Role of synaptic Schwann cells in NMJ and skeletal muscle aging

突触雪旺细胞在 NMJ 和骨骼肌衰老中的作用

• 批准号: 10688321
• 负责人: Gregorio Valdez
• 金额: $ 32.7万
• 依托单位: BROWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-30 至 2024-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10688321
• 关键词: ATAC-seq; Ablation; Affect; Age; Aging; Axon; Calcium; Cell Aging; Cell physiology; Cellular Structures; Data; Deterioration; Elderly; Electron Microscopy; Face; Goals; Health; Image; Impairment; In Vitro; Intercellular Junctions; Knowledge; Mediating; Mediator of activation protein; Molecular; Morphology; Motor; Motor Neurons; Mus; Muscle; Muscle Fibers; Muscular Atrophy; NRG1 gene; Nature; Neuraxis; Neuregulin 1; Neuroglia; Neuromuscular Junction; Pathway interactions; Phagocytes; Physiological; Research; Resolution; Role; Scanning Electron Microscopy; Schwann Cells; Signal Pathway; Signal Transduction; Skeletal Muscle; Spatial Distribution; Specific qualifier value; Synapses; Testing; Therapeutic; Transgenic Mice; age effect; age related; aged; axonal degeneration; base; biophysical properties; experimental study; human old age (65+); in vivo; light microscopy; loss of function; motor deficit; muscle aging; muscle degeneration; muscle form; novel; postsynaptic; preservation; prevent; reinnervation; repair function; repaired; response; sarcopenia; transcriptome sequencing; young adult

Project Summary: Extensive research has established that progressive degeneration of the neuromuscular junction (NMJ) contributes to sarcopenia and motor deficits in old age. Hence, preserving the integrity of the NMJ is likely to be critical in maintaining muscle mass and motor function during aging. For these reasons, significant efforts continue to be devoted to identifying mechanisms that prevent age-related decline of NMJs. To date, there is a wealth of information about the roles of skeletal muscles and motor neurons in NMJ aging. In stark contrast, the role of perisynaptic Schwann cells (PSCs) in NMJ aging remains unknown. PSCs are synaptic glia that exclusively associate with NMJs and are essential for its maturation, stability, function and repair. Highlighting their importance, targeted ablation of PSCs results in axonal degeneration and postsynaptic loss. While several studies have provided clues that PSCs may impact the course of NMJ degeneration with aging, a comprehensive examination of progressive age-related changes in PSCs, as they relate to NMJ deterioration, is a significant knowledge gap. The overarching objective of this proposal is to uncover the cellular and molecular underpinnings of PSC aging to determine their contribution to age-related NMJ and muscle degeneration. Aim 1 will examine the progressive nature of PSC aging and its relationship to NMJ degeneration and muscle atrophy. Accordingly, the timing of age-related morphological changes in PSCs, NMJs and muscle fibers will be determined by light and electron microscopy. The biophysical properties of PSCs will be tracked by calcium imaging. A novel transgenic mouse line along with RNA-Seq and ATAC-Seq will be used to identify molecular pathways intrinsic to PSCs dysregulated during aging. In initial molecular studies, the NGR1-III and MEGF10 were identified as promising regulators of PSC aging. Motor axon-derived NRG1-III is perhaps the best described molecular mediator of PSC physiology. However, downstream effectors of the NRG1-III pathway in PSCs have not been identified and we do not understand how it is impacted by aging. Aim 2 will assess the role of NRG1- III signaling in PSCs aging through gain- and loss-of-function experiments. Preliminary data demonstrate that NRG1-III signaling is heightened in aged PSCs, indicating that curtailing this signaling pathway may protect PSCs during aging. Additional data suggests that NRG1-III signaling affects aging of PSCs by inhibiting MEGF10 expression. MEGF10 is a well-known modulator of cellular spatial organization and synaptic remodeling in the central nervous system (CNS); however, its function in PSCs has not been explored. Aim 3 will examine the role of MEGF10 in specifying the organization and repair functions of aging PSCs using a MEGF10fl/fl mouse line. These studies will be the first to define the physiological, cellular and molecular changes that precipitate aging of PSCs. This proposal will also be the first to determine the function of NRG1-III signaling and MEGF10 in aging PSCs and NMJs. Altogether, these studies will provide new opportunities to develop therapeutics to preserve NMJs during aging, and thereby treat sarcopenia.

项目摘要：广泛的研究已经证实神经肌肉的进行性退化 交界处（NMJ）会导致老年肌少症和运动缺陷。因此，维护完整性 NMJ 可能对于衰老过程中维持肌肉质量和运动功能至关重要。由于这些原因， 我们继续致力于寻找防止 NMJ 与年龄相关的衰退的机制。 迄今为止，关于骨骼肌和运动神经元在 NMJ 衰老中的作用已有大量信息。在 形成鲜明对比的是，突触周围雪旺细胞 (PSC) 在 NMJ 衰老中的作用仍然未知。 PSC 具有突触性 神经胶质细胞专门与 NMJ 相关，对其成熟、稳定性、功能和修复至关重要。 PSC 的定向消融会导致轴突变性和突触后损失，这凸显了它们的重要性。 虽然一些研究提供了 PSC 可能影响 NMJ 随着衰老而退化的过程的线索，但 全面检查 PSC 中与年龄相关的进行性变化（因为它们与 NMJ 恶化相关） 显着的知识差距。该提案的总体目标是揭示细胞和分子 PSC 衰老的基础，以确定其对年龄相关 NMJ 和肌肉退化的贡献。目的 图 1 将检查 PSC 衰老的进行性及其与 NMJ 变性和肌肉萎缩的关系。 因此，PSC、NMJ 和肌纤维中与年龄相关的形态变化的时间将是 通过光学和电子显微镜测定。 PSC 的生物物理特性将通过钙来追踪 成像。新型转基因小鼠品系以及 RNA-Seq 和 ATAC-Seq 将用于鉴定分子 PSCs 内在的通路在衰老过程中失调。在最初的分子研究中，NGR1-III 和 MEGF10 被认为是 PSC 衰老的有前途的调节剂。运动轴突衍生的 NRG1-III 可能是最好的描述 PSC 生理学的分子介质。然而，PSC 中 NRG1-III 通路的下游效应子 尚未确定，我们不了解衰老如何影响它。目标 2 将评估 NRG1 的作用- 通过功能获得和丧失实验研究 PSC 老化中的 III 信号传导。初步数据表明 NRG1-III 信号传导在衰老的 PSC 中增强，表明限制该信号传导途径可能会保护 老化过程中的 PSC。其他数据表明 NRG1-III 信号传导通过抑制 MEGF10 影响 PSC 的衰老 表达。 MEGF10 是众所周知的细胞空间组织和突触重塑的调节剂 中枢神经系统（CNS）；然而，其在 PSC 中的功能尚未被探索。目标 3 将检查角色 MEGF10 在使用 MEGF10fl/fl 小鼠系指定衰老 PSC 的组织和修复功能中的作用。 这些研究将首次定义加速衰老的生理、细胞和分子变化 PSC 的数量。该提案也将首次确定NRG1-III信号传导和MEGF10在衰老中的功能 PSC 和 NMJ。总而言之，这些研究将为开发治疗方法提供新的机会，以保存 衰老过程中的 NMJ，从而治疗肌肉减少症。