Molecular Identity and Physiological Function of Novel Chloride Channels

项目摘要/摘要 氯化物是动物细胞中含量最丰富的游离阴离子。氯离子通道是不令人惊讶的 参与多种功能，如细胞体积调节、上皮液分泌、调节 电兴奋性，以及细胞内细胞器的酸化。它们的生理功能是 氯离子通道突变引起的许多疾病(通道病)令人印象深刻，例如 囊性纤维化(2,000名高加索人中有1名)、肌强直、肾结石和骨化症。然而，尽管最近 进展，氯离子通道与它们的阳离子(钠，钾， 和钙)通道近亲。许多电生理特性良好的氯离子通道仍然缺乏 分子同一性。有几个因素阻碍了这一领域的进展。与阳离子通道不同，它没有序列 已知的氯通道家族之间的同源性(例如，保守的孔衬基序)。缺乏 特定的高亲和力通道配体(如毒素)阻碍了直接纯化。表达克隆，以及 其他强大的技术，是受阻于高内生性的渠道表达在流行 表达系统。分子同一性的缺乏是阐明分子同一性的最大障碍。 这些广泛表达的成孔膜蛋白的精确生物学功能。建议数 研究计划将结合日益强大的基因组学工具(包括生物信息学、蛋白质组学 和基因操作)与电生理和成像技术相结合以识别新的氯离子通道 并用小鼠模型研究它们的生理功能。我们的结果将阐明分子 新的氯离子通道的特性和功能，并可能提供靶向它们的治疗策略 氯离子转运和动态平衡异常的疾病。

PROJECT SUMMARY/ABSTRACT Chloride is the most abundant free anion in animal cells. It's not surprising that chloride channels are involved in a wide range of functions as diverse as cell volume regulation, epithelial fluid secretion, regulation of electrical excitability, and acidification of intracellular organelles. Their physiological function is impressively illustrated by many diseases (channelopathies) caused by chloride channel mutations, such as cystic fibrosis (1 in 2,000 Caucasians), myotonia, kidney stones, and osteopetrosis. However, despite recent progress, chloride channels are considerably under-studied compared to their cation (sodium, potassium, and calcium) channel cousins. Many electrophysiologically well characterized chloride channels still lack molecular identity. Several factors block progress in this field. Unlike cation channels, there are no sequence homologies (for example, conserved pore-lining motif) among known chloride channel families. The lack of specific high-affinity channel ligands (e.g. toxins) hinders direct purification. Expression cloning, an otherwise powerful technique, is hampered by high endogenous expression of channel channels in popular expression systems. The absence of molecular identity presents the biggest roadblock to elucidate the precise biological function of these widely expressed pore-forming membrane proteins. The proposed research program will combine increasingly powerful genomics tools (including bioinformatics, proteomics and gene manipulation) with electrophysiology and imaging techniques to identify novel chloride channels and investigate their physiological function using mouse models. Our results will shed light on the molecular identity and function of new chloride channels and may provide therapeutic strategies to target them for diseases with abnormal chloride transport and homeostasis.