Cell Type Specific Control of Neuronal Signaling

描述(申请人提供)：神经回路功能障碍被认为是神经精神障碍的罪魁祸首，包括强迫症、帕金森氏症和成瘾。G蛋白偶联受体(GPCRs)通过与不同的G蛋白家族(如Gs、Gi和Gq家族)相互作用，以不同的方式调节神经元回路的活动，这些受体是公认的药物靶点。组成这些回路的不同神经元亚群通常表达类似的受体亚型，因此不可能制造出选择性地针对特定回路中的受体的药物。为了确定受体如何调节神经元回路，有必要在体内特定的神经元群体中选择性地激活GPCR信号。在过去的二十年里，人们一直在努力创造工具来选择性地操纵不同神经元群体中的GPCR信号--从小分子配体到基因缺失--但这些方法有偏离目标的效果。这些非靶点效应有效地消除了确定特定神经元群体中的GPCR信号如何影响电路功能的可能性。实现这一特定操作的一个有希望的进展是开发由设计药物(DREADD)受体家族独占激活的设计受体。这项建议的目的是在体内验证这个最近创建的工具，使用在纹状体特定神经元群体中表达Gs DREADD的转基因小鼠。具体目标1将通过测量cAMP积累、ERK1/2磷酸化、DARPP-32磷酸化和c-Fos表达来确定Gs DREADD是否激活典型的Gs信号通路，从而验证该工具。具体目标2将通过评估Gs DREADD对动物行为的影响来验证Gs DREADD诱导的信号的生理相关性。这一提议的完成将为神经科学家提供一个强大的新工具，专门调节特定神经元群体中的GPCR信号。 与公共健康相关：为了了解药物如何在大脑中发挥作用，科学家需要能够以非常精确的方式操纵大脑的某些组成部分。这项提议将验证一种新的工具，该工具旨在为科学家提供前所未有的特异性水平。使用这一工具获得的信息将对大脑功能产生新的见解，并可能导致治疗神经精神疾病的新药的开发。

DESCRIPTION (provided by applicant): Dysfunctional neuronal circuits are thought to be responsible for neuropsychiatric disorders, including obsessive-compulsive disorder, Parkinson's disease and addiction. G protein-coupled receptors (GPCRs) differentially modulate the activity of neuronal circuits by interacting with different G proteins, (e.g. Gs, Gi, and Gq-families), and these receptors are well-established drug targets. Distinct subpopulations of neurons comprising these circuits often express similar receptor subtypes, making it impossible to create drugs that selectively target receptors in specific circuits. In order to determine how receptors might modulate neuronal circuits, it is necessary to selectively activate GPCR signaling in a specific neuronal population in vivo. For the past two decades, efforts have been made to create tools to selectively manipulate GPCR signaling in distinct neuron populations - from small molecule ligands to genetic deletion - but these approaches have off-target effects. These off-target effects effectively eliminate the possibility to determine how GPCR signaling in a specific neuronal population affects circuitry function. A promising advancement to enable this specific manipulation is the development of the Designer Receptors Exclusively Activated by Designer Drug (DREADD) family of receptors. The objective of this proposal is to validate this recently created tool in vivo using a transgenic mouse expressing the Gs DREADD in a specific population of neurons in the striatum. Specific Aim 1 will validate the tool by determining whether the Gs DREADD activates canonical Gs signaling pathways by measuring cAMP accumulation, ERK1/2 phosphorylation, DARPP-32 phosphorylation, and c-Fos expression. Specific Aim 2 will validate the physiological relevance of the Gs DREADD-induced signaling by assessing its effects on animal behavior. The completion of this proposal will provide neuroscientists a powerful new tool to exclusively modulate GPCR signaling in specific neuronal populations. PUBLIC HEALTH RELEVANCE: To understand how drugs work in the brain, scientists need to be able to manipulate certain components of the brain in a very precise manner. This proposal will validate a new tool designed to provide an unprecedented level of specificity to scientists. Information gained using this tool will yield new insight into brain function and may lead to development of new drugs for treating neuropsychiatric diseases.