PP2A Dysregulation in the Pathogenesis of alpha-Synucleinopathies

项目摘要 丝氨酸129位α-突触核蛋白磷酸化是标志路易小体病理性纤维聚集的标志 帕金森氏病(PD)和路易体痴呆中的包裹体，但导致这种情况的确切原因是- 翻译修饰及其在这些疾病发病机制中的作用尚不清楚。这个项目的目的是 通过研究蛋白磷酸酶2A(PP2A)介导的作用来解决这一知识鸿沟 α-突触核蛋白去磷酸化在这些疾病的分子病因学中起作用。PP2A是一个 构成大脑中大部分丝氨酸/苏氨酸磷酸酶活性的保守酶家族 并作为细胞光调节网络的主调节器，控制所需的关键过程 以维持蛋白质平衡和细胞存活。PP2A是一种三聚体酶，由催化的C亚基组成 支架A亚基和调控B亚基，每个亚基由多基因和多个 剪接异构体。PP2A的底物专一性由其亚基组成决定，亚基组成是受调控的 通过其催化的C亚基的甲基化，这种甲基化由一种专用的甲基酯酶控制， PME-1和专用甲基转移酶LCMT-1。负责脱磷的PP2A亚型 α-突触核蛋白是甲基化依赖的，并且药物抑制依赖于PME-1的PP2A去甲基化 减轻α-突触核蛋白转基因小鼠的表型。研究PP2A及其甲基化在血管紧张素转换酶中的作用 α-突触核病症，我们将通过操纵PME-1和LCMT-1的表达来改变体内的PP2A活性 转基因小鼠。特定目标1将检验这样一个假设，即通过增加 PME-1的表达，通过增加α-突触核蛋白的致病性而加重α-突触核蛋白的病变。目标2将 通过增加LCMT-1的表达来增强PP2A甲基化，从而防止 α-突触核蛋白通过降低α-突触核蛋白的致病性而致病。目标3将确定是否操纵PP2A 甲基化通过丝氨酸129位的磷酸化影响α-突触核蛋白介导的病理。到完工时 在这些研究中，我们将更深入地了解PP2A在α-突触核病症和 将其作为潜在的疾病修饰治疗靶点来治疗这些疾病。

Project Summary α-Synuclein phosphorylated at Serine 129 is a marker of pathologic fibrillar aggregates in hallmark Lewy body inclusions in Parkinson's disease (PD) and Dementia with Lewy Bodies, but the precise reason for this post- translational modification and its role in the pathogenesis of these disorders remain unclear. This project aims to address this knowledge gap by studying the role that protein phosphatase 2A (PP2A) mediated dephosphorylation of α-synuclein plays in the molecular etiology of these disorders. PP2A is a member of a family of conserved enzymes that constitute the majority of serine/threonine phosphatase activity in the brain and function as master regulators of cellular phosphoregulatory networks, controlling key processes required for protein homeostasis and cell survival. PP2A is a trimeric enzyme composed of a catalytic C subunit, a scaffolding A subunit, and a regulatory B subunit each of which is encoded by multiple genes and multiple splice isoforms. The substrate specificity of PP2A is determined by its subunit composition, which is regulated by methylation of its catalytic C subunit, and this methylation is controlled by both a dedicated methylesterase, PME-1, and a dedicated methyltransferase, LCMT-1. The PP2A isoform responsible for dephosphorylating α-synuclein is methylation dependent, and pharmacological inhibition of PME-1-dependent PP2A demethylation mitigates the phenotype of α-synuclein transgenic mice. To study the role of PP2A and its methylation in α-synucleinopathies, we will alter PP2A activity in vivo by manipulating PME-1 and LCMT-1 expression using genetically modified mice. Specific aim 1 will test the hypothesis that reducing PP2A methylation, via increased PME-1 expression, exacerbates α-synucleinopathies by increasing the pathogenicity of α-synuclein. Aim 2 will test the hypothesis that enhancing PP2A methylation, via increased LCMT-1 expression, protects against α-synucleinopathies by reducing the pathogenicity of α-synuclein. And aim 3 will determine if manipulating PP2A methylation impacts α-synuclein mediated pathology through phosphorylation at Serine 129. By the completion of these studies we will gain greater insight into the pathogenetic role of PP2A in α-synucleinopathies and advance it as a potential disease modifying therapeutic target for these disorders.