Cell Type Specific Control of Neuronal Signaling

6.项目总结/摘要 神经元回路功能障碍被认为是神经精神疾病的原因，包括强迫症、帕金森病和成瘾。G蛋白偶联受体（GPCR）通过与不同的G蛋白（例如G-α-s、G-α-i和G-α-q家族）相互作用而差异地调节神经元回路的活性，并且这些受体是公认的药物靶标。组成这些回路的不同神经元亚群通常表达相似的受体亚型，这使得不可能创造出选择性靶向特定回路中受体的药物。为了确定受体如何调节神经元回路，有必要在体内选择性地激活特定神经元群体中的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信号传导-从小分子配体到遗传缺失-但这些方法具有脱靶效应。这些脱靶效应有效地消除了确定特定神经元群体中的GPCR信号传导如何影响电路功能的可能性。一个有希望的进展，使这种特定的操纵是设计师受体的设计师药物（DREADD）家族的受体的开发。本提案的目的是使用在纹状体中的特定神经元群体中表达G-α-s DREADD的转基因小鼠在体内验证这种最近创建的工具。具体目标1将通过测量cAMP积累、ERK 1/2磷酸化、DARPP-32磷酸化和c-Fos表达来确定G-α-s DREADD是否激活典型的G-α-s信号通路，从而验证该工具。具体目标2将通过评估其对动物行为的影响来验证G-α-s DREADD诱导信号的生理相关性。该提案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。

6. PROJECT SUMMARY / ABSTRACT 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. G-alpha-s, G-alpha-i, and G-alpha-q-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 G-alpha-s DREADD in a specific population of neurons in the striatum. Specific Aim 1 will validate the tool by determining whether the G-alpha-s DREADD activates canonical G-alpha-s 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 G-alpha-s 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.