MEKK1-MKK4-JNK-AP1 Pathway Negatively Regulates Rgs4 Expression in Colonic Smooth Muscle Cells
Figure 7
JNK pathway interacts with NFκB and p38 MAPK pathways.
A. SP600125 enhances IL-1β-induced activation of canonical IKK2/IκBα/NFκB signaling. Cultured muscle cells after serum starvation for 24 h were pretreated with vehicle DMSO or JNK inhibitor SP600125 (10 µM) for 1 h before treatment with or without IL-1β (10 ng/ml) for 15 min. Activation of NFκB signaling was determined by Western blot analysis using indicated specific antibodies. B. IL-1β-induced phosphorylation of JNK (Thr183/Tyr185) is blocked by SP600125, enhanced by p38 MAPK inhibitor but not affected by MEK1 inhibitor. Cultured and serum-starved muscle cells were pretreated with p38 MAPK inhibitor SB203580 (1 µM) or MEK1 inhibitor PD98059 (20 µM) or JNK inhibitor SP600125 for 1 h before exposure to IL-1β (10 ng/ml) for 15 min. Activation of JNK pathway was determined by Western blot analysis using anti-phospho JNK antibody. The antibodies against GAPDH and β-actin were used for the loading control.