Molecular Mechanisms of Exercise Benefits to Insulin Resistant People

项目总结/摘要 确定运动益处的分子调控点是国家的高度优先事项，因为 有机会开发有针对性的新疗法，使患有与不活动有关的健康的人群受益 这些问题包括T2 DM和前驱糖尿病，其特征在于胰岛素抵抗（IR）。IR最常见于 与肌肉减少症相关的老年人群。我们提出了PGC-1α4（α4）的新的代谢调节作用， 抗阻运动（RE）增强的肥大基因。根据大量的初步数据，我们 假设α4与PPARβ（Rβ）协同作用促进肌肉糖酵解和胰岛素敏感性（IS）， 以及增加肌肉质量和性能。根据我们新的初步数据，我们还将调查 无论是通过糖酵解蛋白的脱乙酰化，RE增强肌肉糖酵解能力。Rβ也降低了 氧化应激不仅增强IS，而且还有助于其他健康益处。基于mRNA的新数据 表明RE减少了蛋白质降解，这将在当前提案中进行研究。我们将 确定3个月的RE训练是否提高了胰岛素敏感性和肌肉性能和质量， IR人通过途径增强糖酵解，糖酵解蛋白脱乙酰化减少蛋白质 降解和增强合成以及改善氧化应激。我们将研究48名50-75岁的IR患者 在每周4次阻力训练或久坐生活3个月之前和之后， 瘦是人。我们将收集股外侧肌活检样本之前和之后的急性运动回合 并在混合餐后测量糖酵解、能量代谢物、糖原合酶 糖原含量、α4、Rβ、胰岛素信号蛋白和蛋白质组分析。我们还将测量 氧化应激包括8-OXO-dg（DNA损伤的量度）、对蛋白质的氧化损伤和随后的 肌肉蛋白质降解，我们假设这是通过增加RE的Rβ抗氧化作用而减少的 训练我们还将利用稳定同位素标记的示踪剂在体内标记特定的肌肉蛋白， 确定α4诱导的肌肉肥大是否不仅通过减少降解， 增强收缩蛋白质合成。虽然我们的初步细胞系研究提供了支持数据， α4和Rβ对IS和糖酵解的直接影响以及对Rβ的抗氧化作用的直接影响， 基因对我们的结果不能在人类中获得。因此，我们将在小鼠模型中进行研究 高脂饮食诱导的IR，表明α4增强IS和糖酵解，Rβ降低氧化应激。我们 也将沉默小鼠肌肉的α4和Rβ，以证实我们基于细胞的结果，即收缩诱导的 变化依赖于α4和Rβ。这些人类和动物研究将共同提供必要的 从机理上解释RE如何增强IS、糖酵解、降低氧化应激和促进肌肉生长 因此，它大大有助于IR人的健康和寿命。

PROJECT SUMMARY/ABSTRACT Identification of the molecular regulatory points of exercise benefits is of high national priority because of the opportunity to develop targeted novel therapeutics benefiting populations suffering from inactivity-related health problems, including T2DM and pre-diabetes, characterized by insulin resistance (IR). IR is most prevalent in the older population associated with sarcopenia. We propose novel metabolic regulatory role of PGC-1α4 (α4), a hypertrophy gene, enhanced by resistance exercise (RE). Based on substantial preliminary data, we hypothesize that α4, in cooperation with PPARβ (Rβ), promotes muscle glycolysis and insulin sensitivity (IS) as well as increasing muscle mass and performance. Based on our novel preliminary data we will also investigate whether by deacetylation of glycolytic proteins, RE enhances muscle glycolytic capacity. Rβ also reduces oxidative stress that not only enhances IS but also contributes to other health benefits. New mRNA based data indicates that RE reduces protein degradation which will be investigated in the current proposal. We will determine whether 3 months of RE training enhances insulin sensitivity and muscle performance and mass in IR people through pathways of enhanced glycolysis, deacetylation of glycolytic proteins reducing protein degradation and enhancing synthesis and ameliorating oxidative stress. We will study 48 IR people 50-75 yrs before and after 3 months of either 4-times/week resistance training or sedentary life and compare them with lean IS people. We will collect vastus lateralis muscle biopsy samples before and after an acute exercise bout and following a mixed meal to measure markers of glycolysis, energy metabolites, glycogen synthase, glycogen content, α4, Rβ, insulin signaling proteins and proteome analysis. We will also measure markers of oxidative stress including 8-OXO-dg (measure of DNA damage), oxidative damage to proteins and subsequent muscle protein degradation, which we hypothesize is reduced by increased anti-oxidant effect of Rβ with RE training. We also will use in vivo labeling of specific muscle proteins utilizing stable isotope labeled tracers to determine whether α4 induced muscle hypertrophy occurs not only by reducing degradation but also by enhancing contractile protein synthesis. Although our preliminary cell line studies provide supporting data on direct effects of α4 and Rβ on IS and glycolysis and on the anti-oxidant effect of Rβ, direct effects of these genes on our outcomes cannot be obtained in humans. Therefore we will perform studies in a mouse model with high-fat diet-induced IR to show that α4 enhances IS and glycolysis and Rβ reduces oxidative stress. We also will silence α4 and Rβ of mouse muscle to confirm our cell based results showing that contraction-induced changes are dependent on α4 and Rβ. Together these human and animal studies will render the necessary mechanistic explanation on how RE enhances IS, glycolysis, reduces oxidative stress and promote muscle performance and mass in IR people, thus substantially contributing to their health and life spans.