Genetic Dissecting Serotonergic Phenotypes in C elegans

描述（由申请人提供）：在末梢分化过程中，每个神经元必须选择一个递质。许多不同的神经元选择相同的递质，因此相同的神经递质可以服务于许多不同的功能。虽然调节神经发生早期阶段的因素开始被阐明，但决定神经递质表型的遗传网络在很大程度上是未知的。本研究采用遗传方法鉴定决定5 -羟色胺能表型的基因，并研究5 -羟色胺能神经元在秀丽隐杆线虫代谢控制中的作用。该实验利用了血清素缺乏的蠕虫完全可存活的优势，并且血清素能系统包括5类，共9个神经元，为遗传和生理分析提供了简单和多样性。首先，我们将确定调节血清素能神经元发育的基因。我们已经分离出两类影响特定血清素能神经元发育的突变。我们将评估突变是否会阻止神经元的产生，或者它们是否会影响最终神经元身份的特定方面。我们将克隆2-3个可能参与末梢分化的基因并确定其表达模式。其次，我们将确定是否存在指导血清素合成的细胞特异性调节因子。通过对5 -羟色胺合成酶基因tph-1启动子的分子解剖，我们将确定离散序列是否直接影响特定神经元中tph-1的表达。我们将测试在5 -羟色胺能神经元子集中tph-1表达所需的pu转录因子UNC-86是否直接调节tph-1。第三，我们将评估血清素能神经元在代谢控制中的作用。我们前期的研究表明血清素通过调节TGF-b和胰岛素神经内分泌通路来调节秀丽隐杆线虫的代谢。我们将测试影响特定5 -羟色胺能神经元的突变是否会影响特定的代谢调节途径，以及恢复特定神经元的5 -羟色胺产生是否会挽救5 -羟色胺缺乏突变体的代谢缺陷。第四，我们将使用遗传上位分析来评估血清素和其他调节代谢的神经信号的相互作用。目的是探索血清素信号是如何整合来调节新陈代谢的。血清素信号的失调与饮食失调、2型糖尿病和肥胖有关。确定5 -羟色胺能表型基因，了解5 -羟色胺能神经元在秀丽隐杆线虫代谢调控中的作用，将为研究人类5 -羟色胺能神经元的发育和功能提供试剂。

DESCRIPTION (provided by applicant): During the terminal differentiation, every neuron must choose a transmitter. Many different neurons choose the same transmitter, thus the same neurotransmitter may subserve many different functions. Although factors regulating early stages of neurogenesis are beginning to be elucidated, the genetic network determining neurotransmitter phenotypes is largely unknown.This proposal uses genetic approaches to identify genes determining the serotonergic phenotype and to study the role of serotonergic neurons in metabolic control in C. elegans. The proposed experiments take advantages that serotonin-deficient worms are fully viable, and the serotonergic system, including 5 classes, a total of 9 neurons, offers both the simplicity and diversity for genetic and physiological analysis.First, we will identify genes regulating serotonergic neuron development. We have isolated 2 classes of mutations affecting the development of particular serotonergic neurons. We will assess if the mutations prevent the neuron generation, or if they affect particular aspects of the final neuronal identity. We will clone 2-3 genes likely acting in the terminal differentiation and determine their expression pattern. Second, we will determine if there are cell-specific regulators directing serotonin synthesis. Through molecular dissection of the promoter of the serotonin synthetic enzyme gene tph-1, we will determine if discrete sequence motifs direct tph-1 expression in particular neurons. We will test if the POU-transcription factor UNC-86 that is required for tph-1 expression in a subset of the serotonergic neurons directly regulates tph-1. Third, we will assess the role of serotonergic neurons in metabolic control. Our previous study indicated that serotonin regulates the TGF-b and insulin neuroendocrine pathways to modulate C. elegans metabolism. We will test if mutations affecting particular serotonergic neurons affect a specific metabolic regulatory pathway, and if restoration of serotonin production in particular neurons rescues the metabolic defects of serotonin deficient mutants. Fourth, We will use genetic epistasis analysis to assess the interaction of serotonin and other neural signaling that also regulate metabolism. The goal is to explore how serotonin signals are integrated to modulate metabolism.Dysregulations of serotonin signaling have been associated with eating disorders, type II diabetes, and obesity. Identification of genes that determine the serotonergic phenotype and understanding the role of serotonergic neurons in the regulation of metabolism in C. elegans will provide reagents to study the development and function of serotonergic neurons in human.