Deranged calcium signaling and polyglutamine expansion disorders

描述(由申请人提供)：该项目广泛的、长期的目标是了解聚谷氨酰胺(PolyQ)扩张性疾病中神经变性的分子基础。多聚Q扩张性疾病属于常染色体显性和致死性神经退行性疾病家族，它们共享共同的分子触发(CAG重复扩张性)。多聚Q扩展蛋白具有许多毒性功能，但到目前为止，对这些疾病所涉及的致病机制缺乏明确的了解。没有一种多Q扩张性疾病是可以治愈的。亨廷顿病(HD)是多Q扩张性疾病中研究最广泛的疾病。HD患者纹状体中棘神经元(MSN)有选择性受累。亨廷顿蛋白(Httexp)中的PolyQ-Expansion是HD的一个分子原因。我的实验室最近发现，Httex p直接结合并激活1型三磷酸肌醇受体(InsP3R1)，这是一种细胞内钙释放通道。此外，我们在体外实验中证实了神经元钙信号异常与HD MSN细胞凋亡之间的直接联系。现在，我建议进一步检验“HD的钙离子假说”。我还建议用类似的观点来理解脊髓小脑性共济失调3型(SCA3)的发病机制，SCA3是多Q扩张性疾病家族的另一个成员。具体来说，我建议： 1.分析InsP3R1与多聚Q扩展亨廷顿蛋白的生化和功能相互作用。用HD-YAC128小鼠HD模型进行实验，验证HD的“钙离子假说”。2.分析InsP3R1与PolyQ-Expanded ataxin-3蛋白的生化和功能相互作用。以SCA3-YAC84Q小鼠SCA3模型验证“SCA3的钙离子假说”。3.为了验证我们在人HD和SCA3患者原代成纤维细胞的钙离子成像和生化实验中的结果，我们的实验将对错乱的钙信号在HD和SCA3发病机制中的作用提供一个关键的检验，并可能对理解和治疗其他多Q扩张性疾病有一定的意义。拟议项目将对公共卫生产生直接和直接的影响。亨廷顿病(HD)和脊髓小脑性共济失调3型(SCA3)是无法治愈的遗传性疾病，会造成巨大的痛苦。赠款中描述的实验旨在测试关于这些疾病发病机制的具体假设，并将提供对治疗方法开发至关重要的信息。

DESCRIPTION (provided by applicant): The broad, long-term objective of the project is to understand the molecular basis for neurodegeneration in polyglutamine (polyQ) expansion disorders. The polyQ-expansion disorders belong to the family of autosomal-dominant and lethal neurodegenerative diseases that share a common molecular trigger (CAG repeat expansion). A number of toxic functions have been assigned to the polyQ-expanded proteins, but so far clear understanding of pathogenic mechanisms involved in these disorders is lacking. None of the polyQ- expansion disorders have a cure. Huntington's disease (HD) is the most extensively studied among polyQ- expansion disorders. Striatal medium spiny neurons (MSN) are selectively affected in HD. PolyQ-expansion in Huntingtin protein (Httexp) is a molecular cause of HD. My laboratory recently discovered that Httexp directly binds to and activates the type 1 inositol 1,4,5-trisphosphate receptor (InsP3R1), an intracellular Ca2+ release channel. Furthermore, we demonstrated a direct connection between abnormal neuronal Ca2+ signaling and apoptosis of HD MSN in in vitro experiments. Now I propose to further test "Ca2+ hypothesis of HD". I also propose to apply similar ideas to understanding the mechanisms of pathogenesis in spinocerebellar ataxia type 3 (SCA3), another member of polyQ-expansion disorders family. Specifically, I propose: 1. To analyze biochemical and functional interactions between InsP3R1 and polyQ-expanded Huntingtin protein. To test "Ca2+ hypothesis of HD" in experiments with HD-YAC128 mouse model of HD. 2. To analyze biochemical and functional interactions between InsP3R1 and polyQ-expanded ataxin-3 protein. To test "Ca2+ hypothesis of SCA3" in experiments with SCA3-YAC84Q mouse model of SCA3. 3. To validate our results in Ca2+ imaging and biochemical experiments with primary fibroblasts from human HD and SCA3 patients Our experiments will provide a critical test for a role of deranged Ca2+ signaling in pathogenesis of HD and SCA3 and may have implications for understanding and treatment of other polyQ-expansion disorders. The proposed project will have direct and immediate relevance for public health. Huntington's disease (HD) and Spinocerebellar Ataxia type 3 (SCA3) are incurable genetic disorders that cause enormous suffering. The experiments described in the grant are aimed at testing specific hypothesis regarding pathogenesis of these diseases and will provide information critical for development of the cure.