FACTORS THAT MODIFY INSULIN ACTION

我们建议继续就三个独立但相关的项目开展工作。 1)我们 从骨骼肌中部分纯化， 非透析因子，推测为肽，可抑制蛋白质 在兔网织红细胞裂解物中的合成，显然在 翻译起始 此外，大鼠半横膈膜孵育 单独的葡萄糖产生的抑制剂活性显著高于那些 在补充有胰岛素和氨基酸的培养基中孵育。 提出 研究包括：a）确认和扩展这些发现，确认肽 肌源性翻译抑制剂的性质和作用位点 胰岛素和氨基酸在其 调节; B）纯化和表征肌肉提取物中的肽 其抑制翻译起始并受胰岛素调节，和/或 氨基酸; c）研究该抑制剂的作用模式和机制 胰岛素和/或氨基酸的抑制。 工作假设是， 该抑制剂促进eIF-2 α的磷酸化， 肌肉的处理降低了抑制剂活性; d）研究生理和 可能调节活性和/或 抑制剂在体内的可抑制性，例如糖尿病的作用， 激素，肌肉工作和去神经支配; 2）运动增强胰岛素 肌肉的敏感性，而固定或短期去神经 导致胰岛素抵抗。 我们研究了离体比目鱼肌6-24 在切断坐骨神经后24小时，观察到胰岛素降低 结合，葡萄糖转运对胰岛素的敏感性降低， 糖原合成的胰岛素抵抗，指示受体和 受体后缺陷 肌肉活动的分子机制 调节胰岛素受体和受体功能偶联， 研究了不同类型的肌肉，并就几个 胰岛素作用的参数：例如葡萄糖转运糖原合成， 糖酵解、氨基酸转运和蛋白质合成。 3)研究 关于支链氨基酸（BCAA）催化剂的调节 将继续在2个领域：a）支链的反馈调节 酮酸脱氢酶，B）介导加速氧化的机制 支链氨基酸的肌肉在糖尿病，空腹和运动期间。 这些研究 与理解糖尿病和其他疾病的代谢改变有关， 与胰岛素抵抗和蛋白质消耗有关的疾病。

We propose to continue work on three separate but related projects. 1) We have partially purified from skeletal muscle a heat and acid stable non-dialysable factor, presumed to be a peptide, which inhibits protein synthesis in rabbit reticulocyte lysates, apparently at the level of translation initiation. Moreover, rat hemidiaphragms incubated with glucose alone yield significantly more inhibitor activity than those incubated in media supplemented with insulin and amino acids. Proposed studies include: a) confirm and extend these findings, confirm peptide nature of the muscle derived translational inhibitor and site of action on initiation and delineate respective role of insulin and amino acids in its regulation; b) purify and characterize peptide(s) in the muscle extract which inhibit translation initiation and are regulated by insulin and/or amino acids; c) study the mode of action of this inhibitor(s) and mechanism of suppression by insulin and/or amino acids. Working hypotheses are that the inhibitor promotes the phosphorylation of eIF-2Alpha and that insulin treatment of muscle reduces inhibitor activity; d) study physiological and pathological conditions which may modulate the activity and/or suppressibility of the inhibitor in vivo e.g. the effects of diabetes, hormones, muscle work and denervation; 2) exercise enhances insulin sensitivity of muscles, while immobilization or short-term denervation causes insulin resistance. We have studied isolated soleus muscles 6-24 hours after cutting the sciatic nerve and observed decreased insulin binding, decreased sensitivity to insulin of glucose transport and marked resistance to insulin of glycogen synthesis, indicating receptor and post-receptor defects. The molecular mechanisms by which muscle activity modulates the insulin receptor and receptor-function coupling will be investigated in different types of muscle, and with respect to several parameters of insulin action: e.g. glucose transport glycogen synthesis, glycolysis, amino acid transport and protein synthesis. 3) Studies concerning the regulation of branched chain amino acid (BCAA) catabolism will be continued in 2 areas: a) feedback regulation of branched chain keto acid dehydrogenase, b) mechanisms mediating accelerated oxidation of BCAA by muscles in diabetes, fasting and during exercise. These studies are relevant to understanding of altered metabolism in diabetes and other diseases associated with insulin resistance and protein wasting.