Loss of Numb in Muscle Dysfunction in Aging

衰老导致的肌肉功能障碍丧失麻木感

• 批准号: 10451758
• 负责人: Marco Brotto
• 金额: $ 44.7万
• 依托单位: BRONX VETERANS MEDICAL RESEARCH FDN
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-15 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10451758
• 关键词: Actins; Adaptor Signaling Protein; Adipose tissue; Age-Months; Aging; Binding; Binding Proteins; Bioinformatics; Caffeine; Calcium; Calcium Channel; Cell Proliferation; Cell division; Cells; Clinical Research; Complex; Coupling; Dihydropyridines; Elderly; Electron Microscopy; Fiber; Fracture; Functional disorder; Future; Gene Expression Profile; Generations; Genetic; Hand Strength; Health Care Costs; Health Expenditures; Human; Impairment; Infiltration; Knock-out; Knockout Mice; Knowledge; Lead; Link; Measures; Messenger RNA; Molecular; Morbidity - disease rate; Mus; Muscle; Muscle Contraction; Muscle Fibers; Muscle Weakness; Muscle function; Muscular Atrophy; Myoblasts; Myosin ATPase; Numbness; Production; Protein Binding Domain; Proteins; Quality of life; Regulation; Research; Reticulum; Role; Ryanodine; STIM1 gene; Sarcolemma; Sarcoplasmic Reticulum; Skeletal Muscle; Skin; Stains; Testing; Therapeutic; Time; Tissues; Triad Acrylic Resin; age related; age-related muscle weakness; aged; behavior test; cardiac pacing; conditional knockout; falls; frailty; gene network; knock-down; muscle aging; muscle form; muscle physiology; normal aging; numb protein; overexpression; prevent; reduced muscle strength; relating to nervous system; sarcopenia; satellite cell; spatial relationship; trafficking; transcriptome sequencing; voltage

Sarcopenia and weakness are inevitable consequences of normal aging that reduce function, predispose to falls and fractures and are thus associated with significant morbidity and healthcare costs. A growing body of evidence implicates weakness and loss of muscle power as important contributors to falls in the elderly; proposed mechanisms include reduced neural drive, loss of fast-twitch fibers, infiltration of muscle by adipose or other tissue types, dysfunction of the myofibrillar apparatus, or impairments in excitation contraction (E-C) coupling. Ineffective E-C coupling is thought to be an important contributor to age-related muscle weakness. EC-Coupling links depolarization of the sarcolemma to a rise in cytosolic calcium concentrations which in turn causes shortening of actin-myosin fibrils and muscle contraction. This application focuses on roles of the adaptor protein Numb in regulation of cytosolic calcium transients required for E-C coupling. We propose that reductions in Numb expression impair E-C coupling and contribute to aging-associated weakness. Numb has critical roles in cell fate determination, asymmetric cell division and vesicular trafficking. In skeletal muscle, Numb is required for satellite cell proliferation and enhances myogenic differentiation potential. No studies have investigated roles of Numb in skeletal muscle E-C coupling or investigated whether reduced Numb expression contributes to weakness during aging. Our preliminary studies show that Numb is present in skeletal muscle fibers where it localizes near DHPR. Expression of Numb was reduced in muscles from 20- month old mice. A knockout of Numb and NumbL (a closely related protein with overlapping functions) in skeletal muscle fibers reduced muscle strength. Studies of primary cultures of mouse myoblasts revealed that a knockdown of Numb reduced the caffeine-induced rise in intracellular calcium concentration. These observations provide compelling evidence for a role of Numb in muscle force production, localize Numb to the triad, and implicate Numb in regulating calcium transients in skeletal muscle fibers. The findings also implicate reduced Numb expression as a causal determinant of impaired E-C coupling of aging. We hypothesize that: 1) diminished specific force generation in our Numb/NumbL double-knockouts is due to reduced Numb expression, 2) Numb is required for proper regulation of EC-coupling because 3) Numb regulates release by RyR1 of calcium stored in the SR and absence of Numb depletes SR calcium stores and 4) that age-related decreases in Numb expression are a cause of weakness. To test these hypotheses we will: Aim 2, Determine the cellular and molecular basis for muscle weakness resulting from Numb/NumbL knockdowns; Aim 2, Determine the role of reduced Numb expression in aging-related declines in force production.

肌肉减少症和虚弱是正常衰老不可避免的后果，会降低功能，导致 跌倒和骨折，因此与显着的发病率和医疗费用相关。不断成长的身体 有证据表明虚弱和肌肉力量丧失是老年人跌倒的重要原因； 提出的机制包括神经驱动减少、快肌纤维损失、脂肪渗透肌肉 或其他组织类型、肌原纤维装置功能障碍或兴奋性收缩 (E-C) 损伤 耦合。无效的电-电耦合被认为是导致与年龄相关的肌肉无力的重要原因。 EC 耦合将肌膜的去极化与胞质钙浓度的升高联系起来，从而反过来 导致肌动蛋白-肌球蛋白原纤维缩短和肌肉收缩。该应用程序的重点是角色 接头蛋白 Numb 调节 E-C 偶联所需的胞质钙瞬变。我们建议 Numb 表达的减少会损害 E-C 耦合并导致与衰老相关的无力。麻木有 在细胞命运决定、不对称细胞分裂和囊泡运输中发挥关键作用。在骨骼肌中， Numb 是卫星细胞增殖所必需的，并增强成肌分化潜力。没有研究 研究了 Numb 在骨骼肌 E-C 耦合中的作用或研究了 Numb 是否减少 表达会导致衰老过程中的虚弱。我们的初步研究表明 Numb 存在于 骨骼肌纤维位于 DHPR 附近。肌肉中 Numb 的表达从 20- 一个月大的老鼠。 Numb 和 NumbL（一种密切相关且功能重叠的蛋白质）的敲除 骨骼肌纤维减少肌肉力量。对小鼠成肌细胞原代培养物的研究表明 Numb 的敲除降低了咖啡因引起的细胞内钙浓度的升高。这些 观察结果为麻木在肌肉力量产生中的作用提供了令人信服的证据，将麻木定位于 三联体，并暗示 Numb 参与调节骨骼肌纤维中的钙瞬变。研究结果还暗示 Numb 表达减少是衰老 E-C 耦合受损的一个决定因素。我们假设：1） 我们的 Numb/NumbL 双敲除中特定力的产生减少是由于 Numb 减少 表达，2) Numb 是正确调节 EC 偶联所必需的，因为 3) Numb 调节释放 SR 中储存的钙的 RyR1 和 Numb 的缺失会耗尽 SR 钙储存，并且 4) 与年龄相关 麻木表达的减少是虚弱的原因。为了检验这些假设，我们将：目标 2，确定 Numb/NumbL 敲低导致肌肉无力的细胞和分子基础；目标2， 确定 Numb 表达减少在与衰老相关的力量产生下降中的作用。