Absence of SHIP-1 results in constitutive phosphorylation of tank-binding kinase 1 and enhanced TLR3-dependent IFN-beta production.
Autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis, result from a loss of tolerance to self-antigens and immune-mediated injury precipitated by the overproduction of type I IFN and inflammatory cytokines. We have identified the inositol 5' phosphatase SHIP-1 as a negative regulator of TLR3-induced type I IFN production. SHIP-1-deficient macrophages display enhanced TLR-induced IFN-beta production, and overexpression of SHIP-1 negatively regulates the ability of TLR3 and its adaptor, Toll/IL-1 receptor domain-containing adaptor-inducing IFN-beta, to induce IFN-beta promoter activity, indicating that SHIP-1 negatively regulates TLR-induced IFN-beta production. Further dissection of the IFN-beta pathway implicates TANK-binding kinase 1 (TBK1) as the target for SHIP-1. Critically, in the absence of SHIP-1, TBK1 appears to be hyperphosphorylated both in unstimulated cells and following TLR3 stimulation. In addition, TBK1 appears to be constitutively associated with Toll/IL-1 receptor domain-containing adaptor-inducing IFN-beta and TNFR-associated factor 3 in SHIP-1 deficient cells, whereas in wild-type cells this association is inducible following TLR3 stimulation. In support of a role for SHIP-1 in regulating complex formation, confocal microscopy demonstrates that TBK1 distribution in the cell is significantly altered in SHIP-1-deficient cells, with more prominent endosomal staining observed, compared with wild-type controls. Taken together, our results point to SHIP-1 as a critical negative regulator of IFN-beta production downstream of TLR3 through the regulation of TBK1 localization and activity.
Gabhann
Joan Ní
JN
Molecular and Cellular Therapeutics, Royal College of Surgeons, Ireland Research Institute, Dublin 2, Ireland.
Higgs
Rowan
R
Brennan
Kiva
K
Thomas
Warren
W
Damen
Jacqueline E
JE
Ben Larbi
Nadia
N
Krystal
Gerald
G
Jefferies
Caroline A
CA
D000634:Aminoquinolines / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D000077271:Imiquimod; D018836:Inflammation Mediators / Q000378:metabolism; D000072181:Inositol Polyphosphate 5-Phosphatases; D016899:Interferon-beta / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000378:metabolism; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000378:metabolism*
D000634:Aminoquinolines; D016207:Cytokines; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D016328:NF-kappa B; C519703:TLR3 protein, mouse; D051196:Toll-Like Receptor 3; D016899:Interferon-beta; C498588:Tbk1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; C000606430:INPP5D protein, human; C000606433:Inpp5d protein, mouse; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D000077271:Imiquimod