Fig. 10.
Effect of claudin-4 knockdown. OK cells expressing the empty vector (V) or overexpressing claudin-4 were treated for 96 h with scrambled RNA (black bars) or claudin-4 small interfering (si)RNA (grey bars). Ussing chamber experiments were then performed to determine TER (A), PNa/PCl (B) and absolute Na+ (C) and Cl− (D) permeability. RT-PCR analysis of claudin -1 (E), -4 (F), -6 (G), -9 (H), and -12 (I) expression in empty vector expressing cells (V) and cells overexpressing claudin-4 (CL4) after transfection with scrambled siRNA or claudin-4 siRNA. Gene expression is represented as percentage of control (OK cells stably expressing pcDNA 3.1+) and normalized to the expression of GAPDH. Data are presented as means ± SE; n ≥ 3 cell lines. *P value < 0.05.