MicroRNA-374b regulates SARS-CoV-2 viral protein mediated endothelial to mesenchymal transition by targeting c-FLIP

The pathophysiological consequences of COVID-19 disease are still unclear, however, endothelial cell (EC) dysfunction has been observed to play a key role in disease progression and severity. Many reports suggests that SARS-CoV-2 mediated endothelial dysfunction is the result of intracellular signaling initiated by the binding of the spike protein to ACE2, which can modify endothelial cell phenotype. Recent reports suggests endothelial to mesenchymal transition (Endo MT) as a process heavily involved in lung fibrosis of COVID 19 patients. EndoMT is involved in many chronic and fibrotic diseases and appears to be regulated by complex molecular mechanisms and different signaling pathways, in particular microRNAs (miRNAs), which constitute a crucial mediator of EndoMT. MicroRNAs (miRNAs), small endogenous RNA molecules that regulate several physiological processes including endothelial homeostasis, and vascular diseases, can be perturbed by infecting viruses. Based on these facts, this study was designed to decipher the role of miR-374b, which was found to be significantly downregulated upon profiling of SARS-CoV-2 viral protein stimulated endothelial cells. Gene profiling of endothelial cells revealed c-FLIP (CFLAR) to be among the most significantly upregulated gene. In silico target prediction analysis using targetscan revealed c-FLIP as the major target of miR-374b. Further it was identified that miR-374b can reverse c-FLIP mRNA and protein levels in SARS-CoV-2 viral protein stimulated endothelial cells under conditions of miR-374b overexpression. Since vascular dysfunction involve, under many circumstances, loss of vascular tone due to mesenchymal transition of endothelial cells, we next checked if fibrotic events are initiated downstream of c-FLIP pathway. Further mechanistic studies involving identification of the expression pattern of mesenchymal markers in SARS-CoV-2 viral protein stimulated endothelial cells in presence or absence of miR-374b provide evidence for the important role of miR-374b in regulating SARS CoV-2 mediated EndoMT and fibrotic events downstream of c-FLIP pathway and may highlight possible new therapeutic approaches targeted at the damaged endothelium.