Interrelationships between age-related skeletal muscle stem cell and NMJ decline

年龄相关骨骼肌干细胞与 NMJ 衰退之间的相互关系

• 批准号: 9000483
• 负责人: Joe Chakkalakal
• 金额: $ 38.38万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-30 至 2020-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9000483
• 关键词: Activities of Daily Living; Address; Adult; Age; Age-Months; Aging; Attenuated; C57BL/6 Mouse; Data; Denervation; Elderly; Feedback; Fracture; Gene Expression; Generations; Genetic Models; Goals; Healthcare Systems; Hybrids; Image; Immunofluorescence Immunologic; Immunohistochemistry; Maintenance; Mitogen-Activated Protein Kinase Kinases; Motor; Mus; Muscle function; Muscle satellite cell; Muscular Atrophy; Natural History; Natural regeneration; Nerve; Neuromuscular Junction; Pathway interactions; Property; Quality of life; Receptor Protein-Tyrosine Kinases; Regulation; Regulatory Element; Research; Rodent; Role; Signal Transduction; Skeletal Muscle; Source; Stem cells; Synapses; Testing; Therapeutic; Toxin; age related; aged; base; cost; design; disability; fall risk; falls; frailty; functional decline; functional loss; insight; nerve supply; neuromuscular; overexpression; prevent; progenitor; public health relevance; receptor expression; reinnervation; response; sarcopenia; satellite cell; therapeutic target; tyrosine receptor

 DESCRIPTION (provided by applicant): Aging is accompanied by a gradual loss of skeletal muscle size and function known as sarcopenia. A contributor to falls, frailty and loss in functional mobility in the elderly, disability associated with sarcopenia is considered to be a burgeoning cost to the US healthcare system. The reasons for age-related skeletal muscle decline and hence therapeutic strategies remain elusive. Features of sarcopenic skeletal muscle include ongoing cycles of denervation and reinnervation, loss of functional neuromuscular junctions (NMJs) and depletion of resident stem cells (satellite cells). However, any interrelationship between age-related satellite cell and NMJ decline remains ambiguous. Hence, this proposal is designed to elucidate the fates and roles of satellite cells and derived progenitors at degenerating NMJs with age. In addition, we propose a strategy to attenuate age-related NMJ decline by specific manipulation of satellite cells. To accomplish these objectives satellite cell-specific mouse genetic models and confocal immunofluorescence imaging of NMJs will be used. We have generated preliminary data that show loss of post-synaptic myonuclei at NMJs together with myofiber type transitions consistent with neuromuscular disruption in aged skeletal muscle. In parallel studies, we find satellite cells are required for the maintenance of post-synaptic myonuclei, myofiber type properties and the reinnervation of adult NMJs by motor nerve terminals in response to experimental neuromuscular disruption. Finally, we demonstrate that satellite cell specific forced expression of the receptor tyrosine kinase feedback regulator sprouty1 (Spry1) is sufficient to attenuate decline of post-synaptic myonuclei at aging NMJs. We will solidify our preliminary findings through the assessment of NMJ integrity, satellite cell proximity, post-synaptic myonuclei and myofiber type properties in skeletal muscles of various ages. We will also assess the consequences of satellite cell depletion and satellite cell specific Spry1 forced expression on the maintenance of NMJs and myofiber type properties with age. The specific aims of this proposal are: 1) To identify whether loss of post-synaptic myonuclei is a feature of aged degenerated NMJs, define regulators of age-related myofiber phenotypic transitions connected to NMJ decline and examine satellite cell derived contributions at aging NMJs, 2) To examine if satellite cell depletion accelerates age-related declines in NMJ integrity and NMJ regulated myofiber properties and 3) To determine if satellite cell-specific forced Spry1 expression attenuates loss of; post-synaptic myonuclei, NMJ integrity and maintains NMJ regulated myofiber properties with age.

 描述（由申请人提供）：衰老伴随着骨骼肌大小和功能的逐渐丧失，称为肌少症。与肌少症相关的残疾是导致老年人跌倒、虚弱和功能活动能力丧失的一个原因，被认为是美国医疗保健系统不断增长的成本。与年龄相关的骨骼肌衰退的原因以及治疗策略仍然难以捉摸。少肌性骨骼肌的特征包括持续的去神经支配和神经支配循环、功能性神经肌肉接头（NMJ）的丧失以及驻留干细胞（卫星细胞）的耗尽。然而，与年龄相关的卫星细胞和 NMJ 衰退之间的相互关系仍然不明确。因此，该提案旨在阐明随年龄增长而退化的 NMJ 中卫星细胞和衍生祖细胞的命运和作用。此外，我们提出了一种通过对卫星细胞进行特定操作来减轻与年龄相关的 NMJ 衰退的策略。为了实现这些目标，将使用卫星细胞特异性小鼠遗传模型和 NMJ 的共焦免疫荧光成像。我们已经生成了初步数据，显示 NMJ 处突触后肌核的丢失以及与衰老骨骼肌中的神经肌肉破坏一致的肌纤维类型转变。在平行研究中，我们发现卫星细胞是维持突触后肌核、肌纤维类型特性以及运动神经末梢对实验性神经肌肉破坏的反应而对成体 NMJ 进行重新神经支配所必需的。最后，我们证明卫星细胞特异性强制表达受体酪氨酸激酶反馈调节因子 sprouty1 (Spry1) 足以减轻衰老 NMJ 中突触后肌核的衰退。我们将通过评估不同年龄骨骼肌的 NMJ 完整性、卫星细胞邻近性、突触后肌核和肌纤维类型特性来巩固我们的初步发现。我们还将评估卫星细胞耗竭和卫星细胞特异性 Spry1 强制表达对随年龄增长而维持 NMJ 和肌纤维类型特性的影响。该提案的具体目标是：1）确定突触后肌核的丢失是否是衰老退化 NMJ 的一个特征，定义与 NMJ 衰退相关的与年龄相关的肌纤维表型转变的调节因子，并检查卫星细胞对衰老 NMJ 的贡献，2）检查卫星细胞耗竭是否会加速与年龄相关的 NMJ 完整性下降和 NMJ 调节肌纤维特性，3) 确定卫星细胞特异性强制 Spry1 表达是否会减弱肌纤维的损失；突触后肌核、NMJ 完整性并随着年龄的增长保持 NMJ 调节的肌纤维特性。