The Endocytic Machinery of Dendritic Spines

描述（由申请人提供）：神经传递需要突触中受体、离子通道和粘附分子的精确数量和排列。这些蛋白在突触后膜的定位或水平的改变可调节突触功能，从而增强或减弱大脑中的突触连接。在所有真核细胞中，各种表面膜蛋白的去除都是通过网格蛋白介导的内吞作用发生的。尽管先前的研究已经帮助定义了非神经元细胞和突触前神经末梢的内吞机制，但对突触后区室中网格蛋白介导的内吞作用的定位和调控及其在突触信号传导中的功能作用仍然知之甚少。为了解决这些重要的问题，我的实验室启动了一个细胞生物学和生理学研究项目，以分析树突棘的内吞机制——树突棘是哺乳动物大脑中主要的突触后隔室。我们发现树突棘包含一个网格蛋白组装和内吞作用区，与突触后密度相邻，但在空间上是分离的。这个“内吞区”形成并持续很长一段时间，它集中了运往内化的货物。此外，我们最近发现了突触后支架复合物和网格蛋白内吞机制之间的直接物理联系，并发现了维持突触附近谷氨酸受体池的局部内吞和循环的新要求。利用这些初步数据和我们监测和操纵树突棘内吞作用的能力，我们提出定义形成、维持和调节棘内吞区潜在的分子和细胞机制，并确定这些区域在突触维持和修饰中的功能作用。这项工作将提供深入了解突触形成和突触可塑性的基本机制。此外，由于网格蛋白介导的内吞作用调节神经元对各种病理损伤和与许多神经和精神疾病相关的治疗剂的反应性，这些研究为开发新的治疗策略提供了希望。公共卫生相关性：该研究将揭示调节脑细胞突触通讯的分子机制。突触功能异常会导致癫痫、记忆力下降、抑郁、自闭症、精神分裂症和成瘾。通过帮助理解神经细胞突触在大脑发育过程中是如何调节的，并随着我们的学习而改变，拟议的研究将为这些破坏性的神经和精神疾病确定新的靶点和治疗策略，这些疾病目前对公众健康产生了深远的负面影响。

DESCRIPTION (provided by applicant): Neurotransmission requires a precise number and arrangement of receptors, ion channels, and adhesion molecules at synapses. Alteration of the localization or levels of these proteins at the postsynaptic membrane regulates synapse function, thereby strengthening or weakening synaptic connections in the brain. In all eukaryotic cells, removal of diverse surface membrane proteins occurs by clathrin-mediated endocytosis. Although previous studies have helped define the endocytic machinery in nonneuronal cells and in the presynaptic nerve terminal, the location and regulation of clathrin- mediated endocytosis within postsynaptic compartments and its functional role in synaptic signaling remain poorly understood. To address these important questions, my laboratory has initiated a program of cell biological and physiological studies to analyze the endocytic machinery of dendritic spines - the primary postsynaptic compartment in the mammalian brain. We have found that dendritic spines contain a zone of clathrin assembly and endocytosis adjacent to, but spatially segregated from, the postsynaptic density. This `endocytic zone' forms and persists over long periods of time, and it serves to concentrate cargo destined for internalization. Further, we have recently identified a direct physical link between the postsynaptic scaffold complex and clathrin endocytic machinery and found a novel requirement for localized endocytosis and recycling in maintaining a synaptically proximate pool of glutamate receptors. Taking advantage of these preliminary data and our ability to monitor and manipulate endocytosis in dendritic spines, we propose to define the underlying molecular and cellular mechanisms that form, maintain, and regulate the endocytic zone of spines, and determine the functional role of such zones in synapse maintenance and modification. This work will provide insight into fundamental mechanisms that underlie synapse formation and synaptic plasticity. Moreover, because clathrin-mediated endocytosis regulates neuronal responsiveness to a wide range of pathologic insults and therapeutic agents relevant to numerous neurologic and psychiatric diseases these studies hold promise for the development of novel therapeutic strategies. PUBLIC HEALTH RELEVANCE: The proposed research will uncover molecular mechanisms that regulate brain cell communication at synapses. Abnormal function of synapses contributes to epilepsy, memory decline, depression, autism, schizophrenia, and addiction. By helping to understand how nerve cell synapses are adjusted during brain development and modified as we learn, the proposed research will define novel targets and therapeutic strategies for these devastating neurological and psychiatric disorders, which currently have a profound negative impact on public health.