Phosphorylation of the insulin receptor by AMP-activated protein kinase (AMPK) promotes ligand-independent activation of the insulin signalling pathway in rodent muscle.
Phosphorylation of the insulin receptor by AMP-activated protein kinase (AMPK) promotes ligand-independent activation of the insulin signalling pathway in rodent muscle.
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DOI：
10.1007/s00125-011-2407-y
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发表时间：
2012-03
期刊：
影响因子：
8.2
通讯作者：
Webster KA
中科院分区：
文献类型：
--
作者：
Chopra I;Li HF;Wang H;Webster KA
肌肉在缺血或输注胰岛素期间可能会出现低血糖。严重低血糖期间，能量产生受阻，AMP:ATP 的增加会激活能量传感器和假定的胰岛素增敏剂 AMP 激活蛋白激酶 (AMPK)。 AMPK 通过关闭合成代谢和激活分解代谢途径来促进能量保存和生存。我们研究了独特的葡萄糖应激防御途径的分子机制，该途径涉及 AMPK 依赖性、非胰岛素依赖性的胰岛素信号传导途径激活。将心肌细胞或骨骼肌细胞置于无葡萄糖和胰岛素的培养中，培养时间间隔逐渐增加，直至 20 小时。使用磷特异性抗体通过蛋白质印迹法对 AMPK 和胰岛素信号传导通路的成分及其靶标进行定量。使用拟磷剂来确定IRS-1 Ser789磷酸化的功能，并使用体外[32P]ATP激酶测定来测量AMPK对纯化的胰岛素受体的磷酸化。葡萄糖剥夺使 Akt-Thr308 和 Akt-Ser473 磷酸化增加了近十倍。糖原合酶激酶3β的磷酸化水平平行增加，但核糖体70S亚基-S6蛋白激酶和雷帕霉素哺乳动物靶点的磷酸化水平降低。 AMPK 抑制剂会阻断，氨基咪唑甲酰胺核糖核苷酸 (AICAR) 会模拟葡萄糖饥饿的影响。葡萄糖剥夺增加了 IRS-1 在丝氨酸 789 上的磷酸化，但磷酸模拟物显示这会产生负调节。葡萄糖剥夺增强了 IRS-1 和胰岛素受体的酪氨酸磷酸化，这种作用被 AMPK 抑制所阻断，并被 AICAR 模拟。使用纯化蛋白的体外激酶测定证实胰岛素受体是 AMPK 的直接靶标。 AMPK 磷酸化并激活胰岛素受体，提供 AMPK 与胰岛素信号通路之间的直接联系；该途径促进了暴露于严重葡萄糖缺乏的肌肉的能量保存和存活。
Muscle may experience hypoglycaemia during ischaemia or insulin infusion. During severe hypoglycaemia energy production is blocked, and an increase of AMP:ATP activates the energy sensor and putative insulin-sensitiser AMP-activated protein kinase (AMPK). AMPK promotes energy conservation and survival by shutting down anabolism and activating catabolic pathways. We investigated the molecular mechanism of a unique glucose stress defence pathway involving AMPK-dependent, insulin-independent activation of the insulin signalling pathway. Cardiac or skeletal myocytes were subjected to glucose and insulin-free incubation for increasing intervals up to 20 h. AMPK, and components of the insulin signalling pathway and their targets were quantified by western blot using phosphor-specific antibodies. Phosphomimetics were used to determine the function of IRS-1 Ser789 phosphorylation and in vitro [32P]ATP kinase assays were used to measure the phosphorylation of the purified insulin receptor by AMPK. Glucose deprivation increased Akt-Thr308 and Akt-Ser473 phosphorylation by almost tenfold. Phosphorylation of glycogen synthase kinase 3 beta increased in parallel, but phosphorylation of ribosomal 70S subunit-S6 protein kinase and mammalian target of rapamycin decreased. AMPK inhibitors blocked and aminoimidazole carboxamide ribonucleotide (AICAR) mimicked the effects of glucose starvation. Glucose deprivation increased the phosphorylation of IRS-1 on serine-789, but phosphomimetics revealed that this conferred negative regulation. Glucose deprivation enhanced tyrosine phosphorylation of IRS-1 and the insulin receptor, effects that were blocked by AMPK inhibition and mimicked by AICAR. In vitro kinase assays using purified proteins confirmed that the insulin receptor is a direct target of AMPK. AMPK phosphorylates and activates the insulin receptor, providing a direct link between AMPK and the insulin signalling pathway; this pathway promotes energy conservation and survival of muscle exposed to severe glucose deprivation.