Role of dMiro Signaling for Axonal Transport of Mitochondria

dMiro 信号传导在线粒体轴突运输中的作用

• 批准号: 7913094
• 负责人: KONRAD ERNST ZINSMAIER
• 金额: $ 3.5万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-05-01 至 2010-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7913094
• 关键词: Acute; Adaptor Signaling Protein; Aging; Apoptosis; Axon; Axonal Transport; Binding; Biological Models; Cardiomyopathies; Cell Respiration; Cell membrane; Chronic; Consumption; Coupling; Dendrites; Development; Disease; Dominant-Negative Mutation; Drosophila genus; Dynein ATPase; EF Hand Motifs; EF-Hand Domain; Fractionation; Goals; Growth Cones; Guanosine Triphosphate Phosphohydrolases; Homeostasis; Image; In Situ; Individual; Intracellular Transport; Kinesin; Label; Life; Link; Malignant Neoplasms; Measures; Microtubules; Mitochondria; Mitochondrial Proteins; Molecular; Molecular Conformation; Motor; Motor Activity; Motor Neurons; Movement; Muscular Dystrophies; Nerve; Nerve Degeneration; Neurons; Neuropathy; Paraplegia; Pathway interactions; Phenotype; Physiological; Plastics; Plus End of the Microtubule; Presynaptic Terminals; Proteins; Role; Signal Pathway; Signal Transduction; Site; Stress; Synapses; System; Temperature; Testing; Time; Work; base; dynactin; in vivo; loss of function mutation; mitochondrial membrane; mutant; overexpression; prevent; respiration regulation; response; rho; sensor; synaptic function; targeted delivery

DESCRIPTION (provided by applicant): Mitochondria are vital for aerobic respiration, the regulation of Ca2+ homeostasis, apoptosis, aging, and cancer. The intracellular distribution of mitochondria is adaptable to physiological stresses and changes in cellular activity. This plastic control is believed to be especially important in neurons where mitochondria are enriched at regions of intense energy consumption like synapses. Despite the significance of mitochondria for synaptic function, we still do not understand the molecular mechanisms controlling their delivery and targeting to synapses. A comprehensive understanding is urgently needed since abnormal mitochondrial transport, like abnormal mitochondrial function, is associated with various forms of muscular dystrophy, cardiomyopathy, neuropathy, paraplegia, and neurodegeneration. Our previous work suggests that the evolutionary conserved mitochondrial Rho-like GTPase Miro may act as a mitochondrial sensor that integrates intracellular signals to control long-distance transport of mitochondria. Specifically, loss of Drosophila Miro (dMiro) function prevents mitochondrial transport into axons and dendrites while gain of dMiro function leads to an abnormal accumulation of mitochondria at motor nerve terminals. Together, these results suggest dMiro may control anterograde axonal transport and the distribution of mitochondria to synaptic sites. To further test this hypothesis, we will take advantage of the model system Drosophila and genetically manipulate dMiro and other proteins of the mitochondrial transport machinery. Mutant effects on mitochondrial transport will be primarily examined in larval motor neurons, their axons and axon terminals by live imaging of GFP-tagged mitochondria to resolve the following key issues: Aim 1 will resolve whether dMiro promotes net-anterograde axonal transport by increasing the efficiency of microtubules (MT) plus end- or decreasing minus end-directed transport. Aim 2 will determine the role of dMiro's EF-hand Ca2+ binding domains for mitochondrial transport and/or the intracellular distribution of mitochondria. Aim 3 will test the molecular mechanisms by which dMiro may control mitochondrial transport. The proposed project is expected to reveal important molecular signaling mechanisms that regulate the long- distance transport of mitochondria and their use-dependent distribution into synaptic terminals. Uncovering these signaling pathways will significantly expand our understanding of basic mechanisms and accelerate the development of new concepts for detecting, treating, and/or preventing disorders that are caused by defective mitochondrial transport pathways and/or impaired mitochondrial function.

描述（由申请人提供）：线粒体对于有氧呼吸、Ca2+稳态调节、细胞凋亡、衰老和癌症至关重要。线粒体的细胞内分布能够适应生理应激和细胞活动的变化。这种可塑性控制被认为对神经元尤其重要，因为线粒体在突触等能量消耗密集的区域富集。尽管线粒体对于突触功能具有重要意义，但我们仍然不了解控制线粒体递送和靶向突触的分子机制。迫切需要全面了解线粒体运输异常，就像线粒体功能异常一样，与各种形式的肌营养不良、心肌病、神经病、截瘫和神经变性有关。我们之前的工作表明，进化保守的线粒体 Rho 样 GTPase Miro 可能充当线粒体传感器，整合细胞内信号来控制线粒体的长距离运输。具体来说，果蝇 Miro (dMiro) 功能的丧失会阻止线粒体转运到轴突和树突，而 dMiro 功能的获得会导致线粒体在运动神经末梢的异常积累。总之，这些结果表明 dMiro 可能控制顺行轴突运输和线粒体到突触位点的分布。为了进一步检验这一假设，我们将利用果蝇模型系统，对 dMiro 和线粒体运输机制的其他蛋白质进行基因操作。通过对 GFP 标记的线粒体进行实时成像，将主要在幼虫运动神经元、其轴突和轴突末端中检查突变对线粒体运输的影响，以解决以下关键问题：目标 1 将解决 dMiro 是否通过提高微管 (MT) 加端或减少负端定向运输的效率来促进净顺行轴突运输。目标 2 将确定 dMiro 的 EF-hand Ca2+ 结合域在线粒体运输和/或线粒体细胞内分布中的作用。目标 3 将测试 dMiro 控制线粒体运输的分子机制。拟议的项目预计将揭示调节线粒体长距离运输及其在突触末端的依赖于使用的分布的重要分子信号传导机制。揭示这些信号通路将显着扩大我们对基本机制的理解，并加速开发新概念，用于检测、治疗和/或预防由线粒体转运通路缺陷和/或线粒体功能受损引起的疾病。