Effect of dietary protein on translation initiation in rat skeletal muscle and liver.
Effect of dietary protein on translation initiation in rat skeletal muscle and liver.
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DOI：
10.1152/ajpendo.1998.275.5.e814
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发表时间：
1998-11
期刊：
影响因子：
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通讯作者：
F. Yoshizawa;S. Kimball;T. Vary;L. Jefferson
中科院分区：
文献类型：
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作者：
F. Yoshizawa;S. Kimball;T. Vary;L. Jefferson
在大鼠饥饿18小时，然后喂食含20%蛋白质（20 P）或不添加蛋白质（0 P）的等热量饮食中，检查饮食蛋白质对mRNA翻译起始的影响。喂食20 P饮食，而不是0 P饮食，刺激骨骼肌和肝脏中的蛋白质合成分别为38%和41%。这种刺激与真核起始因子（eIF）4 E与翻译阻遏物4 E-BP 1的结合减少、活性eIF 4 E-eIF 4G复合物的形成增加以及4 E-BP 1的磷酸化增加有关。相比之下，饲喂0 P饮食对这些参数中的任何一个都没有影响。喂食20 P饮食导致两种组织中eIF 4 E的部分去磷酸化。在肝脏中，重新喂食0 P饮食也导致部分eIF 4 E去磷酸化，表明eIF 4 E的磷酸化状态在这些条件下刺激蛋白质合成并不重要。最后，喂食任一饲料的大鼠的血浆胰岛素浓度相同（20 P和0 P组分别为14.8 ± 4.9和15.5 ± 4.5 μU/ml），表明喂食诱导的血浆胰岛素变化不足以刺激蛋白质合成。相反，可能需要膳食蛋白质和胰岛素的组合来刺激翻译起始。
The effect of dietary protein on the initiation of mRNA translation was examined in rats starved for 18 h and then fed isocaloric diets containing either 20% protein (20P) or no added protein (0P). Feeding the 20P diet, but not the 0P diet, stimulated protein synthesis in skeletal muscle and liver by 38 and 41%, respectively. The stimulation was associated with reduced binding of eukaryotic initiation factor (eIF) 4E to the translational repressor 4E-BP1, increased formation of the active eIF4E-eIF4G complex, and increased phosphorylation of 4E-BP1. In contrast, feeding a 0P diet had no effect on any of these parameters. Feeding a 20P diet resulted in partial dephosphorylation of eIF4E in both tissues. In liver, refeeding a 0P diet also resulted in partial eIF4E dephosphorylation, suggesting that the phosphorylation state of eIF4E is not important in the stimulation of protein synthesis under these conditions. Finally, plasma insulin concentrations were the same in rats fed either diet (14.8 ± 4.9 vs. 15.5 ± 4.5 μU/ml for 20P and 0P groups, respectively), suggesting that feeding-induced changes in plasma insulin are not sufficient to stimulate protein synthesis. Instead, a combination of dietary protein and insulin may be required to stimulate translation initiation.