Excitotoxic Signaling in HD Transgenic Neurons

描述（由申请人提供）：亨廷顿病（HD）是一种 以选择性基底神经节为特征的遗传性神经变性疾病 损伤和运动障碍。导致HD的遗传缺陷是一种 亨廷顿蛋白中的多聚谷氨酰胺重复序列超过 在未受影响的个体中发现。扩张的机制 亨廷顿蛋白中的多聚谷氨酰胺重复序列导致神经元变性和运动神经元变性。 功能障碍未知。基于HD患者和动物模型中的发现， HD它已被认为是遗传缺陷导致代谢妥协 结果是对谷氨酸诱导的神经元损伤的敏感性增加 （兴奋性毒性）。这种兴奋性毒性损伤可能涉及[Ca2+]水平升高。 线粒体功能障碍和氧化应激。最近，几个转基因 表达突变亨廷顿蛋白基因的HD（HDTg）小鼠模型已经被 产生并表现出神经系统症状和病理学， HD.该实验室和其他实验室的最新结果表明，HDTg小鼠确实 缺乏代谢酶活性，神经元对 谷氨酸受体的激活通过表达 突变亨廷顿蛋白我们提出检验突变体 亨廷顿蛋白表达导致线粒体功能障碍和离子迁移 谷氨酸受体介导的神经毒性。这种神经元功能障碍可能 是神经元代谢改变的结果，或直接影响 由突变亨廷顿蛋白表达引起的受体功能。作为HD的典范，我们 将使用荧光成像技术在原代神经元培养HDTg 小鼠和它们的非转基因（WT）同窝仔来检验这一假设。我们 具体目标是确定加强 1)HDTg神经元中谷氨酸受体介导的[Ca 2]i反应。（二） 谷氨酸受体刺激HDTg神经元的线粒体去极化。第三章 HDTg神经元中的兴奋性毒性神经元死亡。这些研究解决了我们的长期问题。 目的是评估代谢妥协对谷氨酸毒性的作用， 与HD中明显的神经元功能障碍和死亡相关。细胞培养 在这项工作中提出的HD模型也应该提供一个方便的手段， 测试HD的相关疗法。

DESCRIPTION (provided by the applicant): Huntington's disease (HD) is a hereditary neurodegenerative disease characterized by selective basal ganglia damage and movement disorders. The genetic defect responsible for HD is an expanded poly-glutamine repeat in the huntingtin protein in excess of that found in unaffected individuals. The mechanism by which the expanded poly-glutamine repeats in huntingtin causes neuronal degeneration and motor dysfunction is unknown. Based on findings in HD patients and animal models of HD it has been suggested that the genetic defect leads to metabolic compromise with consequent increased sensitivity to glutamate-induced neuronal injury (excitotoxicity). This excitotoxic injury may involve elevated levels of [Ca2+] mitochondrial dysfunction and oxidative stress. Recently, several transgenic mouse models of HD (HDTg) which express the mutant huntingtin gene have been created and exhibit neurologic symptoms and pathology similar to that seen in HD. Recent results from this laboratory and others suggest that HDTg mice do have deficits in metabolic enzyme activity and that neuronal responses to glutamate receptor activation are substantially altered by the expression of the mutant huntingtin protein. We propose to test the hypothesis that mutant huntingtin expression leads to mitochondrial dysfunction and ionotropic glutamate receptor mediated neurotoxicity. This glutamatergic dysfunction may be a consequence of alterations in neuronal metabolism or direct effects on receptor function caused by mutant huntingtin expression. As a model of HD, we will use fluorescence imaging techniques in primary neurons cultured from HDTg mice and their non-transgenic (WT) littermates to test this hypothesis. Our specific aims are to identify the mechanism(s) underlying the potentiation of 1) Glutamate-receptor mediated [Ca2]i responses in HDTg neurons. 2) Glutamate-receptor stimulated mitochondrial depolarization in HDTg neurons. 3) Excitotoxic neuronal death in HDTg neurons. These studies address our long-term goal of evaluating the role of metabolic compromise on glutamate toxicity as it relates to the neuronal dysfunction and death evident in HD. The cell culture models of HD proposed in this work should also provide a convenient means for testing relevant therapies for HD.