Let‐7e inhibits TNF‐α expression by targeting the methyl transferase EZH2 in DENV2‐infected THP‐1 cells

Abstract

Tumor necrosis factor α (TNFα), an important inflammatory cytokine, is associated with dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), a severe pathological manifestation of dengue virus (DENV) infection. However, the regulatory mechanism of microRNA on TNFα is currently unknown. Our study showed that the TNFα expression increased immediately and then later decreased, while a marked increase for the miRNA let-7e was detected in dengue virus type 2 (DENV2)-infected peripheral blood mononuclear cells (PBMCs). From this study, we found that let-7e was able to inhibit TNFα expression, but bioinformatics analysis showed that the enhancer of zeste homolog 2 (EZH2) was the potential direct target of let-7e instead of TNFα. EZH2 methyl transferase can produce H3K27me3 and has a negative regulatory role. Using a dual-luciferase reporter assay and Western blotting, we confirmed that EZH2 was a direct target of let-7e and found that siEZH2 could inhibit TNFα expression. In the further study of the regulatory mechanism of EZH2 on TNFα expression, we showed that siEZH2 promoted EZH1 and H3K4me3 expression and inhibited H3K27me3 expression. More importantly, we revealed that siEZH2 down-regulated NF-κB p65 within the nucleus. These findings indicate that the let-7e/EZH2/H3K27me3/NF-κB p65 pathway is a novel regulatory axis of TNFα expression. In addition, we determined the protein differences between siEZH2 and siEZH2-NC by iTRAQ and found a number of proteins that might be associated with TNFα.

Ezh2 Ameliorates Osteoarthritis by Activating TNFSF13B

“…However, the role of Ezh2 as the regulator of inflammatory factors was uncovered by recent studies. In Zhang and colleagues' study, it was revealed that inhibition of EZH2 would reduce TNFα expression by depressing nuclear NF‐κB p65 levels. In other research about breast cancer, EZH2 acted as a co‐activator of RelA and RelB (subunits of NF‐κB protein family) to facilitate the expression of TNFα and IL‐6 .…”

Differential expression of microRNA, miR-150 and enhancer of zeste homolog 2 (EZH2) in peripheral blood cells as early prognostic markers of severe forms of dengue

“…let-7e, which has been reported to directly regulate EZH2 expression is only upregulated in SD patients on day 2 and day 4 from fever onset while the expression is downregulated on day 3. Differential expression of EZH2 as a result of upregulation of let-7e expression was implicated in several viral infections including DENV2 infected peripheral blood mononuclear cells (PBMCs) [40]. Therefore, further studies in DENV infected cultured cells may be needed to evaluate the role of let-7e on the differential expression of EZH2 during SD.…”

Regulation of IL-6 signaling by miR-125a and let-7e in endothelial cells controls vasculogenic mimicry formation of breast cancer cells

“…Previous reports show that miR-125a and let-7e are significantly downregulated in many cancers, and downregulation of these miRNAs leads to enhanced tumor progression, chemoresistance, and metastasis despite strong context dependence of the role of miR-125a and let-7e in cancer (34–40). Although miR-125a and let-7e are highly expressed in ECs (8, 41), and have been studied in different cellular contexts such as in immune cells, preosteoblasts, and in a variety of cancers (23, 24, 34, 37, 42, 43), their role in EC biology remains unclear. Therefore, it is important to understand the role or regulation of miR-125a and let-7e in tumors as well as in tumor microenvironments such as ECs.…”