title: Aggregatibacter actinomycetemcomitans Omp29 is associated with bacterial entry to gingival epithelial cells by F-actin rearrangement.
abstract: The onset and progressive pathogenesis of periodontal disease is thought to be initiated by the entry of Aggregatibacter actinomycetemcomitans (Aa) into periodontal tissue, especially gingival epithelium. Nonetheless, the mechanism underlying such bacterial entry remains to be clarified. Therefore, this study aimed to investigate the possible role of Aa outer membrane protein 29 kD (Omp29), a homologue of E. coli OmpA, in promoting bacterial entry into gingival epithelial cells. To accomplish this, Omp29 expression vector was incorporated in an OmpA-deficient mutant of E. coli. Omp29(+)/OmpA(-) E. coli demonstrated 22-fold higher entry into human gingival epithelial line cells (OBA9) than Omp29(-)/OmpA(-) E. coli. While the entry of Aa and Omp29(+)/OmpA(-) E. coli into OBA9 cells were inhibited by anti-Omp29 antibody, their adherence to OBA9 cells was not inhibited. Stimulation of OBA9 cells with purified Omp29 increased the phosphorylation of focal adhesion kinase (FAK), a pivotal cell-signaling molecule that can up-regulate actin rearrangement. Furthermore, Omp29 increased the formation of F-actin in OBA9 cells. The internalization of Omp29-coated beads and the entry of Aa into OBA9 were partially inhibited by treatment with PI3-kinase inhibitor (Wortmannin) and Rho GTPases inhibitor (EDIN), both known to convey FAK-signaling to actin-rearrangement. These results suggest that Omp29 is associated with the entry of Aa into gingival epithelial cells by up-regulating F-actin rearrangement via the FAK signaling pathway.
authors.affiliation: Department of Immunology, Forsyth Institute, Boston, Massachusetts, United States of America.
authors.forename: Mikihito
authors.initials: M
authors.lastname: Kajiya
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Komatsuzawa
authors.forename: Annatoula
authors.initials: A
authors.lastname: Papantonakis
authors.forename: Makoto
authors.initials: M
authors.lastname: Seki
authors.forename: Seicho
authors.initials: S
authors.lastname: Makihira
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Ouhara
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kusumoto
authors.forename: Shinya
authors.initials: S
authors.lastname: Murakami
authors.forename: Martin A
authors.initials: MA
authors.lastname: Taubman
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kawai
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000382:microbiology*; D004926:Escherichia coli / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D020563:Gammaproteobacteria / Q000378:metabolism*; D005881:Gingiva / Q000382:microbiology*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D008957:Models, Genetic; D009154:Mutation; D010766:Phosphorylation; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D000199:Actins; D001425:Bacterial Outer Membrane Proteins; C117494:Omp29 protein, Actinobacillus actinomycetemcomitans; D051416:Focal Adhesion Protein-Tyrosine Kinases