title: Binding of the pathogen receptor HSP90AA1 to avibirnavirus VP2 induces autophagy by inactivating the AKT-MTOR pathway.
abstract: Autophagy is an essential component of host innate and adaptive immunity. Viruses have developed diverse strategies for evading or utilizing autophagy for survival. The response of the autophagy pathways to virus invasion is poorly documented. Here, we report on the induction of autophagy initiated by the pathogen receptor HSP90AA1 (heat shock protein 90 kDa α [cytosolic], class A member 1) via the AKT-MTOR (mechanistic target of rapamycin)-dependent pathway. Transmission electron microscopy and confocal microscopy revealed that intracellular autolysosomes packaged avibirnavirus particles. Autophagy detection showed that early avibirnavirus infection not only increased the amount of light chain 3 (LC3)-II, but also upregulated AKT-MTOR dephosphorylation. HSP90AA1-AKT-MTOR knockdown by RNA interference resulted in inhibition of autophagy during avibirnavirus infection. Virus titer assays further verified that autophagy inhibition, but not induction, enhanced avibirnavirus replication. Subsequently, we found that HSP90AA1 binding to the viral protein VP2 resulted in induction of autophagy and AKT-MTOR pathway inactivation. Collectively, our findings suggest that the cell surface protein HSP90AA1, an avibirnavirus-binding receptor, induces autophagy through the HSP90AA1-AKT-MTOR pathway in early infection. We reveal that upon viral recognition, a direct connection between HSP90AA1 and the AKT-MTOR pathway trigger autophagy, a critical step for controlling infection.
authors.affiliation: a Key Laboratory of Animal Virology of Ministry of Agriculture ; Zhejiang University ; Hangzhou , China.
authors.forename: Boli
authors.initials: B
authors.lastname: Hu
authors.forename: Yina
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lu
authors.initials: L
authors.lastname: Jia
authors.forename: Huansheng
authors.initials: H
authors.lastname: Wu
authors.forename: Chengfei
authors.initials: C
authors.lastname: Fan
authors.forename: Yanting
authors.initials: Y
authors.lastname: Sun
authors.forename: Chengjin
authors.initials: C
authors.lastname: Ye
authors.forename: Min
authors.initials: M
authors.lastname: Liao
authors.forename: Jiyong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001343:Autophagy; D019202:Avibirnavirus / Q000378:metabolism*; D036022:Capsid Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002645:Chickens; D003600:Cytosol / Q000378:metabolism; D057809:HEK293 Cells; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D036022:Capsid Proteins; D018841:HSP90 Heat-Shock Proteins; C112969:HSP90AA1 protein, human; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; C546842:MTOR protein, human; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases
keywords: AKT-MTOR pathway; ANOVA, analysis of variance; ATG5, autophagy-related 5; BCA, bicinchoninic acid; BECN1, Beclin 1, autophagy-related; CoIP, coimmunoprecipitation; DMEM, Dulbecco's modified Eagle's medium; EBSS, Earle's balanced salt solution; EIF2AK2, eukaryotic translation initiation factor 2-alpha kinase 2; EIF2S1, eukaryotic translation initiation factor 2, subunit 1 alpha; ER, endoplasmic reticulum; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GOPC, golgi-associated PDZ and coiled-coil motif containing; GST, glutathione S-transferase; Gg, Gallus gallus (chicken); HE-IBDV, heat-inactivated IBDV; HSP90AA1; HSP90AA1, heat shock protein 90 kDa alpha (cytosolic), class A member 1; HSV-1, herpes simplex virus 1; Hs, Homo sapiens (human); IBDV, infectious bursal disease virus; IgG, immunoglobulin G; LPS, lipopolysaccharide; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; MOI, multiplicity of infection; MTOR, mechanistic target of rapamycin (serine/threonine kinase); Ni-NTA, nickel-nitrilotriacetic acid; PAMP, pathogen-associated molecular patterns; PBS, phosphate-buffered saline; PI3K, phosphoinositide 3-kinase; PRR, pattern recognition receptors; RNAi, RNA interference; SDS, sodium dodecyl sulfate; SQSTM1, sequestosome 1; SVP, subviral particle; TCID50, 50% tissue culture infectious doses; TLR, toll-like receptors; TSC, tuberous sclerosis complex; VP, viral protein; autophagy; avibirnavirus; cDNA, complementary DNA; dsRNA, double-stranded RNA; eGFP, enhanced green fluorescent protein; hpi, hours post-infection; mAb, monoclonal antibody; shRNA, short hairpin RNA; siRNA, small interfering RNA; viral protein VP2