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三聚体G蛋白来调节神经递质的。 神经元的活动。成瘾性药物激活G蛋白偶联受体， 是由于通过G蛋白的神经传递的改变，因此了解其基本原理至关重要。 神经元中G蛋白信号传导的机制。Gao是G蛋白激活的主要脑G蛋白- 偶联神经递质受体，但对其信号传导机制知之甚少。最近的发现 高在分裂细胞中起作用，调节微管上的力，提出了高也可能 通过微管力作用于神经元以改变细胞结构。Gao信号抑制C. 我们的第一个目标是用它作为研究Gao信号机制的模型。我们将 鉴定产蛋系统中产生和接收Gao介导的信号的细胞。我们将分析 我们已经从遗传学上鉴定出了三个新的基因，它们是这种信号传导所必需的，其中一个我们已经发现了。 已经克隆并显示编码TRP离子通道。我们将测试高通过 细胞骨架，通过荧光标记的神经过程和突触改变神经元的结构， 野生型和Gao突变型动物的产卵系统。我们的第二个目标是利用第二种模式， 高信号。因此，我们将研究高介导的5-羟色胺信号的机制， 与人类抑郁症有关的神经递质。我们正在筛选C的突变体。优雅的人， 对血清素有反应我们将完成这个筛选，克隆并分析一个新的血清素信号基因 我们已经通过这种方法确定了。我们还将分析表达模式和敲除 表型的一组C. elegans血清素受体同系物。我们的第三个目标是识别和分析 作用于Gao下游以介导其效应的分子。我们将完成突变体的基因筛查 干扰Gao下游的神经递质信号。使用这个屏幕和血清素屏幕，我们 已经分离出了五种突变，它们似乎破坏了Gao介导的神经传递， 微管在分裂细胞中的力量产生。这有力地支持了高行为的假设， 这两种功能的机制相同。其中三个突变确定了一个基因，通过上位性分析， 似乎在高的下游运作我们将克隆和分析这些突变所识别的基因。

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.