FIGURE 2.
Effect of β-arrestin siRNAs on AngII-stimulated pMnk1 and peIF4E activation. A, HEK-293 cells stably expressing HA-AT1AR and Mnk1 were transfected with either control siRNA (CTL) or β-arrestin1-specific or β-arrestin-2-specific siRNAs (β-arr1, β-arr2). 72 h post-transfection, cells were serum-starved for 16 h and stimulated with 100 nm AngII for the indicated times. Western blots for phospho-Mnk1 and total Mnk1 were performed. The percentage of pMnk1/tMnk1 was calculated for each data point and plotted as a percentage of maximal activity (CTL-transfected cells at 30 min). These data represent the average of six independent experiments ± S.E. Representative pMnk1- and β-arrestin-silencing Western blots are shown. B, cells were treated as in A and stimulated with 100 nm AngII for 30 min, and Western blots were performed for phospho-eIF4E and total eIF4E. Data in graph represent the means ± S.E. of five experiments; statistical significance was calculated by one way ANOVA with post-test comparison of AngII-stimulated populations (*, p < 0.05). Representative Western blot for p-eIF4E is shown.