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: 8741903
• 负责人: Esther E Dupont-Versteegden
• 金额: $ 18.75万
• 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 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8741903
• 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; 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

DESCRIPTION (provided by applicant): 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.

描述（由申请人提供）：运动功能障碍和骨骼肌浪费是生活质量差，医疗保健成本增加以及老年人制度化的主要原因。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：衰老隔膜的损害会破坏许多重要的行为，例如呼吸，气道保护反射（咳嗽和snee脚）和声音。由于隔膜和辅助呼吸道肌肉必须在一生中保持活跃才能维持通风，因此它们对衰老的反应与其他骨骼肌中所见的反应不足为奇。与肢体肌肉相反，萎缩不能解释衰老隔膜的弱点和疲劳性。但是，由于隔膜不断活跃，因此可能需要恒定重塑。这种概念的间接证据源于以下事实：MDX小鼠的隔膜肌肉中卫星细胞明显耗尽，使其更容易受到损害。是否存在类似的隔膜肌肉以及卫星细胞耗竭和/或功能障碍在随着年龄的降低膜片功能中起作用的卫星细胞耗竭和/或功能障碍是否完全没有探索的问题。我们处于独特的位置，可以使用PAX7-DTA小鼠在衰老中测试卫星细胞在diaphragm肌肉中的作用，这允许对卫星细胞消融的时间和特定控制；我们以前证明，使用此遗传模型，> 90％的卫星细胞在他莫昔芬治疗中被消融。目前尚不清楚卫星细胞在维持隔膜功能中的作用在衰老本身或肌肉功能挑战时的作用。因此，我们的假设是卫星细胞对于维持老化隔膜的结构和功能是必要的，从而可以承受功能挑战。我们将使用两个具体目标检验假设。在AIM 1中，我们将确定PAX7-DTA小鼠中的卫星细胞消融是否会随着衰老而改变隔膜的结构和功能。卫星细胞将在4个月大时消融，小鼠将在6、18和24个月大时进行测试。将测量卫星细胞消融的效率，并将进行分析以评估隔膜的形态学和功能变化，并在体内进行通风。在AIM 2中，我们将确定卫星细胞消融是否会损害衰老隔膜适应功能挑战的能力。卫星细胞将在4个月大时消融，小鼠将患有正常的缺氧4周或跑步活动8周。分析将如在AIM 1中进行，并与AIM 1中的小鼠获得的度量进行比较。我们希望卫星细胞消融会导致老年隔膜的有害功能和结构变化，并且隔膜能够适应功能需求变化的能力受到损害。通过在本应用中提出的研究，我们将洞悉卫星细胞在diaphragm肌肉中的作用，并且年龄不断发展，这是一个未开发的区域。这些知识将使我们能够制定有效的干预策略，以使隔膜功能随着年龄的增长而丧失。