DHX36 Enhances RIG-I Signaling by Facilitating PKR-Mediated Antiviral Stress Granule Formation

• DOI: 10.1371/journal.ppat.1004012
• Publication Date: 2014-03-20T21:04:17Z
• Authors: Ji-Seung Yoo; Kiyohiro Takahasi; Chen Seng Ng; Ryota Ouda; Koji Onomoto; Mitsutoshi Yoneyama; Janice Ching Lai; Simon Lattmann; Yoshikuni Nagamine; Tadashi Matsui; Kuniyoshi Iwabuchi; Hiroki Kato; Takashi Fujita
• Keywords: 0301 basic medicine; QH301-705.5; Fluorescent Antibody Technique; Enzyme-Linked Immunosorbent Assay; Cytoplasmic Granules; Transfection; DEAD-box RNA Helicases; Gene Knockout Techniques; 03 medical and health sciences; RNA Virus Infections; Stress, Physiological; Humans; Immunoprecipitation; RNA Viruses; Biology (General); RNA, Small Interfering; Receptors, Immunologic; RNA, Double-Stranded; 0303 health sciences; Reverse Transcriptase Polymerase Chain Reaction; RC581-607; 3. Good health; HEK293 Cells; DEAD Box Protein 58; RNA, Viral; Immunologic diseases. Allergy; Research Article; HeLa Cells; Signal Transduction

RIG-I is a DExD/H-box RNA helicase and functions as a critical cytoplasmic sensor for RNA viruses to initiate antiviral interferon (IFN) responses. Here we demonstrate that another DExD/H-box RNA helicase DHX36 is a key molecule for RIG-I signaling by regulating double-stranded RNA (dsRNA)-dependent protein kinase (PKR) activation, which has been shown to be essential for the formation of antiviral stress granule (avSG). We found that DHX36 and PKR form a complex in a dsRNA-dependent manner. By forming this complex, DHX36 facilitates dsRNA binding and phosphorylation of PKR through its ATPase/helicase activity. Using DHX36 KO-inducible MEF cells, we demonstrated that DHX36 deficient cells showed defect in IFN production and higher susceptibility in RNA virus infection, indicating the physiological importance of this complex in host defense. In summary, we identify a novel function of DHX36 as a critical regulator of PKR-dependent avSG to facilitate viral RNA recognition by RIG-I-like receptor (RLR).