The Role of TRIM28 Phosphorylation in the Mechanical Regulation of Skeletal Muscle

TRIM28 磷酸化在骨骼肌机械调节中的作用

• 批准号: 10326805
• 负责人: TROY A HORNBERGER
• 金额: $ 32.7万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10326805
• 关键词: Aging; Bed rest; Biochemical; Biogenesis; Biopsy; Cachexia; Cell Nucleus; Cell Proliferation; Cell fusion; Dissociation; Event; FRAP1 gene; Fiber; Future; Genetic Transcription; Goals; Growth; Human; Hypertrophy; Immobilization; Knockout Mice; LacZ Genes; Lead; Light; Link; Maintenance; Mechanical Stimulation; Mechanics; Mediating; Molecular; Molecular Genetics; Mus; Muscle; Muscle satellite cell; Muscular Dystrophies; Mutation; Myoblasts; Myopathy; Outcome; Pathway interactions; Phosphorylation; Phosphotransferases; Play; Process; Protein Biosynthesis; Public Health; Quality of life; Regulation; Reporting; Research; Ribosomes; Role; Sampling; Scaffolding Protein; Serine; Signal Transduction; Skeletal Muscle; TRIM Motif; Testing; Transfection; Translating; Translations; base; disorder prevention; experimental study; gene therapy; genetic corepressor; insight; mechanical load; mechanical signal; mechanical stimulus; muscle form; mutant; novel; phosphoproteomics; prevent; resistance exercise; response; satellite cell; skeletal muscle wasting; targeted treatment; transcription factor

Project Summary / Abstract 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 process are still not known. Hence, the long-term goal of our research is to define the molecular events via which mechanical stimuli regulate skeletal muscle mass. The primary objective of this project is to determine the extent to which changes in the phosphorylation of TRIM28 contribute to the mechanical regulation of muscle mass. We are focusing on this topic because TRIM28 can control the activity of mTOR (a kinase that has been widely implicated in the mechanical regulation of muscle mass). A recent study also identified TRIM28 as a scaffold protein that interacts with key myogenic transcription factors (e.g., Mef2 and MyoD), and it has been shown that phosphorylation of the S473 residue on TRIM28 can act as a switch that unleashes the transcriptional activity of Mef2 and MyoD. This is intriguing because alterations in the activity of MyoD and Mef2 have been widely implicated in the regulation of muscle mass, and a recent phosphoproteomic analysis from our lab revealed that mechanical stimulation leads to a profound increase in TRIM28(S473) phosphorylation. Moreover, we discovered that the expression of a S473 phosphomimetic mutant of TRIM28 is sufficient to induce hypertrophy, and that the hypertrophic effect is dependent on the phosphomimetic mutation. Combined, these observations led us to our central hypothesis: an increase in TRIM28(S473) phosphorylation is a fundamental part of the pathway via which mechanical stimuli promote an increase in muscle mass. To rigorously test this hypothesis, we will first use of a combination of biochemical, molecular and genetic interventions in mice. Importantly, the mouse-based studies will enable us to: i) gain insight into the mechanisms via which TRIM28(S473D) induces hypertrophy, and ii) define the role that both myofiber and satellite cell specific changes in TRIM28(S473) phosphorylation play in mechanical load-induced hypertrophy. In addition to the mouse-based studies, we will also perform a human trial to determine whether the primary conclusions from mice can be translated to the human condition. Collectively, the outcomes of this project are expected to establish TRIM28 as a novel regulator of muscle mass and shed light on some of the basic mechanisms through which alterations in S473 phosphorylation control its hypertrophic effect. The outcomes are also expected to reveal the existence of a TRIM28-dependent pathway that not only enables mechanical stimuli to induce hypertrophy, but also the activation of satellite cell proliferation and fusion. Such outcomes would not only dramatically advance our understanding of how mechanical stimuli regulate muscle mass, but they would also create a new landmark for future studies that are aimed at developing a comprehensive understanding of this highly important process.

项目摘要 /摘要 机械刺激在调节骨骼肌质量和肌肉的维持中起主要作用 质量对预防疾病和生活质量产生了重大贡献。虽然机械之间的联系 信号和肌肉质量的调节已被认可数十年，这是分子机制 驱动此过程尚不清楚。因此，我们研究的长期目标是定义分子 机械刺激调节骨骼肌质量的事件。该项目的主要目的是 确定TRIM28磷酸化的变化程度有助于机械 调节肌肉质量。我们专注于这个主题，因为TRIM28可以控制MTOR的活动（a 激酶已广泛与肌肉质量的机械调节有关）。最近的一项研究 将TRIM28鉴定为一种脚手架蛋白，与关键的肌源性转录因子相互作用（例如MEF2和 Myod），并且已经表明，TRIM28上S473残基的磷酸化可以充当开关 释放MEF2和MYOD的转录活性。这很有趣，因为活动的改变 MYOD和MEF2已广泛与肌肉质量的调节有关 我们实验室的分析表明，机械刺激导致TRIM28的大幅增加（S473） 磷酸化。此外，我们发现Trim28的S473磷酸化突变体的表达是 足以诱导肥大，并且肥大作用取决于磷酸化 突变。这些观察结果结合在一起，使我们提出了中心假设：TRIM28的增加（S473） 磷酸化是通过机械刺激促进增加的途径的基本部分 肌肉质量。为了严格检验这一假设，我们将首先使用生化，分子的组合 和小鼠的遗传干预措施。重要的是，基于鼠标的研究将使我们能够：i）深入了解 TRIM28（S473D）诱导肥大的机制，ii）定义了肌纤维和肌纤维的作用 卫星细胞在机械负荷诱导的肥大中TRIM28（S473）磷酸化的特异性变化。 除了基于小鼠的研究外，我们还将进行人类试验以确定主要的 小鼠的结论可以转化为人类状况。总的来说，这个项目的结果是 预计将建立TRIM28作为肌肉质量的新型调节剂，并在某些基本 S473磷酸化控制其肥大作用的机制。结果 还期望揭示存在依赖性途径的存在，不仅可以机械 刺激会诱导肥大，也诱导卫星细胞增殖和融合的激活。这样的结果 不仅会极大地促进我们对机械刺激如何调节肌肉质量的理解，而且还可以 他们还将为未来的研究创建一个新的地标，旨在发展全面 了解这个非常重要的过程。