The function of gap junctions and chemical synapses in a simple neural circuit

间隙连接和化学突触在简单神经回路中的功能

基本信息

批准号：
10468692
负责人：
ZHAO-WEN WANG
金额：
$ 40.23万
依托单位：
UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-01 至 2024-08-31
项目状态：
已结题

项目摘要

C. elegans locomotion neural circuit is an excellent model for decoding the circuit and gene bases of behaviors. Previous studies have produced a detailed wiring diagram of this circuit, and proposed that two pairs of premotor interneurons, AVA and AVB, play key roles in locomotion by activating A-type and B-type cholinergic motor neurons (A-MNs and B-MNs), respectively. However, how the various neurons interact at the synaptic level is largely unknown. Our recent success in voltage-clamping motor neurons and recording gap junction currents between neurons in worms makes it possible to look into properties of the circuit that are otherwise inaccessible. Our preliminary studies revealed several unexpected and novel properties of the locomotion circuit, including retrograde gap junction currents between the premotor interneurons and motor neurons, a putative degenerin/epithelial sodium channel (DEG/ENaC) serving as a stretch receptor in B-MNs, retrograde regulation of the backward circuit by GABAergic MNs (D-MNs), and electrical coupling between the left and right AVA interneurons. This proposal is to use a combination of electrophysiological, genetic, molecular, and behavioral approaches to test a new model with three specific aims. Aim 1 is to test the hypotheses that B-MNs activate AVB premotor interneurons through gap junctions, and that B-MN activity depends on a stretch receptor. We will determine molecular mechanisms of the gap junction rectification and the effects of deficient electrical coupling on AVB activity and locomotion behavior. We will identify the putative DEG/ENaC in B-MNs and determine its roles in B-MN activity and locomotion. Aim 2 is to investigate the mechanism of the rectifying coupling between AVA and A-MNs, and the physiological role of electrical coupling between the left and right AVA interneurons. We will determine whether the rectification is conferred by the N-terminal of UNC-7 innexin in AVA and whether disrupting the coupling between AVA interneurons alters locomotion behavior. Aim 3 is to test the hypotheses that D-MNs inhibit A-MNs retrogradely via AVA, and that AVB facilitates forward locomotion by inhibiting AVA. We will assess the effect of disrupting the novel D-MN inhibitory circuit on locomotion. We will identify the postsynaptic receptors mediating AVB inhibition on AVA, and analyze the effect that disrupting this receptor has on locomotion. This project may reshape our understanding of the C. elegans locomotion neural circuit, and help us approach the long-term goal of elucidating the circuit and gene bases of behaviors.

线虫运动神经回路是解码行为回路和基因基础的优秀模型。先前的研究已经制作了该电路的详细接线图，并提出两对预电机中间神经元 AVA 和 AVB 通过激活 A 型和 B 型胆碱能运动在运动中发挥关键作用分别是神经元（A-MN 和 B-MN）。然而，各种神经元如何在突触水平上相互作用是很大程度上不为人知。我们最近在电压钳位运动神经元和记录间隙连接电流方面取得了成功蠕虫神经元之间的研究使得研究其他方式无法访问的电路特性成为可能。我们的初步研究揭示了运动回路的一些意想不到的新颖特性，包括前运动中间神经元和运动神经元之间的逆行间隙连接电流，一种假定的退化蛋白/上皮钠通道 (DEG/ENaC) 作为 B-MN 中的牵张受体，逆行调节 GABAergic MN (D-MN) 的反向电路，以及左右 AVA 之间的电耦合中间神经元。该建议是结合使用电生理学、遗传、分子和行为学测试具有三个特定目标的新模型的方法。目标 1 是测试 B-MN 激活的假设 AVB 运动前中间神经元通过间隙连接，而 B-MN 活性依赖于牵张受体。我们将确定间隙连接整流的分子机制以及电耦合不足的影响 AVB 活动和运动行为。我们将识别 B-MN 中假定的 DEG/ENaC 并确定其 B-MN 活动和运动中的作用。目标2是研究之间的整流耦合机制 AVA 和 A-MN，以及左右 AVA 中间神经元之间电耦合的生理作用。我们将确定校正是否是由 AVA 中 UNC-7 innexin 的 N 端赋予的，以及是否破坏 AVA 中间神经元之间的耦合会改变运动行为。目标 3 是检验假设 D-MN 通过 AVA 逆行抑制 A-MN，AVB 通过抑制 AVA 促进向前运动。我们将评估破坏新型 D-MN 抑制回路对运动的影响。我们将确定突触后受体介导 AVB 对 AVA 的抑制，并分析破坏该受体对 AVA 的影响在运动上。这个项目可能会重塑我们对线虫运动神经回路的理解，并且帮助我们实现阐明行为的回路和基因基础的长期目标。