ADAP2 Is an Interferon Stimulated Gene That Restricts RNA Virus Entry.

Qian Shu,Saumendra N Sarkar,Yoel Sadovsky,Carolyn B Coyne,Nicholas J Lennemann,Michael Gale

doi:10.1371/journal.ppat.1005150

Abstract

Interferon stimulated genes (ISGs) target viruses at various stages of their infectious life cycles, including at the earliest stage of viral entry. Here we identify ArfGAP with dual pleckstrin homology (PH) domains 2 (ADAP2) as a gene upregulated by type I IFN treatment in a STAT1-dependent manner. ADAP2 functions as a GTPase-activating protein (GAP) for Arf6 and binds to phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P3) and PI(3,4)P2. We show that overexpression of ADAP2 suppresses dengue virus (DENV) and vesicular stomatitis virus (VSV) infection in an Arf6 GAP activity-dependent manner, while exerting no effect on coxsackievirus B (CVB) or Sendai virus (SeV) replication. We further show that ADAP2 expression induces macropinocytosis and that ADAP2 strongly associates with actin-enriched membrane ruffles and with Rab8a- and LAMP1-, but not EEA1- or Rab7-, positive vesicles. Utilizing two techniques—light-sensitive neutral red (NR)-containing DENV and fluorescence assays for virus internalization—we show that ADAP2 primarily restricts DENV infection at the stage of virion entry and/or intracellular trafficking and that incoming DENV and VSV particles associate with ADAP2 during their entry. Taken together, this study identifies ADAP2 as an ISG that exerts antiviral effects against RNA viruses by altering Arf6-mediated trafficking to disrupt viral entry.

Highlights

The induction of innate immune signaling is critical for host defense against viral infections, and is most commonly initiated by the detection of foreign nucleic acids as non-self
We identify ArfGAP with dual pleckstrin homology (PH) domains 2 (ADAP2) as an interferon-stimulated genes (ISGs) whose expression restricts the replication of dengue virus (DENV), which infects as many
We found that many known ISGs, such as interferon-induced protein 44-like (IFI44L), members of the interferon-induced protein with tetratricopeptide repeats (IFIT) family, radical S-adenosyl methionine domain containing 2 (RSAD2), and members of the 2',5'-Oligoadenylate synthetase (OAS) family were upregulated by IFNβ treatment in a STAT1-mediated manner (Fig 1A and S1 Table)

Summary

Introduction

The induction of innate immune signaling is critical for host defense against viral infections, and is most commonly initiated by the detection of foreign nucleic acids as non-self. Once this system is activated, host cells orchestrate an array of signaling pathways that culminate in the induction of type I interferons (IFNs), which include IFNα and IFNβ. ISGs function to restrict viral replication at various stages of the viral life cycle, with some ISGs targeting the earliest event associated with infection—viral entry into the host cell. The targeting of viruses at the earliest stages of their infectious life cycles serves as a potent step at which ISGs can antagonize viral infections

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