Possible involvement of phosphatidylinositol 3-kinase/Akt pathway in insulin-like growth factor-I-induced alkaline phosphatase activity in osteoblasts.
In the present study, we investigated whether Akt is involved in insulin-like growth factor-I (IGF-I)-stimulated activity of alkaline phosphatase, a marker of mature osteoblast phenotype, in osteoblast-like MC3T3-E1 cells. IGF-I induced the phosphorylation of Akt in these cells. Akt inhibitor significantly suppressed the IGF-I-stimulated alkaline phosphatase activity. The phosphorylation of Akt induced by IGF-I was reduced by the Akt inhibitor. LY294002 and wortmannin, inhibitors of phosphatidylinositol 3-kinase, significantly suppressed the IGF-I-induced alkaline phosphatase activity. The phosphorylation of Akt induced by IGF-I was markedly reduced by LY294002 and wortmannin. These results strongly suggest that phosphatidylinositol 3-kinase/Akt plays a role in the IGF-I-stimulated alkaline phosphatase activity in osteoblasts.
Noda
T
T
Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu, Japan.
Tokuda
H
H
Yoshida
M
M
Yasuda
E
E
Hanai
Y
Y
Takai
S
S
Kozawa
O
O
D000469:Alkaline Phosphatase / Q000096:biosynthesis*; D000818:Animals; D002999:Clone Cells; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D051379:Mice; D010006:Osteoblasts / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
D000469:Alkaline Phosphatase; D007334:Insulin-Like Growth Factor I; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt