Induction of de novo α-synuclein fibrillization in a neuronal model for Parkinson's disease
Induction of de novo α-synuclein fibrillization in a neuronal model for Parkinson's disease
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DOI：
10.1073/pnas.1512876113
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发表时间：
2016-02-16
影响因子：
11.1
通讯作者：
Lashuel, Hilal A.
中科院分区：
文献类型：
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作者：
Fares, Mohamed-Bilal;Maco, Bohumil;Lashuel, Hilal A.
路易小体(Lbs)是主要由纤化的人α-突触核蛋白(hα-Syn)蛋白组成的神经元内包涵体，代表了帕金森病(PD)的主要病理特征。虽然hα-Syn的加倍表达在人类中会引发LB病理，但hα-Syn的过表达并不会在小鼠中引发纤维状LB样包涵体的形成。我们假设外源性hα-Syn和内源性小鼠突触核蛋白同源物之间的相互作用可以减弱小鼠的HA-Syn纤化，因此，我们系统地评估了α-Syn-KO、β-Syn-KO、Gamma-Syn-KO和三种突触核蛋白同源物表达缺失的小鼠神经元中HA-Syn聚集的倾向。在这里，我们发现hα-Syn在α-Syn-KO、β-Syn-KO和Triple-KO小鼠的原代神经元以及体内转基因α-Syn-KO小鼠的大脑中形成了过度磷酸化(在S129)和泛素阳性的LB样包涵体。重要的是，相关的光学和电子显微镜、免疫金标记法和硫代黄素-S结合建立了它们的纤维超微结构，光漂白/光转化实验后的荧光恢复实验表明，这些包涵体尺寸增大，并融合了可溶性蛋白。我们进一步研究了同源α-Syn物种的存在是否会干扰α-Syn病理的播种和传播。我们的结果与越来越多的证据表明，当注射的预成型纤维和宿主表达的α-Syn单体来自同一物种时，α-Syn病理的传播最明显。这些发现将有助于促进神经元和体内模型的发展，有助于了解hα-Syn神经元内纤化的机制及其在帕金森病发病机制中的作用，并为筛选神经元中α-Syn纤化的药理和遗传调节剂提供帮助。
Lewy bodies (LBs) are intraneuronal inclusions consisting primarily of fibrillized human alpha-synuclein (h alpha-Syn) protein, which represent the major pathological hallmark of Parkinson's disease (PD). Although doubling h alpha-Syn expression provokes LB pathology in humans, h alpha-Syn overexpression does not trigger the formation of fibrillar LB-like inclusions in mice. We hypothesized that interactions between exogenous h alpha-Syn and endogenous mouse synuclein homologs could be attenuating ha-Syn fibrillization in mice, and therefore, we systematically assessed ha-Syn aggregation propensity in neurons derived from alpha-Syn-KO, beta-Syn-KO, gamma-Syn-KO, and triple-KO mice lacking expression of all three synuclein homologs. Herein, we show that h alpha-Syn forms hyperphosphorylated (at S129) and ubiquitin-positive LB-like inclusions in primary neurons of alpha-Syn-KO, beta-Syn-KO, and triple-KO mice, as well as in transgenic alpha-Syn-KO mouse brains in vivo. Importantly, correlative light and electron microscopy, immunogold labeling, and thioflavin-S binding established their fibrillar ultrastructure, and fluorescence recovery after photobleaching/photoconversion experiments showed that these inclusions grow in size and incorporate soluble proteins. We further investigated whether the presence of homologous alpha-Syn species would interfere with the seeding and spreading of alpha-Syn pathology. Our results are in line with increasing evidence demonstrating that the spreading of alpha-Syn pathology is most prominent when the injected preformed fibrils and host-expressed alpha-Syn monomers are from the same species. These findings provide insights that will help advance the development of neuronal and in vivo models for understanding mechanisms underlying h alpha-Syn intraneuronal fibrillization and its contribution to PD pathogenesis, and for screening pharmacologic and genetic modulators of alpha-Syn fibrillization in neurons.