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细胞骨架的主动运输。细胞器运输 在神经元中至关重要，神经元是一种将轴突延伸到1米长的细胞。轴突是有限的 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，去除老化的蛋白质和功能失调的细胞器。积累证据 支持特定于货物的轴突运输模型，在该模型中，Kinesin和Kinesin的相反活动 细胞质动力蛋白马达受包括支架在内的一组不同的调节蛋白的调节 蛋白质和激活的适配器。我们感兴趣的是管理密钥传输的机制 细胞器包括线粒体、自噬小体和突触小泡前体。我们也有兴趣 在导致部位特异性递送的机制中，例如靶向新合成的突触 沿着轴突的突触前部位的成分。我们假设这一交付依赖于 细胞骨架动力学和组织的局部调节，直接影响细胞的启动和 终止货物的移动。最后，我们感兴趣的是分子马达和 细胞骨架动力学主动重塑细胞膜，导致管状、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控。沿着轴突运输的每一种细胞器都有一个 与其功能直接相关的独特的运动模式。我们试图了解具体的机制 参与，重点是基本的轴突货物，如线粒体和自噬，测试模型 对马达的特定货物的综合调节允许在长时间尺度上持续运输 和距离。在目标2中，我们试图了解细胞器动态的局部调节。 明确的轴突区，如将突触小泡前体递送到突触前部位 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。我们是 对加强货物运输启动和控制的限速步骤的机制感兴趣 在细胞需求的特定位置提供/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戏剧性的 通过分裂和融合等机制进行重塑。我们假设分子马达和 细胞骨架细丝提供了一个适应性强的工具箱，可以专门调节以调节动力 细胞器形态。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。由于轴突运输缺陷导致神经退化，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。