Mitogen-Activated Protein Kinase Kinase 2, a Novel E2-Interacting Protein, Promotes the Growth of Classical Swine Fever Virus via Attenuation of the JAK-STAT Signaling Pathway

Abstract

The mitogen-activated protein kinase kinase/extracellular regulated kinase (MEK1/2/ERK1/2) cascade is involved in the replication of several members of the Flaviviridae family, including hepatitis C virus and dengue virus. The effects of the cascade on the replication of classical swine fever virus (CSFV), a fatal pestivirus of pigs, remain unknown. In this study, MEK2 was identified as a novel binding partner of the E2 protein of CSFV using yeast two-hybrid screening. The E2-MEK2 interaction was confirmed by glutathione S-transferase pulldown, coimmunoprecipitation, and laser confocal microscopy assays. The C termini of E2 (amino acids [aa] 890 to 1053) and MEK2 (aa 266 to 400) were mapped to be crucial for the interaction. Overexpression of MEK2 significantly promoted the replication of CSFV, whereas knockdown of MEK2 by lentivirus-mediated small hairpin RNAs dramatically inhibited CSFV replication. In addition, CSFV infection induced a biphasic activation of ERK1/2, the downstream signaling molecules of MEK2. Furthermore, the replication of CSFV was markedly inhibited in PK-15 cells treated with U0126, a specific inhibitor for MEK1/2/ERK1/2, whereas MEK2 did not affect CSFV replication after blocking the interferon-induced Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway by ruxolitinib, a JAK-STAT-specific inhibitor. Taken together, our results indicate that MEK2 positively regulates the replication of CSFV through inhibiting the JAK-STAT signaling pathway.IMPORTANCE Mitogen-activated protein kinase kinase 2 (MEK2) is a kinase that operates immediately upstream of extracellular regulated kinase 1/2 (ERK1/2) and links to Raf and ERK via phosphorylation. Currently, little is known about the role of MEK2 in the replication of classical swine fever virus (CSFV), a devastating porcine pestivirus. Here, we investigated the roles of MEK2 and the MEK2/ERK1/2 cascade in the growth of CSFV for the first time. We show that MEK2 positively regulates CSFV replication. Notably, we demonstrate that MEK2 promotes CSFV replication through inhibiting the interferon-induced JAK-STAT signaling pathway, a key antiviral pathway involved in innate immunity. Our work reveals a novel role of MEK2 in CSFV infection and sheds light on the molecular basis by which pestiviruses interact with the host cell.

Rab5 Enhances Classical Swine Fever Virus Proliferation and Interacts with Viral NS4B Protein to Facilitate Formation of NS4B Related Complex

“…Eukaryotic elongation factor 1A binds to CSFV replicase protein NS5A to block virus replication ( Li et al, 2015 ). Mitogen-activated protein kinase 2 interacts with CSFV main antigen protein E2 to promote CSFV growth via the attenuation of the JAK-STAT signaling pathway ( Hu et al, 2016 ; Wang et al, 2016 ). Rab5 interacts with tomato bushy stunt virus replication protein to support virus replication and protects the virus from host antiviral responses ( Xu and Nagy, 2016 ).…”

SERTA Domain Containing Protein 1 (SERTAD1) Interacts with Classical Swine Fever Virus Structural Glycoprotein E2, Which Is Involved in Virus Virulence in Swine

“…E rns has been demonstrated to interact with the laminin receptor [16]. In addition, E2 has been shown to interact with several host proteins including cellular actin [17], thioredoxin [18], annexin 2 [19], mitogen-activated protein kinase 2 [20], protein phosphatase 1 catalytic subunit beta [21] and dynactin 6 [22]. These host-virus protein-protein interactions have been shown to play a role in regulating the virus replication cycle, and in some cases, these protein interactions are involved in virus virulence [12][13][14]22].…”

Dengue virus-1 NS5 genetic variant associated with a severe clinical infection: Possible reduction of the innate immune response by inhibition of interferon type 1 and the Janus kinase-signal transducer and activator of transcription signaling pathway

“…This suggests that genetic variants 372A/G and 496G/A (protein variants 124Ile/Met and 166Gly/Ser) in NS5 of dENV-1 condition the degree of antagonism with type 1 interferon due to interruption of JAK-STAT1. It has recently been reported, in similar viruses, that replication increases through inhibiting the JAK-STAT signaling pathway (34).…”