Structural and Functional Studies of Organellar Ion Channels

细胞器离子通道的结构和功能研究

• 批准号: 10372154
• 负责人: YOUXING JIANG
• 金额: $ 32.8万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10372154
• 关键词: Arrhythmia; Ataxia; Award; Biological; Biological Process; Calcium; Cations; Cell Death; Cell membrane; Complex; Cryoelectron Microscopy; Crystallography; Cytosol; Data; Defect; Electrophysiology (science); Endosomes; Functional disorder; Homeostasis; Hormone secretion; Human; Inner mitochondrial membrane; Ion Channel; Ions; Lipids; Long QT Syndrome; Lysosomal Storage Diseases; Lysosomes; Measures; Mediating; Membrane; Metabolism; Mitochondria; Muscle Contraction; Nerve; Organelles; Physiological; Physiological Processes; Physiology; Play; Potassium Channel; Process; Production; Property; Proteins; Recording of previous events; Regulation; Research; Research Personnel; Role; Seizures; Signal Transduction; Work; biophysical properties; calcium uniporter; cyclic-nucleotide gated ion channels; deafness; design; human disease; insight; interest; particle; protein complex; receptor; three dimensional structure; trafficking; uptake; Arrhythmia; Ataxia; Award; Biological; Biological Process; Calcium; Cations; Cell Death; Cell membrane; Complex; Cryoelectron Microscopy; Crystallography; Cytosol; Data; Defect; Electrophysiology (science); Endosomes; Functional disorder; Homeostasis; Hormone secretion; Human; Inner mitochondrial membrane; Ion Channel; Ions; Lipids; Long QT Syndrome; Lysosomal Storage Diseases; Lysosomes; Measures; Mediating; Membrane; Metabolism; Mitochondria; Muscle Contraction; Nerve; Organelles; Physiological; Physiological Processes; Physiology; Play; Potassium Channel; Process; Production; Property; Proteins; Recording of previous events; Regulation; Research; Research Personnel; Role; Seizures; Signal Transduction; Work; biophysical properties; calcium uniporter; cyclic-nucleotide gated ion channels; deafness; design; human disease; insight; interest; particle; protein complex; receptor; three dimensional structure; trafficking; uptake

ABSTRACT Ion transfer across biological membranes is central to nerve excitation, muscle cell contraction, signal transduction, and hormone secretion. Ion channels play a vital role by providing a passageway within membranes to allow specific ions to traverse down their electrochemical gradient. The immense physiological importance of ion channels is reflected in the fact that their dysfunction underlies a variety of disabling human diseases including seizures, deafness, ataxia, long QT syndrome, and cardiac arrhythmias. There is a long history of physiological work and a large body of functional and structural data on tetrameric cation channels that are localized to the plasma membrane, including the K+, Ca2+, Na+, TRP and cyclic nucleotide-gated channels; however, relatively little is known about organellar cation channels, partly because of the difficulty in directly measuring their activities in organellar membranes. Currently, there is an emerging research interest in the recently identified organellar cation channels due to their importance in organelle physiology and cell signaling. This Maximizing Investigators' Research Award proposal will be focused on our ongoing efforts to dissect the structural and functional properties of two specific groups of organellar cation channels: the endolysosomal cation channels and the mitochondrial calcium uniporters. The insights gained from the proposed studies will facilitate our understanding of how these organellar channels regulate some basic biological functions of lysosome and mitochondria. Endosomes and lysosomes play crucial roles in many biological processes such as protein and lipid degradation, catabolite export, membrane trafficking, and metabolism-sensing, and defects to these processes can result in lysosomal storage diseases. These acidic organelles contain various ion channels that control endolysosomal pH and ionic homeostasis. One major research direction in my lab is designed to reveal the structural basis of gating and selectivity in endolysosomal cation channels, including two-pore channels (TPCs), transient receptor potential mucolipin channels (TRPMLs), and the non-canonical TMEM175 K+ channels. Mitochondria can take up large amounts of Ca2+ from cytosol, a process that can modulate ATP production, alter cytoplasmic Ca2+ dynamics, and trigger cell death. Mitochondrial calcium uptake is mediated by the mitochondria calcium uniporter (MCU), a highly selective Ca2+ channel that is localized to the inner mitochondrial membrane. In humans, the uniporter functions as a protein complex consisting of at least four components: the pore-forming MCU, the essential membrane-spanning subunit EMRE, and the Ca2+-sensing gate-keeping proteins MICU1 and MICU2. Another major project in the lab aims to reveal the structural basis of the human MCU complex assembly and the channel regulation. Our experimental approach utilizes single particle cryo-electron microscopy (cryo-EM) and protein crystallography to determine the three-dimensional structures of these channels, and electrophysiology to elucidate their biophysical properties.

抽象的 离子跨生物膜转移是神经激发，肌肉细胞收缩，信号的核心 转导和激素分泌。离子频道通过在内部提供通道来起着至关重要的作用 膜使特定离子可以横穿其电化学梯度。巨大的生理 离子频道的重要性反映在以下事实的是，它们的功能障碍是多种破坏人的基础 包括癫痫发作，耳聋，共济失调，长QT综合征和心律不齐的疾病。有很长的 生理工作的历史以及四聚阳离子通道上的大量功能和结构数据 位于质膜的位置，包括K+，Ca2+，Na+，TRP和环状核苷酸门控 频道；但是，关于细胞器阳离子通道的了解相对较少，部分原因是 直接测量其在细胞器膜中的活动。目前，对 由于其在细胞器生理和细胞中的重要性，最近确定的细胞器阳离子通道 信号。这项最大化调查人员的研究奖提案将集中在我们正在进行的努力上 剖析两种特定细胞器阳离子通道的结构和功能特性： 内溶性阳离子通道和线粒体钙统一体。从 拟议的研究将促进我们对这些细胞器渠道如何调节一些基本的理解 溶酶体和线粒体的生物学功能。 内体和溶酶体在许多生物学过程中起着至关重要的作用，例如蛋白质和脂质 降解，分解代谢物出口，膜运输和代谢感应以及对这些过程的缺陷 可能导致溶酶体储存疾病。这些酸性细胞器包含控制的各种离子通道 内溶性pH和离子稳态。我实验室中的一个主要研究方向旨在揭示 内溶性阳离子通道中门控和选择性的结构基础，包括两个孔通道 （TPC），瞬态受体电势粘液蛋白通道（TRPML）和非经典TMEM175 K+ 频道。线粒体可以从细胞质中占用大量Ca2+，该过程可以调节ATP 生产，改变细胞质Ca2+动力学并触发细胞死亡。线粒体钙的摄取是介导的 由线粒体钙Uniporter（MCU），这是一种位于内部的高度选择性Ca2+通道 线粒体膜。在人类中，单胞菌充当至少四个蛋白质复合物 组件：形成孔的MCU，必需的膜跨膜亚基EMRE和Ca2+传感器 守门蛋白MICU1和MICU2。实验室的另一个主要项目旨在揭示 人类MCU复合物组件和通道调节。我们的实验方法利用单身 颗粒冷冻电子显微镜（冷冻EM）和蛋白质晶体学以确定三维 这些通道的结构和电生理学阐明其生物物理特性。