Porcine reproductive and respiratory syndrome virus degrades DDX10 via SQSTM1/p62-dependent selective autophagy to antagonize its antiviral activity
Creators: name: Li, Jia
name: Zhou, Yanrong
name: Zhao, Wenkai
name: Liu, Jiao
name: Ullah, Rizwan
name: Fang, Puxian
name: Fang, Liurong
name: Xiao, Shaobo
Publisher: name: Taylor & Francis
Year: 2023
Subjects: subject: Medicine
subject: Cell Biology
subject: Genetics
subject: FOS: Biological sciences
subject: Molecular Biology
subject: Immunology
subject: FOS: Clinical medicine
subject: Biological Sciences not elsewhere classified
subject: Cancer
subject: Mental Health
subject: Infectious Diseases
subject: FOS: Health sciences
subject: Virology

description: Porcine reproductive and respiratory syndrome virus (PRRSV) is a typical immunosuppressive virus devastating the global swine industry. DEAD-box helicases (DDXs) are a family of ATP-dependent RNA helicases that are predominantly implicated in modulating cellular RNA metabolism. Meanwhile, a growing number of studies have suggested that some DDXs are associated with innate immunity and virus infection, so they are considered potential antiviral targets. Herein, we screened 40 DDXs and found that ectopic expression of DDX10 exhibited a significant anti-PRRSV effect, while DDX10 knockdown promoted PRRSV proliferation. Further analysis revealed that DDX10 positively regulates type I interferon production, which may contribute to its anti-PRRSV effect. Interestingly, PRRSV infection promoted DDX10 translocation from the nucleus to the cytoplasm for macroautophagic/autophagic degradation to block the antiviral effect of DDX10. By screening PRRSV-encoded proteins, we found that the viral envelope (E) protein interacted with DDX10. In line with the autophagic degradation of DDX10 during PRRSV infection, E protein could induce autophagy and reduce DDX10 expression in wild-type cells, but not in <i>ATG5</i> or <i>ATG7</i> knockout (KO) cells. When further screening the cargo receptors for autophagic degradation, we found that SQSTM1/p62 (sequestosome 1) interacted with both DDX10 and E protein, and E protein-mediated DDX10 degradation was almost entirely blocked in <i>SQSTM1</i> KO cells, demonstrating that E protein degrades DDX10 by promoting <i>SQSTM1</i>-mediated selective autophagy. Our study reveals a novel mechanism by which PRRSV escapes host antiviral innate immunity through selective autophagy, providing a new target for developing anti-PRRSV drugs.<b>Abbreviations:</b> ACTB: actin beta; ATG: autophagy related; co-IP: co-immunoprecipitation; CQ: chloroquine; DDX10: DEAD-box helicase 10; E: envelope; EGFP: enhanced green fluorescent protein; hpi: hours post infection; hpt: hours post transfection; IFA: indirect immunofluorescence assay; IFN-I: type I IFN; IFNB/IFN-β: interferon beta; IRF3: interferon regulatory factor 3; ISGs: interferon-stimulated genes; KO: knockout; MAP1LC3B/LC3: microtubule associated protein 1 light chain 3 beta; mAb: monoclonal antibody; MOI: multiplicity of infection; NBR1: NBR1 autophagy cargo receptor; NFKB/NF-κB: nuclear factor kappa B; OPTN: optineurin; ORF: open reading frame; PRRSV: porcine reproductive and respiratory syndrome virus; SeV: sendai virus; siRNA: small interfering RNA; SQSTM1/p62: sequestosome 1; TCID<sub>50</sub>: 50% tissue culture infective dose; WT: wild type.