Unravelling the Impact of Adipokines on Muscle Satellite Cell Regulation

在过去的二十年里，随着全球肥胖率的上升，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--肌肉干细胞--的影响几乎是未知的。与我们发现MSCs新调控因子的长期目标一致，我们建议研究部分脂肪因子对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修复损伤的能力。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，并最终削弱骨骼肌的生长和再生。*为了解决这一假设，我们的五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的脂肪因子水平(单独和联合)对原代MSCs的影响。初步实验将测试：Lipocalin-2、视黄醇结合蛋白-4、Vaspin和抵抗素。原代培养的MSC和分离的单个肌肉纤维将用于评估MSC的激活、增殖和分化能力，以响应不同的脂肪因子表达。我们还将评估选定的脂肪因子诱导MSC表观遗传学变化的能力。*目标2：了解脂肪因子水平变化对骨骼肌生长和修复的影响*体内研究将使用有针对性的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。被证明能诱导表观遗传修饰的脂肪因子也将在注射脂肪因子一个月后接受肥大/再生方案，以确定脂肪因子暴露是否对MSC功能有持久的影响。*我和我的受训人员和我在建议的技术和支持网络(同事、合作者)方面拥有被证明的基础设施/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对MSC功能的基本生物学的新见解，并为未来在脂肪因子水平可能失调(肥胖、脂肪营养不良)的情况下改善肌肉质量的药物和医学研究提供基础。鉴于骨骼肌健康和寿命之间的已知关系，这些基础研究具有直接和持久的重要性。这项研究还将为培养10名生理学、细胞/分子生物学和生物化学领域的研究生和本科生提供平台，这些领域是工业、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.