Binding of the pathogen receptor HSP90AA1 to avibirnavirus VP2 induces autophagy by inactivating the AKT-MTOR pathway

• Published in: Autophagy Vol. 11; no. 3; pp. 503 - 515
• Main Authors: Hu, Boli, Zhang, Yina, Jia, Lu, Wu, Huansheng, Fan, Chengfei, Sun, Yanting, Ye, Chengjin, Liao, Min, Zhou, Jiyong
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01-01-2015
• Subjects: 50% tissue culture infectious doses; AKT-MTOR pathway; Animals; ANOVA, analysis of variance; ATG5, autophagy-related 5; Autophagy; avibirnavirus; Avibirnavirus - metabolism; Basic Research Paper; BCA, bicinchoninic acid; BECN1, Beclin 1, autophagy-related; Capsid Proteins - metabolism; cDNA, complementary DNA; Cell Membrane - metabolism; Chickens; CoIP, coimmunoprecipitation; Cytosol - metabolism; DMEM, Dulbecco's modified Eagle's medium; dsRNA, double-stranded RNA; EBSS, Earle's balanced salt solution; eGFP, enhanced green fluorescent protein; 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; Gg, Gallus gallus (chicken); GOPC, golgi-associated PDZ and coiled-coil motif containing; GST, glutathione S-transferase; HE-IBDV, heat-inactivated IBDV; HEK293 Cells; hpi, hours post-infection; Hs, Homo sapiens (human); HSP90 Heat-Shock Proteins - metabolism; HSP90AA1; HSP90AA1, heat shock protein 90 kDa alpha (cytosolic), class A member 1; HSV-1, herpes simplex virus 1; Humans; IBDV, infectious bursal disease virus; IgG, immunoglobulin G; LPS, lipopolysaccharide; Lysosomes - metabolism; mAb, monoclonal antibody; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; Microscopy, Confocal; Microscopy, Electron, Transmission; Microtubule-Associated Proteins - metabolism; 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; Phagosomes - metabolism; Phosphorylation; PI3K, phosphoinositide 3-kinase; Protein Binding; Proto-Oncogene Proteins c-akt - metabolism; PRR, pattern recognition receptors; RNA Interference; RNA, Small Interfering - metabolism; RNAi, RNA interference; SDS, sodium dodecyl sulfate; shRNA, short hairpin RNA; siRNA, small interfering RNA; SQSTM1, sequestosome 1; SVP, subviral particle; TCID; TLR, toll-like receptors; TOR Serine-Threonine Kinases - metabolism; TSC, tuberous sclerosis complex; viral protein VP2; VP, viral protein; TCID50, 50% tissue culture infectious doses; RNAi, RNA interference; TSC, tuberous sclerosis complex; dsRNA, double-stranded RNA; mAb, monoclonal antibody; Gg, Gallus gallus (chicken); HE-IBDV, heat-inactivated IBDV; DMEM, Dulbecco's modified Eagle's medium; HSP90AA1, heat shock protein 90 kDa alpha (cytosolic), class A member 1; ANOVA, analysis of variance; EIF2AK2, eukaryotic translation initiation factor 2-alpha kinase 2; HSP90AA1; autophagy; GST, glutathione S-transferase; IBDV, infectious bursal disease virus; EBSS, Earle's balanced salt solution; EIF2S1, eukaryotic translation initiation factor 2, subunit 1 alpha; BECN1, Beclin 1, autophagy-related; MTOR, mechanistic target of rapamycin (serine/threonine kinase); IgG, immunoglobulin G; Ni-NTA, nickel-nitrilotriacetic acid; SQSTM1, sequestosome 1; LPS, lipopolysaccharide; shRNA, short hairpin RNA; PAMP, pathogen-associated molecular patterns; PI3K, phosphoinositide 3-kinase; cDNA, complementary DNA; HSV-1, herpes simplex virus 1; eGFP, enhanced green fluorescent protein; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; hpi, hours post-infection; SDS, sodium dodecyl sulfate; PBS, phosphate-buffered saline; SVP, subviral particle; ATG5, autophagy-related 5; PRR, pattern recognition receptors; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; CoIP, coimmunoprecipitation; VP, viral protein; BCA, bicinchoninic acid; Hs, Homo sapiens (human); TLR, toll-like receptors; siRNA, small interfering RNA; AKT-MTOR pathway; MOI, multiplicity of infection; viral protein VP2; GOPC, golgi-associated PDZ and coiled-coil motif containing; ER, endoplasmic reticulum; avibirnavirus
• ISSN: 1554-8627; 1554-8635
• DOI: 10.1080/15548627.2015.1017184

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.