Molecular Mechanisms of Axonal Transport and Organelle Dynamics

轴突运输和细胞器动力学的分子机制

• 批准号: 10621591
• 负责人: Erika L Holzbaur
• 金额: $ 71.88万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2028-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10621591
• 关键词: Active Biological Transport; Affect; Afferent Neurons; Aging; Amyotrophic Lateral Sclerosis; Anabolism; Autophagosome; Axon; Axonal Transport; Cells; Charcot-Marie-Tooth Disease; Complement; Cytoplasm; Cytoskeletal Filaments; Cytoskeletal Modeling; Cytoskeleton; Defect; Development; Disease; Dynein ATPase; Exhibits; Future; Goals; Human; In Vitro; Kinesin; Lead; Length; Membrane; Mitochondria; Modeling; Molecular; Molecular Motors; Morphology; Motor; Motor Neurons; Movement; Nerve Degeneration; Neurons; Organelles; Pattern; Protein Biosynthesis; Proteins; Regulation; Resolution; Scaffolding Protein; Site; Synapses; Synaptic Vesicles; Testing; Time; Vesicle; cell motility; genetic regulatory protein; insight; interest; live cell imaging; meter; presynaptic; reconstitution; single molecule; targeted treatment; therapeutically effective

Molecular motors drive the active transport of organelles along the cellular cytoskeleton. Organelle transport is critically important in neurons, cells that extend axons reaching up to 1m in length. Axons have limited capacity for biosynthesis and degradation, thus axonal transport is required to supply newly synthesized proteins and organelles and to remove aging proteins and dysfunctional organelles. Accumulating evidence supports a cargo-specific model for axonal transport, in which the opposing activities of kinesin and cytoplasmic dynein motors are regulated by a distinct complement of regulatory proteins including scaffolding proteins and activating adaptors. We are interested in the mechanisms that regulate the transport of key organelles including mitochondria, autophagosomes, and synaptic vesicle precursors. We are also interested in the mechanisms that lead to site-specific delivery, such as the targeting of newly synthesized synaptic components to presynaptic sites along the axon. We hypothesize that this delivery is dependent on the localized regulation of cytoskeletal dynamics and organization, which directly affect the initiation and termination of cargo motility. Finally, we are interested in the mechanisms by which molecular motors and cytoskeletal dynamics actively remodel organelle membranes, leading to tubulation, fission and fusion. We tackle these questions using the synergistic approaches of live cell imaging and in vitro reconstitution with single molecule resolution. We will continue to focus on three major goals. Goal 1: Understanding the integrated regulation of organelle transport. Each type of organelle transported along the axon has a distinct pattern of motility that directly relates to its function. We seek to understand the specific mechanisms involved, focusing on essential axonal cargos, such as mitochondria and autophagosomes, testing the model that the cargo-specific, integrated regulation of motors allows for sustained transport over long time scales and distances. In Goal 2, we seek to understand the localized regulation of organelle dynamics within defined axonal zones, such as the delivery of synaptic vesicle precursors to presynaptic sites along the axon. These zones exhibit distinct patterns of cytoskeletal organization and cytoskeletal dynamics. We are interested in the mechanisms that enhance the rate-limiting step of transport initiation and control cargo delivery/retention at specific sites of cellular need. And in Goal 3, we will study organelle remodeling driven by molecular motors and/or cytoskeletal dynamics. Organelles such as mitochondria undergo dramatic remodeling via mechanisms including fission and fusion. We hypothesize that molecular motors and cytoskeletal filaments provide an adaptable toolbox that can be specifically tuned to regulate dynamic organelle morphology. Together, these approaches will provide important new insights into organelle dynamics in neurons. As deficits in axonal transport lead to neurodegeneration, we hope that our progress may provide new opportunities for targeted and effective therapeutic approaches.

分子马达驱动细胞器沿着细胞骨架的主动运输。细胞器运输 在神经元中是至关重要的，神经元是将轴突延伸到1米长的细胞。轴突具有有限的 生物合成和降解的能力，因此需要轴突运输来供应新合成的 蛋白质和细胞器，并去除老化蛋白质和功能失调的细胞器。越来越多的证据 支持轴突运输的货物特异性模型，其中驱动蛋白和 细胞质动力蛋白马达由不同的调节蛋白互补物调节， 蛋白质和激活衔接子。我们感兴趣的是调节关键物质运输的机制， 细胞器包括线粒体、自噬体和突触囊泡前体。我们也有兴趣 在导致位点特异性传递的机制中，例如靶向新合成的突触蛋白， 沿沿着轴突将神经元的神经元成分传递到突触前位点。我们假设这种传递依赖于 细胞骨架动力学和组织的局部调节，这直接影响启动和 货物运动的终止。最后，我们感兴趣的是分子马达和 细胞骨架动力学活跃地重塑细胞器膜，导致细胞分裂、分裂和融合。我们 使用活细胞成像和体外重建的协同方法来解决这些问题， 单分子分辨率我们将继续聚焦三大目标。目标1：了解 细胞器运输的综合调节。沿着轴突运输的每种细胞器都有一个 与其功能直接相关的独特运动模式。我们试图了解具体的机制 参与，专注于必要的轴突货物，如线粒体和自噬体，测试模型 针对货物的综合电动机调节允许长时间持续运输 和距离。在目标2中，我们试图了解细胞器动力学的局部调节， 定义轴突区，如传递突触囊泡前体突触前位点沿着 轴突这些区域表现出不同的细胞骨架组织和细胞骨架动力学模式。我们 感兴趣的机制，提高限速步骤的运输启动和控制货物 在细胞需要的特定部位递送/保留。在目标3中，我们将研究细胞器重塑驱动 通过分子马达和/或细胞骨架动力学。线粒体等细胞器经历了剧烈的 通过包括裂变和聚变在内的机制进行重塑。我们假设分子马达和 细胞骨架丝提供了一个适应性强的工具箱，可以专门调整，以调节动态 细胞器形态学总之，这些方法将为细胞器提供重要的新见解 神经元的动力学由于轴突运输的缺陷导致神经退行性变，我们希望我们的进展 可能为有针对性和有效的治疗方法提供新的机会。