Abstract
Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)2D3, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)2D3 mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)2D3 induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)2D3 induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)2D3 induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50-70%, respectively. In addition, the 1,25(OH)2D3 induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)2D3 stimulated VDR protein expression and 1,25(OH)2D3 mediated actions in human osteoblast cells.
| Original language | English |
|---|---|
| Pages (from-to) | 368-371 |
| Number of pages | 4 |
| Journal | Journal of Steroid Biochemistry and Molecular Biology |
| Volume | 103 |
| Issue number | 3-5 |
| DOIs | |
| State | Published - Mar 2007 |
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All Science Journal Classification (ASJC) codes
- Biochemistry
- Endocrinology
Cite this
Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells. / Rapuri, Prema B.; Gallagher, John Christopher G.; Nawaz, Zafar.
In: Journal of Steroid Biochemistry and Molecular Biology, Vol. 103, No. 3-5, 03.2007, p. 368-371.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Caffeine decreases vitamin D receptor protein expression and 1,25(OH)2D3 stimulated alkaline phosphatase activity in human osteoblast cells
AU - Rapuri, Prema B.
AU - Gallagher, John Christopher G.
AU - Nawaz, Zafar
PY - 2007/3
Y1 - 2007/3
N2 - Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)2D3, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)2D3 mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)2D3 induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)2D3 induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)2D3 induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50-70%, respectively. In addition, the 1,25(OH)2D3 induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)2D3 stimulated VDR protein expression and 1,25(OH)2D3 mediated actions in human osteoblast cells.
AB - Of the various risk factors contributing to osteoporosis, dietary/lifestyle factors are important. In a clinical study we reported that women with caffeine intakes >300 mg/day had higher bone loss and women with vitamin D receptor (VDR) variant, tt were at a greater risk for this deleterious effect of caffeine. However, the mechanism of how caffeine effects bone metabolism is not clear. 1,25-Dihydroxy vitamin D3 (1,25(OH)2D3) plays a critical role in regulating bone metabolism. The receptor for 1,25(OH)2D3, VDR has been demonstrated in osteoblast cells and it belongs to the superfamily of nuclear hormone receptors. To understand the molecular mechanism of the role of caffeine in relation to bone, we tested the effect of caffeine on VDR expression and 1,25(OH)2D3 mediated actions in bone. We therefore examined the effect of different doses of caffeine (0.2, 0.5, 1.0 and 10 mM) on 1,25(OH)2D3 induced VDR protein expression in human osteoblast cells. We also tested the effect of different doses of caffeine on 1,25(OH)2D3 induced alkaline phosphatase (ALP) activity, a widely used marker of osteoblastic activity. Caffeine dose dependently decreased the 1,25(OH)2D3 induced VDR expression and at concentrations of 1 and 10 mM, VDR expression was decreased by about 50-70%, respectively. In addition, the 1,25(OH)2D3 induced alkaline phosphatase activity was also reduced at similar doses thus affecting the osteoblastic function. The basal ALP activity was not affected with increasing doses of caffeine. Overall, our results suggest that caffeine affects 1,25(OH)2D3 stimulated VDR protein expression and 1,25(OH)2D3 mediated actions in human osteoblast cells.
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U2 - 10.1016/j.jsbmb.2006.12.037
DO - 10.1016/j.jsbmb.2006.12.037
M3 - Article
VL - 103
SP - 368
EP - 371
JO - Journal of Steroid Biochemistry and Molecular Biology
JF - Journal of Steroid Biochemistry and Molecular Biology
SN - 0960-0760
IS - 3-5
ER -