Epigenetic control of influenza virus: role of H3K79 methylation in interferon-induced antiviral response

Abstract

Influenza virus stablishes a network of virus-host functional interactions, which depends on chromatin dynamic and therefore on epigenetic modifications. Using an unbiased search, we analyzed the epigenetic changes at DNA methylation and post-translational histone modification levels induced by the infection. DNA methylation was unaltered, while we found a general decrease on histone acetylation, which correlates with transcriptional inactivation and may cooperate with the impairment of cellular transcription that causes influenza virus infection. A particular increase in H3K79 methylation was observed and the use of an inhibitor of the specific H3K79 methylase, Dot1L enzyme, or its silencing, increased influenza virus replication. The antiviral response was reduced in conditions of Dot1L downregulation, since decreased nuclear translocation of NF-kB complex, and IFN-β, Mx1 and ISG56 expression was detected. The data suggested a control of antiviral signaling by methylation of H3K79 and consequently, influenza virus replication was unaffected in IFN pathway-compromised, Dot1L-inhibited cells. H3K79 methylation also controlled replication of another potent interferon-inducing virus such as vesicular stomatitis virus, but did not modify amplification of respiratory syncytial virus that poorly induces interferon signaling. Epigenetic methylation of H3K79 might have an important role in controlling interferon-induced signaling against viral pathogens.

Interferon-β Stimulation Elicited by the Influenza Virus Is Regulated by the Histone Methylase Dot1L through the RIG-I-TRIM25 Signaling Axis

“…TRIM25 overexpression reverses the defective innate response mediated by Dot1L inhibition elicited upon virus infection or by overexpression of RIG-I signaling intermediates. Thus, TRIM25 is a control point of the RIG-I recognition pathway controlled by Dot1L and may have a general role in RNA viruses recognized by the RIG-I sensor.Cells 2020, 9, 732 2 of 20 H1N1 virus-infected cells, we observed unaltered DNA methylation and a general decrease in histone acetylation, which correlates with the cell host transcriptional inactivation that takes place during infection.Unexpectedly, we observed an increase in the methylation of lysine 79 of histone 3 (H3K79) in the infected cells [5]. The methylation of H3K79 is carried out by the histone methylase Dot1L, which exclusively methylates this lysine, and its methylation is increased in actively transcribing genes [6,7].…”

“…Unexpectedly, we observed an increase in the methylation of lysine 79 of histone 3 (H3K79) in the infected cells [5]. The methylation of H3K79 is carried out by the histone methylase Dot1L, which exclusively methylates this lysine, and its methylation is increased in actively transcribing genes [6,7].…”

“…Transfection with pIF-LukTer triggered a basal luciferase expression that was not altered when inhibiting Dot1L ( Figure 1A). In addition, the downregulation of Dot1L expression was also performed using lentiviruses expressing shRNA specific for Dot1L (shDot1L.1, shDot1L.2) [5] or a control that expresses irrelevant shRNA (shTM) [31,32].…”

“…We previously described the inhibition of the innate immune response against influenza virus infection by Dot1L inhibition [5]. To validate the transfection system upon viral infection, A549 cells were left untreated or treated with Dot1L inhibitor EPZ.…”

“…The methylation of H3K79 is carried out by the histone methylase Dot1L, which exclusively methylates this lysine, and its methylation is increased in actively transcribing genes [6,7]. The inhibition of Dot1l by pinometostat (EPZ) treatment or by Dot1L silencing, stimulated influenza and vesicular stomatitis virus replication [5]. Further characterization showed decreased nuclear translocation of the NF-kB complex, as well as IFN-β, Mx1 and ISG56 expression in EPZ-treated cells [5] indicating a decreased antiviral type I IFN response, and as a consequence, a stimulation in viral replication.…”