Axonal Varicosity Dynamics in Central Neuron Mechanosensation and Injury

中枢神经元机械感觉和损伤中的轴突静脉曲张动力学

• 批准号: 10211722
• 负责人: CHEN GU
• 金额: $ 38.23万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10211722
• 关键词: 3-Dimensional; Acceleration; Adult; Affect; Alleles; Alzheimer' s Disease; Autopsy; Axon; Behavior; Behavioral; Binding; Biological Assay; Biomechanics; Brain; Brain Concussion; Brain region; Calmodulin; Calmodulin-Binding Proteins; Coculture Techniques; Cognitive; Collaborations; Confocal Microscopy; Corpus Callosum; Cryo-electron tomography; Demyelinations; Development; Diffuse Axonal Injury; Electron Microscopy; Electrophysiology (science); Engineering; Funding; Heterogeneity; Image; Imaging Techniques; Injury; Interneurons; Knock-out; Knockout Mice; Label; Link; Liquid substance; Location; MAPT gene; Mechanical Stress; Mechanics; Mediating; Methods; Microtubule Stabilization; Microtubule-Associated Proteins; Microtubules; Modeling; Morphology; Multiple Sclerosis; Mus; Myelin; Neuraxis; Neurons; Oligodendroglia; Outcome; Pathologic; Process; Property; Proteins; Proteomics; Rattus; Recovery; Regulation; Reporting; Research; Risk; Role; Rotation; Signal Pathway; Small Interfering RNA; Stress; Structure; Swelling; Synapses; Synaptic Transmission; Testing; Tissues; Transmission Electron Microscopy; Varicosity; Virus; axon injury; base; behavior test; behavioral impairment; cell type; chronic traumatic encephalopathy; head impact; in vivo; insight; interdisciplinary approach; knock-down; mild traumatic brain injury; mouse model; nervous system disorder; new therapeutic target; novel; overexpression; polypeptide; protein expression

PROJECT SUMMARY Little is known about the role of micromechanical stress in regulating morphology and function of neurons in the central nervous system (CNS). Axonal varicosities (swelling or beading) are enlarged, heterogeneous structures along axonal shafts, profoundly affecting axonal conduction and synaptic transmission. They are a key pathological feature believed to represent slow accumulation of axonal damage that occurs during irreversible degeneration, for example in mild traumatic brain injury (mTBI), Alzheimer’s disease (AD), and multiple sclerosis. In the first funding period of this R01, we discovered that fluid mechanical stress immediately and reversibly induced varicosities in unmyelinated axons of cultured CNS neurons, and we further visualized varicosity induction in vivo. Most brain regions including the corpus callosum in healthy adults contain both myelinated and unmyelinated axons, while myelin appears to protect the axon from initial mechanical injury. Using a mouse model mimicking concussion, our new studies have found immediate varicosity formation in unmyelinated axons of cortical neurons and delayed demyelination in the cortex after mechanical impact. Our new results have also indicated that microtubule (MT)-associated protein 6 (MAP6) regulates axonal varicosity formation through its properties of MT stabilization and Ca2+/calmodulin binding. Based on our new findings, we hypothesize that mechanical impact immediately induces varicosity formation in unmyelinated axons, which is restrained by MAP6-mediated MT stabilization and subsequently promotes adjacent demyelination that increases axon vulnerability to second impact, leading to a vicious cycle in repeated mTBI and hence worsened behavioral impairment. To test this original hypothesis, we will use a multidisciplinary approach including mTBI and demyelination mouse models, cell-type-specific overexpression, knockout and rescue, confocal and electron microscopy, behavioral testing, electrophysiological recording, a versatile biomechanical assay, myelin coculture and state-of-the-art imaging techniques. We will determine (Aim 1) whether mTBI-induced axonal varicosity formation and behavioral impairment can be aggravated by MAP6 deletion and ameliorated by MAP6-mediated MT stabilization, (Aim 2) how MAP6 regulates axonal varicosity initiation, recovery, location, heterogeneity and long-term fate through distinct signaling pathways in partially myelinated axons, and (Aim 3) how MAP6 regulates oligodendrocyte mechanosensation, and whether preexisting demyelination and/or preexisting axonal varicosities increase the risk of injury from repeated mechanical impact. This project represents an underexplored research field with many open questions. This research is significant because it will provide novel mechanistic insights into central neuron mechanosensation and mTBI primary injury.

项目摘要 关于微力压力在调节形态和功能中的作用的作用知之甚少 中枢神经系统（CNS）中的神经元。轴突静脉曲张（肿胀或串珠）被增强， 沿轴突轴的异质结构，深刻影响轴突传导和突触 传播。它们是据信代表轴突损伤缓慢积累的关键病理特征 发生在不可逆变性期间，例如在轻度创伤性脑损伤（MTBI）中，阿尔茨海默氏症 疾病（AD）和多发性硬化症。在此R01的第一个资金期间，我们发现流体机械 立即和可逆地诱导培养的CNS神经元轴突中的静脉曲张，而我们 进一步可视化的体内静脉曲张诱导。大多数大脑区域包括健康成年人的call体 同时含有髓鞘和无叶状轴突，而髓磷脂似乎可以保护轴突免受初始 机械损伤。使用模仿鼠标模型，我们的新研究发现了立即的 在皮质神经元的无髓鞘轴突中形成静脉曲张，并在皮质中延迟脱髓鞘。 机械影响。我们的新结果还表明，微切管（MT）相关蛋白6（MAP6） 通过MT稳定和Ca2+/钙调蛋白结合的特性来调节轴突静脉曲张的形成。 根据我们的新发现，我们假设机械影响立即引起了静脉曲张。 在不髓鞘的轴突中形成，该轴突由MAP6介导的MT稳定恢复和 随后，促进相邻的脱髓鞘，从而增加轴突脆弱性，对第二影响， 重复的MTBI导致了一个美好的周期，因此行为障碍加剧了。测试这个 原始假设，我们将使用包括MTBI和脱髓鞘鼠标在内的多学科方法， 细胞型特异性过表达，敲除和救援，共聚焦和电子显微镜，行为测试， 电生理记录，一种多功能的生物力学测定，髓鞘共培养和最新成像 技术。我们将确定（AIM 1）MTBI诱导的轴突静脉曲张是否形成和行为 损伤可以通过MAP6缺失汇总，并通过MAP6介导的MT稳定改善（AIM 2） MAP6如何调节轴突静脉曲张倡议，恢复，位置，异质性和长期命运 部分骨髓轴突中的不同信号通路，（目标3）MAP6如何调节少突胶质细胞 机械敏，以及先前存在的脱髓鞘和/或轴突静脉曲张是否会增加 反复机械影响受伤的风险。该项目代表了一个毫无疑问的研究领域 许多开放问题。这项研究很重要，因为它将为中心提供新颖的机械见解 神经元机械敏和MTBI原发性损伤。