Activation and Inhibition Mechanisms of Calcium-Activated Nonselective Cation Channels

项目概要 Ca2 激活的非选择性阳离子 (CAN) 通道是少数可转化的离子通道之一 与大多数离子相反，细胞内 Ca2 信号转导成膜电位的变化 直接或间接利用膜电位调节细胞内Ca2+的通道 发信号。这种独特的特性使得 CAN 通道在许多组织和组织中发挥关键作用 器官。尽管 CAN 通道的存在已为人所知数十年，但最近的证据 已确定单价阳离子渗透性 TRPM4 和 TRPM5 是长期寻求的 对于 CAN 通道。事实上，许多 TRPM4 突变与严重的人类疾病有关， 例如，心脏传导阻滞、布拉加达综合征、PSEK（一种皮肤病）。尽管他们的 功能意义，但对于控制 TRPM4&5 的分子机制知之甚少 渠道活动。 Ca2 是它们唯一已知的生理激活剂，尽管膜 电位还调节通道活性，但仅限于 Ca2 存在的情况下。然而，虽然 Ca2 结合位点已通过冷冻电镜研究确定，Ca2 和电压如何激活 TRPM4&5 通道仍然未知。此外，虽然大多数已知的致病因素 TRPM4 突变导致功能获得表型，目前尚无 TRPM4&5 的有效抑制剂 目前可用。基于我们关于 TRPM4 Ca2 和电压的初步功能数据 激活，我们发现导致人类皮肤病的新型 TRPM4 突变，一种新的 表现出皮肤表型的致病突变通道 CRISPR 小鼠模型，以及我们的 最近发现了一种新的 TRPM4 抑制过程，我们计划使用多学科的方法 旨在揭示 TRPM4&5 激活的基本机制的方法 抑制。

Project Summary Ca2+-activated nonselective cation (CAN) channels are among a few ion channels that convert intracellular Ca2+ signaling into changes in membrane potential, in contrast to most ion channels that directly or indirectly use membrane potential to regulate intracellular Ca2+ signaling. This unique property allows CAN channels to play critical roles in many tissues and organs. While the existence of CAN channels has been known for decades, recent evidence has established that monovalent cation-permeable TRPM4 and TRPM5 are the long sought for CAN channels. Indeed, numerous TRPM4 mutations are linked to severe human diseases, e.g., cardiac conduction block, Bragada syndrome, PSEK (a skin disease). Despite their functional significance, little is known about the molecular mechanisms governing TRPM4&5 channels activity. Ca2+ is the only known physiological activator for them, though membrane potential also regulates channel activity but only in the presence of Ca2+. However, while the Ca2+-binding sites have been identified by cryo-EM studies, how Ca2+ and voltage activate TRPM4&5 channels remains unknown. Furthermore, while most known disease-causing TRPM4 mutations lead to a gain-of-function phenotype, no effective inhibitor for TRPM4&5 is currently available. Based on our preliminary functional data on TRPM4 Ca2+ and voltage activation, our discovery of novel TRPM4 mutations causing human skin disease, a new disease-causing mutant channel CRISPR mouse model exhibiting skin phenotypes, and our recent discovery of a novel TRPM4 inhibition process, we plan to use a multidisciplinary approach aiming at revealing the fundamental mechanisms of TRPM4&5 activation and inhibition.