RESUMO
miRNAs, small non-coding RNAs that regulate gene expression, are involved in various pathological processes, including viral infections. Virus infections may interfere with the miRNA pathway through the inhibition of genes involved in miRNA biogenesis. A reduction in the number and the levels of miRNAs expressed in nasopharyngeal swabs of patients with severe COVID-19 was lately observed by us, pointing towards the potential of miRNAs as possible diagnostic or prognostic biomarkers for predicting outcomes among patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. The objective of the present study was to investigate whether SARS-CoV-2 infection influences the expression levels of messenger RNAs (mRNAs) of key genes involved in miRNA biogenesis. mRNA levels of AGO2, DICER1, DGCR8, DROSHA, and Exportin-5 (XPO5) were measured by quantitative reverse-transcription polymerase chain reaction (RT-qPCR) in nasopharyngeal swab specimens from patients with COVID-19 and controls, as well as in cells infected with SARS-CoV-2 in vitro. Our data showed that the mRNA expression levels of AGO2, DICER1, DGCR8, DROSHA, and XPO5 were not significantly different in patients with severe COVID-19 when compared to patients with non-severe COVID-19 and controls. Similarly, the mRNA expression of these genes was not affected by SARS-CoV-2 infection in NHBE and Calu-3 cells. However, in Vero E6 cells, AGO2, DICER1, DGCR8, and XPO5 mRNA levels were slightly upregulated 24 h after infection with SARS-CoV-2. In conclusion, we did not find evidence for downregulation of mRNA levels of miRNA biogenesis genes during SARS-CoV-2 infection, neither ex vivo nor in vitro.
Assuntos
COVID-19 , MicroRNAs , Humanos , MicroRNAs/genética , MicroRNAs/metabolismo , COVID-19/genética , SARS-CoV-2/genética , SARS-CoV-2/metabolismo , Proteínas de Ligação a RNA/metabolismo , RNA Mensageiro/genética , Ribonuclease III/genética , Ribonuclease III/metabolismo , RNA Helicases DEAD-box/genética , RNA Helicases DEAD-box/metabolismo , Carioferinas/genéticaRESUMO
SARS-CoV-2 has mutually illuminated our collective knowledge and knowledge gaps, particularly in antiviral defense and therapeutic strategies. A recent study in Science (Poirier et al., 2021) uncovers an ancient antiviral mechanism that mammals utilize to suppress viruses, including SARS-CoV-2 and Zika virus, that could have broad implications for therapeutic strategies.
Assuntos
Proteínas Argonautas/metabolismo , COVID-19/prevenção & controle , Interferons/imunologia , Interferência de RNA/fisiologia , Ribonuclease III/metabolismo , Infecção por Zika virus/prevenção & controle , Animais , Linhagem Celular , Células HEK293 , Humanos , RNA Interferente Pequeno/genética , RNA Viral/metabolismo , SARS-CoV-2/genética , SARS-CoV-2/imunologia , Replicação Viral , Zika virus/genética , Zika virus/imunologiaRESUMO
In mammals, early resistance to viruses relies on interferons, which protect differentiated cells but not stem cells from viral replication. Many other organisms rely instead on RNA interference (RNAi) mediated by a specialized Dicer protein that cleaves viral double-stranded RNA. Whether RNAi also contributes to mammalian antiviral immunity remains controversial. We identified an isoform of Dicer, named antiviral Dicer (aviD), that protects tissue stem cells from RNA viruses-including Zika virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-by dicing viral double-stranded RNA to orchestrate antiviral RNAi. Our work sheds light on the molecular regulation of antiviral RNAi in mammalian innate immunity, in which different cell-intrinsic antiviral pathways can be tailored to the differentiation status of cells.