Figure 6.

1α,25(OH)₂D₃ inhibits translation of c-Fos protein in osteoclast precursor cells. Osteoclast precursor cells were isolated from the bone marrow of C57BL/6J mice as M-CSF–dependent adherent cells. (A and B) After RANKL stimulation for 24 hours, osteoclast progenitor cells were pulse-labeled for 30 minutes with ³⁵S-methionine followed by chasing with cold methionine for the indicated times in the absence or presence of 1α,25(OH)₂D₃ treatment. Note that the degradation of c-Fos protein was not accelerated by 1α,25(OH)₂D₃ (open circles), compared with that for vehicle-treated cells (filled circles). (C) After RANKL stimulation for 24 hours, osteoclast progenitor cells were pulse-labeled for 30 minutes with ³⁵S-methionine in the absence or presence of 1α,25(OH)₂D₃. Labeled c-Fos protein was immunoprecipitated. Note that the biosynthesis of c-Fos protein stimulated by RANKL was inhibited by 1α,25(OH)₂D₃ treatment. β-Actin protein served as a loading control.