title: RNA and imidazoquinolines are sensed by distinct TLR7/8 ectodomain sites resulting in functionally disparate signaling events.
abstract: TLRs 7 and 8 are pattern recognition receptors controlling antiviral host defense or autoimmune diseases. Apart from foreign and host RNA, synthetic RNA oligoribonucleotides (ORN) or small molecules of the imidazoquinoline family activate TLR7 and 8 and are being developed as therapeutic agonists. The structure-function relationships for RNA ORN and imidazoquinoline sensing and consequent downstream signaling by human TLR7 and TLR8 are unknown. Proteome- and genome-wide analyses in primary human monocyte-derived dendritic cells here showed that TLR8 sensing of RNA ORN versus imidazoquinoline translates to ligand-specific differential phosphorylation and transcriptional events. In addition, TLR7 and 8 ectodomains were found to discriminate between RNA ORN and imidazoquinolines by overlapping and nonoverlapping recognition sites to which murine loss-of-function mutations and human naturally occurring hyporesponsive polymorphisms map. Our data suggest TLR7 and TLR8 can signal in two different "modes" depending on the class of ligand. Considering RNA ORN and imidazoquinolines have been regarded as functionally interchangeable, our study highlights important functional incongruities whose understanding will be important for developing TLR7 or 8 therapeutics with desirable effector and safety profiles for in vivo application.
authors.affiliation: Junior Research Group Toll-Like Receptors and Cancer, German Cancer Research Center, 69120 Heidelberg, Germany;
authors.forename: Elif
authors.initials: E
authors.lastname: Colak
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom; alexander.weber@uni-tuebingen.de alison.simmons@ndm.ox.ac.uk al.leslie@k-rith.org.
authors.forename: Alasdair
authors.initials: A
authors.lastname: Leslie
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;
authors.forename: Kieran
authors.initials: K
authors.lastname: Zausmer
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;
authors.forename: Elham
authors.initials: E
authors.lastname: Khatamzas
authors.affiliation: Junior Research Group Toll-Like Receptors and Cancer, German Cancer Research Center, 69120 Heidelberg, Germany;
authors.forename: Andriy V
authors.initials: AV
authors.lastname: Kubarenko
authors.affiliation: Department of Immunology, Interfaculty Institute for Cell Biology, University of Tübingen, 72076 Tübingen, Germany;
authors.forename: Tica
authors.initials: T
authors.lastname: Pichulik
authors.affiliation: Department of Immunology, Interfaculty Institute for Cell Biology, University of Tübingen, 72076 Tübingen, Germany;
authors.forename: Sascha N
authors.initials: SN
authors.lastname: Klimosch
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;
authors.forename: Alice
authors.initials: A
authors.lastname: Mayer
authors.affiliation: Department of Genetics, The Scripps Research Institute, La Jolla, CA 92037;
authors.forename: Owen
authors.initials: O
authors.lastname: Siggs
authors.affiliation: Department of Pediatrics I, University of Tübingen, 72076 Tübingen, Germany;
authors.forename: Andreas
authors.initials: A
authors.lastname: Hector
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;
authors.forename: Roman
authors.initials: R
authors.lastname: Fischer
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom;
authors.forename: Benedikt
authors.initials: B
authors.lastname: Klesser
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Headington, Oxford OX3 7BN, United Kingdom;
authors.forename: Anna
authors.initials: A
authors.lastname: Rautanen
authors.affiliation: Core Facility Molecular Structure Analysis, German Cancer Research Center, 69120 Heidelberg, Germany;
authors.forename: Martin
authors.initials: M
authors.lastname: Frank
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Headington, Oxford OX3 7BN, United Kingdom;
authors.forename: Adrian V S
authors.initials: AV
authors.lastname: Hill
authors.affiliation: Institut National de la Santé et de la Recherché Médicale, Unité 1151, 75015 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, 75015 Paris, France; and.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Manoury
authors.affiliation: Center for Genetics of Host Defense, University of Texas Southwestern Medical Center, Dallas, TX 75390.
authors.forename: Bruce
authors.initials: B
authors.lastname: Beutler
authors.affiliation: Department of Pediatrics I, University of Tübingen, 72076 Tübingen, Germany;
authors.forename: Dominik
authors.initials: D
authors.lastname: Hartl
authors.affiliation: Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, United Kingdom; alexander.weber@uni-tuebingen.de alison.simmons@ndm.ox.ac.uk al.leslie@k-rith.org.
authors.forename: Alison
authors.initials: A
authors.lastname: Simmons
authors.affiliation: Junior Research Group Toll-Like Receptors and Cancer, German Cancer Research Center, 69120 Heidelberg, Germany; Department of Immunology, Interfaculty Institute for Cell Biology, University of Tübingen, 72076 Tübingen, Germany;
authors.forename: Alexander N R
authors.initials: AN
authors.lastname: Weber
mesh_terms: D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D009843:Oligoribonucleotides / Q000737:chemistry / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D011806:Quinolinium Compounds / Q000737:chemistry / Q000494:pharmacology*; D012313:RNA / Q000737:chemistry / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D051199:Toll-Like Receptor 7 / Q000235:genetics / Q000276:immunology*; D051200:Toll-Like Receptor 8 / Q000235:genetics / Q000276:immunology*
chemical_list: D009843:Oligoribonucleotides; D011806:Quinolinium Compounds; C495348:TLR7 protein, human; C495349:TLR8 protein, human; D051199:Toll-Like Receptor 7; D051200:Toll-Like Receptor 8; D012313:RNA