title: Spatiotemporal regulation of MyD88-IRF-7 signalling for robust type-I interferon induction.
abstract: Robust type-I interferon (IFN-alpha/beta) induction in plasmacytoid dendritic cells, through the activation of Toll-like receptor 9 (TLR9), constitutes a critical aspect of immunity. It is absolutely dependent on the transcription factor IRF-7, which interacts with and is activated by the adaptor MyD88. How plasmacytoid dendritic cells, but not other cell types (such as conventional dendritic cells), are able to activate the MyD88-IRF-7-dependent IFN induction pathway remains unknown. Here we show that the spatiotemporal regulation of MyD88-IRF-7 signalling is critical for a high-level IFN induction in response to TLR9 activation. The IFN-inducing TLR9 ligand, A/D-type CpG oligodeoxynucleotide (CpG-A), is retained for long periods in the endosomal vesicles of plasmacytoid dendritic cells, together with the MyD88-IRF-7 complex. However, in conventional dendritic cells, CpG-A is rapidly transferred to lysosomal vesicles. We further show that conventional dendritic cells can also mount a robust IFN induction if CpG-A is manipulated for endosomal retention using a cationic lipid. This strategy also allows us to demonstrate endosomal activation of the IFN pathway by the otherwise inactive TLR9 ligand B/K-type oligodeoxynucleotide (CpG-B). Thus, our study offers insights into the regulation of TLR9 signalling in space, potentially suggesting a new avenue for therapeutic intervention.
authors.affiliation: Department of Immunology, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kenya
authors.initials: K
authors.lastname: Honda
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ohba
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yanai
authors.forename: Hideo
authors.initials: H
authors.lastname: Negishi
authors.forename: Tatsuaki
authors.initials: T
authors.lastname: Mizutani
authors.forename: Akinori
authors.initials: A
authors.lastname: Takaoka
authors.forename: Choji
authors.initials: C
authors.lastname: Taya
authors.forename: Tadatsugu
authors.initials: T
authors.lastname: Taniguchi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D001854:Bone Marrow Cells / Q000166:cytology; D002460:Cell Line; D018899:CpG Islands / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003713:Dendritic Cells / Q000145:classification / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D011992:Endosomes / Q000378:metabolism; D050839:Interferon Regulatory Factor-7; D007370:Interferon Type I / Q000276:immunology* / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D051379:Mice; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D051217:Toll-Like Receptor 9
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D004268:DNA-Binding Proteins; D050839:Interferon Regulatory Factor-7; D007370:Interferon Type I; C494235:Irf7 protein, mouse; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9