(-)-Epigallocatechin-3-gallate (EGCG) inhibits fibrillation, disaggregates amyloid fibrils of alpha-synuclein, and protects PC12 cells against alpha-synuclein-induced toxicity
(-)-Epigallocatechin-3-gallate (EGCG) inhibits fibrillation, disaggregates amyloid fibrils of alpha-synuclein, and protects PC12 cells against alpha-synuclein-induced toxicity
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(-)-表没食子儿茶素-3-没食子酸酯 (EGCG) 抑制纤维颤动，分解 α-突触核蛋白的淀粉样原纤维，并保护 PC12 细胞免受 α-突触核蛋白诱导的毒性
DOI：
10.1039/c7ra03752j
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发表时间：
2017
期刊：
影响因子：
3.9
通讯作者：
Zhou Ping
中科院分区：
文献类型：
--
作者：
Zhao Juan;Liang Qingnan;Sun Qing;Chen Congheng;Xu Lihui;Ding Yu;Zhou Ping
α-突触核蛋白 (α-Syn) 聚集体是路易体 (LB) 的主要成分，路易体是帕金森病 (PD) 患者脑组织的病理标志。据报道，(−)-表没食子儿茶素-3-没食子酸酯（EGCG）在生物学上能够穿透血脑屏障并抑制淀粉样蛋白的纤维化。本研究旨在基于 α-Syn 和 EGCG 之间的相互作用，深入了解 EGCG 作为预防和治疗 PD 的潜在候选药物的可能机制。在本研究中，通过硫代黄素T（ThT）荧光光谱、圆二色光谱（CD）、核磁共振（NMR）光谱、原子力显微镜（AFM）和透射电子显微镜（TEM）在分子水平上研究了EGCG对α-Syn纤维化和解聚的影响。此外，在细胞水平上，我们使用3-(4,5-二甲基噻唑-2-基)-2,5-二苯基四唑溴化物(MTT)测定、2,7-二氯二氢荧光素二乙酸酯(DCFH-DA)测定、蛋白质印迹和免疫印迹技术，研究了EGCG对过表达α-Syn的转导PC12细胞中α-Syn诱导的细胞死亡的保护作用。共焦激光扫描显微镜。研究发现，EGCG不仅通过与Ile、Phe和Tyr氨基酸残基结合，显着抑制α-Syn从无规卷曲到β-折叠构象异构体的构象转变，而且通过与Leu、His、Phe和Tyr氨基酸残基结合，以剂量依赖性方式解聚α-Syn的淀粉样原纤维。研究还表明，EGCG 可以通过抑制细胞内 α-Syn 的过度表达和纤维颤动，保护 PC12 细胞免受 α-Syn 诱导的损伤。
α-Synuclein (α-Syn) aggregates are the major component of Lewy bodies (LB), which is a pathological hallmark in the brain tissue of Parkinson's disease (PD) patients. It has been reported that (−)-epigallocatechin-3-gallate (EGCG) is biologically able to penetrate the blood–brain barrier and inhibit the fibrillation of amyloid proteins. This study aimed to provide insight into the possible mechanism of EGCG as a potential candidate agent for the prevention and treatment of PD on the basis of the interaction between α-Syn and EGCG. In the present study, the effects of EGCG on the fibrillation and disaggregation of α-Syn were investigated by thioflavin T (ThT) fluorescence spectroscopy, circular dichroism spectroscopy (CD), nuclear magnetic resonance (NMR) spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM) on a molecular level. In addition, on the cellular level, we investigated the protective effects of EGCG on α-Syn-induced cell death in the transduced PC12 cells which overexpressed α-Syn, using the techniques of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) assay, western blot and confocal laser scanning microscopy. It was found that EGCG not only significantly inhibited the conformational transition of α-Syn from random coil to β-sheet conformers through binding to Ile, Phe and Tyr amino residues, but also disaggregated the amyloid fibrils of α-Syn in a dose-dependent manner, through binding to Leu, His, Phe and Tyr amino residues. It is also demonstrated that EGCG can protect PC12 cells against α-Syn-induced damage by inhibiting the overexpression and fibrillation of α-Syn in the cells.