Apoptosis and survival of osteoblast-like cells are regulated by surface attachment.
We tested the hypothesis that RGDS peptides regulate osteoblast survival in culture. Osteoblast-like MC3T3-E1 cells were allowed to attach to RGDS peptides that had been tethered to a silicone surface utilizing a previously described grafting technique. The RGDS-modified surface caused up-regulation of alpha(v)beta(3) integrin. We noted that there was an increase in expression of activated focal adhesion kinase and activated Akt. There was no change in the expression level of the anti-apoptotic protein Bcl-2, the pro-apoptotic protein Bad, or the inactivated form of Bad, pBad. Attachment to the RGDS-treated membrane completely abolished apoptosis induced by staurosporine, the Ca(2+).P(i) ion pair, and sodium nitroprusside. However, the surface modification did not interfere with apoptosis mediated by the free RGDS peptide or serum-free medium. When the activity of the phosphatidylinositol 3-kinase pathway was inhibited, RGDS-dependent resistance to apoptosis was eliminated. These results indicated that the binding of cells to RGDS abrogated apoptosis via the mitochondrial pathway and that the suppression of apoptosis was dependent on the activity of phosphatidylinositol 3-kinase.
Grigoriou
Vavara
V
Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Shapiro
Irving M
IM
Cavalcanti-Adam
Elisabeta A
EA
Composto
Russell J
RJ
Ducheyne
Paul
P
Adams
Christopher S
CS
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002448:Cell Adhesion; D002470:Cell Survival; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D016023:Integrins / Q000378:metabolism; D051379:Mice; D009842:Oligopeptides / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism
D016023:Integrins; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse