Role of CALHM1 ion channel in taste transduction

CALHM1离子通道在味觉传导中的作用

• 批准号: 8650279
• 负责人: James Kevin FOSKETT
• 金额: $ 34万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-10 至 2018-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8650279
• 关键词: Action Potentials; Age of Onset; Back; Biochemical; Biological; Brain; Cells; Chemicals; Complex; Diabetes Mellitus; Drug Formulations; Electrophysiology (science); Esthesia; Family; Fatty acid glycerol esters; Genes; Goals; Homologous Gene; Human; Ion Channel; Ions; Knockout Mice; Late Onset Alzheimer Disease; Life; Link; Mediating; Medicine; Membrane Proteins; Molecular; Mus; Nervous system structure; Neuraxis; Neurons; Neurotransmitters; Obesity; Perception; Physiological; Physiology; Play; Predisposition; Property; Protein Isoforms; Proteins; Regulation; Role; Sensory; Signal Transduction; Stimulus; System; TRPM5 gene; Taste Buds; Taste Perception; Type II Epithelial Receptor Cell; Wild Type Mouse; cellular imaging; electrical property; extracellular; insight; member; novel; optical imaging; public health relevance; reconstitution; response; voltage

DESCRIPTION (provided by applicant): The broad goal of our proposed studies is to exploit our new insights into the identity of CALHM1 as a founding member of a novel ion channel family. CALHM1, a gene of unknown function, was identified as a susceptibility factor for late-onset Alzheimer's disease that influences the age of onset. CALHM1 encodes a membrane protein expressed throughout the brain and in taste buds that lacks significant homology to other functionally characterized proteins, although five human homologs have been identified, and CALHM1 is conserved across species. We recently identified CALHM1 as the pore-forming subunit of Ca2+ permeable ion channel with unusual permeation properties and gating regulation by both voltage and extracellular Ca2+ concentration (Ca2+o). We have discovered that CALHM1 is essential for the perceptions of sweet, bitter and umami tastes, since CALHM1 knockout mice cannot perceive these tastants. Furthermore, we have identified the molecular mechanism that links CALHM1 expression to taste perception by discovering that CALHM1 is an ATP permeable channel, and that tastants activate ATP release as a neurotransmitter through CALHM1 channels by a voltage dependent mechanism that transduces taste in the periphery to the central nervous system. We will employ a combination of biophysical (electrophysiology, optical imaging), biochemical and cell biological approaches to define the molecular physiology of CALHM1 in taste perception. We will record the electrical properties of taste cells from wild-type mice and mice with CALHM1 genetically deleted and fully characterize the properties of CALHM channels in taste cells. We will define the role of CALHM1 in taste cell signal transduction by single cell imaging of intracellular Ca2+ and whole cell electrophysiology. Because a CALHM1 channel is multimeric, type II taste cells also express CALHM2 and CALHM3, and co-expression of CALHMs 1 and 3 generates a novel ATP-permeable channel, we will determine the biochemical and functional interactions and roles of all three CALHMs to define their channel properties with the goal to reconstitute the ATP release channel currents in taste cells. Finally we will use electrophysiological recordings of heterologous cells and taste cells to understand the mechanisms by which taste cell electrical responses activate CALHM channels and are in turn modified by CALHM channel activation. The results of these studies will provide new insights into the properties and regulation of this unique voltage-gated Ca2+ and ATP permeable ion channel and its essential role in taste sensory perception.

描述（由申请人提供）：我们提出的研究的总体目标是利用我们对 CALHM1 作为新型离子通道家族创始成员身份的新见解。 CALHM1 是一种功能未知的基因，被确定为晚发性阿尔茨海默病的易感因素，影响发病年龄。 CALHM1 编码一种在整个大脑和味蕾中表达的膜蛋白，尽管已鉴定出 5 个人类同源物，但与其他功能性蛋白质缺乏显着的同源性，并且 CALHM1 在物种间是保守的。我们最近发现 CALHM1 是 Ca2+ 渗透性离子通道的成孔亚基，具有不寻常的渗透特性以及电压和细胞外 Ca2+ 浓度 (Ca2+o) 的门控调节。我们发现 CALHM1 对于甜味、苦味和鲜味的感知至关重要，因为 CALHM1 敲除小鼠无法感知这些促味剂。此外，我们发现CALHM1是一种ATP可渗透通道，并且促味剂通过电压依赖性机制将外周味觉转导至中枢神经系统，通过CALHM1通道激活ATP作为神经递质的释放，从而确定了将CALHM1表达与味觉联系起来的分子机制。我们将结合生物物理（电生理学、光学成像）、生物化学和细胞生物学方法来定义 CALHM1 在味觉感知中的分子生理学。我们将记录野生型小鼠和 CALHM1 基因缺失小鼠的味觉细胞的电特性，并全面表征味觉细胞中 CALHM 通道的特性。 我们将通过细胞内 Ca2+ 的单细胞成像和全细胞电生理学来定义 CALHM1 在味觉细胞信号转导中的作用。由于 CALHM1 通道是多聚体，II 型味觉细胞也表达 CALHM2 和 CALHM3，并且 CALHM 1 和 3 的共表达产生了一种新型 ATP 可渗透通道，因此我们将确定所有三种 CALHM 的生化和功能相互作用以及作用，以定义其通道特性，目标是重建味觉细胞中的 ATP 释放通道电流。最后，我们将使用异源细胞和味觉细胞的电生理记录来了解味觉细胞电反应激活 CALHM 通道并反过来通过 CALHM 通道激活进行修改的机制。这些研究的结果将为了解这种独特的电压门控 Ca2+ 和 ATP 可渗透离子通道的特性和调节及其在味觉感官知觉中的重要作用提供新的见解。