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Identification of CALHM proteins as ion channels

CALHM 蛋白作为离子通道的鉴定

基本信息

批准号：
10044119
负责人：
James Kevin FOSKETT
金额：
$ 16.21万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-15 至 2021-11-14
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10044119
关键词：
Action Potentials Binding Biochemical Biological Assay Biological Process Brain Caenorhabditis elegans Caliber Cell Line Cell membrane Cells Chromosome 10 Chromosome 6 Chromosomes Connexins Drosophila genus Electrophysiology (science)Evolution Family G-Protein-Coupled Receptors Gene Family Genes Genetic Goals Grant Homologous Gene Human Ion Channel Ion Channel Gating Ion Channel Protein Knockout Mice Knowledge Lead Mammalian Cell Membrane Membrane Proteins Molecular Mus Nerve Neuraxis Neurotransmitters Oocytes Perception Permeability Physiological Physiology Property Proteins Regulation Research Role Sequence Homology Signal Transduction Structure Taste Bud Cell Taste Buds Taste Perception Testing Therapeutic Tissues Type II Epithelial Receptor Cell Vertebrates Work Xenopus oocyte Yeasts extracellular insight member novel novel therapeutics optical imaging response success voltage

项目摘要

PROJECT SUMMARY The goal of our proposed studies is to determine whether IDG-eligible CALHM4, CALHM5 and CALHM6 are ion channels or ion channel subunits. The CALHM (formerly FAM26) gene family is comprised of six homologs. We previously discovered the molecular mechanisms and physiological roles of CALHM1 and CALHM3 as novel ion channels. CALHM1 encodes a membrane protein expressed throughout the brain and in taste buds that lacks significant homology to other proteins, although five homologs have been identified with 20-44% sequence similarity, and CALHM proteins are 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 whereas CALHM3 expression does not confer a novel ion channel, it is an essential component of the native voltage-gated ATP-release channel, contributing as a pore-forming subunit with CALHM1 to create a hetero-hexameric ATP-release channel in type II cells. Genetic deletion of CALHM3 also eliminates the ability of mice to perceive sweet, bitter and umami substances. These results suggest that other CALHM homologs are also ion channels or ion channel subunits, but there is no information regarding their molecular function. We hypothesize that CALHM4, CALHM5 and CALHM6 are ion channels, and furthermore that the CALHM family represents a family of ATP-release channels the contributes to purinergic signaling throughout the body. We will exploit our insights and technical approaches used to elucidate functions of CALHM1 and CALHM3 to determine whether CALHM4, CALHM5 and CALHM6 are ion channels or ion channel subunits. We will employ electrophysiology, optical imaging, ATP-release assays and biochemical approaches to test this overarching hypothesis. The impact of our research is expected to be the discovery of the functions of CALHM4, CALHM5 and CALHM6. Given the identification of CALHM1 and CALHM3 as ion- channel subunits, our findings are expected to provide information about whether CALHMs are a family of ion channel proteins. Identification of novel ion channels is expected to lead to new understanding of cell and tissue physiology, as our previous work in taste buds and taste perception did with the discoveries of the functions of CALHM1 and CALHM3. Accordingly, identification of the roles of the other CALHM homologs may inform new physiological insights and therapeutic opportunities.

项目摘要我们提出的研究的目标是确定符合IDG条件的CALHM 4、CALHM 5和CALHM 6是否离子通道或离子通道亚单位。CALHM（以前的FAM 26）基因家族由六个同源物组成。我们先前发现了CALHM 1和CALHM 3的分子机制和生理作用，新型离子通道。CALHM 1编码一种在整个大脑和味蕾中表达的膜蛋白与其他蛋白质缺乏显著的同源性，尽管已经鉴定了五种同源物，其中20-44% 序列相似性，并且CALHM蛋白在物种间是保守的。我们发现CALHM 1是一个孔- 形成具有大孔径的离子通道亚基，并通过电压和细胞外 Ca 2+（Ca 2 + 0）。我们发现CALHM 1对于甜味、苦味和鲜味的感知是必不可少的， II型味蕾细胞，因为CALHM 1敲除小鼠不能感知这些促味剂。我们确定了通过发现CALHM 1是一种电压门控ATP渗透性离子通道，味觉诱发的Na+动作电位通过CALHM 1相关的神经递质触发ATP释放，将味觉信息从外周传递到中枢神经系统的通道。我们进一步他们发现，尽管CALHM 3的表达并没有赋予一个新的离子通道，但它是一个必需的离子通道。天然电压门控ATP释放通道的组成部分，作为孔形成亚基， CALHM 1在II型细胞中创建异源六聚体ATP释放通道。CALHM 3的遗传缺失也消除了老鼠感知甜、苦和鲜味物质的能力。这些结果表明，其他 CALHM同源物也是离子通道或离子通道亚基，但没有关于它们的信息。分子功能我们假设CALHM 4、CALHM 5和CALHM 6是离子通道，而且 CALHM家族代表了一个ATP释放通道家族，在整个身体。我们将利用我们的见解和技术方法来阐明的功能， CALHM 1和CALHM 3来确定CALHM 4、CALHM 5和CALHM 6是离子通道还是离子通道通道子单元。我们将采用电生理学，光学成像，ATP释放测定和生化来检验这个假设。我们研究的影响预计将是发现 CALHM 4、CALHM 5和CALHM 6的功能。鉴于CALHM 1和CALHM 3被鉴定为离子，通道亚基，我们的研究结果有望提供有关CALHMs是否是一个家庭的离子通道蛋白新型离子通道的发现有望对细胞和细胞外基质的研究产生新的认识。组织生理学，就像我们以前在味蕾和味觉方面的工作一样， CALHM 1和CALHM 3的功能。因此，鉴定其他CALHM同源物的作用可以提供新的生理学见解和治疗机会。