RESUMEN
The concept of tRNA recycling has recently emerged from the studies of ribosome-associated quality control. Therein tRNase ZS removes the 2', 3'>p from the ANKZF1-cleaved tRNA and the subsequent TRNT1 action re-generates the intact tRNA. To know the roles of the tRNA recycling in vivo, we investigated how viral infection affects the tRNA recycling system by analyzing the mRNA levels of tRNase ZS and TRNT1. We found that both genes in HeLa cells are upregulated in response to infection of Theiler's mouse encephalitis virus but not to that of an influenza A virus. Upregulation was also observed in cells infected with encephalomyocarditis virus with reduced efficiency. The levels of the IFN-ß mRNA appeared to positively correlate with those of the tRNase ZS and TRNT1 mRNAs. The tRNase ZS gene may be regulated post-transcriptionally in the cells infected with Theiler's mouse encephalitis virus.
Asunto(s)
Endorribonucleasas/genética , Interacciones Huésped-Patógeno/genética , Nucleotidiltransferasas/genética , Procesamiento Postranscripcional del ARN , ARN de Transferencia/genética , Theilovirus/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Virus de la Encefalomiocarditis/genética , Virus de la Encefalomiocarditis/crecimiento & desarrollo , Virus de la Encefalomiocarditis/metabolismo , Endorribonucleasas/metabolismo , Células HeLa , Humanos , Virus de la Influenza A/genética , Virus de la Influenza A/crecimiento & desarrollo , Virus de la Influenza A/metabolismo , Interferón beta/genética , Interferón beta/metabolismo , Isoenzimas/genética , Isoenzimas/metabolismo , Nucleotidiltransferasas/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN de Transferencia/metabolismo , Ribosomas/genética , Ribosomas/metabolismo , Theilovirus/crecimiento & desarrollo , Theilovirus/metabolismo , Carga ViralRESUMEN
tRNase ZS (ELAC1) and TRNT1 function in tRNA recycling. Recently, we have shown that these genes are upregulated in the cells infected with Theiler's mouse encephalitis virus (TMEV), implying that tRNA recycling functions in response to viral infection. To address the molecular mechanism underlying the ELAC1 upregulation in the cells infected with TMEV, we performed luciferase assays using various plasmid constructs harboring the ELAC1 promoter region. The luciferase expression from a construct containing the full-length ELAC1 promoter was augmented by TMEV, poly IC, IFN-ß, or IFN-γ. We identified four IFN-stimulated responsible elements (ISREs) in the proximal promoter region. The luciferase expression from the constructs that lack all the ISREs was strongly reduced compared with that from the constructs with the four ISREs in the presence of IFN-ß or IFN-γ. The observation that the ISREs from the ELAC1 promoter are essential for the gene upregulation by IFN-ß or IFN-γ suggests that the ELAC1 gene is upregulated by IFNs.