Vesicular stomatitis virus infection alters the eIF4F translation initiation complex and causes dephosphorylation of the eIF4E binding protein 4E-BP1
Vesicular stomatitis virus infection alters the eIF4F translation initiation complex and causes dephosphorylation of the eIF4E binding protein 4E-BP1
复制标题
DOI：
10.1128/jvi.76.20.10177-10187.2002
复制
发表时间：
2002-10-01
影响因子：
5.4
通讯作者：
Lyles, DS
中科院分区：
文献类型：
--
作者：
Connor, JH;Lyles, DS
水泡性口炎病毒（VSV）以允许其自身5 '-加帽mRNA翻译但抑制宿主mRNA翻译的方式调节感染细胞中的蛋白质合成。先前的数据表明，eIF 2 α的失活对于VSV诱导的宿主蛋白质合成抑制是重要的。我们测试了eIF 4F是否在这种抑制中起作用。多亚基eIF 4F复合物通过帽结合蛋白eIF 4 E（eIF 4F的亚基）的磷酸化参与蛋白质合成的调节。宿主mRNA的翻译在eIF 4 E去磷酸化的条件下显著减少。为了确定VSV感染是否改变了eIF 4F复合物，我们分析了eIF 4 E磷酸化以及eIF 4 E与其他翻译起始因子（如eIF 4G和翻译抑制剂4 E-BPI）的相关性。VSV感染HeLa细胞后3 ~ 6 h，eIF 4 E在丝氨酸209处发生去磷酸化。这一时间过程与VSV感染诱导的宿主蛋白质合成抑制的时间过程相一致。用VSV突变体感染的细胞抑制宿主蛋白质合成的能力延迟，eIF 4 E的去磷酸化也延迟。除eIF 4 E磷酸化水平降低外，VSV感染还导致eIF 4 E结合蛋白4 E-BPI在感染后3 - 6 h脱磷酸化和活化。帽结合复合物的分析表明，VSV感染减少了eIF 4 E与eIF 4G支架亚基的关联，同时其与4 E-BPI的关联增加，并且这些时间过程与eIF 4 E的去磷酸化相关。eIF 4F复合物中的这些变化发生在与病毒蛋白合成开始相同的时间段内，表明4 E-BPI的活化不会抑制病毒mRNA的翻译。为了支持这一观点，VSV蛋白合成不受雷帕霉素（一种阻断4 E-BP 1磷酸化的药物）的影响。这些数据表明，VSV感染导致与宿主蛋白质合成抑制相关的eIF 4F复合物的修饰，并且尽管活性帽结合eIF 4F复合物的浓度降低，但仍发生VSV mRNA的翻译。这是在产生用于蛋白质翻译的加帽mRNA的病毒中首次注意到eIF 4 E和4 E-BP 1磷酸化水平的修饰。
Vesicular stomatitis virus (VSV) modulates protein synthesis in infected cells in a way that allows the translation of its own 5'-capped mRNA but inhibits the translation of host mRNA. Previous data have shown that inactivation of eIF2alpha is important for VSV-induced inhibition of host protein synthesis. We tested whether there is a role for eIF4F in this inhibition. The multisubunit eIF4F complex is involved in the regulation of protein synthesis via phosphorylation of cap-binding protein eIF4E, a subunit of eIF4F. Translation of host mRNA is significantly reduced under conditions in which eIF4E is dephosphorylated. To determine whether VSV infection alters the eIF4F complex, we analyzed eIF4E phosphorylation and the association of eIF4E with other translation initiation factors, such as eIF4G and the translation inhibitor 4E-BPI. VSV infection of HeLa cells resulted in the dephosphorylation of eIF4E at serine 209 between 3 and 6 h postinfection. This time course corresponded well to that of the inhibition of host protein synthesis induced by VSV infection. Cells infected with a VSV mutant that is delayed in the ability to inhibit host protein synthesis were also delayed in dephosphorylation of eIF4E. In addition to decreasing eIF4E phosphorylation, VSV infection also resulted in the dephosphorylation and activation of eIF4E-binding protein 4E-BPI between 3 and 6 h postinfection. Analysis of cap-binding complexes showed that VSV infection reduced the association of eIF4E with the eIF4G scaffolding subunit at the same time as its association with 4E-BPI increased and that these time courses correlated with the dephosphorylation of eIF4E. These changes in the eIF4F complex occurred over the same time period as the onset of viral protein synthesis, suggesting that activation of 4E-BPI does not inhibit translation of viral mRNAs. In support of this idea, VSV protein synthesis was not affected by the presence of rapamycin, a drug that blocks 4E-BP1 phosphorylation. These data show that VSV infection results in modifications of the eIF4F complex that are correlated with the inhibition of host protein synthesis and that translation of VSV mRNAs occurs despite lowered concentrations of the active cap-binding eIF4F complex. This is the first noted modification of both eIF4E and 4E-BP1 phosphorylation levels among viruses that produce capped mRNA for protein translation.