TRPA1: a polymodal sensor for aversive stimuli

描述（由申请人提供）：拟议研究的长期目标是使用果蝇（Drosophila melanogaster）作为动物模型，揭示昆虫对感觉线索（从温度变化到驱虫剂）的反应机制。这些问题可能与控制害虫有关，因为传播疾病的蚊子是通过热感觉、视觉和化学线索吸引到人类身上的。令人厌恶的温度和化学驱虫剂可以阻止昆虫。因此，了解回避行为背后的机制可能为害虫防治提供重要的见解。瞬时受体电位（TRP）阳离子通道是感知环境刺激的一组关键受体蛋白。在13个果蝇成员中，TRPA1是特别值得注意的，因为它是一系列有害感官输入的探测器，包括微暖或高温、驱虫剂和过度的光线。在这里，我们建议剖析TRPA1使幼虫和成虫逃避厌恶刺激的分子、细胞和行为机制。为了实现我们的目标，我们建议采用多学科方法，结合分子遗传学，生物化学，细胞生物学，电生理学和行为方法。Aim 1将验证一种假说，即幼虫会避开明亮的光线，通过一种独立于细胞表面蛋白的光探测新机制激活TRPA1。在Aim 2中，我们提出验证TRPA1作为探测器的假设，该探测器允许果蝇使用温度的日常变化来设置运动活动的昼夜周期。Aim 3中提出的实验将测试有关TRPA1通过热感觉信号级联激活的功能和机制的假设。与众所周知的通过温度变化直接激活“热TRP”相比，这种级联反应代表了一种新的TRP通道激活模式。目的4是观察到TRPA1是苍蝇避免驱蚊剂香茅醛所必需的，这种反应在蚊子和果蝇中都通过直接和间接机制发生。在本研究的第一部分，我们将检验一个额外的TRPA通道在对其他驱蚊剂（香叶醇和樟脑）的厌恶反应中起作用的假设。aim 4的第二部分验证了g蛋白偶联受体直接检测驱蚊剂，并启动导致TRP通道间接激活的信号级联反应的假设。拟议的研究最终可能导致鉴定新一代更安全、更有效的驱蚊剂，通过鉴定和表征这些化合物的分子靶点来控制虫媒疾病。

DESCRIPTION (provided by applicant): The long-term goal of the proposed research is to use the fruit fly, Drosophila melanogaster, as an animal model to unravel the mechanisms through which insects respond to sensory cues, ranging from changes in temperature to insect repellents. These questions are of potential relevance to the control of insect pests, since mosquitoes that spread diseases are attracted to humans through thermosensory, visual and chemical cues. Aversive temperatures and chemical repellents deter insects. Therefore, understanding the mechanisms underlying avoidance behavior may provide important insights into insect pest control. A key group of receptor proteins that sense environmental stimuli are Transient Receptor Potential (TRP) cation channels. Among the 13 Drosophila members, TRPA1 is of particular note as it is a detector for a wide array of noxious sensory inputs, including slightly warm or hot temperatures, insect repellents, and excessive light. Here, we propose to dissect the molecular, cellular and behavioral mechanisms through which TRPA1 allows larvae and adult flies to elude aversive stimuli. To accomplish our goals, we propose to employ a multidisciplinary approach, using a combination of molecular genetics, biochemistry, cell biology, electrophysiology and behavioral approaches. Aim 1 will test the hypothesis that bright light, which larvae avoid, activates TRPA1 through a novel mechanism of light detection that is independent of a cell surface protein. In Aim 2 we propose to test the hypothesis that TRPA1 functions as a detector that allow flies to use the daily changes in temperature to set circadian cycles of locomotor activity. The experiments proposed in Aim 3 will test hypotheses concerning the function and mechanism by which TRPA1 is activated via a thermosensory signaling cascade. This cascade represents a new mode of activation of TRP channels in contrast to the well-known direct activation of "thermoTRPs" by changes in temperature. Aim 4 is an outgrowth of the observation that TRPA1 is required for flies to avoid the insect repellent, citronellal, and this response occurs through both direct and indirect mechanisms in both mosquitoes and fruit flies. In the first part of this aim we will test the hypothesis that an additional TRPA channel functions in the aversive responses to other insect repellents (geraniol and camphor). The second part of aim 4 tests the hypothesis that G-protein coupled receptors detect repellents directly, and initiate signaling cascades that lead to indirect activation of TRP channels. The proposed studies ultimately could lead to the identification of a new generation of safer and more effective repellents to control insect-borne disease by identifying and characterizing molecular targets for such compounds.