Examining neuronal resilience in a mouse model of sporadic ALS

检查散发性 ALS 小鼠模型的神经元弹性

基本信息

批准号：
10381720
负责人：
VIRGINIA M LEE
金额：
$ 35.22万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-04-01 至 2024-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10381720
关键词：
Acute Amyotrophic Lateral Sclerosis Area Attenuated Autopsy Axon Brain Cells Code Complement Complementary DNA Denervation Development Disease Disease Progression Electrophysiology (science)Fiber Financial compensation Gene Targeting Genes Grouping Health Human Image Immune Impairment Individual Injury Intramuscular Lasers Measures Mediating Microglia Modeling Molecular Molecular Profiling Motor Motor Endplate Motor Neurons Movement Mus Muscle Nerve Nerve Crush Neurodegenerative Disorders Neuroglia Neuromuscular Junction Neurons Onset of illness Paralysed Pathogenesis Pathologic Pathway interactions Patients Pattern Pharmacology Physiology Population Preparation Process Proteins RNA Recovery Resistance Sampling Series Silver Spinal Cord Synapses Techniques Time TimeLine Tissues Tracer Transgenes adeno-associated viral vector base coping mechanism design esterase experimental study gait examination insight kinematics knock-down motor behavior mouse model muscle physiology muscle reinnervation nerve damage nerve supply neuron loss overexpression prevent protein TDP-43 reinnervation resilience response restoration sciatic nerve sporadic amyotrophic lateral sclerosis therapeutic target therapy development tibialis anterior muscle transcriptome transcriptome sequencing transcriptomics transgene expression

项目摘要

Project Summary/Abstract Following an injury to the brain, healthy neurons that are adjacent to the damaged area can sometimes take over the functions performed by the impaired neurons. This process has been best studied after acute nerve damage, but there is evidence that compensation by surviving neurons is also happening in the early stages of neurodegenerative diseases. In amyotrophic lateral sclerosis (ALS), the fiber type grouping in muscle samples taken from patients suggests that after an initial loss of connections between motor neurons (MNs) and muscles, new nerves are able to reconnect to allow patients to maintain movement during the disease process. A second observation made at the time of autopsy is that the vast majority of patients have an accumulation of a mislocalized protein called TDP-43 in the surviving MNs. However, because these cells are inaccessible in early disease stages, the molecular mechanisms for coping with disease processes in the MNs that send out new connections to muscles are unknown. In order to determine the dynamic responses that could allow a subpopulation of MNs to cope specifically with mislocalized TDP-43 and send out new axonal connections to muscles to prevent paralysis, we developed a mouse model in which we can induce neuronal expression of mislocalized human TDP-43, called rNLS8 mice. We then showed that rNLS8 mice have certain subsets of MNs that are uniquely vulnerable to disease, and that surviving MNs can effectively take the place of these cells, even late into the disease course. In this study, we will now identify the populations of MNs responsible for the reinnervation and restoration of function of vulnerable muscles after the initial TDP-43 triggered MN loss (Aim 1), using a combination of neuronal tracing techniques, muscle physiology, and imaging at the neuromuscular junction. We will then look for the upstream contribution of the brain's immune cells, microglia, to MN plasticity and the resultant circuit changes (Aim 2) by pharmacologically eliminating microglia and selectively reintroducing microglial derived factors that have been previously shown to influence neuronal function. Finally, molecular differences between MNs that innervate the same muscle before and after TDP-43 triggered axonal dieback will be uncovered by RNA- Sequencing and the top gene targets will be validated for their effect on motor function during ALS-like disease in rNLS8 mice (Aim 3). Completion of these studies should provide valuable insights into the potential mechanisms by which subsets of MNs can tolerate a build-up of cytoplasmic TDP-43. Moreover, understanding the mechanisms of neuronal compensation could allow for the development of therapies aimed at supporting surviving cells in order to extend their natural plasticity to slow disease and maintain function in patients.

项目概要/摘要大脑受伤后，邻近受损区域的健康神经元有时会采取影响受损神经元执行的功能。这个过程在急性神经损伤之后得到了最好的研究损伤，但有证据表明，存活神经元的补偿也在损伤的早期阶段发生神经退行性疾病。在肌萎缩侧索硬化症 (ALS) 中，肌肉样本中的纤维类型分组从患者身上采集的数据表明，在运动神经元（MN）和肌肉之间的连接最初丧失后，新的神经能够重新连接，使患者在疾病过程中保持运动。一秒钟尸检时的观察结果是，绝大多数患者体内都积累了幸存的 MN 中名为 TDP-43 的蛋白质被错误定位。然而，由于这些细胞在早期是无法接触到的。疾病阶段，在发出新信号的 MN 中应对疾病过程的分子机制与肌肉的联系尚不清楚。为了确定动态响应，可以允许 MN 亚群专门应对错误定位的 TDP-43 并发送新的轴突连接为了防止肌肉瘫痪，我们开发了一种小鼠模型，在该模型中我们可以诱导神经元表达错误定位的人类 TDP-43，称为 rNLS8 小鼠。然后我们证明 rNLS8 小鼠具有某些 MN 子集这些细胞特别容易受到疾病的影响，而幸存的 MN 可以有效地取代这些细胞，甚至进入病程晚期。在这项研究中，我们现在将确定负责神经支配和恢复的 MN 群体。初始 TDP-43 触发 MN 损失后脆弱肌肉的功能（目标 1），使用神经元组合追踪技术、肌肉生理学和神经肌肉接头成像。然后我们将寻找大脑免疫细胞、小胶质细胞对 MN 可塑性的上游贡献以及由此产生的回路变化（目标 2）通过药理学消除小胶质细胞并选择性地重新引入小胶质细胞衍生因子，先前已被证明会影响神经元功能。最后，MN 之间的分子差异在TDP-43触发的轴突枯死之前和之后支配同一块肌肉将被RNA-发现将验证测序和顶级基因靶点对 ALS 样疾病期间运动功能的影响在 rNLS8 小鼠中（目标 3）。完成这些研究应该为潜在的机会提供有价值的见解 MN 亚群能够耐受细胞质 TDP-43 积聚的机制。此外，了解神经元补偿机制可以允许开发旨在支持的疗法存活细胞，以扩展其自然可塑性，从而减缓疾病并维持患者的功能。