Suppression of viral replication by stress-inducible GADD34 protein via the mammalian Serine/Threonine protein kinase mTOR pathway
Suppression of viral replication by stress-inducible GADD34 protein via the mammalian Serine/Threonine protein kinase mTOR pathway
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DOI：
10.1128/jvi.01063-07
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发表时间：
2007-10-01
影响因子：
5.4
通讯作者：
Inoue, Hirokazu
中科院分区：
文献类型：
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作者：
Minami, Kahori;Tambe, Yukihiro;Inoue, Hirokazu
Gadd34是一种由多种应激源诱导的蛋白质，包括DNA损伤、热休克、营养缺乏、能量耗竭和内质网应激。在这里，我们证明了水泡性口炎病毒(VSV)感染诱导的Gadd34抑制了野生型(WT)小鼠胚胎成纤维细胞(MEF)中的病毒复制，而Gadd34缺陷(Gadd34-KO)MEF中的复制被增强。Gadd34的逆转录病毒基因拯救降低了Gadd34-KO MEF中增强的病毒复制。Gadd34-KO MEF的VSV蛋白表达水平显著高于WT MEF。在Gadd34-KO MEF中，eIF2α的磷酸化和细胞蛋白合成都与病毒复制无关。另一方面，mTOR下游蛋白S6和4EBP1的磷酸化在WT MEF中被VSV感染抑制，而在Gadd34-KO MEF中不受抑制。Gadd34能够与TSC1/2结合并在Thr1462处使TSC2去磷酸化。VSV在TSC2缺失细胞中的复制高于在TSC2表达细胞中的复制，并且结构性活性Akt增强了VSV复制。另一方面，mTOR抑制剂雷帕霉素显著抑制VSV在Gadd34-KO MEF中的复制。这些结果表明，VSV感染诱导的Gadd34通过抑制mTOR通路抑制病毒复制，表明应激诱导的Gadd34与mTOR信号通路之间的串扰在抗病毒防御中发挥关键作用。
GADD34 is a protein that is induced by a variety of stressors, including DNA damage, heat shock, nutrient deprivation, energy depletion, and endoplasmic reticulum stress. Here, we demonstrated that GADD34 induced by vesicular stomatitis virus (VSV) infection suppressed viral replication in wild-type (WT) mouse embryo fibroblasts (MEFs), whereas replication was enhanced in GADD34-deficient (GADD34-KO) MEFs. Enhanced viral replication in GADD34-KO MEFs was reduced by retroviral gene rescue of GADD34. The level of VSV protein expression in GADD34-KO MEFs was significantly higher than that in WT MEFs. Neither phosphorylation of eIF2 alpha nor cellular protein synthesis was correlated with viral replication in GADD34-KO MEFs. On the other hand, phosphorylation of S6 and 4EBP1, proteins downstream of mTOR, was suppressed by VSV infection in WT MEFs but not in GADD34-KO MEFs. GADD34 was able to associate with TSC1/2 and dephosphorylate TSC2 at Thr1462. VSV replication was higher in TSC2-null cells than in TSC2-expressing cells, and constitutively active Akt enhanced VSV replication. On the other hand, rapamycin, an mTOR inhibitor, significantly suppressed VSV replication in GADD34-KO MEFs. These findings demonstrate that GADD34 induced by VSV infection suppresses viral replication via mTOR pathway inhibition, indicating that cross talk between stress-inducible GADD34 and the mTOR signaling pathway plays a critical role in antiviral defense.