Analysis of nicotinic acetylcholine receptor function in C. elegans

描述：尼古丁胆碱能信号在哺乳动物神经系统中起着关键作用。烟碱乙酰胆碱受体作为突触后受体介导神经元之间的兴奋性信号，并从突触外位点调节大脑和脊髓几乎每个区域的不同突触类型的神经递质释放。尼古丁胆碱能信号的改变与许多使人衰弱的神经系统疾病有关，包括阿尔茨海默病、精神分裂症和某些形式的癫痫。此外，尼古丁与神经系统中的尼古丁受体结合，引发细胞和分子级联反应，导致尼古丁成瘾。尽管尼古丁信号在正常脑生理和神经元功能障碍中具有明显的重要性，但我们对尼古丁信号实现的分子机制的理解仍存在重大差距，并且影响神经系统胆碱能信号的调节途径仍然不明确。本研究采用了一种高度可处理的模型系统，即秀丽隐杆线虫，来研究特定神经系统中胆碱能信号的分子细节。我们的初步数据表明，在线虫运动回路中，尼古丁受体在调节运动神经元的兴奋性中起关键作用。在Aim 1中，我们将验证特定受体类型的表达和定位仅限于运动神经元子集的假设，确定尼古丁受体在神经元上正确定位的重要途径的分子性质，并测试特定受体类型在秀丽隐杆线虫行为控制中的作用。在Aim 2中，我们将使用膜片钳电生理学直接测量运动神经元的胆碱能电流，并评估这些受体在运动神经元生理学中的作用。在Aim 3中，我们将使用一种强大的遗传方法来揭示调节神经元胆碱能信号的新分子途径的组成部分。我们期望我们的研究将为中枢神经系统中尼古丁受体功能的机制提供基本的见解。此外，在我们的实验中，对调节突触形成和功能的遗传途径的识别和功能表征将最终产生新的药物靶点，用于治疗涉及胆碱能信号的神经系统疾病。公共卫生相关性：神经系统中的细胞通讯需要神经递质乙酰胆碱，乙酰胆碱介导的信号改变是各种退行性神经系统疾病和尼古丁成瘾的标志，但我们对神经系统中调节这一过程的分子途径知之甚少。本研究将探索乙酰胆碱在神经系统细胞间传递信息的机制，并揭示这一过程中所需的新基因。我们的工作将为乙酰胆碱介导的信号传导机制提供基本的见解，并有望导致治疗这一过程中缺陷引起的疾病的新疗法的发展。

DESCRIPTION: Nicotinic cholinergic signaling plays key roles in the mammalian nervous system. Nicotinic acetylcholine receptors mediate excitatory signaling between neurons as post-synaptic receptors and, from extrasynaptic sites, modulate neurotransmitter release at diverse synapse types across virtually every area of the brain and spinal cord. Alterations in nicotinic cholinergic signaling are associated with a number of debilitating neurological disorders including Alzheimer's disease, schizophrenia and certain forms of epilepsy. Moreover, nicotine binding to nicotinic receptors in the nervous system initiates the cellular and molecular cascade that results in nicotine addiction. Despite the clear importance of nicotinic signaling in normal brain physiology and neuronal dysfunction, there are major gaps in our understanding of the molecular mechanisms by which nicotinic signaling is achieved, and the regulatory pathways that impact cholinergic signaling in the nervous system remain poorly defined. This proposal employs a highly tractable model system, the nematode C. elegans, to investigate the molecular details of cholinergic signaling in a defined nervous system. Our preliminary data show that nicotinic receptors play key roles in regulating the excitability of motor neurons in a well-characterized C. elegans motor circuit. In Aim 1, we will test the hypothesis that the expression and localization of specific receptor types are restricted to subsets of motor neurons, determine the molecular nature of pathways important for proper localization of nicotinic receptors on neurons, and test the roles of specific receptor types in the control of C. elegans behavior. In Aim 2, we will use patch clamp electrophysiology to directly measure cholinergic currents from motor neurons and assess the roles of these receptors in motor neuron physiology. In Aim 3, we will use a powerful genetic approach to uncover components of novel molecular pathways that regulate cholinergic signaling onto neurons. We expect that our studies will provide fundamental insights into the mechanisms of nicotinic receptor function in the central nervous system. Additionally, the identification and functional characterization of genetic pathways that regulate synapse formation and function in our experiments will ultimately yield novel drug targets for therapeutic strategies designed to treat neurological disorders involving cholinergic signaling. PUBLIC HEALTH RELEVANCE: Cellular communication in the nervous system requires the neurotransmitter acetylcholine and alterations in acetylcholine-mediated signaling are a hallmark of a wide variety of degenerative neurological disorders and nicotine addiction, yet we know very little about the molecular pathways that regulate this process in the nervous system. This proposal will explore the mechanisms by which acetylcholine transmits information between cells of the nervous system and uncover new genes required in this process. Our work will provide fundamental insights into the mechanisms of acetylcholine-mediated signaling and is expected to lead to the development of new therapies for the treatment of disorders arising from deficits in this process.