Paxillin phosphorylation and integrin expression in osteoblasts infected by Porphyromonas gingivalis.
OBJECTIVE
We investigated early biological events initiated by Porphyromonas gingivalis infection of human osteoblasts, focusing on tyrosine-phosphorylation and the expression of key components in focal adhesion and cell signalling.


METHODS
Human primary osteoblasts were challenged for 1h with Porphyromonas gingivalis. Tyrosine-phosphorylation of paxillin and focal adhesion kinase (FAK) was examined by Western blotting. Changes in alpha3- and beta1-integrin mRNA expression were quantified by RT-PCR.


RESULTS
Tyrosine-phosphorylation of paxillin was proportional to the size of the Porphyromonas gingivalis inoculum. FAK, a potential kinase for paxillin, was not activated. The amount of alpha3- and beta1-integrins, determined by Western blotting, did not vary significantly, while the corresponding mRNA levels fell 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 alpha3- and beta1-integrin mRNA expression. This infection thus appears to have different effects on components with essential roles in focal adhesion (paxillin) and cell signalling (FAK and integrins).
Elkaim
René
R
Parogène, 11 rue Humann, 67085 Strasbourg Cedex, France.
Obrecht-Pflumio
Sophie
S
Tenenbaum
Henri
H
D001422:Bacterial Adhesion; D016866:Bacteroidaceae Infections / Q000378:metabolism*; D015153:Blotting, Western; D002478:Cells, Cultured; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D006801:Humans; D039422:Integrin alpha3 / Q000235:genetics; D019012:Integrin beta1 / Q000235:genetics; D016023:Integrins / Q000378:metabolism*; D010006:Osteoblasts / Q000382:microbiology* / Q000473:pathology; D051419:Paxillin / Q000378:metabolism*; D010766:Phosphorylation; D016966:Porphyromonas gingivalis / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014443:Tyrosine / Q000378:metabolism*
D039422:Integrin alpha3; D019012:Integrin beta1; D016023:Integrins; D051419:Paxillin; D012333:RNA, Messenger; D014443:Tyrosine; D051416:Focal Adhesion Protein-Tyrosine Kinases