title: Activator protein 1 is triggered by Aspergillus fumigatus beta-glucans surface-exposed during specific growth stages.
abstract: Aspergillus fumigatus has been shown to trigger the activation of nuclear factor-kappaB (NF-kappaB), but it remains unclear whether other transcription factors are also induced following infection by this organism. In this study, we demonstrated that A. fumigatus also triggers activator protein 1 (AP-1), a transcription factor that plays an important role during the production of cytokines and chemokines. Swollen conidia strongly induce the activation of AP-1, and more than 80% of these were stained positively with anti-beta-glucan antibodies by fluorescence microscopy. Hyphae were also stained with anti-beta-glucan antibodies, albeit significantly weaker compared with swollen conidia. Furthermore, our present findings also showed that A. fumigatus triggers the activation of AP-1 in a dectin-1 (receptor for beta-glucan)-dependent manner. These data thus suggest that AP-1 is triggered by beta-glucan recognition on the surface of A. fumigatus. We also showed that Syk tyrosine kinase is required for AP-1 induction in this pathway. We therefore speculate that the dectin-1/Syk/AP-1 signaling pathway plays an important role in the host defense response to fungal infection.
authors.affiliation: Division of Fungal Infection, Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba City, Chiba, Japan. tome@restaff.chiba-u.jp
authors.forename: Takahito
authors.initials: T
authors.lastname: Toyotome
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Adachi
authors.forename: Akira
authors.initials: A
authors.lastname: Watanabe
authors.forename: Eri
authors.initials: E
authors.lastname: Ochiai
authors.forename: Naohito
authors.initials: N
authors.lastname: Ohno
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Kamei
mesh_terms: D000908:Antibodies, Fungal / Q000276:immunology; D019677:Artificial Gene Fusion; D001232:Aspergillus fumigatus / Q000276:immunology*; D017930:Genes, Reporter; D025301:Hyphae / Q000276:immunology; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology; D037181:Lectins, C-Type; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000276:immunology; D009419:Nerve Tissue Proteins / Q000276:immunology; D011505:Protein-Tyrosine Kinases / Q000276:immunology; D013172:Spores, Fungal / Q000276:immunology; D000072377:Syk Kinase; D018808:Transcription Factor AP-1 / Q000096:biosynthesis*; D047071:beta-Glucans / Q000276:immunology*; D000099181:Dectin-1
chemical_list: D000908:Antibodies, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D037181:Lectins, C-Type; D008156:Luciferases; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011505:Protein-Tyrosine Kinases; D000072377:Syk Kinase; D018808:Transcription Factor AP-1; D047071:beta-Glucans; D000099181:Dectin-1