Deranged calcium signaling and polyglutamine expansion disorders

描述（由申请方提供）：该项目的广泛、长期目标是了解多聚谷氨酰胺（polyQ）扩张性疾病中神经变性的分子基础。polyQ-扩增障碍属于常染色体显性和致死性神经退行性疾病家族，其共享共同的分子触发因子（CAG重复扩增）。许多毒性功能已被分配给polyQ-扩展的蛋白质，但到目前为止，这些疾病中涉及的致病机制缺乏明确的理解。所有的多聚Q扩张症都无法治愈。亨廷顿氏病（HD）是多聚Q-扩增障碍中研究最广泛的疾病。纹状体中棘神经元（MSN）在HD中选择性地受到影响。亨廷顿蛋白中的PolyQ扩增（Httexp）是HD的分子原因。我的实验室最近发现，Httexp直接结合并激活1型肌醇1，4，5-三磷酸受体（InsP 3R 1），这是一种细胞内Ca 2+释放通道。此外，我们在体外实验中证明了异常神经元Ca 2+信号传导与HD MSN细胞凋亡之间的直接联系。现拟进一步验证“钙离子假说”。我还建议应用类似的想法来理解脊髓小脑共济失调3型（SCA 3）的发病机制，另一个多聚Q-扩展障碍家族的成员。具体而言，我建议： 1.分析InsP 3R 1和polyQ-扩增的亨廷顿蛋白之间的生物化学和功能相互作用。在HD-YAC 128小鼠HD模型的实验中验证“HD的Ca 2+假说”。2.分析InsP 3R 1和polyQ-扩增的共济失调蛋白-3蛋白之间的生化和功能相互作用。在SCA 3-YAC 84 Q小鼠SCA 3模型的实验中验证“SCA 3的Ca 2+假说”。3.为了验证我们的结果，在钙离子成像和生化实验与原代成纤维细胞从人类HD和SCA 3患者，我们的实验将提供一个关键的测试的作用，错乱的钙2+信号在HD和SCA 3的发病机制，并可能有影响的理解和治疗其他polyQ-扩张疾病。拟议的项目将直接和立即关系到公共卫生。亨廷顿氏病（HD）和脊髓小脑共济失调3型（SCA 3）是无法治愈的遗传性疾病，造成巨大的痛苦。赠款中描述的实验旨在测试有关这些疾病发病机制的特定假设，并将为治疗的发展提供关键信息。

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.