Role of TRPV channels in pain and temperature sensation

描述(申请人提供)：急性和慢性疼痛在美国代表着严重的和未得到充分治疗的健康问题，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够深入。TRPV1是一种热门离子通道，对某些方面的热痛是必需的，但不是所有方面。三个相关的通道，TRPV2，TRPV3和TRPV4，也可以被温度升高激活，因此可能有助于检测到疼痛的热感。TRPV2在非常高的温度(&gt；52摄氏度)下被激活，并且在一部分感觉神经元中表达最高。TRPV3和TRPV4在摄氏32度的温度下被激活。在皮肤中，TRPV3和TRPV4在上皮角质形成细胞中的表达最显著，这增加了这些细胞参与TRPV3和TRPV4间接热感觉模式的可能性。TRPV2和TRPV4也可被细胞肿胀激活，提示它们可能参与了机械感觉。这项建议旨在实现以下目标：(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刺激和机械刺激。(2)确定角质形成细胞TRPV3和TRPV4是否参与了伤害性和/或无害性的热感觉和机械感觉。(3)确定角质形成细胞如何将热刺激的存在传递给邻近的感觉神经元。为了实现这些目标，将分析TRPV2和TRPV4缺失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将选择性地在角质形成细胞中过度表达，并从行为上评估其对温度感觉的影响。最后，将使用生化电生理学、荧光钙成像和行为学方法来识别分子，热暴露的角质形成细胞通过这些分子与附近的感觉神经元通信。

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.