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缺失突变体)表现为共济失调、痉挛和阵挛连接运动， 以及反张，表明他们在中枢神经系统中存在缺陷。 功能。死亡发生在大约3周大的时候。一种罕见的人类基因 已发现一种由基因突变引起的疾病(格里斯塞利病) 肌球蛋白V基因，与老鼠的突变相似，可能是致命的。稀释剂 小鼠模型因其独特的表型而特别吸引人 由肌球蛋白V缺失突变体表现出来，结合它是一种 在少数几个基因产物已被鉴定的突变和功能 被广泛研究的蛋白质。最近的形态数据也 在平滑内质网定位中发现了一个特定的缺陷 稀释性致死小鼠小脑浦肯野细胞。还有更多的证据 肌球蛋白V与突触小泡结合，可能有助于调节 肌动蛋白沿肌动蛋白细丝运输这些细胞器或其前体 此外，肌球蛋白V可能与负责 NMDA型谷氨酸受体的锚定。将这些结果综合在一起 提示稀释性致死小鼠(和人类)的神经缺陷可能 由于细胞器运输受损和蛋白质 神经元的定位。因为涉及到细胞器和蛋白质， 这可能会对突触的功效产生深远的影响。因此，该系统允许 申请同时研究肌球蛋白V功能的分子机制和 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 突触之间突触生理学的稀释性致死结构缺陷 颗粒细胞和浦肯野细胞，(2)决定了 肌球蛋白V靶向平滑内质网至树突棘，(3) 确定肌球蛋白V缺失对NMDA定位的影响 受体和相关突触后蛋白，以及(4)决定突触前 稀致性颗粒细胞末梢细胞器转运异常 正在处理。为了实现这些目标，电生理学、 将使用实时成像和形态技术。

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.