title: Hsp90 regulates activation of interferon regulatory factor 3 and TBK-1 stabilization in Sendai virus-infected cells.
abstract: Interferon regulatory factor 3 (IRF3) plays a crucial role in mediating cellular responses to virus intrusion. The protein kinase TBK1 is a key regulator inducing phosphorylation of IRF3. The regulatory mechanisms during IRF3 activation remain poorly characterized. In the present study, we have identified by yeast two-hybrid approach a specific interaction between IRF3 and chaperone heat-shock protein of 90 kDa (Hsp90). The C-terminal truncation mutant of Hsp90 is a strong dominant-negative inhibitor of IRF3 activation. Knockdown of endogenous Hsp90 by RNA interference attenuates IRF3 activation and its target gene expressions. Alternatively, Hsp90-specific inhibitor geldanamycin (GA) dramatically reduces expression of IRF3-regulated interferon-stimulated genes and abolishes the cytoplasm-to-nucleus translocation and DNA binding activity of IRF3 in Sendai virus-infected cells. Significantly, virus-induced IRF3 phosphorylation is blocked by GA, whereas GA does not affect the protein level of IRF3. In addition, TBK1 is found to be a client protein of Hsp90 in vivo. Treatment of 293 cells with GA interferes with the interaction of TBK1 and Hsp90, resulting in TBK1 destabilization and its subsequent proteasome-mediated degradation. Besides maintaining stability of TBK1, Hsp90 also forms a novel complex with TBK1 and IRF3, which brings TBK1 and IRF3 dynamically into proximity and facilitates signal transduction from TBK1 to IRF3. Our study uncovers an essential role of Hsp90 in the virus-induced activation of IRF3.
authors.affiliation: Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Yang
authors.forename: Hexin
authors.initials: H
authors.lastname: Shi
authors.forename: Rong
authors.initials: R
authors.lastname: Qi
authors.forename: Shaogang
authors.initials: S
authors.lastname: Sun
authors.forename: Yujie
authors.initials: Y
authors.lastname: Tang
authors.forename: Bianhong
authors.initials: B
authors.lastname: Zhang
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
mesh_terms: D000818:Animals; D016227:Benzoquinones; D001665:Binding Sites; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000172:deficiency / Q000378:metabolism*; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000737:chemistry / Q000378:metabolism*; D047029:Lactams, Macrocyclic; D051379:Mice; D046912:Multiprotein Complexes; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011809:Quinones / Q000494:pharmacology; D034622:RNA Interference; D029082:Sendai virus / Q000502:physiology*; D013816:Thermodynamics
chemical_list: D016227:Benzoquinones; D018841:HSP90 Heat-Shock Proteins; D050838:Interferon Regulatory Factor-3; D047029:Lactams, Macrocyclic; D046912:Multiprotein Complexes; D011809:Quinones; D017346:Protein Serine-Threonine Kinases; C403191:TBK1 protein, human; C001277:geldanamycin