Figure 2.

Aberrant Snail1 activation impairs osteoclastogenesis. Calcium (A), phosphate (B), alkaline phosphatase (ALP, C) and 25(OH)D₃ (D) concentrations in serum samples from 16-week-old mice after 8 weeks of corn oil or tamoxifen administration. The results are expressed as the means±s.d. from five samples. (E, F) The 25(OH)D₃ hydroxylase Cyp271b is unaltered in both the kidney and the bone of Snail1-ER transgenic mice regardless of whether tamoxifen is administered. (G) Snail1 activation inhibits vitamin D receptor mRNA expression and protein accumulation. (H) Snail1 activation is also accompanied by a decrease in the expression of the Rankl osteoclastogenic factor and an increase in that of the osteoclastogenesis inhibitor Osteoprotegerin. The results are expressed as the mean±s.d. from three independent experiments carried out on limbs obtained from 16-week-old Snail1-ER mice after 8 weeks of treatment with tamoxifen. (I, J) Osteoclasts are revealed by tartrate-resistant acid phosphatase (TRAP) staining. Sections are counterstained with alcian blue. (K) Quantification of the osteoclast population by histomorphometric analysis of bones from 16-week-old wild-type and Snail1-ER mice (n=10). (L–N) Osteoclast differentiation in culture is not affected by Snail1 activation. Oc.N., osteoclast number; B.Pm., bone perimeter. Scale bar, 100 μm. ANOVA analysis, ^**P<0.01 and ^***P<0.001.