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: 9925170
• 负责人: Marco Brotto
• 金额: $ 46.66万
• 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 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9925170
• 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; Genes; 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; 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.

骨质疏松症和虚弱是正常衰老的不可避免的后果，它降低了功能，容易患上 跌倒和骨折，因此与显著的发病率和医疗费用有关。不断增长的 有证据表明，虚弱和肌肉力量的丧失是老年人跌倒的重要原因； 已提出的机制包括神经驱动减少，快抽动纤维丢失，脂肪渗透肌肉 或其他组织类型，肌原纤维装置功能障碍，或兴奋性收缩受损(E-C) 耦合。无效的E-C偶联被认为是年龄相关性肌肉无力的重要因素。 EC偶联将肌膜去极化与胞浆钙浓度升高联系在一起，而胞浆钙浓度的升高反过来又导致肌膜去极化。 导致肌动蛋白-肌球蛋白纤维缩短和肌肉收缩。此应用程序侧重于 调节E-C偶联所需胞浆钙瞬变的接头蛋白数目。我们建议 数字表达减少会削弱E-C偶联，并导致衰老相关的虚弱。Numb有 在决定细胞命运、细胞不对称分裂和囊泡运输中的关键作用。在骨骼肌中， Numb是卫星细胞增殖所必需的，并增强了成肌分化潜能。没有研究 研究了Numb在骨骼肌E-C偶联中的作用或研究了Numb是否减少 在衰老过程中，表情会导致身体虚弱。我们初步研究表明，这一数字存在于 位于DHPR附近的骨骼肌纤维。Numb在肌肉中的表达从20- 一个月大的老鼠。Numb和NumbL(一种功能重叠的密切相关蛋白)的敲除 骨骼肌纤维会降低肌肉力量。对小鼠成肌细胞原代培养的研究表明 Numb的抑制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作用提供了令人信服的证据，将麻木定位于 三联体，并涉及调节骨骼肌纤维中钙瞬变的NAMB。这些发现还牵连到 数量表达减少是衰老E-C偶联受损的原因决定因素。我们假设：1) 在我们Numbers/NhumL双击倒中产生的比力减少是由于Numbers/NhumL双击倒的减少 表达，2)数字是适当调节EC偶联所必需，因为3)数字通过以下方式调节释放 储存在SR中的钙的RyR1和缺乏Numb会耗尽SR的钙库，并且4)与年龄相关 数字表达减少是虚弱的一个原因。为了检验这些假设，我们将：目标2，确定 Numb/NhumL击倒导致肌肉无力的细胞和分子基础；目标2， 确定数量表达减少在与衰老相关的力量产生下降中的作用。