Paxillin phosphorylation and integrin expression in osteoblasts infected by Porphyromonas gingivalis

Objective: We investigated early biological events initiated by Porphyromonas gingivalis infection of human osteobtasts, focusing on tyrosine-phosphorylation and the expression of key components in focal adhesion and cell signalling. Design: Human primary osteobtasts were challenged for 1 h with Porphyromonas gingivalis. Tyrosine-phosphorylation of paxillin and focal adhesion kinase (FAK) was examined by Western blotting. Changes in alpha 3- and beta 1-integrin mRNA expression were quantified by RT-PCR. Results: Tyrosine-phosphorytation of paxillin was proportional to the size of the Porphyromonas gingivalis inoculum. FAK, a potential kinase for paxillin, was not activated. The amount of alpha 3- and beta 1-integrins, determined by Western blotting, did not vary significantly, white the corresponding mRNA levels felt significantly when a large bacterial inoculum was used. Conclusions: These results indicate that Porphyromonas gingivalis infection of osteoblasts in vitro triggers tyrosine-phosphorylation of paxillin but not FAK and modify alpha 3- and beta 1-integrin mRNA expression. This infection thus appears to have different effects on components with essential rotes in focal adhesion (paxillin) and cell signalling (FAK and integrins). (c) 2006 Elsevier Ltd. All rights reserved.