Targeting Cerebellar Endoplasmic Reticulum Calcium Handling in Essential Tremor

项目总结/摘要 特发性震颤（ET）是最常见的震颤障碍，影响美国总人口的2.2%。此外， 一种进行性疾病，随着时间的推移，震颤变得更加严重。尽管其发病率很高， ET的选择远不能令人满意，部分原因是对疾病机制的理解不清楚， 使许多病人致残。通过NIH长期资助的收集死后ET大脑的努力，我们 已经确定了ET小脑的形态学变化，反映了浦肯野细胞（PC）的细胞损伤。 遗传学和神经病理学的最新证据表明，异常的内质网 内质网（ER）钙处理ET。具体来说，一个关键的ER钙通道称为兰尼碱受体1型 （RyR1），表达于小脑皮质的PC中，经历位点特异性磷酸化，在这种情况下， 国家变得越来越脆弱。我们发现ET小脑的磷酸化RyR1水平显著增加， 这在对照组或帕金森氏症患者的小脑中是看不到的，在ET中产生了慢性ER钙渗漏状态。 小脑我们建立了一个小鼠模型，在RyR1中携带一个点突变，模拟组成性位点- 特异性磷酸化，重现RyR1渗漏表型（RyR1-S2844D "渗漏"小鼠）， 小鼠模型出现小脑生理学改变和进行性ET样震颤。这些发现支持 异常的内质网钙处理会导致震颤然而，ER异常的详细机制如何 钙处理导致震颤并且其操作是否可用于治疗震颤仍不清楚， 这是治疗发展的主要障碍。为了解决这一知识差距，我们建议测试 这一假说认为，功能失调的ER钙处理导致结构和生理改变， 引起震颤的小脑在拟议的五年研究中，我们将使用两种小鼠模型（Aim 1，Aim 2） 和死后人ET脑（目的3），以解决ER钙处理对震颤产生的作用： 目的1：我们将确定RyR1-leaky在小脑PC中的具体结构和生理变化 小鼠在震颤的出现和发展中起作用。目标2：我们将确定是否双向调制 ER钙处理改变RyR1-leaky小鼠的PC生理学和震颤，并检查 这些变化。目的3：我们将确定是否上游调控RyR1生化重塑 和RyR1泄漏的程度在死后的人ET小脑中改变，并将这些改变与死亡相关。 指标与震颤严重程度和PC病理变化。这些数据将促进我们对ET的理解 从观察性研究到机制性洞察，这将作为治疗的科学依据 发展

PROJECT SUMMARY/ ABSTRACT Essential tremor (ET) is the most common tremor disorder, affecting 2.2% of the total US population. ET is also a progressive disorder, with tremor becoming more severe over time. Despite its high prevalence, therapeutic options for ET are far from satisfactory, in part due to an unclear understanding of disease mechanisms, leaving many patients disabled. Through long-term NIH funded efforts to collect postmortem ET brains, we have identified morphological changes in the ET cerebellum that reflect cellular damage in Purkinje cells (PCs). Recent converging evidence of genetics and neuropathology has identified a role for abnormal endoplasmic reticulum (ER) calcium handling in ET. Specifically, a key ER calcium channel called ryanodine receptor type 1 (RyR1), which is expressed in PCs in cerebellar cortex, undergoes site-specific phosphorylation and in this state becomes leaky. We found that ET cerebellum has markedly increased levels of phosphorylated RyR1, which is not seen in control or Parkinson’s cerebellum, creating a chronic ER calcium leak state in the ET cerebellum. We established a mouse model harboring a point mutation in RyR1 that mimics constitutive site- specific phosphorylation, recapitulating the RyR1 leaky phenotype (RyR1-S2844D “leaky” mice), and this mouse model develops altered cerebellar physiology and progressive ET-like tremor. These findings support that abnormal ER calcium handling contributes to tremor. However, the detailed mechanism how abnormal ER calcium handling leads to tremor and whether its manipulation can be used to treat tremor remains unclear, which is a major obstacle for therapy development. Towards solving this knowledge gap, we propose to test the hypothesis that dysfunctional ER calcium handling leads to structural and physiological alterations in cerebellum that drive tremor. In the proposed five year study, we will use both mouse models (Aim 1, Aim 2) and postmortem human ET brains (Aim 3) to address the role of ER calcium handling for tremor generation: Aim 1: We will determine how specific structural and physiological changes in cerebellar PCs of RyR1-leaky mice play a role in tremor emergence and progression. Aim 2: We will determine if bi-directional modulation of ER calcium handling alters PC physiology and tremor in RyR1-leaky mice and examine the PC specificity of these alterations. Aim 3: We will determine whether the upstream regulators for RyR1 biochemical remodeling and the degree of RyR1 leakiness are altered in the postmortem human ET cerebellum and correlate these metrics with tremor severity and PC pathologic changes. These data will advance our understanding of ET from observational studies into mechanistic insight, which will serve as scientific rationale for therapy development.