Figure 2. Surface expression and the half-life of ENaC is greatly reduced by Nedd4-2.
Panel A: Nedd4-2 isoforms or a control empty vector was transfected with ENaC subunits as indicated into HEK293 cells and biotinylated surface proteins (panel above) and total cellular lysates (panel below) were blotted with an anti-FLAG antibody, the epitope carried by the αENaC subunit. Each of the Nedd4-2 isoforms reduces surface expression of αENaC in a dose dependent manner with Nedd4-2ΔC2 being most potent. Representative of at least two separate experiments. Panel B: ENaC subunits were cotransfected with Nedd4-2 in HEK 293 cells. Cells were treated with 20 μg/ml cycloheximide to arrest translation and at indicated time points lysates prepared and immunoblotted with an anti-FLAG antibody and after stripping re-probed with anti-α tubulin antibody. Overexpression of Nedd4-2 decreases αENaC stability.