Mechanism of mitogenic effect of fluoride on fetal rat osteoblastic cells: evidence for Shc, Grb2 and P-CREB-dependent pathways.
Fluoride stimulates bone cell proliferation and nodule formation in fetal rat calvarial osteoblastic cells. In addition, fluoride enhances alkaline phosphatase activity, a marker of osteoblastic differentiation, in a dose-dependent manner. The effects of fluoroalumino complex (AlFx) on cell proliferation and differentiation were markedly reduced by tyrosine kinase inhibitor; 1 mM genistein or 1 microg/ml herbimycin. It suggests that tyrosine kinase-mediated mitogenic signaling involves a series of protein-protein interactions between tyrosine-phosphorylated receptors, Shc and Grb2, resulting in an AlFx-induced mitogenic effect. The results indicate that AlFx dose-dependently enhances the tyrosine phosphorylation of the adaptor molecule Shc (p52) and its association with Grb2 in the tyrosine kinase mediated pathway. In addition, AlFx decreases the phosphorylation level of CREB without any change on the amount of CREB protein. Taken together, the results suggest that adaptor proteins, including Shc and Grb2 of the protein tyrosine kinase cascade are implicated in fluoride-induced mitogenic activity of fetal rat calvarial osteoblastic cells. Furthermore, CREB which passes signals from cAMP to transcriptional factor CRE, modulates the fluoroaluminate-induced metabolism of bone cells via a decrease of phosphorylation level.
Chae
H J
HJ
Department of Dental Pharmacology and Institute of Wonkwang Biomaterial Implant, Chonbuk, South Korea.
Chae
S W
SW
Kang
J S
JS
Kim
D E
DE
Kim
H R
HR
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D016227:Benzoquinones; D002455:Cell Division / Q000187:drug effects; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D005333:Fetus / Q000166:cytology; D005459:Fluorides / Q000494:pharmacology*; D051380:GRB2 Adaptor Protein; D019833:Genistein / Q000494:pharmacology; D066298:In Vitro Techniques; D047029:Lactams, Macrocyclic; D008934:Mitogens / Q000494:pharmacology; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017828:Rifabutin / Q000031:analogs & derivatives; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000187:drug effects; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D013936:Thymidine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D016227:Benzoquinones; D017362:Cyclic AMP Response Element-Binding Protein; D051380:GRB2 Adaptor Protein; C495950:Grb2 protein, rat; D047029:Lactams, Macrocyclic; D008934:Mitogens; D011506:Proteins; D011809:Quinones; D055765:Shc Signaling Adaptor Proteins; C528035:Shc1 protein, rat; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D017828:Rifabutin; C020754:herbimycin; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D000469:Alkaline Phosphatase; D005459:Fluorides; D013936:Thymidine