Deficiency in either 4E-BP1 or 4E-BP2 augments innate antiviral immune responses.

Atef Nehdi,Rodney Colina,Izzar Linares,Maritza Jaramillo,Polen Sean,Tommy Alain,Volker Thiel

doi:10.1371/journal.pone.0114854

Abstract

Genetic deletion of both 4E-BP1 and 4E-BP2 was found to protect cells against viral infections. Here we demonstrate that the individual loss of either 4E-BP1 or 4E-BP2 in mouse embryonic fibroblasts (MEFs) is sufficient to confer viral resistance. shRNA-mediated silencing of 4E-BP1 or 4E-BP2 renders MEFs resistant to viruses, and compared to wild type cells, MEFs knockout for either 4E-BP1 or 4E-BP2 exhibit enhanced translation of Irf-7 and consequently increased innate immune response to viruses. Accordingly, the replication of vesicular stomatitis virus, encephalomyocarditis virus, influenza virus and Sindbis virus is markedly suppressed in these cells. Importantly, expression of either 4E-BP1 or 4E-BP2 in double knockout or respective single knockout cells diminishes their resistance to viral infection. Our data show that loss of 4E-BP1 or 4E-BP2 potentiates innate antiviral immunity. These results provide further evidence for translational control of innate immunity and support targeting translational effectors as an antiviral strategy.

Highlights

The 59 end of all nuclear-transcribed mRNAs possesses a cap structure that is recognized by the eukaryotic translation initiation factor 4E [1,2,3]. eIF4EPLOS ONE | DOI:10.1371/journal.pone.0114854 December 22, 2014Deficiency in 4E-BP1 or 4E-BP2 Augments Innate Antiviral Immunity binds to the cap as a subunit of a complex containing the large scaffolding protein eIF4G and the RNA helicase eIF4A [3,4,5]
Wild type (WT) mouse embryonic fibroblasts (MEFs) transduced with lentiviruses expressing shRNA against 4EBP1 showed little to no detectable 4E-BP1 protein, as compared to MEFs transduced with a scrambled shRNA (Fig. 1A)
Stable 4E-BP1 or 4E-BP2 knockdown MEFs were infected with Vesicular stomatitis virus (VSV)-green fluorescent protein (GFP) at a multiplicity of infection (MOI) of 1

Summary

Introduction

Deficiency in 4E-BP1 or 4E-BP2 Augments Innate Antiviral Immunity binds to the cap as a subunit of a complex (termed eIF4F) containing the large scaffolding protein eIF4G and the RNA helicase eIF4A [3,4,5]. The eIF4F complex facilitates 40S ribosome recruitment and canonical initiation factors, eIF4E and eIF4G, stimulate this reaction [6]. The interaction between eIF4E and eIF4G is regulated by members of the eIF4E-binding proteins (4E-BPs), a family of translational repressors [8,9,10]. The activity of 4E-BPs is controlled by the mammalian target of rapamycin (mTOR) kinase complex I (mTORC1), which consists of the protein kinase mTOR, RAPTOR (regulatory associated protein of mTOR), GbL (GTPase b-like protein) DEPTOR (disheveled, Egl-10, pleckstrin domain containing mTOR interacting protein) and PRAS40 (proline-rich Akt substrate of 40 kDa) [14,15,16]. A large body of evidence indicates that the mTOR pathway is an integral part of innate immunity through its critical roles in signaling and translational control of interferon stimulated genes (ISGs) [19,20,21,22]

Methods

Results

Conclusion