Unravelling the Impact of Adipokines on Muscle Satellite Cell Regulation

在过去的二十年里，随着全球肥胖症的增加，脂肪细胞分泌的信号分子（脂肪因子）在改变骨骼肌代谢中的作用引起了人们的极大兴趣。然而，脂肪因子对肌肉的卫星细胞（MSC）群体（肌肉的干细胞）的影响几乎是未知的。与我们的长期目标一致，发现新的MSC调节因子，我们建议研究选定的脂肪因子对MSC功能的影响，并确定操纵脂肪因子水平是否会影响小鼠骨骼肌生长或损伤修复的能力。我们假设改变这些脂肪因子水平将对MSC功能产生负面影响，并最终减弱骨骼肌的生长和再生。为了解决这一假设，我们的5年计划将寻求实现以下目标：* 目标#1：确定特定脂肪因子对MSC功能的影响 * 体外研究将用于研究操纵选定脂肪因子水平（单独和组合）对原代MSC的影响。初始实验将检测：脂质运载蛋白-2、视黄醇结合蛋白-4、Vaspin和抵抗素。原代MSC培养物和分离的单根肌纤维将用于评估MSC响应于不同脂肪因子表达的活化、增殖和分化的能力。我们还将评估选定的脂肪因子诱导MSC表观遗传变化的能力。* 目标2：了解改变的脂肪因子水平对骨骼肌生长和修复的影响 * 体内研究将使用靶向方法来操纵小鼠的血浆脂肪因子水平（例如脂肪因子或脂肪因子抑制剂的微渗透泵/注射、转基因小鼠），以评估骨骼肌生长、肥大和修复的能力。被证明诱导表观遗传修饰的脂肪因子也将在脂肪因子施用后一个月经历肥大/再生方案，以确定脂肪因子暴露是否对MSC功能具有持久影响。我和我的学员在建议的技术和支持网络（同事，合作者）方面具有已证明的基础设施/专业知识，以确保成功完成建议的研究。**本文提出的研究将揭示MSC功能的基础生物学的新见解，并为未来的药物和医学研究提供基础，以改善脂肪因子水平可能失调的情况下的肌肉质量（肥胖症，脂肪代谢障碍）。鉴于骨骼肌健康和长寿之间的已知关系，这些基础研究具有直接和持久的重要性。这项研究还将为生理学，细胞/分子生物学和生物化学领域的10多名研究生和本科生的培训提供平台;工业，学术界，专利法和教育领域的高需求领域。

The role of adipocyte-secreted signaling molecules (adipokines) in altering skeletal muscle metabolism has garnered much interest in the past twenty years with the global rise in obesity. However, the impact of adipokines on muscle's Satellite Cell (MSC) population, the stem cells of muscle, is virtually unknown. Consistent with our long-term objective to uncover novel regulators of MSCs, we propose to investigate the effects of selected adipokines on MSC function and determine if manipulating adipokine levels will impact the ability of mouse skeletal muscle to grow or repair from injury. We hypothesize that altering these adipokine levels will negatively impact MSC function and ultimately attenuate skeletal muscle growth and regeneration.******To address this hypothesis, our 5 year plan will seek to achieve the following goals: ***Goal #1: Define the impact of specific adipokines on MSC function***In vitro studies will be used to investigate the effects of manipulating selected adipokine levels (alone and in combination) on primary MSCs. Initial experiments will test: Lipocalin-2, Retinol binding protein-4, Vaspin and Resistin. Primary MSC cultures and isolated single muscle fibres will be used to assess the capacity for MSC activation, proliferation and differentiation in response to varying adipokine expression. We will also assess the ability of selected adipokines to induce epigenetic changes on MSC. ***Goal #2: Understand the effects of altered adipokine levels on skeletal muscle growth & repair***In vivo studies will use targeted approaches to manipulate plasma adipokine levels (e.g. mini-osmotic pumps/injections of adipokines or adipokine inhibitors, transgenic mice) in mice to assess the capacity for skeletal muscle growth, hypertrophy and repair. Adipokines demonstrated to induce epigenetic modifications will also undergo hypertrophy/regeneration protocols one month after adipokine administration to determine if adipokine exposure had lasting effects on MSC function.***My trainees and I have the demonstrated infrastructure/expertise in the proposed techniques and the support network (colleagues, collaborators) to ensure the successful completion of the proposed studies.******The research proposed herein will uncover novel insight into the basic biology of MSC function as well as provide a foundation for future pharmaceutical and medical research into improving muscle quality in conditions where adipokine levels may be dysregulated (obesity, lipodystrophy). Given the known relationship between skeletal muscle health and longevity, these foundational studies are of immediate and lasting importance. This research will also provide the platform for the training of >10 graduate and undergraduate students in the areas of physiology, cellular/molecular biology and biochemistry; high-demand areas within industry, academia, patent law and education.