Figure 2. Regulation of Cthrc1 gene expression.

(A) Cthrc1 mRNA expression was strongly induced in osteoclasts cultured on HA. Osteoclasts were cultured on plastic plates, dentin slices, or Osteologic discs composed of HA crystals, and RNAs were prepared. Real-time RT-PCR for Cthrc1 was performed. (B) Increasing extracellular calcium concentrations increased Cthrc1 transcription in osteoclasts on plastic dishes. Osteoclasts were cultured at the indicated CaCl₂ concentrations for 24 hours. (C) Alendronate (ALN) inhibited the Cthrc1 expression induced in osteoclasts cultured on dentin or HA. (D) Proton pump inhibitors or calcitonin inhibited Cthrc1 expression. Osteoclasts were cultured on different substrates (plastic plates, dentin slices, or HA discs) in the presence of 100 nM bafilomycin A1 (BM), 1 μM N-ethylmaleimide (NEM), or 1 nM calcitonin (CT). n = 3. *P < 0.05; **P < 0.01; ***P < 0.001.