Reduced AMP-activated protein kinase activity in mouse skeletal muscle does not exacerbate the development of insulin resistance with obesity
Reduced AMP-activated protein kinase activity in mouse skeletal muscle does not exacerbate the development of insulin resistance with obesity
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DOI：
10.1007/s00125-009-1483-8
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发表时间：
2009-11-01
期刊：
影响因子：
8.2
通讯作者：
Steinberg, G. R.
中科院分区：
文献类型：
--
作者：
Jorgensen, S. Beck;O'Neill, H. M.;Steinberg, G. R.
AIMS/假说肥胖相关的胰岛素抵抗与骨骼肌中生物活性脂肪的积累有关。AMP激活的蛋白激酶(AMPK)通过抑制乙酰辅酶A羧化酶-2(ACC2)和促进线粒体的生物合成来调节肌肉中的脂质氧化。我们研究了在高脂饮食过程中肌肉AMPK水平降低是否促进了脂肪堆积和胰岛素抵抗。方法雄性C57/BL6野生型小鼠和肌肉中高表达α2AMPK激酶死亡(KD)的转基因小鼠分别饲喂对照组和高脂饲料。通过葡萄糖和胰岛素耐量试验，以及通过测量空腹和喂养的血清胰岛素和葡萄糖来评估全身葡萄糖稳态。通过测定培养的比目鱼肌和趾长伸肌对2-脱氧-[H-3]葡萄糖的摄取和Akt的磷酸化来确定胰岛素在肌肉中的作用。用薄层层析法测定肌肉中三酰甘油、二酰甘油和神经酰胺的含量。结果KD小鼠骨骼肌α2AMPK活性降低(腓肠肌50%，比目鱼肌和指长伸肌80%)，ACC2 Ser228磷酸化水平降低(90%)。高脂肪喂养增加了体重和肥胖，并损害了胰岛素和糖耐量；然而，野生型和KD产仔之间没有差异。高脂饮食降低胰岛素刺激的肌肉葡萄糖摄取和Akt-磷酸化，同时增加肌肉三酰甘油、二酰甘油(p=0.07)和神经酰胺，但这些影响在KD小鼠中没有加剧。作为对高脂饮食的响应，野生型和KD肌肉中线粒体蛋白的水平增加到相似的水平。结论/解释肥胖诱导的脂肪堆积和胰岛素抵抗在AMPK KD小鼠中没有加剧，提示肌肉α2AMPK水平降低并不促进肥胖相关糖尿病早期的胰岛素抵抗。
Aims/hypothesis Obesity-related insulin resistance is associated with accumulation of bioactive lipids in skeletal muscle. The AMP-activated protein kinase (AMPK) regulates lipid oxidation in muscle by inhibiting acetyl-CoA carboxylase-2 (ACC2) and increasing mitochondrial biogenesis. We investigated whether reduced levels of muscle AMPK promote lipid accumulation and insulin resistance during high-fat feeding.Methods Male C57/BL6 wild-type mice and transgenic littermates overexpressing an alpha 2AMPK kinase-dead (KD) in muscle were fed control or high-fat diet. Whole-body glucose homeostasis was assessed by glucose and insulin tolerance tests, and by measuring fasting and fed serum insulin and glucose. Insulin action in muscle was determined by measuring 2-deoxy-[H-3] glucose uptake and Akt phosphorylation in incubated soleus and extensor digitorum longus muscles. Muscle triacylglycerol, diacylglycerol and ceramide content was measured by thin-layer chromatography. Mitochondrial proteins were measured by immunoblotting.Results KD mice had reduced skeletal muscle alpha 2AMPK activity (50% in gastrocnemius and >80% in soleus and extensor digitorum longus) and ACC2 Ser228 phosphorylation (90% in gastrocnemius). High-fat feeding increased body mass and adiposity, and impaired insulin and glucose tolerance; however, there were no differences between wild-type and KD littermates. High-fat feeding impaired insulin-stimulated muscle glucose uptake and Akt-phosphorylation, while increasing muscle triacylglycerol, diacylglycerol (p=0.07) and ceramide, but these effects were not exacerbated in KD mice. In response to high-fat feeding, mitochondrial proteins were increased to similar levels in wild-type and KD muscles.Conclusions/interpretation Obesity-induced lipid accumulation and insulin resistance were not exacerbated in AMPK KD mice, suggesting that reduced levels of muscle alpha 2AMPK do not promote insulin resistance in the early phase of obesity-related diabetes.