Role of TRPV channels in pain and temperature sensation

描述（由申请人提供）：在美国，急性和慢性疼痛代表了严重的和治疗不足的健康问题，部分原因是我们对外周神经系统检测有害刺激的机制不完全了解。TRPV 1是一种热门控离子通道，对热诱发疼痛的某些方面但不是所有方面都是必需的。三个相关的通道，TRPV 2，TRPV 3和TRPV 4，也可以通过升高的温度激活，因此可能有助于检测疼痛的热量。TRPV 2在非常高的温度（>52摄氏度）下被激活，并且在感觉神经元的子集中表达最高。TRPV 3和TRPV 4在>32 ℃的温度下被激活。在皮肤中，TRPV 3和TRPV 4的表达在上皮角质形成细胞中最为突出，这提高了这些细胞参与涉及TRPV 3和TRPV 4的间接温度感觉模式的可能性。TRPV 2和TRPV 4也可以被细胞肿胀激活，这表明它们可能参与机械感觉。本研究旨在实现以下目标：（1）确定TRPV 2和TRPV 4是否以及如何参与疼痛和非疼痛的热刺激和机械刺激的检测。(2)确定角质形成细胞TRPV 3和TRPV 4是否有助于有害和/或无害的温度感觉和机械感觉。(3)确定角质形成细胞如何将热刺激的存在传达给邻近的感觉神经元。为了实现这些目标，将分析TRPV 2和TRPV 4无效突变小鼠对机械和热刺激的急性反应性以及炎症或神经损伤后热敏感性或机械敏感性的增强。TRPV 3或TRPV 4的野生型或显性阴性形式将在角质形成细胞中选择性地过表达，并从行为上评估对温度感觉的影响。最后，生化电生理，荧光钙成像，和行为的方法将被用来确定分子通过热暴露的角质形成细胞与附近的感觉神经元进行通信。

DESCRIPTION (provided by applicant): Acute and chronic pain represent significant and under-treated health problems in the U.S. due, in part, to our incomplete understanding of the mechanisms by which the peripheral nervous system detects noxious stimuli. TRPV1 is a heat-gated ion channel required for some, but not all aspects of heat-evoked pain. Three related channels, TRPV2, TRPV3, and TRPV4, can also be activated by elevated temperatures and therefore may contribute to the detection of painful heat. TRPV2 is activated at very high temperatures (>52 degrees C) and expressed most highly in a subset of sensory neurons. TRPV3 and TRPV4 are activated at temperatures >32 degrees C. In the skin, TRPV3 and TRPV4 expression is most prominent in epithelial keratinocytes, raising the possibility that these cells participate in an indirect mode of thermosensation involving TRPV3 and TRPV4. TRPV2 and TRPV4 can also be activated by cell swelling, suggesting that they may participate in mechanosensation. This proposal is aimed at achieving the following goals: (1) To determine whether and how TRPV2 and TRPV4 contribute to the detection of painful and nonpainful thermal and mechanical stimuli. (2) To determine whether keratinocyte TRPV3 and TRPV4 contribute to noxious and/or innocuous thermosensation and mechanosensation. (3) To determine how keratinocytes communicate the presence of thermal stimuli to adjacent sensory neurons. To achieve these goals, TRPV2 and TRPV4 null mutant mice will be analyzed for acute responsiveness to mechanical and thermal stimuli and for enhancement of thermo- or mechanosensitivity following inflammation or nerve injury. Wild-type or dominant negative forms of TRPV3 or TRPV4 will be overexpressed selectively in keratinocytes and the effects on thermosensation evaluated behaviorally. Finally, biochemical electrophysiological, fluorescent calcium imaging, and behavioral methods will be used to identify molecules through which heat-exposed keratinocytes communicate with nearby sensory neurons.