Effect of Satellite Cell Ablation on the Aging Diaphragm

卫星细胞烧蚀对老化隔膜的影响

• 批准号: 8638431
• 负责人: Esther E Dupont-Versteegden
• 金额: $ 22.5万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-30 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8638431
• 关键词: A Mouse; Ablation; Age; Age-Months; Aging; Area; Behavior; Breathing; Coughing; Data; Diphtheria Toxin; Elderly; Environmental air flow; Exercise; Extracellular Matrix Protein Gene; Fibrosis; Functional disorder; Genetic Models; Health; Health Care Costs; Hypoxia; Impairment; In Vitro; Institutionalization; Intervention; Knowledge; Lead; Life; Limb structure; Maintenance; Measures; Mediating; Modeling; Motor; Mus; Muscle; Muscle Fibers; Muscle function; Muscle satellite cell; Muscular Atrophy; Pathology; Play; Positioning Attribute; Process; Protein Biosynthesis; Quality of life; Reflex action; Respiratory Diaphragm; Respiratory Muscles; Respiratory physiology; Role; Running; Skeletal Muscle; Sneezing; Structure; Tamoxifen; Testing; Time; Voice; Work of Breathing; Workload; age related; aged; combat; effective intervention; frailty; in vivo; insight; mdx mouse; muscle aging; muscular structure; protein degradation; public health relevance; respiratory; response; satellite cell; skeletal muscle wasting; stem; therapy design

Motor dysfunction and skeletal muscle wasting are major causes of poor quality of life, increased health care costs, and institutionalization in the elderly. However, age-related dysfunction of the respiratory muscles has an even greater impact on quality of life: impairment of the aging diaphragm disrupts a number of important behaviors, such as breathing, airway protective reflexes (coughing and sneezing), and voice. Since the diaphragm and accessory respiratory muscles must be active throughout life to sustain ventilation, it is not surprising that their response to aging diverges from that seen in other skeletal muscles. In contrast to limb muscles, atrophy does not explain the weakness and increased fatigability of the aging diaphragm; however, since the diaphragm is constantly active it may have a need for constant remodeling. Indirect evidence for this notion stems from the fact that there is an apparent depletion of satellite cells in diaphragm muscle of mdx mice, rendering it more susceptible to damage. Whether a similar situation exists for aging diaphragm muscle and whether satellite cell depletion and/or dysfunction play a role in decreased diaphragm function with age are completely unexplored issues. We are in the unique position to test the role of satellite cells in diaphragm muscle with aging using the Pax7-DTA mouse, which allows for temporal and specific control of satellite cell ablation; we showed previously that >90% of satellite cells are ablated in response to tamoxifen treatment using this genetic model. It is currently unknown what the role of satellite cells is in the maintenance of diaphragm function with aging by itself, or when the muscle is functionally challenged. Therefore our hypothesis is that satellite cells are necessary to sustain the structure and function of the aging diaphragm, allowing it to withstand functional challenges. We will test the hypothesis using two specific aims. In Aim 1 we will determine whether satellite cell ablation in Pax7-DTA mice alters structure and function of the diaphragm with aging. Satellite cells will be ablated at 4 months of age and mice will be tested at 6, 18, and 24 months of age. The efficiency of satellite cell ablation will be measured, and analyses will be performed to assess morphological as well as functional changes in the diaphragm, and in ventilation in vivo. In Aim 2 we will establish whether satellite cell ablation impairs the ability of the aging diaphragm to adapt to functional challenges. Satellite cells will be ablated at 4 months of age and mice will be subjected to normobaric hypoxia for 4 weeks or running activity for 8 weeks. Analyses will be performed as in Aim 1 and compared to measures obtained from mice in Aim 1. We expect that satellite cell ablation causes detrimental functional and structural changes in the aged diaphragm, and that the ability of the diaphragm to adapt to changes in functional demand is impaired, particularly in the aged. With the studies proposed in this application, we will provide insight into the role of satellite cells in diaphragm muscle with advancing age, which is an unexplored area; this knowledge will enable us to develop effective intervention strategies for the loss of diaphragm function with age.

运动功能障碍和骨骼肌萎缩是生活质量差、医疗保健增加的主要原因 成本和老年人的机构化。然而，与年龄相关的呼吸肌功能障碍 对生活质量的影响更大：老化隔膜的损伤会扰乱许多重要的功能 行为，例如呼吸、气道保护性反射（咳嗽和打喷嚏）和声音。自从 膈肌和辅助呼吸肌必须在整个生命过程中保持活跃以维持通气，但事实并非如此 令人惊讶的是，它们对衰老的反应与其他骨骼肌的反应不同。与肢体相反 肌肉萎缩并不能解释老化隔膜的无力和疲劳性增加；然而， 由于横膈膜一直处于活动状态，因此可能需要不断重塑。间接证据证明这一点 这个想法源于这样一个事实：mdx 的膈肌中的卫星细胞明显减少 老鼠，使其更容易受到损坏。老化的膈肌是否也存在类似的情况 以及卫星细胞耗竭和/或功能障碍是否在随年龄增长的膈肌功能下降中发挥作用 都是完全未探索的问题。我们处于独特的位置来测试卫星细胞在隔膜中的作用 使用 Pax7-DTA 小鼠进行肌肉老化，可以对卫星细胞进行时间和特定的控制 消融；我们之前表明，>90% 的卫星细胞因他莫昔芬治疗而被消融 使用这种遗传模型。目前尚不清楚卫星细胞在维持 随着年龄的增长，或者肌肉功能受到挑战，膈肌功能也会受到影响。因此我们的 假设卫星细胞对于维持老化隔膜的结构和功能是必要的， 使其能够承受功能挑战。我们将使用两个具体目标来检验该假设。在目标 1 中，我们 将确定 Pax7-DTA 小鼠的卫星细胞消融是否会改变膈肌的结构和功能 随着衰老。卫星细胞将在 4 个月大时被消融，小鼠将在 6、18 和 24 个月时进行测试 年龄。将测量卫星细胞消融的效率，并进行分析以评估 膈肌和体内通气的形态和功能变化。在目标 2 中，我们将 确定卫星细胞消融是否会损害老化隔膜适应功能的能力 挑战。卫星细胞将在4个月大时被消融，小鼠将遭受常压缺氧 4 周或跑步活动 8 周。将按照目标 1 进行分析并与测量结果进行比较 从目标 1 中的小鼠中获得。我们预计卫星细胞消融会导致有害的功能和结构 老化隔膜的变化，以及隔膜适应功能需求变化的能力 身体受到损害，尤其是老年人。通过本申请中提出的研究，我们将深入了解 随着年龄的增长，卫星细胞在膈肌中的作用是一个尚未探索的领域；这些知识 将使我们能够针对随年龄增长而丧失的膈肌功能制定有效的干预策略。