Inhibition of EHMT2 Induces a Robust Antiviral Response Against Foot-and-Mouth Disease and Vesicular Stomatitis Virus Infections in Bovine Cells

Abstract

The genetic regulatory network controlling the innate immune system is well understood in many species. However, the role of the epigenetic mechanisms underlying the expression of immunoregulatory genes is less clear, especially in livestock species. Histone H3 lysine 9 dimethylation (H3K9me2) is an epigenetic modification associated with transcriptional silencing within the euchromatin regions. Euchromatic histone-lysine Nmethyltransferase 2 (EHMT2; also known as G9a) is a crucial enzyme responsible for regulating the dynamics of this epigenetic modification. It has been shown that histone modifications play a role in regulating type I interferon (IFN) response. In the present study, we investigated the role of EHMT2 in the epigenetic regulation of bovine antiviral innate immunity and explored its therapeutic potential against viral infections. We evaluated the effects of pharmacological and RNAi-mediated inhibition of EHMT2 on the transcription of IFN-b and other IFN-inducible antiviral genes, as well as its effect on foot-and-mouth disease virus (FMDV) and vesicular stomatitis virus (VSV) replication in bovine cells. We show that treatment of primary bovine cells with the synthetic EHMT2 inhibitor (UNC0638) either before or shortly after virus infection resulted in a significant increase in transcript levels of bovine IFN-b (boIFN-b; 300-fold) and other IFN-inducible genes, including IFNstimulated gene 15 (ISG-15), myxovirus resistance 1 (Mx-1), Mx-2, RIG-I, 2¢,5¢-oligoadenylate synthetase 1 (OAS-1), and protein kinase R (PKR). Expression of these factors correlated with a significant decrease in VSV and FMDV viral titers. Our data confirm the involvement of EHMT2 in the epigenetic regulation of boIFN-b and demonstrate the activation of a general antiviral state after EHMT2 inhibition.

RNA-Seq Revealed a Circular RNA-microRNA-mRNA Regulatory Network in Hantaan Virus Infection

“…It has been reported that IFI44 is an IFN-inducible protein, related to infection of several viruses (Balan et al, 2006;Power et al, 2015;deDiego et al, 2019). Other studies documented that OAS1 plays an important role in antiviral activity as antiviral factor (Knapp et al, 2003;Melchjorsen et al, 2009;Singh et al, 2016). CASP1 participates in the composition of the inflammasome which actives the pro-inflammatory cytokines IL-18 and IL-1β, resulting in the proinflammatory cell death known as pyroptosis (Lupfer et al, 2015).…”

Molecular Mechanisms of Foot-and-Mouth Disease Virus Targeting the Host Antiviral Response

“…The role of an enzyme involved in epigenetics modifications, the histone methyltransferase EHMT2, in regulation of bovine IFN-β gene expression and in the establishment of an antiviral state in primary bovine fibroblast cells has been reported, as well as the prophylactic and therapeutic use of EHMT2 inhibitors to control FMDV replication (Singh et al, 2016). …”

“…Experiments in pigs showed a good correlation between IFN-induced protection against FMDV and induction of ISGs in skin, peripheral blood mononuclear cells, and lymphoid tissues (Diaz-San Segundo et al, 2010 ). The role of an enzyme involved in epigenetics modifications, the histone methyltransferase EHMT2, in regulation of bovine IFN-β gene expression and in the establishment of an antiviral state in primary bovine fibroblast cells has been reported, as well as the prophylactic and therapeutic use of EHMT2 inhibitors to control FMDV replication (Singh et al, 2016 ).…”

Use of IFN-Based Biotherapeutics to Harness the Host Against Foot-And-Mouth Disease

“…Studies in porcine cells demonstrated that FMDV Lpro can promote its self-binding to the transcription factor activity-dependent neuroprotective protein (ADNP) and negatively regulate the activity of the IFN-α promoter ( 57 ). In contrast, chromatin changes that favor the upregulation of IFN and ISGs can inhibit FMDV replication ( 58 ). Interestingly, deletion or mutations in different domains of Lpro result in viral attenuation in vitro and in vivo ( 59 – 63 ).…”