title: Fusobacterium nucleatum activates the immune response through retinoic acid-inducible gene I.
abstract: Retinoic acid-inducible gene I (RIG-I) is a cytosolic pattern recognition receptor involved in the sensing of RNA viruses and the initiation of antiviral responses. Fusobacterium nucleatum, a Gram-negative anaerobic bacterium associated with periodontal disease, is capable of invading cells. We hypothesized that F. nucleatum's ability to invade cells allows the microorganism to activate the immune response through RIG-I. Bacterial invasion was found to be necessary for F. nucleatum-induced nuclear factor kappa B (NF-κB) activation. Following invasion of the human periodontal ligament fibroblast (PDLF), F. nucleatum was located in the cytosol. F. nucleatum infection led to an 80-fold increase in RIG-I expression. Silencing RIG-I in PDLF by siRNA led to a significant decrease of NF-κB activation and expression of proinflammatory genes. Additionally, F. nucleatum was able to secrete nucleic acids, and introduction of F. nucleatum RNA into PDLF led to a RIG-I-dependent activation of NF-κB. Our findings showed RIG-I to be involved in the recognition of F. nucleatum. The function of RIG-I is likely to be broad and not limited to sensing of viruses only. Hence, this receptor may play an important role in detecting invasive forms of oral pathogens and contribute to inflammation in periodontal tissues.
authors: Faculty of Dentistry, National University of Singapore, Singapore.
authors: P
authors: P
authors: Lee
authors: K S
authors: KS
authors: Tan
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology; D001431:Bacteriological Techniques; D018929:Cell Culture Techniques; D015638:Cytochalasin D / Q000494:pharmacology; D003600:Cytosol / Q000276:immunology / Q000382:microbiology; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D005347:Fibroblasts / Q000276:immunology / Q000382:microbiology; D005674:Fusobacterium Infections / Q000276:immunology; D016967:Fusobacterium nucleatum / Q000187:drug effects / Q000276:immunology*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D007378:Interleukins / Q000276:immunology; D016328:NF-kappa B / Q000276:immunology; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010513:Periodontal Ligament / Q000166:cytology / Q000276:immunology / Q000382:microbiology; D010957:Plasmids / Q000235:genetics; D018713:Prevotella intermedia / Q000276:immunology; D012329:RNA, Bacterial / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D011971:Receptors, Immunologic; D051192:Receptors, Pattern Recognition / Q000276:immunology
chemical_list: D007378:Interleukins; D016328:NF-kappa B; D019384:Nucleic Acid Synthesis Inhibitors; D012329:RNA, Bacterial; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; D051192:Receptors, Pattern Recognition; D015638:Cytochalasin D; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases
keywords: bacterial RNA; cytokines; nuclear factor kappa B; pattern recognition receptor; periodonal disease; periodontal ligament fibroblast