title: Paxillin phosphorylation and integrin expression in osteoblasts infected by Porphyromonas gingivalis.
abstract: 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).
authors.affiliation: Parogène, 11 rue Humann, 67085 Strasbourg Cedex, France.
authors.forename: René
authors.initials: R
authors.lastname: Elkaim
authors.forename: Sophie
authors.initials: S
authors.lastname: Obrecht-Pflumio
authors.forename: Henri
authors.initials: H
authors.lastname: Tenenbaum
mesh_terms: 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*
chemical_list: D039422:Integrin alpha3; D019012:Integrin beta1; D016023:Integrins; D051419:Paxillin; D012333:RNA, Messenger; D014443:Tyrosine; D051416:Focal Adhesion Protein-Tyrosine Kinases