Role of HCMV miRNAs to inhibit cellular apoptosis in HEK293T cells by targeting the 3’ UTR of pro-apoptotic genes

Abstract

Every living cell regulates its different cellular mechanisms either through proteins or through stretches of nucleotide i.e., small RNAs. As far as regulation of the different cellular mechanisms is concerned, a small tiny non-coding RNA molecule (s) encoded by the cells of plants, viruses, or humans is involved known as MicroRNA. The miRNAs are about 18 to 25 nucleotides long and play a devastating role in post-transcriptional regulation of gene expression and it is reported to be involved in normal and pathological processes. Human Cytomegalovirus is one of the pathogenic virus which causes life-long latency inside the host body. Primary HCMV infection is generally asymptomatic, but if this virus reverts to its lytic phase, it shows deleterious effects on the host and can cause severe and sometimes fatal disease (s) especially in immunocompromised individuals.^1–4

Several reports pertaining that the HCMV encoded miRNAs helps in its survival inside the host. We reported the inhibitory role of HCMV miRNAs in cellular apoptosis. Our in-silico studies revealed that HCMV encoded miRNAs target the cellular pro-apoptotic genes i.e., MOAP1, ERN1 and PHAP1, which are involved in the mitochondrial induced apoptosis.^5–9

Further, our in vitro experiments using HEK293T cells shows that hcmv-miR-UL70-3p and hcmv-miR-UL148D are targeting the MOAP1 (Modulator of Apoptosis-1) gene by binding to the 3’ UTR. Further studies shows that these miRNAs i.e., miR-UL70-3p and hcmv-miR-UL148D can downregulate the H₂O₂ induced apoptosis which is evaluated microscopically and through flow cytometry. The extent of inhibition of apoptosis was found to be 11%, and this study shows that the HCMV uses its miRNAs machinery for regulating the cellular apoptosis for its prolonged survival inside the host cells.¹⁰