Epigenetic Changes Mediated by MicroRNA miR29 Activate Cyclooxygenase 2 and Lambda-1 Interferon Production during Viral Infection

Abstract

Lambda-1 interferon (IFN-1) and cyclooxygenase-2 (COX-2) were reported to play an important role in host antiviral defense. However, the mechanism by which IFN-1 and COX2 are activated and modulated during viral infection remains unclear. In this study, we found that expression of both circulating IFN-1 and COX2-derived prostaglandin E2 (PGE2) was coordinately elevated in a cohort of influenza patients compared to healthy individuals. Expression of IFN-1 was blocked by a selective COX2 inhibitor during influenza A virus infection in A549 human lung epithelial cells but enhanced by overexpression of COX2, indicating that the production of IFN-1 is COX2 dependent. COX2 was able to increase IFN-1 expression by promoting NF-B binding to the enhancer in the IFN-1 promoter. We found that epigenetic changes activate COX2 expression and PGE2 accumulation during viral infection. The expression of DNA methyltransferase 3a (DNMT3a) and DNMT3b, but not that of DNMT1, was downregulated following influenza A virus infection in both A549 cells and peripheral blood mononuclear cells (PBMCs). We showed that microRNA miR29 suppresses DNMT activity and thus induces expression of COX2 and PGE2. Furthermore, miR29 expression was elevated 50-fold in virally infected A549 cells and 10-fold in PBMCs from influenza patients, compared to expression after mock infection of A549 cells or in healthy individuals, respectively. Activation of the protein kinase A signaling pathway and phosphorylation of CREB1 also contributed to COX2 expression. Collectively, our work defines a novel proinflammatory cascade in the control of influenza A virus infection.

Transforming growth factor-β induces microRNA-29b to promote murine alveolar macrophage dysfunction after bone marrow transplantation

“…Although the effects on methylation following transfection of miR-29b are rapid, these observation are supported by previous publications highlighting changes in PGE 2 production following 24-h transfection of A549 cells with siRNA against DNMT1, DNMT3a, or DNMT3b (20) and DNMT activity following 48-h transfection of a lung fibroblast cell line with siRNA against DNMTs (17). Furthermore, a study investigating gene methylation in breast cancer cells following transfection with miR-29b showed significant changes in methylation following 72-h transfection of pre-miR-29b (52).…”

“…As mentioned earlier, miR-29b has putative binding sites in the 3=UTR of DNMT3a and DNMT3b. A previous study confirmed these binding sites and showed direct binding of miR-29b on the 3=UTR (20). A previous study also showed that miR-29b can indirectly downregulate DNMT1 by targeting Sp1 (21).…”

“…DNMT3a and DNMT3b contain a miR29b target sequence in their 3=UTR (TargetScan) (20). To determine whether the altered expressions of DNMTs were a result of direct regulation by miR-29b, primary AMs from WT mice were transiently transfected with miR-29b for 24 h. Following overexpression of miR-29b, DNMT3a and DNMT3b as well as DNMT1 expression decreased significantly (Fig.…”

“…Our study presented here identifies the microRNA miR-29b as significantly upregulated in BMT AMs. Interestingly, miR-29b contains predicted target sites within the 3=UTR of the de novo DNA methyltransferases (DNMT), DNMT3a and DNMT3b (TargetScan, Cambridge, MA) (12,20,22,55), and has been shown to directly target DNMT3a and DNMT3b (20) while indirectly targeting DNMT1 by targeting a transactivator of DNMT1, Sp1 (21). DNMTs are responsible for the transfer of methyl groups onto CpG residues and for maintaining methylation patterns (29).…”

Overexpression of MicroRNA-25 by Withaferin A Induces Cyclooxygenase-2 Expression in Rabbit Articular Chondrocytes

“…In a previous study, they show that miR-29 suppresses DNMT activity and thus induces expression of COX-2 and PGE 2 . These findings reveal a novel proinflammatory cascade in the control of influenza A virus infection (31).…”