FIGURE 5.

The truncated form of OSTM1 inhibits the expression of OC markers through the down-regulation of BLIMP1 and NFATc1 expression. A, inhibition of OC marker expression after treatment with OSTM1ΔTM-hFc. Total RNAs were prepared from BMOCs and subjected to real-time PCR analysis. The data were normalized to β-actin. Open boxes indicate treatment of the cultures with OSTM1ΔTM-hFc. hFc was used as a control (black box). B, enhancement of the expression of anti-osteoclastogenic genes after OSTM1ΔTM-hFc treatment. C, inhibition of NFATc1 expression after OSTM1ΔTM-hFc treatment. D, negative effect of NFATc1 and c-Fos expression after OSTM1ΔTM-hFc treatment. BMOCs were prepared and analyzed by immunoblotting with antibodies. TRAF6 was used as the internal control. β-Actin was used as the loading control. E, effects of NFATc1 overexpression. A constitutively active form of NFATc1 (caNFATc1) was transduced into BMMs through retroviral infection. caNFATc1-overexpressed BMMs were further cultured with M-CSF and RANKL after treatment with the purified proteins (25 μg/ml). BMOCs were analyzed through TRAP staining (left panels; original magnification, ×100). The TRAP solution assay was performed (top right panel). The number of TRAP⁺ MNCs (≥3 nuclei) was counted (bottom right panel). Open boxes, retrovirus-transduced caNFATc1. The empty vector was used as a control (mock; black box). F, effects of c-Fos overexpression. Open boxes, retrovirus-transduced c-Fos. The empty vector was used as a control (mock; black box). G, effects of BLIMP1 overexpression. Open boxes, retrovirus-transduced BLIMP1. The empty vector was used as a control (mock; black box). **, p < 0.01. Error bars, S.D.