Function of the Myo-adipo Axis in Human Obesity and Type 2 Diabetes

描述(由申请人提供)： 肥胖和2型糖尿病(T2D)的代谢功能障碍涉及多个组织的胰岛素抵抗。最近，由脂肪组织产生和分泌的因子(称为脂肪因子)在代谢调节中的关键作用已被确定，这些因子可以诱导胰岛素抵抗或改善胰岛素敏感性。对骨骼肌产生的也可能影响胰岛素敏感性以及影响脂肪组织(AT)积累和功能的因素关注较少。需要检验的假说是：骨骼肌产生和释放的因子(肌动蛋白)可以自动作用于肌肉，增强或阻碍新陈代谢和胰岛素的作用，以及以内分泌的方式影响AT的代谢和积累。肥胖型2型糖尿病患者的肌肉会产生更多的肌细胞因子，从而诱导胰岛素抵抗和刺激脂肪堆积。1)测定人骨骼肌产生和分泌GRO、IL-8和IL-15的能力，并通过炎症和抗炎信号调节这种产生。2)建立这些特定的肌细胞因子对骨骼肌糖代谢和胰岛素敏感性的自分泌作用及其信号转导途径。糖尿病肌肉细胞对这些肌动蛋白的作用是更敏感还是更不敏感？3)评估特定的肌动蛋白对脂肪细胞的分化和凋亡、AT血管生成和脂代谢的影响，重点是潜在的储藏(皮下和内脏)差异以及肥胖和T2D的影响。这个项目将完全在人类身上进行，他们的组织和来自这些组织的细胞。胰岛素在骨骼肌中的作用将在体内和体外在肌肉组织、培养的肌肉细胞和脂肪组织中进行研究。肌肉和AT活检将用于评估Gro、IL-8和IL-15的mRNA和蛋白含量。来自活组织切片的卫星细胞将在培养中繁殖并分化为肌管，以评估肌肉特异性产生感兴趣的肌肉运动因子。肌管还将接受炎症和抗炎信号以及个别肌细胞因子的治疗，以确定对这些因素的反应是否因糖尿病而异。这些因子在肌管中的表达也将受到遗传手段的控制。在培养中保持At，用所建议的感兴趣的肌动蛋白处理，随后成熟脂肪细胞的脂肪生成和凋亡。AT还将接受单独的肌动蛋白治疗，以跟踪血管生成的影响。该项目的结果将提供肥胖和T2D体内代谢功能障碍的分子机制，并确定治疗干预的可能靶点。

DESCRIPTION (provided by applicant): Metabolic dysfunction in obesity and type 2 diabetes (T2D) involves insulin resistance in multiple tissues. Recently key roles in metabolic regulation have been identified for factors produced by and secreted from adipose tissue (termed adipokines) that can either induce insulin resistance or improve insulin sensitivity. Less attention has been paid to factors produced by skeletal muscle (myokines) that could also influence insulin sensitivity, as well as impact adipose tissue (AT) accumulation and function. The hypothesis to be tested is: Skeletal muscle produces and releases factors (myokines) that can act in an autocine manner on muscle to augment or impede metabolism and insulin action as well as act in an endocrine manner to influence AT metabolism and accumulation. Muscle from obese type 2 diabetic individuals produces more of the myokines that induce insulin resistance and stimulate fat accumulation. There are 3 Specific Aims.1) Determine the ability of human skeletal muscle to produce and secrete GRO¿, IL-8, and IL-15 and regulation of this production by inflammatory and anti- inflammatory signals. 2) Establish the autocrine effects of these specific myokines on glucose metabolism and insulin sensitivity in skeletal muscle, and the signaling pathways involved. Are diabetic muscle cells more or less sensitive to the actions of these myokines? 3) Evaluate the effects of specific myokines on the differentiation and apoptosis of adipocytes, angiogenesis in AT, and lipid metabolism, with an emphasis on potential depot (subcutaneous vs visceral) differences and the impacts of obesity and T2D. This project will be performed totally in humans, their tissues and cells derived from those tissues. Insulin action in skeletal muscle will be studied both in vivo and in vitro in muscle tissue and cultured muscle cells and adipose tissue. Muscle and AT biopsies will be obtained for evaluation of the content of GRO¿, IL-8, and IL-15 mRNA and protein. Satellite cells from the biopsies will be propagated in culture and differentiated into myotubes to evaluate muscle specific production of the myokines of interest. Myotubes will also be treated with inflammatory and anti-inflammatory signals as well as individual myokines to determine if responsiveness to the factors varies with diabetes. Expression of the factors in myotubes will also be manipulated by genetic means. AT will be maintained in culture, treated with the proposed myokines of interest and both adipogenesis and apoptosis of mature adipocytes followed. AT will also be treated with individual myokines to follow effects on angiogenesis. Results from this project will provide molecular mechanisms for metabolic dysfunction seen in vivo in obesity and T2D and identify possible targets for therapeutic interventions.