FIGURE 2:

PIAS4 knockdown reduces CFTR expression in CFBE airway cells. (A, B) Knockdown performed in stable CFBE-WT or -F508del cells. shRNA targeting PIAS4 was transduced using a recombinant adenovirus, compared with adenotransduced scrambled shRNA. CFTR expression was evaluated by IB with the indicated antibodies after 48 h virus exposure. For all experiments here, bar graphs provide composite means ± SEM from at least four independent experiments (**p < 0.01; ***p < 0.001), and a bracket indicates the gel region used in quantitation. (C) Overexpression of PIAS4 promotes CFTR cell-surface expression. CFBE-WT cells were transduced with PIAS4 or GFP for 72 h and biotinylation assays performed; streptavidin elution was followed by IB with the indicated antibodies, as described under Materials and Methods. Surface CFTR signals were normalized to the actin loading control. (D) PIAS4 knockdown reduces CFTR surface expression. CFBE-WT cells were transduced with adenovirus vector shRNA targeting PIAS4 or scrambled shRNA for 72 h and then subjected to surface biotinylation and analysis as described in C and under Materials and Methods.