Calmodulin Kinases and Control of Skeletal Muscle Glucose Metabolism

 描述（由申请人提供）：2型糖尿病目前困扰着> 2580万美国人，每年花费美国医疗保健系统超过2450亿美元。它是一种以高血糖症、高胰岛素血症和骨骼肌胰岛素抵抗为特征的疾病，骨骼肌是负责体内胰岛素介导的葡萄糖摄取的主要组织。尽管肌肉在维持血糖稳态中的重要性，但目前还没有靶向不依赖于胰岛素的肌肉葡萄糖摄取的糖尿病药物治疗。抗阻运动/肌肉收缩活动刺激葡萄糖摄取到肌肉中;重要的是，在2型糖尿病中，运动刺激肌肉葡萄糖摄取的能力仍然发挥作用。因此，针对运动/收缩介导的肌肉葡萄糖摄取的潜在机制是降低2型糖尿病患者血糖水平的有效策略。不幸的是，这些机制并没有得到很好的理解。这项研究的长期目标是确定肌肉内调节胰岛素非依赖性葡萄糖摄取的分子，细胞或代谢机制，并测试靶向这些机制是否有效改善2型糖尿病的高血糖症。最近的证据表明，Ca 2+激活的丝氨酸/苏氨酸激酶，Ca 2 +/钙调蛋白依赖性蛋白激酶激酶（CaMKK）是运动敏感性、胰岛素非依赖性肌肉葡萄糖摄取的关键调节因子，这表明CaMKK激酶可能是治疗2型糖尿病肌肉葡萄糖摄取受损的一个有前途的新靶点。不幸的是，CaMKK β调节肌肉葡萄糖摄取能力的潜在机制仍不清楚。本提案的具体目标是鉴定肌肉中由CaMKK β激活的细胞内信号蛋白[即底物];确定CaMKK β如何刺激肌肉葡萄糖利用;并确定能量消耗过程的同时激活是否是持续CaMKK β介导的肌肉葡萄糖摄取所必需的。为了实现这些目标，将应用最先进的方法和方法的组合，包括使用ATP类似物来筛选肌肉中的新型CaMKK β底物，体内肌肉基因转移/电穿孔以允许基因在小鼠肌肉中快速瞬时表达，以及产生肌肉特异性CaMKK β敲除小鼠。预计拟议的研究将阐明CaMKK β刺激胰岛素敏感和胰岛素抵抗肌肉中葡萄糖摄取能力的细胞内机制;这是开发2型糖尿病新疗法的关键第一步，旨在刺激骨骼肌中的胰岛素非依赖性葡萄糖摄取。

 DESCRIPTION (provided by applicant): Type 2 diabetes currently afflicts >25.8 million Americans and costs the US healthcare system over $245 billion/year. It is a disease characterized by hyperglycemia, hyperinsulinemia, and insulin resistance in skeletal muscle, the primary tissue responsible for insulin-mediated glucose uptake in the body. Despite the importance of muscle in maintaining blood glucose homeostasis, there are currently no pharmaceutical treatments for diabetes that target muscle glucose uptake independent of insulin. Resistance exercise/muscle contractile activity stimulates glucose uptake into muscle; and importantly in type 2 diabetes the ability of exercise to stimulate muscle glucose uptake remains functional. Thus, targeting the mechanisms underlying exercise/contraction-mediated muscle glucose uptake is an effective strategy for lowering blood glucose levels in type 2 diabetes. Unfortunately, these mechanisms are not well understood. The long-term goals of this research are to identify the molecular, cellular or metabolic mechanisms within muscle that regulate insulin-independent glucose uptake and to test whether targeting those mechanisms is effective at ameliorating hyperglycemia in type 2 diabetes. Recent evidence has now implicated the Ca2+-activated, serine/threonine kinase, Ca2+/calmodulin-dependent protein kinase kinase  (CaMKK) as a key regulator of exercise-sensitive, insulin-independent muscle glucose uptake, suggesting that CaMKK may be a promising new target for treating impaired muscle glucose uptake in type 2 diabetes. Unfortunately, the mechanism(s) underlying the ability of CaMKK to regulate muscle glucose uptake remains unclear. The specific objectives of this proposal are to identify the intracellular signaling protein(s) [i.e. substrate(s)] activated by CaMKK in muscle; to determine how CaMKK stimulates muscle glucose utilization; and to determine whether simultaneous activation of an energy consuming process is necessary for sustained CaMKK -mediated muscle glucose uptake. To achieve these objectives, a combination of state-of-the-art approaches and methodologies will be applied including use of an ATP analog to screen for novel CaMKK substrates in muscle, in vivo muscle gene transfer/electroporation to allow for the rapid, transient expression of genes in mouse muscle, and generation of a muscle-specific CaMKK knockout mouse. It is anticipated that the proposed research will elucidate the intracellular mechanism(s) governing the ability of CaMKK to stimulate glucose uptake in both insulin-sensitive and insulin-resistant muscle; a critical first step towards the development of new treatments for type 2 diabetes aimed at stimulating insulin-independent glucose uptake into skeletal muscle.