title: FOXO responses to Porphyromonas gingivalis in epithelial cells.
abstract: Porphyromonas gingivalis is a prominent periodontal, and emerging systemic, pathogen that redirects host cell signalling pathways and modulates innate immune responses. In this study, we show that P. gingivalis infection induces the dephosphorylation and activation of forkhead box-O (FOXO)1, 3 and 4 in gingival epithelial cells. In addition, immunofluorescence showed that FOXO1 accumulated in the nucleus of P. gingivalis-infected cells. Quantitative reverse transcription PCR demonstrated that transcription of genes involved in protection against oxidative stress (Cat, Sod2, Prdx3), inflammatory responses (IL1β) and anti-apoptosis (Bcl-6) was induced by P. gingivalis, while small-interfering RNA (siRNA)-mediated knockdown of FOXO1 suppressed the transcriptional activation of these genes. P. gingivalis-induced secretion of interleukin (IL)-1β and inhibition of apoptosis were also impeded by FOXO1 knockdown. Neutralization of reactive oxygen species (ROS) by N-acetyl-l-cysteine blocked the activation of FOXO1 by P. gingivalis and concomitantly suppressed the activation of oxidative stress responses, anti-apoptosis programmes and IL-β production. Inhibition of c-Jun-N-terminal kinase (JNK) either pharmacologically or by siRNA, reduced FOXO1 activation and downstream FOXO1-dependent gene regulation in response to P. gingivalis. The results indicate that P. gingivalis-induced ROS activate FOXO transcription factors through JNK signalling, and that FOXO1 controls oxidative stress responses, inflammatory cytokine production and cell survival. These data position FOXO as an important signalling node in the epithelial cell-P. gingivalis interaction, with particular relevance to cell fate and dysbiotic host responses.
authors.affiliation: Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
authors.forename: Maryta
authors.initials: M
authors.lastname: Sztukowska
authors.affiliation: Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
authors.forename: Akintunde
authors.initials: A
authors.lastname: Ojo
authors.affiliation: Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Scott
authors.affiliation: Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
authors.forename: Huizhi
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, KY, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lamont
mesh_terms: D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000382:microbiology*; D000071161:Forkhead Box Protein O1; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000378:metabolism*; D020869:Gene Expression Profiling; D055785:Gene Knockdown Techniques; D054884:Host-Pathogen Interactions; D006801:Humans; D016966:Porphyromonas gingivalis / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C085126:FOXO1 protein, human; C499517:FOXO3 protein, human; C108803:FOXO4 protein, human; D000071161:Forkhead Box Protein O1; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D014157:Transcription Factors