Esclatine Audrey, Taddeo Brunella, Roizman Bernard
The Marjorie B. Kovler Viral Oncology Labs, The University of Chicago, 910 E. 58th St., Chicago, IL 60637, USA.
J Virol. 2004 Aug;78(16):8582-92. doi: 10.1128/JVI.78.16.8582-8592.2004.
Herpes simplex virus 1 causes a shutoff of cellular protein synthesis through the degradation of RNA that is mediated by the virion host shutoff (Vhs) protein encoded by the U(L)41 gene. We reported elsewhere that the Vhs-dependent degradation of RNA is selective, and we identified RNAs containing AU-rich elements (AREs) that were upregulated after infection but degraded by deadenylation and progressive 3'-to-5' degradation. We also identified upregulated RNAs that were not subject to Vhs-dependent degradation (A. Esclatine, B. Taddeo, L. Evans, and B. Roizman, Proc. Natl. Acad. Sci. USA 101:3603-3608, 2004). Among the latter was the RNA encoding tristetraprolin, a protein that binds AREs and is known to be associated with the degradation of RNAs containing AREs. Prompted by this observation, we examined the status of the ARE binding proteins tristetraprolin and TIA-1/TIAR in infected cells. We report that tristetraprolin was made and accumulated in the cytoplasm of wild-type virus-infected human foreskin fibroblasts as early as 2 h and in HEp-2 cells as early as 6 h after infection. The amounts of tristetraprolin that accumulated in the cytoplasm of cells infected with a mutant virus lacking U(L)41 were significantly lower than those in wild-type virus-infected cells. The localization of tristetraprolin was not modified in cells infected with a mutant lacking the gene encoding infected cell protein 4 (ICP4). TIA-1 and TIAR are two other proteins that are associated with the regulation of ARE-containing RNAs and that normally reside in nuclei. In infected cells, they started to accumulate in the cytoplasm after 6 h of infection. In cells infected with the mutant virus lacking U(L)41, TIA-1/TIAR accumulated in the cytoplasm in granular structures reminiscent of stress granules in a significant percentage of the cells. In addition, an antibody to tristetraprolin coprecipitated the Vhs protein from lysates of cells late in infection. The results indicate that the Vhs-dependent degradation of ARE-containing RNAs correlates with the transactivation, cytoplasmic accumulation, and persistence of tristetraprolin in infected cells.
单纯疱疹病毒1型通过由U(L)41基因编码的病毒体宿主关闭（Vhs）蛋白介导的RNA降解，导致细胞蛋白质合成的关闭。我们在其他地方报道过，Vhs依赖的RNA降解是选择性的，并且我们鉴定出含有富含AU元件（ARE）的RNA，这些RNA在感染后上调，但通过去腺苷酸化和渐进性的3'到5'降解而被降解。我们还鉴定出不受Vhs依赖降解影响的上调RNA（A. Esclatine、B. Taddeo、L. Evans和B. Roizman，《美国国家科学院院刊》101:3603 - 3608，2004）。后者中包括编码三指四脯氨酸蛋白的RNA，该蛋白结合ARE，并且已知与含有ARE的RNA的降解相关。受这一观察结果的启发，我们研究了感染细胞中ARE结合蛋白三指四脯氨酸蛋白和TIA - 1/TIAR的状态。我们报告，早在感染后2小时，野生型病毒感染的人包皮成纤维细胞的细胞质中就产生并积累了三指四脯氨酸蛋白，在HEp - 2细胞中则早在感染后6小时就开始积累。缺乏U(L)41的突变病毒感染的细胞细胞质中积累的三指四脯氨酸蛋白的量显著低于野生型病毒感染的细胞。在缺乏编码感染细胞蛋白4（ICP4）基因的突变体感染的细胞中，三指四脯氨酸蛋白的定位没有改变。TIA - 1和TIAR是另外两种与含有ARE的RNA的调控相关且通常位于细胞核中的蛋白。在感染细胞中，它们在感染6小时后开始在细胞质中积累。在缺乏U(L)41的突变病毒感染的细胞中，TIA - 1/TIAR在细胞质中以颗粒结构形式积累，在相当比例的细胞中类似于应激颗粒。此外，针对三指四脯氨酸蛋白的抗体在感染后期从细胞裂解物中共沉淀出Vhs蛋白。结果表明，Vhs依赖的含有ARE的RNA的降解与三指四脯氨酸蛋白在感染细胞中的反式激活、细胞质积累和持续存在相关。
