PHYSIOLOGY OF RESPIRATORY MUSCLE MIRCO MECHANICS

描述：我们建议研究力传递的机制 骨骼肌。特别是，我们将研究 desmin 的贡献 和肌营养不良蛋白，膜细胞骨架的细胞内成分， 膜受体 α-7-整合素，以及细胞外分子 merosin 膈肌的力传递。结蛋白缺乏会导致 结膜病，一种罕见疾病。肌营养不良蛋白、merosin 或 α-7-整合素导致各种形式的肌营养不良症，其中更多 常见疾病。缺乏任何这些蛋白质都会导致骨骼肌 退化、慢性吸气肌无力，最终导致呼吸肌无力 供血不足会导致呼吸衰竭并最终死亡。的 与大多数其他骨骼肌不同，膈肌在体内是双向加载的。 也就是说，隔膜沿着肌肉纤维承受负载并横向于肌肉纤维。 收缩活动期间的纤维。此应用程序是最初的第一步 旨在了解膈肌的机械行为 细胞水平。我们的中心假设是力在 隔膜由横向纤维负载调制并由联动装置介导 跨膜蛋白的特定胞内和胞外成员 网络。这个假设将通过研究自发的和工程的来检验 突变小鼠品系；使用缺少跨膜关键元件的菌株 蛋白质网络，我们将测试双轴力学性能的响应 隔膜和后肢肌肉的缺失导致这些蛋白质的缺失。的 该研究计划的长期目标是了解肌肉力量 在蛋白质水平上骨骼肌中的传输并建立详细的 正常骨骼肌中的机械耦合模型解释了 力从细胞骨架传递到细胞外的机制 矩阵。该项目的具体目标是确定被动机械 小鼠膈肌的特性及其对收缩功能的影响 并评估细胞内、跨膜和细胞外的作用 膜片中力的双轴传递元件。使用 电子显微镜和双轴加载技术应用于整个隔膜 和体外肢体骨骼肌，我们将在以下时间测试以下假设： 组织和肌节水平：（1）横向应力介导力 正常隔膜中组织和肌节水平的传输， 隔膜的被动和收缩特性都被改变 存在横向应力； (2)细胞内跨膜成员 蛋白质网络、结蛋白和抗肌营养不良蛋白对于整合横向整合至关重要 隔膜的纵向机械性能和强度 确定肌原纤维和质膜之间的机械连接 主要由这些蛋白质组成； (3)肌原纤维之间的机械耦合 细胞外基质对于沿和横向的力传递至关重要 正常骨骼肌的纤维，力的传递受到损害 由于 α-7-整合素或 merosin 的丢失。这些目标解决了 由特定细胞骨架介导力传递的机制 和骨骼肌中的细胞外蛋白。

DESCRIPTION: We propose to investigate the mechanisms of force transmission in skeletal muscles. In particular, we will investigate the contribution of desmin and dystrophin, intracellular components of the membrane cytoskeleton, the membrane receptor alpha-7-integrin, and the extracellular molecular merosin to force transmission in diaphragm muscle. Desmin deficiency leads to desminopathy, a rare disease. Deficiencies of dystrophin, merosin, or alpha-7-integrin lead to various form of muscular dystrophy, which are more common diseases. Lack of any of these proteins causes skeletal muscle degeneration, chronic inspiratory muscle weakness, and ultimately respiratory insufficiency that leads to respiratory failure and eventually death. The diaphragm, unlike most other skeletal muscles, is loaded biaxially in vivo. That is the diaphragm experiences loads along muscle fibers and transverse to fibers during contractile activity. This application is an initial first step towards understanding the mechanical behavior of diaphragm muscle at the cellular level. Our central hypothesis is that force transmission in the diaphragm is modulated by transverse fiber loading and mediated by the linkage of specific intra- and extracellular members of the transmembrane protein network. This hypothesis will be tested by studying spontaneous and engineered mutant mouse strains; using strains missing key elements of the transmembrane protein network, we will test the response of the biaxial mechanical properties of the diaphragm and hindlimb muscles to the absence of these proteins. The long term goals of this research program are to understand muscle force transmission in skeletal muscles at the protein level and build a detailed model of mechanical coupling in normal skeletal muscles that explains the mechanism(s) by which force is transmitted from cytoskeleton to extracellular matrix. The specific aims of this project are to determine passive mechanical properties of the mouse diaphragm and their influence on contractile function and to evaluate the role of intracellular, transmembrane, and extracellular elements on the biaxial transmission of force in the diaphragm. Using a electron microscopy and biaxial loading technique applied to whole diaphragm and limb skeletal muscles in vitro, we will test the following hypotheses at both tissue and sarcomere levels: (1) transverse stress mediates force transmission in the normal diaphragm at both tissue and at sarcomere levels, and both passive and contractile properties of the diaphragm are altered by the presence of transverse stress; (2) intracellular members of the transmembrane protein network, desmin and dystrophin, are essential in integrating transverse and longitudinal mechanical properties of the diaphragm, and the strength of the mechanical linkage between myofibrils and the plasma membrane is determined primarily by these proteins; and (3) the mechanical coupling between myofibrils and extracellular matrix is crucial to force transmission along and transverse to the fibers in normal skeletal muscles, and force transmission is compromised by loss of either alpha-7-integrin or merosin. These aims address the mechanism(s) by which force transmission is mediated by specific cytoskeletal and extracellular proteins in skeletal muscles.