Extracellular Matrix Signaling in Axon Outgrowth and Regeneration

轴突生长和再生中的细胞外基质信号转导

• 批准号: 8202484
• 负责人: Jesse Isaacman-Beck
• 金额: $ 4.18万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8202484
• 关键词: Axon; Axotomy; Binding; Cell physiology; Cells; Collagen; Collagen Type IV; Collagen Type XVIII; Complex; Critical Pathways; Cues; Defect; Deposition; Development; Embryo; Embryonic Development; Environment; Enzymes; Ephrins; Esthesia; Extracellular Matrix; Extracellular Matrix Proteins; Extracellular Structure; Foundations; Goals; Individual; Injury; Lasers; Lead; Locomotion; Mediating; Modification; Molecular; Motor; Motor Activity; Motor Neurons; Movement; Muscle; Mutation; Natural regeneration; Nerve; Nerve Regeneration; Pathway interactions; Patients; Peripheral Nerves; Peripheral nerve injury; Play; Population; Post-Translational Protein Processing; Protein Binding Domain; Proteins; Proteoglycan; Research; Role; Sensory; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Spinal; Spinal Cord; Spinal cord injury; Staging; Synapses; Testing; Transgenes; Vertebrates; Zebrafish; axon guidance; axon regeneration; axonal guidance; extracellular; glycosyltransferase; in vivo; loss of function; member; mutant; neuromuscular; novel therapeutics; prospective; reconstitution; reinnervation; research study

DESCRIPTION (provided by applicant): In vertebrates, movement requires that spinal motor neurons form precise connections with target muscles. In both embryonic development and nerve regeneration, axons find their targets by integrating signals from guidance cues to navigate a highly structured extracellular environment. These cues are generated by cells neighboring the prospective axonal path and are bound by or built into the extracellular matrix (ECM) to guide axons and establish neuromuscular synapses. Although much research has focused on delineating 'classical' axon guidance pathways mediated by cues like Netrins, Ephrins, and Slits, the mechanisms by which ECM components and their modifications direct axons during embryonic outgrowth and regeneration are not fully understood. The goal of this proposal is to define the molecular and cellular processes governed by ECM components and their modifications to guide spinal motor axons during development and regeneration. In zebrafish, recent studies demonstrate that mutations in lh3/diwanka, a glycosyltransferase that is expressed in cells bordering the axonal path, lead to axon pathfinding errors. Moreover, loss-of-function experiments suggest that lh3/diwanka provides guidance through the ECM proteoglycan Collagen XVIII (col18a1). Col18a1 is an atypical collagen that contains protein interaction domains for several signaling molecules important for axon pathfinding. Finally, ECM proteins, including col18a1, are upregulated at axon injury sites and along the path taken by regenerating axons, consistent with a possible function during axonal regeneration. In this proposal, I will define the mechanisms that ECM components and their modifications utilize to direct spinal motor axons during development and regeneration. First I will determine the temporal requirements of ECM modifications in guiding two distinct classes of spinal motor axons. Secondly, I will determine the col18a1 signaling mechanism(s) in motor axon guidance by defining the protein interaction domains that are necessary for proper motor axon guidance. Lastly, I will determine the role of lh3/diwanka- mediated ECM modifications in nerve regeneration by comparing the rate and fidelity of wild type nerve regrowth to that in the absence of these modifications. Together these experiments will define ECM mediated guidance pathways necessary for the development and reconstitution of neuromuscular connections. PUBLIC HEALTH RELEVANCE: Victims of spinal cord injury suffer from lifelong loss of movement and sensation because damaged nerves in the spinal cord fail to regenerate. In contrast, sheared nerves peripheral to the spinal cord regenerate and reinitiate sensory and motor activity. Results from these studies will define mechanisms that guide peripheral nerves to their targets with the hope that these pathways will provide avenues to new therapeutic treatment for patients suffering from nerve damage, including spinal cord injury.

描述（由申请人提供）：在脊椎动物中，运动需要脊髓运动神经元与目标肌肉形成精确的连接。在胚胎发育和神经再生中，轴突通过整合引导信号的信号来导航高度结构化的细胞外环境来找到目标。这些线索由邻近预期轴突路径的细胞产生，并与细胞外基质 (ECM) 结合或内置于细胞外基质 (ECM) 中，以引导轴突并建立神经肌肉突触。尽管许多研究都集中在描绘由 Netrins、Ephrins 和 Slits 等信号介导的“经典”轴突引导途径，但 ECM 成分及其修饰在胚胎生长和再生过程中指导轴突的机制尚未完全了解。 该提案的目标是定义由 ECM 成分及其修饰控制的分子和细胞过程，以在发育和再生过程中指导脊髓运动轴突。在斑马鱼中，最近的研究表明，lh3/diwanka（一种在轴突路径边缘的细胞中表达的糖基转移酶）的突变会导致轴突寻路错误。此外，功能丧失实验表明 lh3/diwanka 通过 ECM 蛋白聚糖 XVIII 胶原蛋白 (col18a1) 提供指导。 Col18a1 是一种非典型胶原蛋白，包含多种信号分子的蛋白质相互作用域，这些信号分子对轴突寻路很重要。最后，包括 col18a1 在内的 ECM 蛋白在轴突损伤部位和再生轴突所采取的路径上调，这与轴突再生过程中可能的功能一致。 在本提案中，我将定义 ECM 组件及其修饰在发育和再生过程中用于指导脊髓运动轴突的机制。首先，我将确定 ECM 修改在引导两种不同类型的脊髓运动轴突时的时间要求。其次，我将通过定义正确的运动轴突引导所需的蛋白质相互作用域来确定运动轴突引导中的 col18a1 信号传导机制。最后，我将通过比较野生型神经再生的速率和保真度与没有这些修饰的情况来确定 lh3/diwanka 介导的 ECM 修饰在神经再生中的作用。这些实验将共同定义神经肌肉连接的发展和重建所必需的 ECM 介导的引导途径。 公众健康相关性：脊髓损伤的受害者会终生失去运动和感觉，因为脊髓中受损的神经无法再生。相反，脊髓周围被剪切的神经会再生并重新启动感觉和运动活动。这些研究的结果将确定引导周围神经到达目标的机制，希望这些途径能为遭受神经损伤（包括脊髓损伤）的患者提供新的治疗途径。