Role of TRPV cation channels in mast cells

描述(申请人提供)：肥大细胞是存在于组织中的多能效应细胞。它们通过向周围组织释放强有力的生物介质来对各种刺激做出反应。这些介质包括细胞外蛋白酶、组胺和5-羟色胺，以及许多细胞因子、趋化因子和生长因子。在免疫学上，肥大细胞在抗原性攻击的反应中，在炎症的产生和维持中起着关键作用。除了对免疫刺激的反应外，肥大细胞还对多碱促分泌剂和物理刺激有反应。 通过对物理刺激(热、渗透和机械输入)的反应，肥大细胞促进了组织的动态平衡，并促进了伤害性侮辱后的创伤过程。肥大细胞激活的每一种机制都依赖于通过特定的质膜阳离子通道的钙内流。在这里，我们报道了TRPV家族的钙离子通道在肥大细胞中表达。TRPV离子通道是一个新认识的传感器家族，它接收物理环境信号并对其做出反应，包括热刺激、渗透刺激和机械刺激。目前提议的中心前提是TRPV通道转导生理和病理生理信号，这些信号在功能上与肥大细胞中的钙信号和介质释放相耦合。 我们建议在肥大细胞环境中研究TRPV阳离子通道的调节和功能。我们的第一个特定目的是测试这样一个假设，即TRPV2的表达赋予肥大细胞一种特定的、热诱发的阳离子电导。在第二个具体目标中，我们将探索一种新的TRPV2调控机制。我们的初步数据表明，在肥大细胞中，TRPV2是蛋白激酶A磷酸化的靶点，这种相互作用是由一种新的适配蛋白PAP7介导的。PAP7专门连接TRPV2和PKA。我们将探索PKA磷酸化TRPV2的功能后果和上游调控机制，以及PAP7的贡献。在具体目标3中，我们将研究TRPV通道在真皮肥大细胞中的表达和功能，探索TRPV在皮肤中耦合肥大细胞对环境刺激的反应的假设。

DESCRIPTION (provided by applicant): Mast cells are pluripotent effector cells that reside in tissue. They respond to diverse stimuli by releasing potent biological mediators into the surrounding tissue. These mediators include extracellular proteases, histamine and serotonin, as well numerous cytokines, chemokines, and growth factors. Immunologically, mast cells play a crucial role in the generation and maintenance of inflammation, in response to antigenic challenge. In addition to responses to immunological stimulation, mast cells also respond to polybasic secretagogues and physical stimuli. Through responsiveness to physical stimuli (thermal, osmotic and mechanical inputs), mast cells contribute to both tissue homeostasis, and the wounding process that follows noxious insults. Each mechanism for mast cell activation relies on calcium influx through specific plasma membrane cation channels. Here, we report that calcium-permeant cation channels of the TRPV family are expressed in mast cells. TRPV ion channels are a newly recognized family of sensors, which receive, and react to, physical environmental cues, including thermal, osmotic and mechanical stimuli. The central premise of the current proposal is that TRPV channels transduce physiological, and pathophysiological, signals that are functionally coupled to calcium signaling and mediator release in mast cells. We propose to study the regulation, and function, of TRPV cation channels in the mast cell context. Our first Specific Aim tests the hypothesis that expression of TRPV2 confers a specific, thermally-evoked, cation conductance upon mast cells. In the second Specific Aim, we will explore a novel regulatory mechanism for TRPV2. Our preliminary data show that TRPV2 is a target for phosphorylation by protein kinase A in mast cells, and that this interaction is mediated by a novel adapter protein, PAP7. PAP7 specifically bridges TRPV2 and PKA. We will explore the functional consequences and upstream regulatory mechanisms for phosphorylation of TRPV2 by PKA, and the contribution of PAP7. In Specific Aim 3, we will examine the representation and functionality of TRPV channels in dermal mast cells, exploring the hypothesis that TRPVs couple mast cell responses to environmental stimuli in the skin.