Role of titin in the pathophysiology of diaphragm weakness during mechanical vent

肌联蛋白在机械通气期间膈肌无力病理生理学中的作用

• 批准号: 8614046
• 负责人: Coen Ottenheijm
• 金额: $ 37.12万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8614046
• 关键词: Affect; Animal Model; Animals; Antibodies; Applications Grants; Atrophic; Binding Proteins; Biophysics; Biopsy; Breathing; Clinical; Data; Denervation; Development; Environmental air flow; Failure; Fiber; Functional disorder; Gene Targeting; Genetic Engineering; Goals; Growth; Hour; Human; Hypertrophy; Intensive Care Units; Lead; Link; Location; Lung; Lung diseases; Mechanical Stress; Mechanical ventilation; Mechanics; Mediating; Microfilaments; Modeling; Molecular; Morphology; Mus; Muscle; Mutation; Oxygen; Patients; Pilot Projects; Play; Property; Proteins; RNA Recognition Motif; RNA Splicing; Rattus; Research; Respiration; Respiratory Diaphragm; Roentgen Rays; Role; Signal Pathway; Signal Transduction; Stretching; Structure; Testing; Time; Vent; Weaning; Work; X ray diffraction analysis; X-Ray Diffraction; base; connectin; innovation; link protein; mortality; mouse model; muscle form; novel; novel therapeutics; preconditioning; protein degradation; public health relevance; response; sensor; tool; uptake

7. Summary. The long-term goal of this proposal is to gain detailed understanding of how the diaphragm - the main muscle of respiration - rapidly weakens in response to mechanical unloading and of the mechanisms whereby the giant elastic protein titin influences this response. The diaphragm is a unique muscle in that it is constantly subjected to mechanical loading. Recent work suggests that diaphragm strength is remarkably sensitive to mechanical unloading, as occurs during mechanical ventilation in the ICU. How unloading affects diaphragm strength is poorly understood. Increasing this understanding is critically important: within hours, diaphragm unloading during mechanical ventilation causes diaphragm weakness in ICU patients, which leads to difficulties in weaning patients from ventilatory support and contributes to mortality. The search for the molecular triggers for the development of diaphragm weakness during mechanical unloading is ongoing. The potential role of mechanosensor proteins, that link diaphragm unloading to protein turnover, is unexplored but is an exciting and novel concept that needs to be studied. A candidate mechanosensor is titin, a giant elastic protein that has been suggested to sense mechanical stress and link this to trophic signalling pathways. The elucidation of titin's role in diaphragm trophicity and in diaphragm weakness during mechanical ventilation is central to this grant proposal. Aim 1 will critically test whether titin affects muscle trophicity. I will use unilateral diaphragm denervation (UDD), a condition that is clinically important and that presents itself as a great tool for this work as it induces rapid hypertrophy of the denervated hemidiaphragm due to cyclic passive stretch. I will study UDD in two novel titin KO mouse models: one in which titin stiffness is increased through deletion of Ig domains (Ig KO) and another in which titin stiffness is decreased through deletion of the titin splice factor rbm20 (Rbm20 KO). I anticipate that the hypertrophic response following UDD is exaggerated in Ig KO mice and blunted in Rmb20 KO mice, and that this response is mediated by altered titin signaling. Aim 2 will study whether low titin stiffness protects the diaphragm from weakening during mechanical ventilation-induced unloading and will use a rat model with low titin stiffness. If titin-based mechanosensing mediates the response of the diaphragm to mechanical unloading, then I anticipate that low titin stiffness, by preconditioning the diaphragm to reduced mechanosensing, blunts this response. Aim 3 will study the mechanistic basis for diaphragm weakness in mechanically ventilated ICU patients using, for the first time, diaphragm fibers isolated from biopsies of mechanically ventilated ICU patients. The goal is to investigate whether the findings of animal studies extrapolate to patients. The innovation of this proposal lies in the novel research foci with innovative guiding hypotheses, its novel mouse models, unique diaphragm biopsies from mechanically ventilated ICU patients, and its novel experimental tools. The proposal's integrative approach is expected to lead to a significant step forward in our understanding of diaphragm function and the role of titin therein.

7。摘要。 该提议的长期目标是详细了解隔膜的主要肌肉 呼吸 - 响应机械卸载和机制而迅速减弱 巨型弹性蛋白滴定会影响这种反应。 隔膜是一种独特的肌肉，因为它不断受到机械负荷的影响。最近的工作 表明隔膜强度对机械卸载非常敏感，就像在 ICU中的机械通气。卸载如何影响隔膜强度的理解很少。增加 这种理解至关重要：在数小时内，机械通气过程中的隔膜卸载 导致ICU患者的隔膜弱点，这导致断奶患者的通气困难 支持并导致死亡率。寻找分子触发因素的发展 机械卸载期间的弱点正在进行中。机械传感器蛋白的潜在作用，该连接 将膜片卸载到蛋白质周转中，尚未探索，但是一个令人兴奋且新颖的概念，需要是 研究。候选机械传感器是Titin，这是一种巨大的弹性蛋白 机械应力并将其与营养信号通路联系起来。阐明泰丁在膜片中的作用 机械通气期间的营养和隔膜弱点对于这一赠款提案至关重要。 AIM 1将批判性地测试Titin是否影响肌肉营养。我将使用单侧隔膜神经支配 （udd），在临床上很重要的条件，并将自己作为这项工作的重要工具，因为它引起了这项工作 由于循环被动拉伸而导致的无型半肌的快速肥大。我将在两本小说中学习UDD TITIN KO小鼠模型：一种通过删除Ig域（IG KO）和 另一个通过删除Titin剪接因子RBM20（RBM20 KO）降低了Titin刚度。我 预计在IG KO小鼠中夸大了UDD后的肥厚反应并在RMB20中钝化 KO小鼠，并且这种响应是由TITIN信号改变介导的。 AIM 2将研究是否低滴定 刚度可保护膜片在机械通气引起的卸载过程中弱化，并将使用 较低滴定刚度的大鼠模型。如果基于TITIN的机械感应介导diaphragm对 机械卸载，然后我预计通过预处理膜片减少来减少滴定刚度 机械感应，钝此响应。 AIM 3将研究隔膜无力的机械基础 机械通风的ICU患者首次使用从活检中分离出的diaphragm纤维 机械通风的ICU患者。目的是调查动物研究的结果 推断患者。 该提议的创新在于新颖的研究重点，具有创新的指导假设，其小说 小鼠模型，来自机械通气的ICU患者的独特隔膜活检及其新颖 实验工具。预计该提议的综合方法将导致迈出的重要一步 我们对隔膜功能的理解及其在其中的作用。