NARP AND GLUTAMATE RECEPTOR CLUSTERING

描述(逐字摘自申请者摘要)：我们的研究重点是 蛋白质合成依赖型突触的分子机制 可塑性。特别是，我们正在研究一种即刻早期基因(IEG)。 被称为Narp，是根据其快速上调以响应 突触活动(Tsui等人，1996)。神经元活动调节 五聚体)是一种分泌的、自我多聚化的蛋白质，由 神经元。在最近的研究中，我们发现Narp选择性地在 轴-树突触兴奋性突触。此外，NARP还诱导了AMPA类型的星团 异种细胞表面谷氨酸受体，并选择性地 与脑内AMPA受体共沉淀。Narp显示广泛 与AMPA受体在突触发生前后的共同定位，以及 NARP的短暂上调导致兴奋性神经元数的增加 突触。基于这些观察，我们假设NARP调制 AMPA受体的突触聚集及其在兴奋性中的作用 突触发生。目标1-3中描述的研究将定义 NARP膜表面自聚集和结构-功能关系的研究 因为它与AMPA受体有关。常规突变分析和 将使用遗传方法来定义关键的相互作用位置 这些分子。基于这一信息，多肽和抗体拮抗剂 将被开发来扰乱Narp的集群活动并测试其作用 在自然的突触发生中。AIMS 4-5将检查细胞的生物学特性 在大脑神经元中的表达。研究将检验纳洛普是 以特定的兴奋性突触为靶点，它可以改变它们的 兴奋性突触的形态和功能特性。因为Narp是 作为IEG，我们的研究将为分子和细胞提供新的见解 活性依赖突触可塑性的机制。

DESCRIPTION (Verbatim from the Applicant's Abstract): Our research focuses on molecular mechanisms that underlie protein synthesis-dependent synaptic plasticity. In particular, we are examining an immediate early gene (IEG) termed Narp that was identified based on its rapid up-regulation in response to synaptic activity (Tsui et al., 1996). Narp (Neuronal activity-regulated Pentraxin) is a secreted, self-multimerizing protein that is expressed by neurons. In recent studies, we find that Narp is selectively enriched at axo-dendritic excitatory synapses. Moreover, Narp induces clusters of AMPA-type glutamate receptors on the surface of heterologous cells, and selectively co-immunoprecipitates with AMPA receptors from brain. Narp shows extensive co-localization with AMPA receptors, both before and after synaptogenesis, and transient up-regulation of Narp results in an increased number of excitatory synapses. Based on these observations, we hypothesize that Narp modulates synaptic clustering of AMPA receptors and plays a role in excitatory synaptogenesis. Studies described in Aims 1-3 will define the structure-function relationships for Narp membrane surface self-clustering and for its association with AMPA receptors. Conventional mutation analyses and genetic approaches will be used to define the critical sites of interaction for these molecules. Based on this information, peptide and antibody antagonists will be developed to perturb the clustering activity of Narp and test its role in natural synaptogenesis. Aims 4-5 will examine the cell biological properties of Narp in brain neurons. Studies will test the hypotheses that Narp is targeted to specific excitatory synapses and that it can modify their morphological and functional properties of excitatory synapses. Since Narp is an IEG, our research will provide new insights into the molecular and cellular mechanisms of activity dependent synaptic plasticity.