G Protein Signaling in the C. elegans Nervous System

我们试图了解神经递质是如何通过异源三聚体G蛋白来调节 神经元的活动。成瘾药物激活G蛋白偶联受体，以及一些精神疾病 是由于通过G蛋白的神经传递的改变，所以理解基本的 G蛋白在神经元中的信号转导机制。Gao是由G蛋白激活的主要脑G蛋白。 偶联神经递质受体，但对其信号传递机制知之甚少。一项最新发现 是Gao参与了细胞分裂以调节微管上的力，提出了Gao也可能 通过微管力作用于神经元，改变细胞结构。GAO信号对中华绒毛虫产卵行为有抑制作用。 我们的第一个目标是将其作为研究GAO信号机制的模型。因此，我们将 确定产卵系统中产生和接收高信号的细胞(S)。我们将分析 我们已经从基因上确定了三个新的基因，它们是这种信号所必需的，其中一个 已经克隆并显示编码色氨酸离子通道。我们将检验高晓松通过 细胞骨架通过荧光标记神经突起和突触来改变神经元的结构 野生型和高突变型动物的产卵系统。我们的第二个目标是利用第二个模型 高发信号。因此，我们将研究5-羟色胺介导的Gao信号转导机制。 神经递质与人类抑郁症有关。我们正在筛选线虫的突变体，这些突变未能 对血清素有反应。我们将完成这一筛选并克隆和分析一个新的5-羟色胺信号基因 我们已经通过这种方法确定了。我们还将分析表达模式和基因敲除 线虫5-羟色胺受体同源物的表型。我们的第三个目标是识别和分析 作用于Gao下游以调节其影响的分子。我们将完成突变人的基因筛查 这会扰乱高的下游神经递质信号。使用这个屏幕和5-羟色胺屏幕，我们 已经分离出五个突变，这些突变似乎既破坏了高压氧介导的神经传递，也破坏了 分裂细胞中微管力的产生。这有力地支持了这样的假设，即高按照 两种功能的机制相同。其中三个突变确定了单个基因，通过上位性分析， 似乎在高的下游发挥作用。我们将克隆和分析由这些突变鉴定的基因(S)。

We seek to understand how neurotransmitters signal through heterotrimeric G proteins to modulate the activities of neurons. Addictive drugs activate G protein-coupled receptors, and a number of mental diseases are due to alterations in neurotransmission through G proteins, so it is critical to understand the fundamental mechanims of G protein signaling in neurons. Gao is the major brain G protein activated by G protein- coupled neurotransmitter receptors, but little is known about its mechanism of signaling. A recent discovery is that Gao acts in dividing cells to regulate force on microtubules, raising the hypothesis that Gao may also act in neurons via microtubule force to modify cell structure. Gao signaling inhibits egg-laying behavior in C. elegans, and our first aim is to use this as a model to study the Gao signaling mechanism. Thus we will identify the cells of the egg-laying system that generate and receive Gao-mediated signal(s). We will analyze three new genes we have genetically identified that are required for this signaling, one of which we have already cloned and shown to encode a TRP ion channel. We will test the hypothesis that Gao acts via the cytoskeleton to alter the structure of neurons by fluorescently labeling the neural processes and synapses of the egg-laying system in wild-type and Gao-mutant animals. Our second aim exploits a second model for Gao signaling. Thus we will study the mechanism of Gao-mediated signaling by serotonin, a neurotransmitter involved in depression in humans. We are screening for mutants of C. elegans that fail to respond to serotonin. We will complete this screen and clone and analyze a new serotonin signaling gene that we have already identified by this approach. We will also analyze the expression patterns and knockout phenotypes for a set of C. elegans serotonin receptor homologs. Our third aim is to identify and analyze the molecules that act downstream of Gao to mediate its effects. We will complete a genetic screen for mutants that disrupt neurotransmitter signaling downstream of Gao.Using this screen and the serotonin screen, we have already isolated five mutations that appear to disrupt both Gao-mediated neurotransmission as well as microtubule force generation in dividing cells. This strongly supports the hypothesis that Gao acts by the same mechanism for both functions. Three of the mutations identify a single gene that, by epistasis analysis, appears to function downstream of Gao. We will clone and analyse the gene(s) identified by these mutations.