AMP-activated protein kinase α2 activity is not essential for contraction- and hyperosmolarity-induced glucose transport in skeletal muscle
AMP-activated protein kinase α2 activity is not essential for contraction- and hyperosmolarity-induced glucose transport in skeletal muscle
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DOI：
10.1074/jbc.m504208200
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发表时间：
2005-11-25
影响因子：
4.8
通讯作者：
Goodyear, LJ
中科院分区：
文献类型：
--
作者：
Fujii, N;Hirshman, MF;Goodyear, LJ
为了研究 AMP 激活蛋白激酶 ( AMPK) 在肌肉葡萄糖转运中的作用，我们生成了携带非活性 α 2 (α 2i TG) 和 α 1 (α 1i TG) 催化亚基 cDNA 的肌肉特异性转基因小鼠 (TG)。分离野生型和 TG 小鼠的趾长伸肌 (EDL) 肌肉并进行一系列体外培养实验。在α2i TG小鼠中，几乎检测不到基础α2活性，而基础α1活性仅部分降低。已知的 AMPK 刺激物，包括 5-氨基咪唑-4-甲酰胺-1-β-4-呋喃核苷 (AICAR)、鱼藤酮（复合物 I 抑制剂）、二硝基苯酚（线粒体解偶联剂）、肌肉收缩和山梨醇（产生高渗性休克）不会增加 α 2i TG 小鼠的 AMPK α 2 活性，而 α1 激活仅减弱 30 - 50%。使用来自 alpha 2i TG 小鼠的分离 EDL 肌肉在体外测量葡萄糖转运。 AICAR 和鱼藤酮刺激的葡萄糖转运在 α 2iTG 小鼠中被完全抑制；然而，缺乏 AMPK α 2 活性对收缩或山梨醇诱导的葡萄糖转运没有影响。与体外的这些观察结果类似，通过 2-脱氧-D-[H-3] 葡萄糖掺入 EDL、胫骨前肌和腓肠肌进行体内评估，在 α2i TG 小鼠中，收缩刺激的葡萄糖转运是正常的。因此，AMPK α 2 激活对于某些（但不是全部）胰岛素依赖性葡萄糖转运至关重要。肌肉收缩和高渗透压诱导的葡萄糖转运可能受到冗余机制的调节，其中 AMPK α 2 是多种信号传导途径之一。
To examine the role of AMP-activated protein kinase ( AMPK) in muscle glucose transport, we generated muscle-specific transgenic mice (TG) carrying cDNAs of inactive alpha 2 (alpha 2i TG) and alpha 1 (alpha 1i TG) catalytic subunits. Extensor digitorum longus (EDL) muscles from wild type and TG mice were isolated and subjected to a series of in vitro incubation experiments. In alpha 2i TG mice basal alpha 2 activity was barely detectable, whereas basal alpha 1 activity was only partially reduced. Known AMPK stimuli including 5-aminoimidazole-4-carboxamide-1- beta-4-ribofuranoside (AICAR), rotenone ( a Complex I inhibitor), dinitrophenol ( a mitochondrial uncoupler), muscle contraction, and sorbitol ( producing hyperosmolar shock) did not increase AMPK alpha 2 activity in alpha 2i TG mice, whereas alpha 1 activation was attenuated by only 30 - 50%. Glucose transport was measured in vitro using isolated EDL muscles from alpha 2i TG mice. AICAR- and rotenone-stimulated glucose transport was fully inhibited in alpha 2iTG mice; however, the lack of AMPK alpha 2 activity had no effect on contraction or sorbitol-induced glucose transport. Similar to these observations in vitro, contraction-stimulated glucose transport, assessed in vivo by 2-deoxy-D-[H-3] glucose incorporation into EDL, tibialis anterior, and gastrocnemius muscles, was normal in alpha 2i TG mice. Thus, AMPK alpha 2 activation is essential for some, but not all, insulin-independent glucose transport. Muscle contraction- and hyperosmolarity-induced glucose transport may be regulated by a redundant mechanism in which AMPK alpha 2 is one of multiple signaling pathways.