FIGURE 1.

Reduction of membrane cholesterol by Mβ-CD down-regulates α1 Na/K-ATPase. LLC-PK1 cells were treated with 10 mm Mβ-CD in the serum-free medium at 37 °C for 1 h, washed, and then collected after the washed cells were cultured in serum-free medium for 0, 6, and 24 h. A, cholesterol content in the cell lysates from different time points were measured, adjusted to protein level, and compared. B, representative Western blots are shown on the levels of the α1 subunit, the insulin receptor β subunit, and α-tubulin (used as loading control). Quantitative data in A and B are combined from four separate experiments and expressed as mean ± S.E. The calculations are based on paired analyses between control and Mβ-CD at each time point. *, p < 0.05; **, p < 0.01. C, representative confocal images of the cellular distribution of α1 Na/K-ATPase in the non-treated cells (top) and Mβ-CD-treated cells (bottom) are displayed.