Function of Neuroligin in Synapse Formation in the CNS

描述(申请人提供)：这些研究的长期目标是了解中枢神经系统中突触形成和目标识别的分子机制。本申请提出的研究目的是：(1)剖析神经连接素的突触活性的结构基础，神经连接素是一种突触后黏附分子，可以触发突触前元件在接触轴突时的组装；(2)识别突触前细胞中的神经连接素受体；(3)分析神经连接素在体内的作用。AIM 1和AIM 2将在体外用基于功能细胞的分析进行研究，允许直接操纵突触前和突触后的机制。我们将研究神经连接蛋白家族蛋白作为候选神经连接蛋白受体，但同时我们将对突触形成过程中可能与神经连接蛋白相关的所有分子进行无偏见的生化纯化。为了分析神经连接蛋白在体内的功能，将产生专门降解神经连接蛋白mRNAs的锤头状核酶。这些核酶将在小鼠的小脑中表达，要么通过病毒载体将基因转移到选定的细胞中，要么通过转基因动物表达。突触的形成是大脑中神经元回路产生的关键过程。异常的突触形成和突触功能障碍会导致严重的神经系统疾病，如癫痫、精神分裂症和智力低下。神经连接素本身也被认为与人类的精神发育迟滞有关。除了神经系统障碍，了解突触形成的机制对于控制或刺激损伤后突触电路的再生也是最重要的，例如，损伤导致瘫痪后脊髓的连通性。

DESCRIPTION (provided by applicant): The long-term goal of these studies is to understand the molecular mechanism of synapse formation and target recognition in the central nervous system. The aims of the research proposed in this application are: (1) to dissect the structural basis for the synaptogenic activity of neuroligin, a post-synaptic adhesion molecule that can trigger the assembly of pre-synaptic elements in contacting axons, (2) to identify receptors for neuroligin in the pre-synaptic cell, and (3) to analyze the role of neuroligin in vivo. Aim 1 and Aim 2 will be studied with functional cell-based assays in vitro that permit direct manipulation of the pre- and post-synaptic machinery. The neurexin family of proteins will be studied as candidate neuroligin receptors, but at the same time we will perform an unbiased biochemical purification of all molecules that might associate with neuroligin during synapse formation. To analyze neuroligin function in vivo, hammer-head ribozymes will be generated that specifically degrade neuroligin mRNAs. These ribozymes will be expressed in the cerebellum of mice, either by gene transfer into selected cells with a viral vector or in a transgenic animal. Synapse formation is a crucial process in the generation of neuronal circuits in the brain. Aberrant synapse formation and synaptic dysfunction lead to severe nervous system disorders such as epilepsy, schizophrenia, and mental retardation. Neuroligins themselves have been implicated in mental retardation in humans. Besides nervous system disorders, understanding the mechanism of synapse formation will also be most important for controlling or stimulating the regeneration of synaptic circuits after injury, as for example the connectivity in the spinal cord after injuries that lead to paralysis.