Gingival epithelial cell signalling and cytoskeletal responses to Porphyromonas gingivalis invasion

Abstract

Porphyromonas gingivalis, an oral pathogen, can internalize within primary gingival epithelial cells (GECs) through an invasion mechanism mediated by interactions between P. gingivalis fimbriae and integrins on the surface of the GECs. Fimbriae-integrin-based signalling events were studied by fluorescence microscopy, and the subcellular localization of integrin-associated signalling molecules paxillin and focal adhesion kinase (FAK), and the architecture of the actin and microtubule cytoskeleton were examined. GECs infected with P. gingivalis for 30 min demonstrated significant redistribution of paxillin and FAK from the cytosol to cell peripheries and assembly into focal adhesion complexes. In contrast, a fimbriae-deficient mutant of P. gingivalis did not contribute substantially to activation of paxillin or FAK. After 24 h, the majority of paxillin and FAK had returned to the cytoplasm with significant co-localization with P. gingivalis in the perinuclear region. Wild-type P. gingivalis induced nucleation of actin filaments forming microspike-like protrusions and long stable microfilaments distributed throughout the cells. Fimbriae mutants promoted a rich cortical actin meshwork accompanied by membrane ruffling dispersed along the cell membrane. Remarkable disassembly and nucleation of the actin and microtubule filamentous network was observed following 24 h infection with either wild-type or fimbriae-deficient mutants of P. gingivalis. The results show that fimbriated P. gingivalis cells induce formation of integrin-associated focal adhesions with subsequent remodelling of the actin and tubulin cytoskeleton.

Molecular Dissection of Internalization of Porphyromonas gingivalis by Cells using Fluorescent Beads Coated with Bacterial Membrane Vesicle

“…The number of the completely internalized beads increased along the incubation time, and reached saturation at 40 min. The kinetics of internalization was found to be quite similar to that of living bacteria reported in previous studies (Yilmaz et al, 2004;Yilmaz et al, 2003).We also examined the localization of a5b1-integrin which was reported to be responsible for the initial binding of P. gingivalis to the cells (Nakagawa et al, 2005;Yilmaz et al, 2002). Consistent with those previous reports, recruitment of a5b1-integrin was observed at the bead internalization site (Fig.…”

Human Cytomegalovirus-Regulated Paxillin in Monocytes Links Cellular Pathogenic Motility to the Process of Viral Entry

“…Reports have documented that paxillin regulation can be directly initiated by pathogen-host cell interactions. For example, bacterial lipopolysaccharide (LPS) and fimbriae of the Gram-negative anaerobe Porphyromonas gingivalis can trigger paxillin phosphorylation (18,52,53). Additionally, the HIV transactivator protein Tat has been demonstrated to activate paxillin; however, this process was not a result of a direct interaction of the virus with the cell, as the Tat protein must be expressed to have a stimulating effect on surrounding cells (16).…”

Genomic Recombination through Plasmid-Encoded Recombinase Enhances Hemolytic Activity and Adherence to Epithelial Cells in the Periodontopathogenic BacteriumEikenella corrodens

“…35) Moreover, Yilmaz et al reported that fimbriated P. gingivalis cells induce the formation of integrin-associated focal adhesion, with subsequent remodeling of the actin and tubulin cytoskeleton for internalization. 36) To determine whether type-IV pili are involved in invasion by E. corrodens of oral epithelial cells, we performed an invasion assay using a phase variant of strain 23834. It has been reported that E. corrodens exhibits phase variation resulting from a loss of type-IV pili, which is reflected in irreversible morphological changes in colonies, from corroding to non-corroding.…”