Figure 7.

Knockdown of USP48 or inhibition of TNIK and JNK promotes epithelial barrier integrity. A) Scheme showing principle of ECIS system. B) Knockdown of USP48 increases TEER in A549 cells. A549 cells cultured on ECIS gold electrodes were transfected with control siRNA or Usp48 siRNA. After transfection, changes in TEER at 0 to 36 h were measured with ECIS. Data are presented as means ± sd (n = 4). C) Knockdown of USP48 increases TEER in Beas2B cells. Beas2B cells cultured on ECIS gold electrodes were transfected with control siRNA or Usp48 siRNA. After transfection, changes in TEER at 48 h were measured with ECIS. Data are presented as means ± sd (n = 4). P < 0.01 compared to control siRNA–transfected cells. The rest of the cells were analyzed by USP48, TRAF2, and β-actin immunoblotting. D) Inhibition of TNIK or JNK increases TEER. Beas2B cells cultured on ECIS gold electrodes were treated with DMSO (10 μM), KY-05009 (10 μM), or SP600125 (10 μM), and changes in TEER at 0 to 36 h were measured with ECIS. Data are presented as means ± sd, n = 4. E) Knockdown of USP48 promotes LPA-increased TEER. Human bronchial epithelial cells cultured on ECIS gold electrodes were transfected with control siRNA or Usp48 siRNA and incubated for 3 d. Cells were then challenged with LPA (0.5 μM), and changes in TEER were measured with ECIS. F) Scheme showing GSK3β phosphorylates and activates USP48, thus stabilizing TRAF2 and influencing TNIK/JNK-mediated E-cadherin expression and epithelial barrier integrity.