Mechanisms of Heat Activation and Multimodal Functions of VR1 Receptor Channels

描述（由申请人提供）：疼痛开始于被称为伤害感受器的专门感觉神经元的外周神经末梢处的转导。了解这些伤害性感受器如何对产生疼痛的刺激做出反应是了解疼痛生物学的关键一步。这项研究涉及离子通道的伤害性感受，特别是克隆的香草素受体TRPV 1。最近的研究表明，该通道的功能和调节的复杂性在以前没有预料到的水平，并牵连它在检测和整合外源性有害刺激，如热，香草酸和内源性促炎信号。该项目的目标是确定，在分子水平上，受体如何作为一个多功能的有害检测器和集成器，以响应各种刺激，使用单通道电生理学结合分子生物学的方法。第一个目标将集中在通道的多模态激活的机制。实验提出，以确定是否热敏感性所需的其他刺激激活通道，以及如何刺激的不同形式的受体内相互作用。这项工作还将开发变构模型，统一通道的多模态门控。第二个目标是研究多模态激活的结构基础。这项研究将检查不同刺激的门控机制在多大程度上是分开的，并将描绘出每种刺激的分子结构域，并确定其功能机制。第三个目标涉及通道的脱敏和恢复。实验拟量化和建立的机制，磷脂酰肌醇-45-二磷酸（PIP 2）的激活TRPV 1引起的消耗，并阐明脱敏状态的性质。拟议的研究将提高我们对伤害性感觉传导的认识，并将有利于疼痛治疗的临床进展，特别是寻找具有全新作用模式和前所未有的伤害感受器选择性的镇痛药物。

DESCRIPTION (provided by applicant): Pain begins with transduction at peripheral nerve terminals of specialized sensory neurons called nociceptors. Understanding how these nociceptors respond to pain-producing stimuli is a key step towards understanding the biology of pain. This research concerns ion channels underlying nociception, in particular, the cloned vanilloid receptor TRPV1. Recent studies of the channel have shown a previously unsuspected level of complexity in its function and regulation and have implicated it in detection and integration of both exogenous noxious stimuli such as heat, vanilloids and acids and endogenous proinflammatory signals. The goal of the project is to determine, at the molecular level, how the receptor functions as a versatile noxious detector and integrator in response to various stimuli, using methods of single-channel electrophysiology combined with molecular biology. The first aim will focus on the mechanisms of the polymodal activation of the channel. Experiments are proposed to determine whether the heat sensitivity is required by other stimuli to activate the channel and how the stimuli of different modality interact within the receptor. The work will also develop allosteric models that unify the polymodal gating of the channel. The second objective is to investigate the structural basis of the polymodal activation. The study will examine to what extent the gating machinery for different stimuli are separated and will delineate the molecular domains specific to each stimulus and determine their functional mechanisms. The third aim concerns the desensitization and recovery of the channel. Experiments are proposed to quantify and establish the mechanisms of the depletion of phosphatidylinositol-45-bisphosphate (PIP2) caused by activation of TRPV1, and to elucidate the nature of the desensitized states. The proposed research will improve our knowledge of nociceptive sensory transduction and will benefit clinical advances in pain therapy, in particular, the search for analgesic drugs that have an entirely new mode of action and an unprecedented selectivity for nociceptors.