Physiological and Genetic Analysis of Calhm1 function in C. elegans

描述（申请人提供）：离子通道调节细胞钙在可兴奋细胞信号传导和神经退行性疾病中起重要作用。最近，我们证明了人类Calhm1基因编码一种新的钙渗透离子通道，人类Calhm1基因多态性可能与晚发性阿尔茨海默病有关。虽然这些发现指出突变的Calhm1在疾病中的潜在作用，但Calhm1的生理功能尚不清楚。秀丽隐杆线虫表达一个单一的Calhm1同源物，clhm-1。异源表达的clhm-1产生与人类calhm -1相似的电流。与人类的Calhm-1一样，蠕虫的clhm-1在可兴奋细胞中表达。基于这些数据，我们假设Calhm的生理功能从蠕虫进化到人类是保守的。为了定义这些函数，我们将追求两个目标。首先，我们将分析秀丽隐杆线虫clhm-1的生物物理特性，以确定Calhm通道功能的保守方面，使用异源表达和原代秀丽隐杆线虫细胞培养。其次，我们将使用clhm-1敲除菌株和clhm-1过表达策略来研究clhm-1在活蠕虫中的功能作用。我们的研究将首次提供体内Calhm功能的详细研究，并将为这种新的离子通道家族提供重要的见解。

DESCRIPTION (provided by applicant): Ion channel regulation of cell calcium plays critical roles in excitable cell signaling and neurodegenerative diseases. Recently, we demonstrated that the human Calhm1 gene encodes for a novel calcium-permeable ion channel and that a human polymorphism in Calhm1 may be linked to late-onset Alzheimer's disease. While these findings point to a potential role for mutant Calhm1 in disease, the physiological function(s) of Calhm1 is unknown. C. elegans expresses a single Calhm1 homolog, clhm-1. Heterologously expressed clhm-1 gives rise to currents with characteristics similar to human Calhm1. Like human Calhm-1, worm clhm-1 is expressed in excitable cells. Based on these data, we hypothesize that the physiological function(s) of Calhm is evolutionarily conserved from worms to humans. To define these functions, we will pursue two aims. First, we will analyze the biophysical properties of C. elegans clhm-1 to determine conserved aspects of Calhm channel function, using both heterologous expression and primary C. elegans cell cultures. Second, we will investigate the functional roles of clhm-1 in live worms, using both clhm-1 knockout strains and clhm-1 overexpression strategies. Our studies will provide the first detailed study of Calhm function in vivo and will offer crucial insights into this new ion channel family. PUBLIC HEALTH RELEVANCE: Proper regulation of cellular calcium levels is essential for cellular function, and derangements in such regulation are associated with numerous human neurodegenerative diseases. We discovered that a new calcium ion channel, called Calhm1, regulates cellular calcium levels and a human Calhm1 mutation accelerates the pathology of Late-onset Alzheimer's disease. Beyond these observations, the cellular function(s) of Calhm1 are unknown. Our proposed studies will investigate Calhm1 function in the model system C. elegans and will provide deeper insights into how this new protein may contribute to human disease.