TRP Ion Channels in Vomernasal and Taste Transduction

描述(申请人提供)：最近的工作表明，脊椎动物的犁鼻器和味觉信号转导途径相似：G蛋白偶联受体通过磷脂酶C(PLC)打开Trp家族离子通道的一个成员，TRPC2负责犁鼻器(VNO)，Trpm5用于味觉。这些离子通道在TRPC2基因敲除小鼠中对信息素缺乏反应，在Trpm5基因敲除动物中对苦、甜和氨基酸的味道缺乏反应，突显了这些离子通道对化学感觉的重要性。了解Trp离子通道的门控机制在任何系统中都被证明是困难的，并且仍然是理解味觉和VNO转导的基本目标。在上一个授权期，我们发现Trpm5被细胞内的Ca+激活，提示Ca+可能是某些形式的味觉转导的第二信使。在下一个授权期，我们的目标是了解Trpm5调节的分子机制，以及Trpm5的分子特性如何影响味觉。我们将具体解决以下问题：(1)Trpm5通道激活和失活的机制是什么？在这些研究中，我们将使用膜片钳记录Trpm5的表达，以及对该通道的药理和结构操作。(2)Trpm5阻断剂是否干扰味觉检测？将通过膜片钳记录从表达Trpm5的细胞中识别阻滞剂，并将确定已识别的阻滞剂对小鼠味觉阈值的影响。(3)与Trpm5类似的通道在VNO转导中是否发挥作用？Trpm5及其相关通道在体内广泛表达，这些通道的突变可能是某些病理状态的基础。通过了解这些通道的调节，我们可以理解它们在健康和疾病中对信号的贡献。

DESCRIPTION (provided by applicant): Recent work indicates that vomeronasal and taste transduction in vertebrates share similar transduction pathways: G protein-coupled receptors signal through phospholipase C (PLC) to open a member of the TRP family of ion channels, TRPC2 for the vomeronasal organ (VNO) and TRPM5 for taste. The importance of these ion channels for chemosensation is highlighted by the lack of response to pheromones in TRPC2 knockout mice and to bitter, sweet and amino acid tastes in TRPM5 knockout animals. Understanding the mechanisms by which TRP ion channels are gated, has proven difficult in any system, and remains an essential goal for understanding taste and VNO transduction. In the last grant period, we discovered that TRPM5 is activated by intracellular Ca +, suggesting that Ca + may be the second messenger for some forms of taste transduction. In the next grant period we aim to understand the molecular mechanisms that underlie regulation of TRPM5, and how molecular properties of TRPM5 influence taste sensation. We will specifically address the following questions: (1) What are the mechanisms by which TRPM5 channels are activation and inactivated? In these studies we will use patch-clamp recording of expressed TRPM5, together with pharmacological and structural manipulations of the channel. (2) Do blockers of TRPM5 interfere with taste detection? Blockers will be identified by patch-clamp recording from cells expressing TRPM5 and the effects of identified blockers on taste thresholds in mice will be determined (3) Do similar channels to TRPM5 play a role in VNO transduction? TRPM5 and related channels are widely expresed in the body, and mutations in these channels may underlie certain pathological states. By understanding the regulation of these channels, we can understand their contribution to signaling in health and disease.