Mechanisms of Ras signaling in single synapses

摘要 Ras超家族的小GTP酶蛋白对于突触传递所必需的许多神经元过程是重要的。 可塑性，包括长时程突触增强、新突触的形成和细胞兴奋性的调节。 在Ras超家族中，一个特别重要的亚家族是一组称为Rab的蛋白质，其调节 突触可塑性过程中膜和谷氨酸受体的运输。与重要性相一致 Rab信号在突触可塑性中的作用，Rab信号异常与引起认知功能障碍的疾病有关 损伤和学习缺陷。然而，Rab蛋白在突触形成过程中的时空动态， 可塑性及其在单个树突棘上的确切功能尚未完全了解。因此， 该项目旨在阐明Rab蛋白在突触可塑性过程中在树枝状棘中的机制和作用。 我们已经开发了高灵敏度的生物传感器，用于Rab4，Rab5，Rab8和Rab10的成像活性。我们 初步数据表明，Rab蛋白在不同的时间窗口被激活或失活， 突触可塑性基于这些初步数据和以前的文献，我们的中心假设是， 蛋白质调节不同内部膜室之间的膜运输平衡， 树突棘调节树突棘的功能和结构可塑性，这反过来又调节 突触可塑性、学习和记忆。在本项目中，我们将进一步分析Rab介导的信号传导 蛋白质及其在突触可塑性过程中膜和受体运输中的作用。我们的具体目标是 1)揭示突触可塑性过程中Rab活动的时空动态，并确定上游 2）阐明Rab蛋白在刺的结构和功能中的作用， 3）确定Rab蛋白在谷氨酸受体中的作用 利用生物化学分析，阐明Rab蛋白在突触形成中的作用， 可塑性，学习和记忆。这项工作将推进我们对Rab如何将钙与 突触可塑性、学习和记忆。

ABSTRACT The Ras superfamily of small GTPase proteins is important for many neuronal processes essential to synaptic plasticity, including long-term synaptic potentiation, formation of new synapses, and regulation of cell excitability. Among the Ras superfamily, a particularly important subfamily is a group of proteins called Rab, which regulate trafficking of membrane and glutamate receptors during synaptic plasticity. Consistent with the importance of Rab signaling in synaptic plasticity, abnormal Rab signaling is associated with diseases causing cognitive impairments and learning deficits. However, the spatiotemporal dynamics of Rab proteins during synaptic plasticity and their exact functions at individual dendritic spines are not fully understood. Thus, the objective of this project is to elucidate the mechanisms and roles of Rab protiens in dendritic spines during synaptic plasticity. We have developed highly sensitive biosensors for imaging activity of Rab4, Rab5, Rab8 and Rab10. Our preliminary data suggest that Rab proteins are activated or inactivated in different temporal windows during synaptic plasticity. Based on these preliminary data and previous literatures, our central hypothesis is that Rab proteins regulate the balance of membrane trafficking between different internal membrane compartments in dendritic spines to regulate functional and structural plasticity of dendritic spines, and this in turn modulates synaptic plasticity, learning and memory. In this project, we will further analyze signaling mediated by Rab proteins and their roles in trafficking of membrane and receptors during synaptic plasticity. Our specific aims are 1) to reveal the spatiotemporal dynamics of Rab activity during synaptic plasticity and to identify upstream regulators of Rab proteins, 2) to elucidate the roles of Rab proteins in structure and function of spines and in membrane trafficking during synaptic plasticity, 3) to identify the roles of Rab proteins in glutamate receptor internalization and recycling using biochemical assays, and 4) to elucidate the roles of Rab proteins in synaptic plasticity, learning and memory. This work will advance our understanding of how Rab couples calcium with synaptic plasticity, learning and memory.