Vitamin D receptor in chondrocytes promotes osteoclastogenesis and regulates FGF23 production in osteoblasts
J. Clin. Invest. Ritsuko Masuyama, et al. 116:3150 doi:10.1172/JCI29463 [
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Figure 6Signaling of 1,25(OH)
2D
3 in chondrocytes promotes osteoclast differentiation by the RANKL pathway.
(
A–
F) Microscopic observation of TRAP-positive multinuclear cells formed after 1 week of coculturing osteoblasts or chondrocytes with
Cre–VDRfl/fl splenocytes. Osteoclast formation was similar whether osteoblasts from
Cre–VDRfl/fl (
A) or
Cre+VDRfl/fl mice (
B) were used and treated with 1,25(OH)
2D
3 (10
–8 M). Chondrocytes from
Cre–VDRfl/fl mice induced TRAP-positive cells when stimulated with 1,25(OH)
2D
3 (
C) or 10
–6 M PGE
2 (
E) whereas chondrocytes from
Cre+VDRfl/fl mice induced osteoclasts only when treated with PGE
2 (
F) and not with 1,25(OH)
2D
3 (
D). Scale bar: 100 μm. (
G) qRT-PCR analysis of
RANKL mRNA expression in primary osteoblast or chondrocyte cultures from
Cre–VDRfl/fl and
Cre+VDRfl/fl mice stimulated by 10
–8 M 1,25(OH)
2D
3 or 10
–6 M PGE
2 for 2 days. Values are calculated as ratio to
HPRT mRNA copies and expressed relative to vehicle set as 100%. *
P < 0.05; **
P < 0.01 versus vehicle.
