MYOSIN V FUNCTION IN THE NERVOUS SYSTEM

描述（改编自申请人的摘要）：稀释致死小鼠（即， 肌球蛋白V无效突变体）表现出共济失调，痉挛伴阵挛性连接运动， 角弓反张提示中枢神经系统有缺陷。 功能死亡发生在大约3周龄。一种罕见的人类基因 已经鉴定出由以下突变引起的疾病（Griscelli病）： 肌球蛋白V基因与小鼠突变相似，可能是致命的。稀 小鼠模型由于其独特的表型而特别有吸引力 显示的肌球蛋白V无效突变体，结合的事实，它是一个 少数突变的基因产物已被确定，功能 广泛研究的蛋白质。最近的形态学数据也 发现了一个特定的缺陷，在滑面内质网定位， 稀释致死小鼠的小脑浦肯野细胞。还有其他证据表明 肌球蛋白V与突触囊泡相关，可能有助于调节 这些细胞器或其前体沿着肌动蛋白丝的运输。 此外，肌球蛋白V可能与一种蛋白质复合物有关， NMDA型谷氨酸受体的锚定。综合这些结果 这表明，稀释致死小鼠（和人类）的神经缺陷可能 是由于受损的细胞器运输和蛋白质 定位于神经元。由于细胞器和蛋白质的参与， 这可能对突触功效有深远的影响。因此，该系统允许 申请人致力于解决肌球蛋白V功能的分子机制， 它的活动对神经系统的重要影响， 细胞和行为水平。 申请人目前的目标是：（1）确定 突触生理学的稀释致死性结构缺陷 颗粒细胞和浦肯野细胞，（2）确定的机制， 肌球蛋白V将滑面内质网定位于树突棘，（3） 确定肌球蛋白V缺失对NMDA定位的影响 受体和相关的突触后蛋白，和（4）确定是否突触前 稀释致死颗粒细胞的末端有异常的细胞器转运， 处理.为了实现这些目标，电生理学， 将使用实时成像和形态学技术。

DESCRIPTION (adapted from applicant's abstract): Dilute-lethal mice (i.e., myosin V null mutants) exhibit ataxia, convulsion with clonic link movements, and opisthotonus suggesting that they have defects in central nervous system. function. Death occurs at about 3 weeks of age. a certain rare human genetic disease (Griscelli disease) has been identified which results from mutations in the myosin V gene, and similar to the mouse mutation, can be lethal. The dilute mouse model is particularly attractive because of the distinct phenotype exhibited by the myosin V null mutants, combined with the fact that it is one of few mutations in which the gene product has been identified and the function of the protein extensively studied. Recent morphological data has also identified a specific defect in smooth endoplasmic reticulum localization in cerebellar Purkinje cells of dilute-lethal mice. There is additional evidence that myosin V associates with synaptic vesicles and may contribute to regulate the transport of these organelles or their precursors along actin filaments. Furthermore, myosin V may associate with a complex of proteins responsible for the anchoring of NMDA type glutamate receptors. Taken together these results suggest that the neurological defects in dilute-lethal mice (and humans) may result from a combination of impaired organelle trafficking and protein localization in neurons. Because of the organelles and proteins involved, this could have profound effects on synaptic efficacy. Thus, this system allows the applicants to address both the molecular mechanism of myosin V function and the important consequences of its activity for the nervous system at both cellular and behavioral levels. The applicant's current goals are to: (1) determine the consequences of the dilute-lethal structural defects for synaptic physiology at the synapse between granule cells and Purkinje cells, (2) determine the mechanism through which myosin V targets smooth endoplasmic reticulum to dendritic spines, (3) determine the consequences of myosin V's absence on the localization of NMDA receptors and associate postsynaptic proteins, and (4) determine if presynaptic terminals of dilute-lethal granule cells have abnormal organelle transport of processing. To accomplish these goals, a combination of electrophysiological, live imaging and morphological techniques will be used.