Suppression of astrocytic autophagy by αB-crystallin contributes to α-synuclein inclusion formation
Suppression of astrocytic autophagy by αB-crystallin contributes to α-synuclein inclusion formation
复制标题
α B-晶状体蛋白抑制星形胶质细胞自噬有助于形成 α-突触核蛋白包涵体
DOI：
10.1186/s40035-018-0143-7
复制
发表时间：
2019-01-18
影响因子：
12.6
通讯作者：
Zhou, Jia-wei
中科院分区：
文献类型：
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作者：
Lu, Shen-zhao;Guo, Yong-shun;Zhou, Jia-wei
背景：帕金森病(Parkinson‘s Disease，PD)是以多巴胺能神经元的慢性缺失和黑质残留神经元内存在蛋白质包涵体(Luy小体)为特征的疾病。近年来，在包括帕金森病在内的一些神经退行性疾病中也发现了星形胶质包涵体。然而，星形胶质蛋白聚集形成的潜在分子机制在很大程度上仍不清楚。在此，我们研究了小分子热休克蛋白-αB-晶体蛋白(CryAB)在星形细胞α-突触核蛋白包涵体形成中的作用。方法：采用小干扰RNA(SiRNA)介导的CryAB(SiCRYAB)基因敲除或CryAB过表达的方法，观察CryAB对人脑胶质母细胞瘤U251细胞自噬的影响。免疫共沉淀(co-IP)和免疫印迹分析多个蛋白质之间的相互作用。免疫细胞化学方法检测α-突触核蛋白的体外清除能力。用CryAB转基因小鼠和高表达人α-突触核蛋白A30P突变型的转基因小鼠检测了CryAB对α-突触核蛋白在体内蓄积的影响。结果：在U251细胞和原代培养的星形胶质细胞中，CryAB基因的敲除导致自噬活性明显增强。相反，外源CryAB通过与BAG3结合来破坏BAG3-HSPB8HSC70复合体的组装，从而抑制自噬活性。此外，CryAB调节的自噬与帕金森病的发病机制有关。CryAB基因敲除可显著促进α-突触核蛋白预成纤维(Pff)的胞质清除。相反，在表达人α-突触核蛋白A30P突变体的转基因小鼠中，选择性过表达CryAB显著抑制了自噬，导致脑内α-突触核蛋白聚集体的聚集。结论：本研究揭示了CryAB作为星形细胞自噬天然抑制因子的新功能，并表明敲除CyRAB可能为联核病等蛋白质病提供治疗靶点。
Background: Parkinson's disease (PD) is characterized by a chronic loss of dopaminergic neurons and the presence of proteinaceous inclusions (Lewy bodies) within some remaining neurons in the substantia nigra. Recently, astroglial inclusion body has also been found in some neurodegenerative diseases including PD. However, the underlying molecular mechanisms of how astroglial protein aggregation forms remain largely unknown. Here, we investigated the contribution of alpha B-crystallin (CRYAB), a small heat shock protein, in alpha-synuclein inclusion formation in astrocytes.Methods: Small interfering RNA (siRNA)-mediated CRYAB (siCRYAB) knockdown or CRYAB overexpression was performed to investigate the impact of CRYAB on the autophagy in human glioblastoma cell line U251 cells. Coimmunoprecipitation (co-IP) and immunoblotting were used to dissect the interaction among multiple proteins. The clearance of alpha-synuclein in vitro was evaluated by immunocytochemistry. CRYAB transgenic mice and transgenic mice overexpressing A30P mutant form of human alpha-synuclein were used to examine the influence of CRYAB to alpha-synuclein accumulation in vivo.Results: We found that knockdown of CRYAB in U251 cells or primary cultured astrocytes resulted in a marked augmentation of autophagy activity. In contrast, exogenous CRYAB disrupted the assembly of the BAG3-HSPB8HSC70 complex via binding with BAG3, thereby suppressing the autophagy activity. Furthermore, CRYAB-regulated autophagy has relevance to PD pathogenesis. Knockdown of CRYAB remarkably promoted cytoplasmic clearance of alpha-synuclein preformed fibrils (PFFs). Conversely, selective overexpression of CRYAB in astrocytes markedly suppressed autophagy leading to the accumulation of alpha-synuclein aggregates in the brain of transgenic mice expressing human alpha-synuclein A30P mutant.Conclusions: This study reveals a novel function for CRYAB as a natural inhibitor of astrocytic autophagy and shows that knockdown of CYRAB may provide a therapeutic target against proteinopathies such as synucleinopathies.