Journal of Dental Research, Vol 80, 1653-1659, Copyright © 2001 by International & American Associations for Dental Research Online Journals
Transforming growth factor-beta1 and basic fibroblast growth factor modulate osteocalcin and osteonectin/SPARC syntheses in vitamin-D-activated pulp cells
H. Shiba, Y. Uchida, K. Kamihagi, M. Sakata, T. Fujita, S. Nakamura, T. Takemoto, Y. Kato and H. Kurihara
Department of Periodontology and Endodontology, Hiroshima University Faculty of Dentistry, Japan. bashihi@hiroshima-u.ac.jp
Vitamin D deficiency elicits hypocalcified dentin. However, little is known
about the action of vitamin D on the syntheses of dentin matrix proteins.
In this study, we examined the effects of 1,25-dihydroxyvitamin D3
[1,25(OH)2D3] on the expressions of osteocalcin and osteonectin/secreted
protein, acidic and rich in cysteine (SPARC), by human pulp cells in the
presence or absence of transforming growth factor-beta1 (TGF-beta1) or
basic fibroblast growth factor (bFGF). 1,25(OH)2D3 markedly increased
osteocalcin at protein and mRNA levels. The osteocalcin level induced by
1,25(OH)2D3 was decreased and increased by TGF-beta1 and bFGF,
respectively. 1,25(OH)2D3 suppressed SPARC synthesis at protein and mRNA
levels. TGF-beta1, but not bFGF, increased SPARC synthesis in the presence
of 1,25(OH)2D3. SPARC, but not osteocalcin, increased DNA synthesis in pulp
cells. These findings suggest that 1,25(OH)2D3 and growth factors
interactively regulate the expression of osteocalcin and SPARC in pulp
cells, and that SPARC can stimulate DNA synthesis by pulp cells.
