Function and Pathogenic Mechanism of alpha-synuclein in Parkinson's Disease

α-突触核蛋白在帕金森病中的功能及致病机制

• 批准号: 8931621
• 负责人: Huaibin Cai
• 金额: $ 33.4万
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8931621
• 关键词: Acetylation; Address; Affect; Alpha-Synuclein transgenic mouse; Automobile Driving; Cell Line; Cells; Data; Development; Disease; Dopamine; Event; Exhibits; Functional disorder; Gene Expression; Gene Mutation; Genes; Genetic; Genetic Models; Golgi Apparatus; Impairment; In Vitro; Knowledge; Lewy Bodies; Lysosomes; Maintenance; Mediating; Midbrain structure; Mitochondria; Molecular; Molecular Target; Motor; Movement Disorders; Mus; Mutant Strains Mice; Mutation; Names; Nerve Degeneration; Neurites; Neurodegenerative Disorders; Neurons; Nuclear Receptors; Parkinson Disease; Pathogenesis; Pathway interactions; Phosphorylation; Post-Translational Protein Processing; Predisposition; Proteasome Inhibition; Proteins; Rattus; Regulation; Research; Role; Synaptic Transmission; Syndrome; System; Tetracyclines; Transcriptional Regulation; Transgenic Mice; Transgenic Organisms; Tyrosine 3-Monooxygenase; Ubiquitination; alpha synuclein; base; cytotoxicity; dopaminergic neuron; early onset; in vivo; multicatalytic endopeptidase complex; mutant; new therapeutic target; presynaptic; promoter; protein expression; research study; transcription factor

Parkinsons disease (PD) is pathologically characterized by a preferential loss of midbrain dopaminergic (mDA) neurons and the presence of alpha-synuclein (alpha-syn)-positive intracytoplasmic inclusions named Lewy bodies (LBs) and Lewy neurites (LNs) (Schapira, 1997;Spillantini et al., 1997). While both missense and multiplication mutations of alpha-syn cause early-onset autosomal dominant familial form of PD, the alpha-syn gene locus also associates with the more common sporadic PD (Polymeropoulos et al., 1997;Singleton et al., 2003;Simon-Sanchez et al., 2009;Satake et al., 2009). Together, these genetic and pathological studies clearly point out an important role of alpha-syn in the pathogenesis of PD. Extensive studies have been performed to understand the underlying pathogenic mechanisms of alpha-syn-induced cell loss. It has been shown that over-expression of both wild-type and PD-related mutant alpha-syn leads to a variety of cytotoxicity, including the impairment of proteasome and lysosome activities (Cuervo et al., 2004;Stefanis et al., 2001;Tanaka et al., 2001;Chen et al., 2006), the disruption of ER-Golgi transport (Cooper et al., 2006;Gosavi et al., 2002;Lin et al., 2009), the perturbation of the mitochondrial function (Hsu et al., 2000;Martin et al., 2006;Song et al., 2004;Nakamura et al., 2011), and the inhibition of synaptic transmission (Nemani et al., 2010). However, most of these results were obtained from cell lines and non-mDA neurons. It remains to determine whether these pathogenic pathways are pathophysiologically relevant to the degeneration of mDA neurons. While the loss of nigral DA neurons underlie the main motor syndrome of PD, the progress of PD research has been especially hindered by a lack of effective mouse genetic model that carries PD-related genetic mutations and develops progressive degeneration of mDA neurons (Hisahara and Shimohama, 2010). Many lines of PD-related mutant alpha-syn transgenic mice have been generated previously; however, few of them exhibited robust and progressive degeneration of mDA neurons (Kahle et al., 2001;van der et al., 2000;Matsuoka et al., 2001;Lee et al., 2002;Lin et al., 2009;Chesselet, 2008;Harvey et al., 2008;Richfield et al., 2002;Gispert et al., 2003;Wakamatsu et al., 2008;Thiruchelvam et al., 2004). Noticeably, only a scarce or low levels of transgenic alpha-syn expression were observed in the mDA neurons of these mutant mice, in which the transgenic alpha-syn is often under the transcriptional control of pan neuronal promoters or a rat tyrosine hydroxylase (TH) promoter. To investigate the pathogenic mechanism of alpha-syn-dependent dopaminergic dysfunction in vivo, we generated a new line of alpha-syn transgenic mice by driving the expression of PD-related A53T alpha-syn in the mDA neurons using a binary tetracycline-dependent inducible gene expression system. The mutant mice developed profound movement disorders as well as robust and progressive mDA neurodegeneration, which thereby may provide a valuable mouse genetic model to investigate how alpha-syn induces the degeneration of mDA neurons. Towards to this direction, we systematically examined the alpha-syn-mediated subcellular abnormalities in the mDA neurons of mutant mice. Moreover, we identified nuclear receptor related 1 protein (Nurr1), a master transcription factor for the development and maintenance of mDA neurons, as a key downstream molecular target for the alpha-syn-induced preferential degeneration of mDA neurons. A contribution of Nurr1 dysfunction in PD has been proposed previously (Le et al., 2003;Chu et al., 2002;Baptista et al., 2003). We extended these early studies and demonstrated that over-expression of both wild-type and A53T alpha-syn promoted a proteasome-dependent degradation of Nurr1. We further demonstrated that inhibition of proteasome-mediated degradation of Nurr1 ameliorated alpha-syn-induced loss of mDA neurons. These data suggest that the suppression of Nurr1 protein expression by alpha-syn is a key molecular determinant for the preferential dysfunction and loss of mDA neurons in PD. In line with this notion, a conditional deletion of Nurr1 in the mDA neurons results in a very similar rearing impairments and mDA neurodegeneration compared to the A53T conditional transgenic mice (Kadkhodaei et al., 2009). Multiple post-translational modifications have been found to modulate the stability and function of Nurr1 protein, including phosphorylation, ubiquitination (Jo et al., 2009), sumoylation (Galleguillos et al., 2004), and acetylation (Kang et al., 2010). alpha-syn may regulate the degradation of Nurr1 protein through various molecular cascades. In addition, it remains to determine whether other PD-related genes also affect the expression and stability of Nurr1 protein in PD. In summary, this study describes a new line of alpha-syn A53T transgenic mice that display robust and progressive degeneration of mDA neurons. The dynamic regulation of Nurr1 protein stability by alpha-syn in the mDA neurons may not only help to address the molecular mechanism of the preferential susceptibility of mDA neurons in PD, but may also provide new therapeutic targets for the treatment of the disease.

帕金森氏病（PD）在病理上的特征是中脑多巴胺能（MDA）神经元的优先丧失，并且存在α-突触核蛋白（alpha-syn） - 阳性型内质体内夹杂物（Lewy Bodies（LBS）和Lewy Neurites（Lewy Neurites）（Schapira）（Schapira，1997年），虽然α-Syn的错义和乘法突变引起PD的早期常染色体主导性家族形式，但α-Syn基因基因座也与更常见的散发性PD相关联（Polymeropoulopoulos等，1997; Singleton et al。总之，这些遗传和病理研究清楚地指出了α-Syn在PD发病机理中的重要作用。 已经进行了广泛的研究，以了解α-Syn诱导的细胞损失的潜在致病机制。已经表明，野生型和与PD相关的突变体α-Syn的过度表达会导致多种细胞毒性，包括蛋白酶体和溶酶体活性的损害（Cuervo等，2004; Stefanis et al。，2001; Tanaka et al。 Al。，2006; Gosavi等，2002; Lin等，2009），线粒体功能的扰动（Hsu等，2000; Martin等，2006; Martin等，2006; Song等，2004; Nakamura et al。，Nakamura et al。，2011）以及突触传播的抑制（Nemani et anemani等）。但是，大多数结果是从细胞系和非MDA神经元获得的。仍然要确定这些致病途径是否与MDA神经元的退化在病理生理上是否相关。 虽然nigral da神经元的丧失是PD的主要运动综合征，但缺乏有效的小鼠遗传模型的PD研究进展尤其阻碍，该模型携带了与PD相关的遗传突变并发展了MDA神经元的渐进性变性（Hisahara和Shimohama，2010年）。以前已经产生了许多与PD相关的突变体α-Syn转基因小鼠。然而，其中很少有MDA神经元的强大而渐进的变性（Kahle等，2001; van der等，2000; Matsuoka等，2001; Lee等，2002; Lin等，2009; Chesselet; Chesselet; Chesselet; Chesselet; Chesselet，2008; Harvey等，2008; Richfield et al。 2008; Thiruchelvam等，2004）。明显的是，在这些突变小鼠的MDA神经元中仅观察到稀缺或低水平的转基因α-Syn表达，其中转基因α-Syn通常在泛神经元启动子的转录控制下或大鼠酪氨酸酪氨酸羟基酶（TH）启动子的转录控制下。 为了研究体内α-Syn依赖性多巴胺能功能障碍的致病机制，我们通过使用binary tetracycline clacycline rpentent clentent centent lodecible Gene contipible Gene contipible Gene contipible neurons在MDA Neurons中驱动PD相关A53T Alpha-Syn的表达，从而产生了新的Alpha-Syn转基因小鼠。突变小鼠出现了深刻的运动障碍以及鲁棒和进行性的MDA神经变性，从而可以提供有价值的小鼠遗传模型，以研究α-Syn如何诱导MDA神经元的变性。朝向这个方向，我们系统地检查了突变小鼠MDA神经元中α-syn介导的亚细胞异常。此外，我们确定了与核受体相关的1蛋白（NURR1），这是MDA神经元开发和维持的主要转录因子，是α-Syn诱导的MDA神经元优先变性的关键下游分子靶标。 先前已经提出了NURR1功能障碍在PD中的贡献（Le等，2003； Chu等，2002； Baptista等，2003）。我们扩展了这些早期研究，并证明野生型和A53Tα-Syn的过度表达促进了Nurr1的蛋白酶体依赖性降解。我们进一步证明，抑制蛋白酶体介导的Nurr1降解降解α-Syn-syn诱导的MDA神经元丧失。这些数据表明，α-Syn对Nurr1蛋白表达的抑制是PD中MDA神经元的优先功能障碍和丢失的关键分子决定因素。与这个概念相一致，与A53T条件转基因小鼠相比，MDA神经元中NurR1的条件缺失导致非常相似的饲养障碍和MDA神经变性（Kadkhodaei等，2009）。已经发现多种翻译后修饰可调节Nurr1蛋白的稳定性和功能，包括磷酸化，泛素化（Jo等，2009），sumoylation（Galleguillos等，2004）和乙酰化（Kang等，2010）。 α-Syn可以通过各种分子级联反应调节Nurr1蛋白的降解。此外，仍然要确定其他与PD相关的基因是否还影响PD中Nurr1蛋白的表达和稳定性。 总而言之，这项研究描述了一种新系列的α-Syn A53T转基因小鼠，这些小鼠表现出MDA神经元的强大而渐进的变性。 MDA神经元中Alpha-Syn对Nurr1蛋白稳定性的动态调节不仅有助于解决MDA神经元在PD中优先敏感性的分子机制，而且还可能为治疗疾病提供新的治疗靶标。