Kumar Vinayshree, Frost Robert A, Lang Charles H
Department of Cellular and Molecular Physiology, Pennsylvania State College of Medicine, Hershey, Pennsylvania 17033, USA.
Am J Physiol Endocrinol Metab. 2002 Nov;283(5):E917-28. doi: 10.1152/ajpendo.00181.2002.
The present study determined whether acute alcohol (ethanol; EtOH) intoxication in rats impaired components of the insulin- and IGF-I-signaling pathway in skeletal muscle. Rats were administered EtOH, and 2.5 h thereafter either insulin, IGF-I, or saline was injected and the gastrocnemius removed. EtOH did not alter the total amount or tyrosine phosphorylation of the insulin receptor, IGF-I receptor, insulin receptor substrate (IRS)-1, or protein kinase B (PKB)/Akt under basal or hormone-stimulated conditions. In contrast, the ability of insulin or IGF-I to phosphorylate T389 and T421/S424 on S6K-1 was markedly diminished by EtOH, and these changes were associated with a reduction in the phosphorylation of the ribosomal protein S6. Under basal conditions, EtOH altered the distribution of eukaryotic initiation factor (eIF)4E, as evidenced by a decreased amount of active eIF4E. eIF4G complex, an increased amount of inactive eIF4E. 4E-binding protein (BP)1 complex, and decreased 4E-BP1 phosphorylation. In contrast, EtOH did not impair the ability of either hormone to reverse the changes in eIF4E distribution or 4E-BP1 phosphorylation. Pretreatment with a glucocorticoid receptor antagonist was unable to attenuate either the basal EtOH-induced changes in eIF4E distribution or the impaired ability of IGF-I to stimulate S6K1 and S6 phosphorylation. Hence, acute alcohol intoxication alters selected aspects of translational control under both basal and anabolic hormone-stimulated conditions in skeletal muscle in a glucocorticoid-independent manner.
本研究确定了大鼠急性酒精(乙醇;EtOH)中毒是否会损害骨骼肌中胰岛素和胰岛素样生长因子-I(IGF-I)信号通路的组成部分。给大鼠施用EtOH,2.5小时后注射胰岛素、IGF-I或生理盐水,然后取出腓肠肌。在基础或激素刺激条件下,EtOH不会改变胰岛素受体、IGF-I受体、胰岛素受体底物(IRS)-1或蛋白激酶B(PKB)/Akt的总量或酪氨酸磷酸化。相比之下,EtOH显著降低了胰岛素或IGF-I使S6K-1上的T389和T421/S424磷酸化的能力,这些变化与核糖体蛋白S6磷酸化的减少有关。在基础条件下,EtOH改变了真核起始因子(eIF)4E的分布,表现为活性eIF4E的量减少、eIF4G复合物增加、非活性eIF4E.4E结合蛋白(BP)1复合物增加以及4E-BP1磷酸化减少。相比之下,EtOH不会损害任何一种激素逆转eIF4E分布变化或4E-BP1磷酸化的能力。用糖皮质激素受体拮抗剂预处理无法减弱基础EtOH诱导的eIF4E分布变化或IGF-I刺激S6K1和S6磷酸化的受损能力。因此,急性酒精中毒以糖皮质激素非依赖的方式改变了骨骼肌在基础和合成代谢激素刺激条件下翻译控制的某些方面。