How Ephexin Signaling Promotes Neuronal Stability

目的：控制神经功能稳定性的因素影响着多种神经系统疾病的发生和发展。然而，人们对神经兴奋和抑制的机制知之甚少。许多研究表明，稳态信号机制参与了神经功能的调节，特别是通过调节突触连接的强度。该项目旨在阐明突触内稳态信号的机制。 背景/原理：我们发表了一项研究，证明了Ephexin信号系统在突触动态平衡中的作用。Ephexin是一种Rho-型鸟嘌呤交换因子。果蝇Ephexin在突触前是突触停留所必需的，并且定位于神经末梢的其他成分附近。Rho型GTP酶位于Ephexin gef功能的下游，对执行体内平衡补偿非常重要，尤其是CDC42。在Ephexin的上游，果蝇Eph受体(Eph)与Ephexin结合，Eph突变体破坏了突触的动态平衡。该信号系统的各组成部分之间以及与CaV2.1钙通道突变体之间表现出很强的遗传相互作用。我们推测，这个突触前信号系统将突触质膜上的稳态逆行信号与突触前CaV2.1功能的调节和神经递质的释放联系在一起。 R00阶段设计：已知在其他系统中调节钙通道功能和Eph/Ephexin/GTP信号的候选分子将被测试在突触内稳态中的作用。确实在动态平衡中发挥作用的分子将被置于我们的突触前信号系统的背景下。这项工作将在为期三年的R00阶段使用多种方法：突触功能的电生理分析、基因突变分析、靶分子的药理抑制、基因表达和蛋白质定位分析、转基因拯救以及遗传上位性和通路分析。 实习生：我的实验室新招募的成员将接受本项目各方面的培训。在三年的课程中，这可能包括一名技术员、两名研究生和一名博士后研究员。

OBJECTIVE: The causes and progression of several neurological diseases are influenced by factors that control the stability of neural function. Yet the mechanisms that dictate neural excitation and inhibition are poorly understood. Many studies indicate that homeostatic signaling mechanisms participate in the regulation of neural function, in particular by modulating the strength of synaptic connections. This project aims to clarify the mechanisms of synaptic homeostatic signaling. BACKGROUND/RATIONALE: We published a study demonstrating a role in synaptic homeostasis for an Ephexin signaling system. Ephexin is a Rho-type guanine exchange factor (GEF). Drosophila Ephexin is required presynaptically for synaptic homestasis and localizes in proximity of other components of the nerve terminal. Downstream of Ephexin GEF function, Rho-type GTPases are important for executing homeostatic compensation, in particular Cdc42. Upstream of Ephexin, the Drosophila Eph receptor (Eph) binds Ephexin and Eph mutants have impaired synaptic homeostasis. Components of this signaling system show strong genetic interactions with each other and with CaV2.1 calcium channel mutants. We postulate that this presynaptic signaling system couples homeostatic retrograde signaling at the synaptic plasma membrane to the modulation of presynaptic CaV2.1 function and neurotransmitter release. R00 PHASE DESIGN: Candidate molecules already known in other systems to regulate calcium channel function and Eph/Ephexin/GTP signaling will be tested for roles in synaptic homeostasis. Molecules that do show a role in homeostasis will be placed into the context of our presynaptic signaling system. This work will utilize a combination of approaches for the three-year R00 phase: electrophysiological analysis of synaptic function, genetic mutant analyses, pharmacological inhibition of target molecules, analyses of gene expression and protein localization, transgenic rescue, and genetic epistasis and pathway analyses. TRAINEES: New recruited members of my laboratory will be trained in all aspects of this project. Over the course of three years, this may include a technician, two graduate students, and a postdoctoral fellow.