mTOR, AMPK, and GCN2 coordinate the adaptation of hepatic energy metabolic pathways in response to protein intake in the rat
mTOR, AMPK, and GCN2 coordinate the adaptation of hepatic energy metabolic pathways in response to protein intake in the rat
复制标题
DOI：
10.1152/ajpendo.91000.2008
复制
发表时间：
2009-12-01
影响因子：
5.1
通讯作者：
Tome, Daniel
中科院分区：
文献类型：
--
作者：
Chotechuang, Nattida;Azzout-Marniche, Dalila;Tome, Daniel
Chotechuang N，Azzout-Marniche D，Bos C，Chaumontet C，Gausseres N，Steiler T，Gausseron C，托姆D. mTOR、AMPK和GCN 2协调肝脏能量代谢途径对大鼠蛋白质摄入的适应。Am J Physiol Endocrinol Metab 297：E1313-E1323，2009.首次发表于2009年9月8日; doi：10.1152/ajpendo.91000.2008。肝脏中的氨基酸（AA）传感涉及三种转导途径：哺乳动物雷帕霉素靶蛋白（mTOR）、AMP活化蛋白激酶（AMPK）和一般控制非抑制性激酶2（GCN 2）。然而，没有研究调查参与这些信号通路在肝AA传感。为了解决肝脏AA传感和信号传导对高蛋白（HP）饮食供应的响应问题，我们通过蛋白质印迹法研究了肝脏mTOR（p-mTOR）、AMPK α（p-AMPK α）和GCN 2（p-GCN 2）磷酸化状态的变化。与接受正常蛋白质（NP）饮食的大鼠相比，在喂食HP饮食14天的大鼠中，肝脏p-AMPK α和p-GCN 2较低（P < 0.001），p-mTOR和真核起始因子4 E结合蛋白-1磷酸化（p-4 E-BP 1）较高（P < 0.01）。在原代培养的肝细胞中，无论是否存在胰岛素，高浓度AA均降低AMPK α磷酸化水平（P < 0.01）。无论是AA还是胰岛素都可以刺激p-mTOR，但这不足以刺激需要两者的4 E-BP 1磷酸化（P < 0.01）。正如预期的那样，支链氨基酸（BCAA）或亮氨酸刺激mTOR的磷酸化，但胰岛素和BCAA或亮氨酸都需要4 E-BP 1磷酸化。GCN 2磷酸化被AA和胰岛素降低（P < 0.01），这首次表明翻译抑制剂GCN 2不仅感测到AA缺乏，而且感测到肝脏中AA增加。目前的研究结果表明，氨基酸和胰岛素发挥协调作用的翻译和参与mTOR，AMPK，和GCN 2转导途径。
Chotechuang N, Azzout-Marniche D, Bos C, Chaumontet C, Gausseres N, Steiler T, Gaudichon C, Tome D. mTOR, AMPK, and GCN2 coordinate the adaptation of hepatic energy metabolic pathways in response to protein intake in the rat. Am J Physiol Endocrinol Metab 297: E1313-E1323, 2009. First published September 8, 2009; doi:10.1152/ajpendo.91000.2008.-Three transduction pathways are involved in amino acid (AA) sensing in liver: mammalian target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), and general control nondepressible kinase 2 (GCN2). However, no study has investigated the involvement of these signaling pathways in hepatic AA sensing. To address the question of liver AA sensing and signaling in response to a high-protein (HP) dietary supply, we investigated the changes in the phosphorylation state of hepatic mTOR (p-mTOR), AMPK alpha (p-AMPK alpha), and GCN2 (p-GCN2) by Western blotting. In rats fed a HP diet for 14 days, the hepatic p-AMPK alpha and p-GCN2 were lower (P < 0.001), and those of both the p-mTOR and eukaryotic initiation factor 4E-binding protein-1 phosphorylation (p-4E-BP1) were higher (P < 0.01) compared with rats receiving a normal protein (NP) diet. In hepatocytes in primary culture, high AA concentration decreased AMPK alpha phosphorylation whether insulin was present or not (P < 0.01). Either AAs or insulin can stimulate p-mTOR, but this is not sufficient for 4E-BP1 phosphorylation that requires both (P < 0.01). As expected, branchedchain AAs (BCAA) or leucine stimulated the phosphorylation of mTOR, but both insulin and BCAA or leucine are required for 4E-BP1 phosphorylation. GCN2 phosphorylation was reduced by both AAs and insulin (P < 0.01), suggesting for the first time that the translation inhibitor GCN2 senses not only the AA deficiency but also the AA increase in the liver. The present findings demonstrate that AAs and insulin exert a coordinated action on translation and involved mTOR, AMPK, and GCN2 transduction pathways.