanced the activity of macroautophagy in the cultured cells. Moreover, time-dependent reductions of LAMP2a and Hsc70 were also observed in the brain tissues of hamster-adapted scrapie agent 263K-infected hamsters, indicating an impairment of CMA during prion infection. Those data indicate that the overexpression of PLK3-mediated degradation of abnormal PrP is largely dependent on CMA pathway.