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着严重且未得到治疗的健康问题，部分原因是我们对周围神经系统检测有害刺激的机制了解不完全。TRPV1是热门控离子通道，在热诱发疼痛的某些方面是必需的，但不是所有方面。三个相关通道，TRPV2， TRPV3和TRPV4也可以被高温激活，因此可能有助于检测疼痛热。TRPV2在非常高的温度下（约52℃）被激活，并在感觉神经元的一个子集中高度表达。在皮肤中，TRPV3和TRPV4在上皮性角质形成细胞中表达最为突出，这提高了这些细胞参与间接热感觉模式的可能性，包括TRPV3和TRPV4。TRPV2和TRPV4也可被细胞肿胀激活，提示它们可能参与机械感觉。本提案旨在实现以下目标：(1)确定TRPV2和TRPV4是否以及如何有助于检测疼痛和非疼痛的热和机械刺激。(2)确定角化细胞TRPV3和TRPV4是否参与有害和/或无害的热感觉和机械感觉。(3)确定角化细胞如何将热刺激的存在传递给相邻的感觉神经元。为了实现这些目标，将分析TRPV2和TRPV4零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或机械敏感性的增强。野生型或显性阴性形式的TRPV3或TRPV4将在角化细胞中选择性过表达，并对热感觉的影响进行行为评估。最后，生化电生理、荧光钙成像和行为方法将用于识别热暴露的角化细胞与附近感觉神经元通信的分子。

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.