Molecular Mechanisms and Functions of Mitochondrial Ca2+ transport in Neurons

神经元线粒体 Ca2+ 转运的分子机制和功能

• 批准号: 9240345
• 负责人: Yuriy M Usachev
• 金额: $ 39.2万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9240345
• 关键词: ATP Synthesis Pathway; Action Potentials; Agonist; Alzheimer' s Disease; Back; Bioenergetics; Buffers; Cellular Metabolic Process; Cessation of life; Chemicals; Cytosol; Data; Development; Electrophysiology (science); Gene Expression; Genetic; Glutamates; Hippocampus (Brain); Homeostasis; Image; Inner mitochondrial membrane; Ischemia; Ischemic Stroke; Knock-out; Knockout Mice; Knowledge; Lead; Life; Mediating; Membrane Potentials; Middle Cerebral Artery Occlusion; Mitochondria; Mitochondrial Matrix; Modeling; Molecular; Monitor; Mus; Neuraxis; Neurodegenerative Disorders; Neurons; Oxidoreductase; Parkinson Disease; Peripheral; Play; Production; Regulation; Role; Sensory; Shapes; Signal Transduction; Spinal Ganglia; Stroke; Synapses; Synaptic Transmission; TRPV1 gene; Testing; Toxic effect; Work; base; excitotoxicity; in vivo; interdisciplinary approach; killings; meetings; mitochondrial membrane; mouse model; nervous system disorder; neuron loss; neuronal survival; neuroprotection; neurotoxicity; neurotransmission; new therapeutic target; novel; novel therapeutic intervention; patch clamp; presynaptic; research study; response; sensor; stroke treatment; uptake

Mitochondria play a central role in cell metabolism and control multiple aspects of neuronal signaling. By efficiently buffering Ca2+ influx during neuronal excitation and slowly releasing Ca2+ back into the cytosol, mitochondria shape [Ca2+]i transients and regulate Ca2+-dependent neuronal functions, such as excitability, synaptic transmission and gene expression. Ca2+ rise in the mitochondrial matrix stimulates Ca2+-dependent dehydrogenases and boosts ATP production to meet the increase in energy demand during excitation. However, mitochondrial overload with Ca2+ can kill neurons, and mitochondrial Ca2+ dysregulation is implicated in neuronal damage during stroke and in neurodegenerative disorders, such as Alzheimer's and Parkinson's diseases. Despite the importance of mitochondrial Ca2+ transport to neuronal life and death, the molecules that mediate mitochondrial Ca2+ uptake and release in neurons are not known. This knowledge gap presents a major obstacle in our progress toward understanding and therapeutically correcting mitochondrial functions in neurons. The main objectives of this proposal are to identify molecules that mediate mitochondrial Ca2+ uptake in peripheral and central neurons, and to establish their roles in neuronal Ca2+ signaling, ATP synthesis, synaptic transmission and excitotoxicity. Our preliminary studies indicate that two novel molecules, MCU (CCDC109A) and MCUb (CCDC109B), are broadly expressed in the peripheral and central nervous systems, and that MCU is required for mitochondrial Ca2+ uptake in neurons whereas MCUb inhibits this Ca2+ transport mechanism. Moreover, our pilot data using MCU KO mice showed that MCU loss dramatically, but not completely, reduced mitochondrial Ca2+ uptake, altered Ca2+ signaling and mitochondrial function and provided remarkable protection against glutamate-induced toxicity. Our central hypothesis is that MCU and MCUb play important but opposite roles in the regulation of mitochondrial Ca2+ uptake in neurons, bioenergetics, Ca2+ signaling and synaptic transmission, and that knockout of MCU, but not of MCUb, protects neurons from excitotoxicity and reduces neuronal damage in ischemic stroke. We will employ a multidisciplinary approach involving genetic Ca2+ and ATP sensors, patch-clamp recording, knockout mice and a mouse model of ischemic stroke to test this hypothesis in three specific aims. Aim 1 will establish the roles of MCU and MCUb in mitochondrial Ca2+ transport and Ca2+ signaling in central and peripheral neurons. Aim 2 will examine the impact of MCU and MCUb on presynaptic Ca2+ signaling and synaptic transmission. Aim 3 will establish the roles of MCU and MCUb in excitotoxicity and ischemic stroke. We anticipate that this work will be transformative because it will establish the molecular basis for genetic and pharmacological manipulation of mitochondrial Ca2+ transport in neurons, and may lead to the development of new therapeutics that target mitochondrial Ca2+ uniporters for treating stroke and other neurological disorders associated with excitotoxicity.

线粒体在细胞新陈代谢中起着核心作用，控制着神经元信号的多个方面。通过 有效地缓冲神经元兴奋过程中的钙离子内流，并缓慢地将钙离子释放回胞浆， 线粒体塑造[Ca~(2+)]i瞬变并调节钙依赖的神经元功能，如兴奋性， 突触传递和基因表达。线粒体基质中钙离子的升高刺激钙依赖 脱氢酶并促进ATP的产生，以满足兴奋过程中增加的能量需求。 然而，线粒体钙超载可导致神经元死亡，并与线粒体钙调节失调有关。 在中风和神经退行性疾病，如阿尔茨海默氏症和帕金森氏症中，神经元损伤 疾病。尽管线粒体钙离子转运对神经元的生死很重要，但参与线粒体钙转运的分子 神经元中线粒体钙摄取和释放的中介作用尚不清楚。这一知识差距呈现出一种 我们在理解和治疗纠正线粒体功能方面取得进展的主要障碍 神经元。这项提议的主要目标是确定介导线粒体钙摄取的分子。 在外周和中枢神经元，并确定它们在神经元钙信号转导，ATP合成， 突触传递和兴奋性毒性。我们的初步研究表明，两个新的分子MCU (CCDC109A)和MCUb(CCDC109B)广泛表达于外周和中枢神经系统， 而MCU是神经元摄取线粒体钙所必需的，而MCUb则抑制这种钙转运 机制。此外，我们使用MCU KO小鼠的试点数据显示，MCU损失显著，但没有 完全减少线粒体钙摄取，改变钙信号和线粒体功能，并提供 对谷氨酸诱导的毒性有显著的保护作用。我们的中心假设是MCU和MCUb 在神经元线粒体钙摄取调节中的重要但相反的作用，生物能量学，钙 信号和突触传递，以及MCU而不是MCUb基因敲除，保护神经元免受 兴奋性毒性和减少缺血性中风的神经元损伤。我们将采用多学科的方法。 涉及遗传钙和三磷酸腺苷感受器、膜片钳记录、基因敲除小鼠和 在三个特定的目标上检验这一假说。目标1将确定MCU和MCUb的角色 中枢神经元和外周神经元的线粒体钙转运和钙信号转导。Aim 2将研究 MCU和MCUb对突触前钙信号和突触传递的影响。目标3将建立 MCU和MCUb在兴奋性毒性和缺血性卒中中的作用。我们预计这项工作将是 具有变革性，因为它将为遗传和药物操作奠定分子基础 线粒体钙离子在神经元中的运输，并可能导致新的靶向治疗药物的开发 线粒体钙离子转运体用于治疗中风和其他与兴奋性毒性相关的神经疾病。