Molecular physiology of CALHM ion channels

CALHM 离子通道的分子生理学

• 批准号: 10647746
• 负责人: James Kevin FOSKETT
• 金额: $ 57.35万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10647746
• 关键词: Action Potentials; Address; Affect; Brain; Central Nervous System; Charge; Cryoelectron Microscopy; Dependence; Diabetes Mellitus; Diameter; Electrophysiology (science); Elements; Engineering; Esthesia; Evoked Potentials; Family; Food; Formulation; G-Protein-Coupled Receptors; Genetic; Goals; Homologous Gene; Human; Ion Channel; Ions; Kinetics; Knockout Mice; Life; Mediating; Medicine; Membrane Proteins; Methods; Modeling; Molecular; Mus; Mutagenesis; Nerve; Neurons; Neurotransmitters; Nutritional; Obesity; Pathway interactions; Perception; Peripheral; Permeability; Physiological; Physiology; Play; Proteins; Regulation; Role; Scheme; Signal Transduction; Structure; System; TRPM5 gene; Taste Bud Cell; Taste Buds; Taste Perception; Temperature; Type II Epithelial Receptor Cell; base; extracellular; insight; mouse model; mutant; neurotransmitter release; novel; pharmacologic; response; taste system; taste transduction; voltage

The broad goal of our proposed studies is to exploit our new insights into the molecular mechanisms and physiological roles of CALHM1 and CALHM3 as components of a novel ion channel in taste perception. We discovered CALHM1 as a membrane protein that expressed throughout the brain and in taste buds that lacks significant homology to other proteins, although five homologs have been identified, and CALHM1 is conserved across species. We identified CALHM1 as a pore-forming subunit of an ion channel with a large pore diameter and gating regulation by voltage and extracellular Ca2+ (Ca2+o). We discovered that CALHM1 is essential for perceptions of sweet, bitter and umami tastes by type II taste bud cells, since CALHM1-knockout mice cannot perceive these tastants. We identified the essential role of CALHM1 by discovering that it is a voltage-gated ATP-permeable ion channel, and that tastant-evoked Na+ action potentials trigger ATP release as a neurotransmitter through CALHM1-associated channels to transduce taste information from the periphery to the central nervous system. We further discovered that CALHM3 is an essential component of the native voltage-gated ATP-release channel, contributing as a pore-forming subunit with CALHM1 to create a heteromeric ATP-release channel in type II cells. Genetic deletion of CALHM3 also eliminates the ability of mice to perceive sweet, bitter and umami substances. The molecular mechanisms and structural bases of ion permeation and gating of CALHM channels are not understood despite their physiological importance. Nor is it understood how integration of CALHM3 into a CALHM1/3 channel so strongly affects voltage-gated activation, a key feature that allows CALHM1/3 channels to respond to action potentials. Temperature notably influences taste perception with physiological and hedonistic implications, but the contribution of peripheral taste-transduction mechanisms to the effects of temperature on the perception and sensation of tastes is largely unknown. We have discovered that temperature strikingly influences CALHM1/3 conductance as well as the electrical excitability of type II cells. We will employ electrophysiology in native taste bud cells and heterologous expression systems, mutagenesis, cryo-EM, and modeling to define the gating mechanisms of CALHM1 and CALHM1/3 channels, how CALHM3 as a pore-forming subunit enhances voltage-gated activation of CALHM1/3 channels, and how CALHM1/3 channels respond to action potentials evoked by tastant stimulation over a wide range of temperatures. Using a novel mouse model in which CALHM1/3 in taste bud cells has been engineered to have distinct temperature sensitivity, we will define how differential effects of temperature on ATP-release channel gating and excitability may provide a mechanism for how a temperature-sensitive channel in the peripheral gustatory system contributes to the influence of temperature on taste sensitivity and perception.

我们提出的研究的总体目标是利用我们对分子机制和 CALHM1 和 CALHM3 作为味觉感知中新型离子通道的组成部分的生理作用。我们 发现 CALHM1 作为一种膜蛋白，在整个大脑和味蕾中表达，而缺乏 尽管已鉴定出 5 个同源物，但 CALHM1 与其他蛋白质具有显着的同源性 跨物种保守。我们将 CALHM1 确定为离子通道的成孔亚基，具有大的 孔径和电压和细胞外 Ca2+ (Ca2+o) 的门控调节。我们发现CALHM1是 由于 CALHM1 敲除，II 型味蕾细胞对甜味、苦味和鲜味的感知至关重要 小鼠无法感知这些促味剂。我们通过发现 CALHM1 是一个 电压门控 ATP 渗透性离子通道，促味剂诱发的 Na+ 动作电位触发 ATP 释放 作为神经递质，通过 CALHM1 相关通道传递来自外周的味觉信息 到中枢神经系统。我们进一步发现CALHM3是天然的重要组成部分 电压门控 ATP 释放通道，与 CALHM1 一起作为成孔亚基，形成 II 型细胞中的异聚 ATP 释放通道。 CALHM3 的基因删除也消除了 小鼠感知甜味、苦味和鲜味物质。离子的分子机制和结构基础 尽管 CALHM 通道具有重要的生理意义，但其渗透和门控尚不清楚。也不是 了解 CALHM3 集成到 CALHM1/3 通道中如何强烈影响电压门控激活， 这是允许 CALHM1/3 通道响应动作电位的关键功能。温度影响显着 味觉具有生理和享乐意义，但外围味觉传导机制对温度对味觉和感觉的影响的贡献在很大程度上是 未知。我们发现温度显着影响 CALHM1/3 电导以及 II 型细胞的电兴奋性。我们将在天然味蕾细胞中应用电生理学 异源表达系统、诱变、冷冻电镜和建模来定义门控机制 CALHM1 和 CALHM1/3 通道，CALHM3 作为成孔亚基如何增强电压门控 CALHM1/3 通道的激活，以及 CALHM1/3 通道如何响应由 在很宽的温度范围内的促味刺激。使用一种新颖的小鼠模型，其中 CALHM1/3 味蕾细胞被设计为具有不同的温度敏感性，我们将定义如何区分 温度对 ATP 释放通道门控和兴奋性的影响可能提供一种机制 外周味觉系统中的温度敏感通道有助于温度的影响 关于味觉敏感性和知觉。

项目成果

Taste transduction and channel synapses in taste buds.

• DOI: 10.1007/s00424-020-02464-4
• 发表时间: 2021-01
• 期刊: PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
• 影响因子: 4.5
• 作者: Taruno, Akiyuki;Nomura, Kengo;Kusakizako, Tsukasa;Ma, Zhongming;Nureki, Osamu;Foskett, J. Kevin
• 通讯作者: Foskett, J. Kevin

Acute Regulation of Habituation Learning via Posttranslational Palmitoylation.

• DOI: 10.1016/j.cub.2020.05.016
• 发表时间: 2020-07-20
• 期刊: Current biology : CB
• 作者: Nelson JC;Witze E;Ma Z;Ciocco F;Frerotte A;Randlett O;Foskett JK;Granato M
• 通讯作者: Granato M