Non-classical roles for opsins in taste and smell

摘要 拟议项目的目标是建立在我们最近发现的不同类型的视蛋白的非经典作用的基础上。 感官背景，特别是揭示它们对味觉和嗅觉的贡献。事实证明， 作为光感受器已经被研究了100年的视蛋白是在视觉之外表达的 在各种感觉模式中的系统和功能。我们不是专门为光感技术服务，而是 发现视蛋白是广泛需要的感官受体，潜在地发挥着与色氨酸一样广泛的作用 频道。在哺乳动物中，视蛋白在多种视网膜外细胞和器官中表达。然而， 这些视蛋白的眼外作用基本上还没有被研究过。我们建议采取广泛的措施 在果蝇中使用的工具组合，以阐明视蛋白在视网膜外的作用。该项目将 采用一套广泛的体内方法，包括电生理学和钙离子成像，行为学 分析，细胞生物学和最新的分子遗传学方法，研究我们发现的非常规作用 用于味觉和嗅觉方面的视觉素。除了视觉系统所需的六种视紫红质 (RH1-Rh6)，苍蝇编码第七个家庭成员(Rh7)。目标1将阐明Rh7在体内的光独立作用 味觉感受器神经元(GRN)对厌恶味觉的反应。我们将测试Rh7的提议 连接到一个信号级联，使GRN对这种令人厌恶的化学物质高度敏感。目标2将 研究视蛋白在嗅觉中的潜在作用。在概念上类似于我们最近发现的opsins 在温度感觉神经元中的表达使苍蝇在舒适的环境中感觉到温度的小幅上升 ，我们建议测试视蛋白在嗅觉感受器神经元中的作用，以检测微量的 通过放大级联产生的恶臭物质。目标3侧重于阐明两个方面的潜在作用 在基于质地的食品鉴别中的观点。食品的物理特性包括粘度 液体食物的硬度和固体食物的硬度。然而，食物质地感觉的潜在机制 人们对此了解甚少。我们将研究两种光学蛋白在感知分子的物理性质方面的贡献。 食物。温度也会影响食物的适口性。目标4将解决以下概念：温度- 依赖于含糖食物吸引力的变化，需要视蛋白家族的一员。总而言之， 提出的项目将加深我们对Opsins在味觉和嗅觉中不依赖光的作用的理解， 并形成这样的建议，即OPTINS是广泛的、多模式的传感器。鉴于眼球外的广泛表情 对于哺乳动物的视蛋白，我们认为这个项目将为探索类似的 视蛋白在哺乳动物中的作用。最后，味道和气味对昆虫病媒的识别和叮咬至关重要。 人类宿主，从而传播每年折磨十多亿人的疾病。因此，拆解 昆虫中高度敏感的味觉和嗅觉受体具有开发新的 干扰昆虫病媒对人类的识别和吸引的策略。

Abstract The goal of the proposed project is to build on our recent discovery of non-classical roles for opsins in diverse sensory contexts, and specifically to unravel their contributions to the senses of taste and smell. It turns out that opsins, which have been studied for >100 years as light sensors, are expressed outside of the visual system and function in a variety of sensory modalities. Rather than serving exclusively in photosensation, we are finding that opsins are broadly required sensory receptors, potentially playing roles as far-ranging as TRP channels. In mammals, opsins are expressed in a large variety of extra-retinal cell types and organs. However, the extra-ocular roles of these opsins are essentially unexplored. We propose to bring to bear a wide combination of tools available for use in Drosophila to elucidate extra-retinal roles for opsins. The project will employ an extensive suite of in vivo approaches including electrophysiology and Ca2+ imaging, behavioral assays, cell biology and state-of-the art molecular genetic approaches, to study unconventional roles we found for opsins in gustation and olfaction. In addition to the six rhodopsins that are required in the visual system (Rh1-Rh6), flies encode a seventh family member (Rh7). Aim 1 will clarify a light-independent role for Rh7 in the response of gustatory receptor neurons (GRNs) to an aversive tastant. We will test the proposal that Rh7 couples to a signaling cascade that endows GRNs with high sensitivity to the aversive chemical. Aim 2 will investigate a potential role for an opsin in olfaction. Conceptually similar to our recent discovery that opsins expressed in thermosensory neurons allow flies to sense small increases in temperature in the comfortable range, we propose to test that an opsin acts in olfactory receptor neurons to detect minute concentrations of an aversive odorant through an amplification cascade. Aim 3 focuses on illuminating the potential roles of two opsins in the discrimination of foods on the basis of texture. The physical features of food include the viscosity of liquid foods, and the hardness of solid foods. However, the mechanisms underlying food texture sensation are poorly understood. We will investigate the contributions of two opsins to sensing the physical properties of foods. Temperature also influences food palatability. Aim 4 will address the concept that the temperature- dependent change in appeal of sugar-containing foods requires a member of the opsin family. In summary, the proposed project will deepen our understanding of light-independent roles of opsins in gustation and olfaction, and shape the proposal that opsins are broad, polymodal sensors. In view of the wide extra-ocular expression of mammalian opsins, we suggest that this project will provide the conceptual framework for exploring similar roles for opsins in mammals. Finally, taste and smell are critical for insect disease vectors to identify and bite human hosts, and thereby spread diseases that afflict over a billion people annually. Therefore, unraveling highly sensitive receptors for gustation and olfaction in insects has important potential for developing new strategies for interfering with the recognition and attraction of humans by insect disease vectors.