title: Role of cyclophilin B in activation of interferon regulatory factor-3.
abstract: IRF-3 is a member of the interferon regulatory factors (IRFs) and plays a principal role in the induction of interferon-beta (IFN-beta) by virus infection. Virus infection results in the phosphorylation of IRF-3 by IkappaB kinase epsilon and TANK-binding kinase 1, leading to its dimerization and association with the coactivators CREB-binding protein/p300. The IRF-3 holocomplex translocates to the nucleus, where it induces IFN-beta. In the present study, we examined the molecular mechanism of IRF-3 activation. Using bacterial two-hybrid screening, we isolated molecules that interact with IRF-3. One of these was cyclophilin B, a member of the immunophilins with a cis-trans peptidyl-prolyl isomerase activity. A GST pull-down assay suggested that one of the autoinhibition domains of IRF-3 and the peptidyl-prolyl isomerase domain of cyclophilin B are required for the binding. A knockdown of cyclophilin B expression by RNA interference resulted in the suppression of virus-induced IRF-3 phosphorylation, leading to the inhibition of the subsequent dimerization, association with CREB-binding protein, binding to the target DNA element, and induction of IFN-beta. These findings indicate that cyclophilin B plays a critical role in IRF-3 activation.
authors.affiliation: Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Obata
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Masanobu
authors.initials: M
authors.lastname: Miyazaki
authors.forename: Kunitada
authors.initials: K
authors.lastname: Shimotohno
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kohno
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Matsuyama
mesh_terms: D000595:Amino Acid Sequence; D050882:CREB-Binding Protein; D045744:Cell Line, Tumor; D021983:Cyclophilins / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D050838:Interferon Regulatory Factor-3; D007372:Interferons / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D020218:Response Elements / Q000235:genetics; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D004268:DNA-Binding Proteins; C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C081786:cyclophilin B; D007372:Interferons; D050882:CREB-Binding Protein; C494363:CREBBP protein, human; D021983:Cyclophilins; D019696:Peptidylprolyl Isomerase