Figure 1From: TNF-α induces matrix metalloproteinase-9-dependent soluble intercellular adhesion molecule-1 release via TRAF2-mediated MAPKs and NF-κB activation in osteoblast-like MC3T3-E1 cellsTNF-α induces MMP-9 expression through transcription and translation levels. (A) MC3T3-E1 cells were incubated with various concentrations of TNF-α for the indicated time intervals. The conditioned media were collected and analyzed by gelatin zymography. The proteolytic activities of MMP-9 and MMP-2 were manifested as horizontal white bands on a blue background, and the expression of MMP-2 served as an internal control. (B) Cells were treated with TNF-α (15 ng/ml) for various time intervals. The total RNA were collected and analyzed by RT-PCR and real-time PCR. (C) Growth-arrested cells were pretreated with various concentrations of either Act. D or CHI for 1 h and then incubated with TNF-α (15 ng/ml) for 24 h. The conditioned media were collected and assayed by gelatin zymography. The cell lysates were analyzed by Western blot to determine the expression of GAPDH as an internal control. (D) Cells were pretreated with Act.D (1 nM) or CHI (100 nM) for 1 h and then incubated with TNF-α (15 ng/ml) for 6 h. The isolated RNA samples were analyzed for the level of MMP-9 mRNA by real-time PCR. Data are expressed as mean±SEM of three independent experiments. *P < 0.05, #P <0.01, as compared to the cells treated with vehicle (A,B) and TNF-α alone (C,D).Back to article page