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.

肌肉减少症和无力是正常衰老的必然后果，降低功能，倾向于 跌倒和骨折，因此与大量发病率和医疗保健成本有关。越来越多的身体 证据表明，肌肉力量的无力和丧失是使老年人跌倒的重要贡献者。 建议的机制包括降低神经驱动，快速纤维的损失，脂肪浸润肌肉 或其他组织类型，肌原纤维设备的功能障碍或激发收缩（E-C）的损害 耦合。无效的E-C耦合被认为是导致与年龄相关的肌肉无力的重要因素。 EC偶联将肌膜的去极化连接到胞质钙浓度的升高，然后 导致肌动蛋白肌球蛋白原纤维和肌肉收缩的缩短。该应用程序着重于 衔接蛋白在调节E-C耦合所需的胞质钙瞬变时麻木。我们提出了这一点 麻木表达的减少会损害E-C耦合，并导致与衰老相关的弱点。麻木具有 在细胞命运确定，不对称细胞分裂和囊泡运输中的关键作用。在骨骼肌中， 卫星细胞增殖需要麻木并增强肌源分化潜力。没有研究 已经研究了麻木在骨骼肌E-C耦合中的作用或研究了麻木 表达在衰老过程中导致无力。我们的初步研究表明，麻木存在于 它位于DHPR附近的骨骼肌纤维。在20-的肌肉中降低麻木的表达 一个月大的老鼠。麻木和numbl的敲除（与重叠功能的紧密相关蛋白质） 骨骼肌纤维降低了肌肉力量。对小鼠成肌细胞原发性培养的研究表明 麻木的敲低降低了咖啡因诱导的细胞内钙浓度上升。这些 观察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 三合会，并暗示麻木在调节骨骼肌纤维中的钙瞬变。发现也暗示 降低的麻木表达是衰老E-C偶联受损的因果决定因素。我们假设：1） 在麻木/numbl双敲击中，特定力的产生减少是由于麻木减少 表达式2）适当调节EC耦合需要麻木，因为3）Numb调节释放 钙的RyR1存储在SR中，不存在麻木耗尽SR钙存储和4）与年龄有关的 麻木表达的降低是造成无力的原因。为了检验这些假设，我们将：目标2，确定 肌肉无力的细胞和分子基础，由麻木/数字敲低；目标2， 确定麻木表达在衰老相关的力量下降中的作用。