Figure 8

TGF-β1 induces MMP-9 expression and activation in the rat primary cultured astrocytes. (A) Time dependence of TGF-β1-induced MMP-9 expression and activation. Cells were treated with TGF-β1 (15 ng/ml) for the indicated time intervals. The conditioned media were collected and analyzed MMP-9 activity by gelatin zymography (upper panel). For MMP-9 protein level, conditioned media were immunoprecipitated with an anti-MMP-9 antibody and analyzed by western blot (lower panel). (B) Cells were pretreated with SB431542 (SB43, 10 μM), NAC (100 μM), U0126 (10 μM), SB202190 (SB20, 10 μM), SP600125 (SP, 10 μM), or Bay11-7082 (Bay, 1 μM) for 1 h, and then treated with TGF-β1 for 24 h. (C) Schematic pathway for TGF-β1-induced ROS-dependent MMP-9 expression and cell migration in RBA-1 cells. Each solid line and arrow represents a step in an activating pathway. TGF-β1 induces MMP-9 expression via TGF-β receptor, ROS-dependent activation of ERK1/2 and JNK1/2, and transcription factor NF-κB pathway, which results in the promotion of cell migration in RBA-1 cells.