Mechanotransduction and the Regulation of Skeletal Muscle Mass

机械传导和骨骼肌质量的调节

基本信息

批准号：
9084789
负责人：
TROY A HORNBERGER
金额：
$ 0.8万
依托单位：
UNIVERSITY OF WISCONSIN-MADISON
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-09-01 至 2020-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9084789
关键词：
Address Aging Bed rest Biochemical Biosensor Cachexia Data Diacylglycerol Kinase Event Future Goals Hypertrophy Immobilization Knockout Mice Knowledge Lead Link Maintenance Maps Mass Spectrum Analysis Mechanical Stimulation Mechanics Mediating Metabolism Molecular Movement Muscle Muscular Dystrophies Myopathy Outcome Pathway interactions Phosphatidic Acid Phosphorylation Play Process Protein Biosynthesis Protein Synthesis Induction Proteins Proteome Proteomics Public Health Quality of life Raptors Ras homolog enriched in brain Regulation Research Role Signal Transduction Signaling Protein Sirolimus Skeletal Muscle Stimulus System TSC2 gene Techniques Testing Transfection Work base disorder prevention human FRAP1 protein human TSC2 protein in vivo inhibitor/antagonist insight late endosome mTOR protein muscle form novel prevent protein complex public health relevance research study response targeted treatment

项目摘要

DESCRIPTION (provided by applicant): Mechanical stimuli play a major role in the regulation of skeletal muscle mass, and the maintenance of muscle mass contributes significantly to disease prevention and quality of life. Although the link between mechanical signals and the regulation of muscle mass has been recognized for decades, the molecular mechanisms that drive this vital process are still not known. Hence, the long-term goal of our research is to defin the molecular events through which mechanical stimuli regulate muscle mass. In this project, we aim to identify the mechanisms via which mechanical stimuli activate signaling by the mammalian target of rapamycin (mTOR). Specifically, it is now known that mTOR can exert both rapamycin-sensitive and rapamycin-insensitive signaling events, and in this project we will focus on rapamycin-sensitive mTOR (RSmTOR) signaling. We are focusing on RSmTOR signaling because our previous work established that: i) mechanical stimuli can robustly activate RSmTOR signaling; ii) RSmTOR signaling is necessary for a mechanically-induced hypertrophic response; and iii) the activation of RSmTOR signaling, in and of itself, is sufficient to induce hypertrophy. Since mechanical stimuli activate RSmTOR signaling, it follows that a mechanotransduction pathway must exist for converting mechanical information into the biochemical events that activate RSmTOR signaling. Based on our preliminary data, we are proposing that the late endosomal / lysosomal system (LEL) is a central component of this pathway. The first three aims of this project will address this concept by testing the following hypotheses: 1) Raptor is necessary for the targeting of mTOR to the LEL and, in turn, the mechanical activation of RSmTOR signaling; 2) the mechanical activation of RSmTOR signaling is due, in part, to a diacylglycerol kinase ? (DGK?)-dependent increase in phosphatidic acid (PA) at the LEL; and 3) mechanical stimuli induce an increase in the phosphorylation of tuberin (TSC2), which causes it to dissociate from the LEL, and as a result, Rheb at the LEL becomes activated and stimulates RSmTOR signaling. In addition to testing these hypotheses, we will also define the extent to which Raptor, DGK?/PA and TSC2/Rheb contribute to mechanically-induced changes in protein synthesis and the induction of hypertrophy. Importantly, through the use of advanced techniques, we will be able to test all of our hypotheses in-vivo (e.g., in-vivo transfection with biosensors, skeletal muscle specific inducible knockout mice, rescue experiments in knockout mice, etc.) Furthermore, in the last aim, we will use a state-of-the-art mass spectrometry technique (NeuCode) to globally map the mechanically-regulated proteome / phosphoproteome, and with our approach, we will be able to determine which events are mediated downstream versus upstream / parallel to the activation of RSmTOR signaling. Thus, we expect that the outcomes of this project will not only fill key gaps in our current knowledge, but they will also generate a new body of knowledge that will guide the fundamental direction of future studies that are aimed at fully defining how mechanical stimuli regulate skeletal muscle mass.

描述（由申请人提供）：机械刺激在调节骨骼肌质量的调节中起着重要作用，并且肌肉质量的维持对预防疾病和生活质量产生了重要贡献。尽管机械信号与肌肉质量调节之间的联系已被认可数十年，但驱动这一重要过程的分子机制仍不清楚。因此，我们研究的长期目标是确定机械刺激调节肌肉质量的分子事件。在该项目中，我们旨在确定机械刺激通过哺乳动物靶标（MTOR）激活信号传导的机制。具体而言，现在已经知道MTOR可以发挥雷帕霉素敏感性和对雷帕霉素不敏感的信号传导事件，在这个项目中，我们将重点关注雷帕霉素敏感的MTOR（RSMTOR）信号传导。我们关注的是RSMTOR信号传导，因为我们以前的工作确定：i）机械刺激可以牢固地激活RSMTOR信号传导； ii）RSMTOR信号对于机械诱导的肥厚反应是必需的； iii）RSMTOR信号的激活本身足以诱导肥大。由于机械刺激激活了RSMTOR信号传导，因此必须存在机械转导途径，以将机械信息转换为激活RSMTOR信号传导的生化事件。根据我们的初步数据，我们提出了晚期内体 /溶酶体系统（LEL）是该途径的核心组成部分。该项目的前三个目标将通过测试以下假设来解决这一概念：1）猛禽对于将mTOR靶向LEL是必需的，而RSMTOR信号传导的机械激活又是必要的； 2）RSMTOR信号传导的机械激活部分归因于二酰基甘油激酶？（DGK？） - 依赖性磷脂酸（PA）在LEL处的增加； 3）机械刺激会诱导Tuberin（TSC2）的磷酸化增加，从而导致其与LEL解离，结果，LEL处的Rheb被激活并刺激RSMTOR信号传导。除了测试这些假设外，我们还将定义猛禽DGK？/pA和TSC2/RHEB在多大程度上有助于机械诱导的蛋白质合成变化和肥大的诱导。重要的是，通过使用先进的技术，我们将能够测试我们的所有假设（例如，使用生物传感器的体内转染，体内转染，骨骼肌特异性诱导型敲除小鼠，敲除小鼠的救援实验等。蛋白质组 /磷蛋白质组，通过我们的方法，我们将能够确定哪些事件是下游介导的，而与上游 /平行于RSMTOR信号的激活。因此，我们预计该项目的结果不仅会填补我们当前知识的关键空白，而且还将产生新的知识体系，这将指导未来研究的基本方向，旨在完全定义机械刺激如何调节骨骼肌质量。