G protein-gated K+ channels and inhibitory signaling

描述(申请人提供)：情绪相关的疾病，如焦虑和抑郁，与许多大脑结构的功能障碍有关，包括海马体。许多有效和有前景的治疗情绪相关疾病的新药直接或间接针对调节多种效应器活动的G蛋白偶联受体(GPCRs)。特定的gpr-效应器相互作用对正常和病理性情绪相关行为的相对意义，以及相关的解剖位置，目前尚不清楚。这项建议的前提是，通过跨越分子、超微结构、电生理和行为分析水平的跨学科方法，更好地了解GPCR-效应器相互作用，最终将改善我们理解和治疗具有强烈情感成分的精神障碍的方式。本研究的重点是G蛋白门控内向整流钾(GIRK/KIR3)通道，它介导了许多神经递质的突触后抑制效应，包括几种与情绪相关的行为，如GABA、5-羟色胺和腺苷，这些行为通过激活GPCRs来影响神经元的兴奋性。最近的研究发现了GIRK调节的新模式，并在海马区对GIRK信号进行了显著的依赖于GPCR的区划。本研究的目的是在此基础上探讨影响GPCRGIRK信号强度和敏感性的因素、GPCR型GIRK信号在海马区区划的机制以及海马区GPCRGIRK信号对情绪相关行为和认知的贡献。努力将集中在三个相互关联的特定目标上：(1)了解GPCR-GIRK信号的Girk1依赖的增强。对Girk1亚单位对GPCR-GIRK信号的积极贡献的结构性洞察将继续进行，并将检验Girk1加强受体和通道之间的物理相互作用的假设。(2)确定GIRK信号依赖于GPCR区隔化的潜在因素。海马区GIRK信号的分子组成和亚细胞分布以GPCR依赖的方式不同的假设将得到检验。(3)检测海马区GPCRGIRK信号对情绪和认知的影响。情绪相关的行为和认知将在表现出GPCR信号减弱或增强的结构性基因敲除小鼠中进行测量，并在对海马区GIRK信号进行药物和/或遗传操作的小鼠中进行测量。从这些研究中收集到的分子、亚细胞和行为方面的见解将加强我们对神经元GPCR-GIRK信号的理解，同时为与情绪相关的行为和认知的分子和解剖学基础提供新的见解。因此，这项拟议的研究与国家心理健康研究所的几个高度优先的研究领域一致，是朝着更全面地理解和更有效地治疗情绪相关疾病迈出的必要一步。 公共卫生相关性：焦虑症和抑郁症与涉及情绪的大脑区域的功能障碍有关。许多有效和有希望的治疗这种疾病的新方法是以神经元(受体)表面的蛋白质为靶标，这些蛋白质控制着神经元(效应器)内这些脑区的许多蛋白质的活动。这项拟议的研究将为相关大脑区域中影响焦虑相关行为的受体-效应器相互作用提供新的线索，为更全面地理解和改进情绪相关障碍的治疗铺平道路。

DESCRIPTION (provided by applicant): Mood-related disorders such as anxiety and depression are linked to dysfunction in many brain structures, including the hippocampus. Many effective and promising new drugs for the treatment of mood-related disorders target, directly or indirectly, G protein-coupled receptors (GPCRs) that modulate the activity of multiple effectors. The relative significance of specific GPCR-effector interactions to normal and pathological mood-related behaviors, and pertinent anatomic loci, are unclear. The premise of this proposal is that a better understanding of GPCR-effector interactions, obtained with an interdisciplinary approach spanning molecular, ultrastructural, electrophysiological, and behavioral levels of analysis, will ultimately improve how we understand and treat mental disorders with strong affective components. The focus of this study is the G protein-gated inwardly-rectifying K+ (Girk/KIR3) channel, which mediates the postsynaptic inhibitory effect of many neurotransmitters - including several linked mood-related behavior such as GABA, serotonin, and adenosine - that influence neuronal excitability via activation of GPCRs. Recent studies have identified new modes of Girk regulation and a striking GPCR-dependent compartmentalization of Girk signaling in the hippocampus. The goal of the proposed research is to build on this foundation by pursuing factors influencing the strength and sensitivity of GPCR-Girk signaling, mechanisms underlying the GPCR-dependent compartmentalization of Girk signaling in the hippocampus, and the contributions made by hippocampal GPCR-Girk signaling to mood-related behavior and cognition. Effort will be centered on three inter-related Specific Aims: (1) To understand the Girk1-dependent potentiation of GPCR-Girk signaling. Structural insights into the positive contribution made by the Girk1 subunit to GPCR-Girk signaling will be pursued, and the hypothesis that Girk1 strengthens the physical interaction between receptor and channel will be tested. (2) To identify factors underlying the GPCR-dependent compartmentalization of Girk signaling. The hypothesis that the molecular composition and subcellular distribution of hippocampal Girk signaling differs in a GPCR- dependent manner will be tested. (3) To measure the impact of hippocampal GPCR-Girk signaling on mood and cognition. Mood-related behavior and cognition will be measured in constitutive knockout mice exhibiting diminished or enhanced GPCR signaling, and in mice following pharmacologic and/or genetic manipulation of Girk signaling in the hippocampus. The molecular, subcellular, and behavioral insights gleaned from these studies will enhance our understanding of neuronal GPCR-Girk signaling, while offering new insights into the molecular and anatomic basis of mood-related behavior and cognition. Accordingly, the proposed research aligns with several high-priority research areas at the National Institute of Mental Health and constitutes a necessary step toward a more comprehensive understanding of, and more effective treatments for, mood- related disorders. PUBLIC HEALTH RELEVANCE: Anxiety disorders and depression are linked to dysfunction in brain regions involved with emotion. Many effective and promising new treatments for such disorders target proteins on the surface of neurons (receptors), which control the activity of many proteins inside the neurons (effectors), in these brain regions. The proposed research will shed new light on receptor-effector interactions in pertinent brain regions that shape anxiety-related behavior, paving the way toward a more comprehensive understanding of, and improved treatments for, mood-related disorders.