The effect of bone morphogenetic protein-7 on the expression of type I inositol 1,4,5-trisphosphate receptor in G-292 osteosarcoma cells and primary osteoblast cultures

Bone morphogenetic protein-7 (BMP-7) affects differentiation of preosteoblasts enabling the resultant cells to respond optimally to acutely acting regulators. As the phosphoinositide cascade and, particularly, the calcium-mobilizing inositol 1,4,5-trisphosphate (InsP 3) receptor are integral to stim...

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Bibliographic Details
Published in:Archives of oral biology 2000-02, Vol.45 (2), p.159-166
Main Authors: Bradford, Peter G, Maglich, Jodi M, Ponticelli, Alfred S, Kirkwood, Keith L
Format: Article
Language:English
Subjects:
Alkaline Phosphatase - genetics
Ascorbic Acid - pharmacology
Blotting, Northern
Bone Morphogenetic Protein 7
Bone morphogenetic protein receptor
Bone Morphogenetic Protein Receptors
Bone Morphogenetic Proteins - pharmacology
Calcification, Physiologic
Calcium Channels - drug effects
Calcium Channels - genetics
Cell Differentiation
Cells, Cultured
Collagen - genetics
Dentistry
ErbB Receptors - genetics
G-292 osteosarcoma
Gene Expression Regulation
Gene Expression Regulation, Neoplastic
Glycerophosphates - pharmacology
Humans
Immunoblotting
Inositol 1,4,5-Trisphosphate - metabolism
Inositol 1,4,5-trisphosphate receptor
Inositol 1,4,5-Trisphosphate Receptors
Integrin-Binding Sialoprotein
Osteoblasts - drug effects
Osteoblasts - metabolism
Osteocalcin
Osteocalcin - genetics
Osteosarcoma - genetics
Osteosarcoma - pathology
Phosphatidylinositols - metabolism
Polymerase Chain Reaction
Receptors, Cell Surface - genetics
Receptors, Cytoplasmic and Nuclear - drug effects
Receptors, Cytoplasmic and Nuclear - genetics
Receptors, Growth Factor
RNA, Messenger - genetics
Sialoglycoproteins - genetics
Space life sciences
Transforming Growth Factor beta - pharmacology
Tumor Cells, Cultured
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Summary:Bone morphogenetic protein-7 (BMP-7) affects differentiation of preosteoblasts enabling the resultant cells to respond optimally to acutely acting regulators. As the phosphoinositide cascade and, particularly, the calcium-mobilizing inositol 1,4,5-trisphosphate (InsP 3) receptor are integral to stimulus–secretion coupling in osteoblasts, the hypothesis that BMP-7 affects InsP 3 receptor expression was examined in the G-292 human osteosarcoma cell line and in primary cultures of human osteoblasts. G-292 osteosarcoma cells were found to be a valid experimental model for primary human osteoblasts, expressing osteoblastic mRNAs encoding osteocalcin, bone sialoprotein, alkaline phosphatase, α1-collagen, epidermal growth-factor receptor, and BMP type II receptor. When cultured long term in the presence of ascorbic acid and β-glycerophosphate, G-292 cells underwent further osteoblastic differentiation, forming nodules and exhibiting restricted mineralization. G-292 cells responded to BMP-7 with an increase in InsP 3 receptor density. Ligand-binding studies established that BMP-7 (50 ng/ml) treatment of G-292 cells increased InsP 3 receptor density 2.4-fold with no apparent change in affinity. Immunoblot analysis with antibodies specific for type I, type II, and type III InsP 3 receptors revealed that BMP-7 (50 ng/ml) treatment resulted in a specific increase (206±8%) in the type I receptor. Reverse transcription-polymerase chain reaction and Northern blot analyses of G-292 and primary human osteoblasts confirmed an increase in type I InsP 3 receptor mRNA upon BMP-7 treatment. These results demonstrate that G-292 cells respond to BMP-7 with an increase InsP 3 receptor density, consistent with the enhanced capacity of these cells to respond to Ca 2+-mobilizing secretory hormones during osteoblast differentiation.
ISSN:0003-9969
1879-1506
DOI:10.1016/S0003-9969(99)00122-3