FIGURE 3.

MMP-13 expression required the presence of PDGFR-α. Schematic representation of PDGFR-α short hairpin RNA expression plasmid and the putative structure of the dsRNA formed by sh-PDGFR-α_778 were shown (A). The plasmids for vector control (pTOPO-U6II), small interfering RNA for firefly luciferase (Ffl) and shPDGFR-α were transiently transfected into MC3T3-E1 osteoblast-like cells. Cells were incubated for 24 h, and then serum-free conditioned overnight before testing for 30 min. The culture medium and cell lysates were collected for the immunoblot analysis of MMP-13 and PDGFR-α, respectively (C). The MMP-13 activities were revealed by zymogram (B). The vector control or Ffl alone did not affect MMP-13 and PDGFR-α (B and C). However, two doses of the shPDGFR-α at 4 and 8 μg/ml (B and C) blocked PDGFR-α and attenuated MMP-13 and its activities. ^#, p < 0.01, as compared with the strained cells. This was a result of four sets of independent experiments.