Figure 11.

Silencing of the β₂ subunit in ARPE-19 cells affects the apical distribution of Na⁺, K⁺-ATPase. The transfected siRNAs for the β₂ isoform are labeled with Cy3. Red fluorescent spots thus identify transfected cells. Confocal images of mock-transfected cells in which the β₂ and α₂ subunits are immunostained (A,D), respectively show an apical distribution pattern for both subunits. Images of silenced cells show an apical expression of the β₂ (B) and α₂ (E) subunits (green) in non-transfected cells. Arrows in (B) indicate the lack of β₂ expression in the apical domain of siRNA-transfected cells. The absence of α₂ immunostaining in the apical domain is also indicated by arrows in panel (E), implying the mislocalization of Na⁺, K⁺-ATPase from the apical domain. The fluorescence intensity of β₂ (C) and α₂ subunits (F) in silenced cells was measured in 10 different fields, and the mean ± SEM is shown. Scale bar: 10 μm.