title: A role for APPL1 in TLR3/4-dependent TBK1 and IKKε activation in macrophages.
abstract: Endosomes have important roles in intracellular signal transduction as a sorting platform. Signaling cascades from TLR engagement to IRF3-dependent gene transcription rely on endosomes, yet the proteins that specifically recruit IRF3-activating molecules to them are poorly defined. We show that adaptor protein containing a pleckstrin-homology domain, a phosphotyrosine-binding domain, and a leucine zipper motif (APPL)1, an early endosomal protein, is required for both TRIF- and retinoic acid-inducible gene 1-dependent signaling cascades to induce IRF3 activation. APPL1, but not early endosome Ag 1, deficiency impairs IRF3 target gene expression upon engagement of both TLR3 and TLR4 pathways, as well as in H1N1-infected macrophages. The IRF3-phosphorylating kinases TBK1 and IKKε are recruited to APPL1 endosomes in LPS-stimulated macrophages. Interestingly, APPL1 undergoes proteasome-mediated degradation through ERK1/2 to turn off signaling. APPL1 degradation is blocked when signaling through the endosome is inhibited by chloroquine or dynasore. Therefore, APPL1 endosomes are critical for IRF3-dependent gene expression in response to some viral and bacterial infections in macrophages. Those signaling pathways involve the signal-induced degradation of APPL1 to prevent aberrant IRF3-dependent gene expression linked to immune diseases.
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Tieu-Lan
authors.initials: TL
authors.lastname: Chau
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Serkan Ismail
authors.initials: SI
authors.lastname: Göktuna
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Ayman
authors.initials: A
authors.lastname: Rammal
authors.affiliation: Department of Veterinary Pathology, Fundamental and Applied Research for Animals and Health, University of Liege, 4000 Liege, Belgium;
authors.forename: Tomás
authors.initials: T
authors.lastname: Casanova
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Hong-Quan
authors.initials: HQ
authors.lastname: Duong
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Jean-Stéphane
authors.initials: JS
authors.lastname: Gatot
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Pierre
authors.initials: P
authors.lastname: Close
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Molecular Immunology and Signal Transduction, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; and.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Dejardin
authors.affiliation: Department of Veterinary Pathology, Fundamental and Applied Research for Animals and Health, University of Liege, 4000 Liege, Belgium;
authors.forename: Daniel
authors.initials: D
authors.lastname: Desmecht
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium;
authors.forename: Kateryna
authors.initials: K
authors.lastname: Shostak
authors.affiliation: Interdisciplinary Cluster of Applied Genoproteomics, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Laboratory of Medical Chemistry, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Unit of Signal Transduction, GIGA-Research, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium; Walloon Excellence in Life Sciences and Biotechnology, Hospital University of Liege Sart-Tilman, University of Liege, 4000 Liege, Belgium alain.chariot@ulg.ac.be.
authors.forename: Alain
authors.initials: A
authors.lastname: Chariot
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000276:immunology*; D000818:Animals; D018501:Antirheumatic Agents / Q000494:pharmacology; D002738:Chloroquine / Q000494:pharmacology; D011992:Endosomes / Q000235:genetics / Q000276:immunology; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D057809:HEK293 Cells; D006801:Humans; D006835:Hydrazones / Q000494:pharmacology; D051550:I-kappa B Kinase / Q000235:genetics / Q000276:immunology*; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000276:immunology; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000276:immunology; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000276:immunology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000276:immunology*; D059748:Proteolysis / Q000187:drug effects; D051196:Toll-Like Receptor 3 / Q000235:genetics / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology*
chemical_list: C464801:APPL1 protein, human; D048868:Adaptor Proteins, Signal Transducing; D018501:Antirheumatic Agents; C510733:Appl1 protein, mouse; C513308:Dmp1 protein, mouse; D016326:Extracellular Matrix Proteins; D006835:Hydrazones; C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; C494233:Irf3 protein, mouse; C511794:N'-(3,4-dihydroxybenzylidene)-3-hydroxy-2-naphthahydrazide; C495344:TLR3 protein, human; C519703:TLR3 protein, mouse; C495345:TLR4 protein, human; C493487:Tlr4 protein, mouse; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; D002738:Chloroquine; C498588:Tbk1 protein, mouse; D017346:Protein Serine-Threonine Kinases; C403191:TBK1 protein, human; D051550:I-kappa B Kinase; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3