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. 2008 Apr 18;283(16):10611–10620. doi: 10.1074/jbc.M710515200

FIGURE 6.

FIGURE 6.

β-Arrestin2 signaling stimulates Mnk1 activation and protein synthesis in vascular smooth muscle cells. A, rVSMCs were serum-starved and pretreated with vehicle Me2SO (DMSO), the PKC inhibitor Ro31–8425, or the MEK inhibitor U0126 for 30 min. Cells were stimulated with either 100 nm AngII (A) or 10 μm SII-AngII (S) for an additional 30 min. Western blots for pMnk1 were performed and quantitated. Results depicted are representative of four experiments ± S.E. Statistical significance was calculated using a one-way ANOVA with post test. Me2SO-nonstimulated was compared with the following, Me2SO AngII (**, p < 0.01), Me2SO SII (*, p < 0.05), Ro31 AngII (***, p < 0.001), and Ro31 SII (**, p < 0.01). No other conditions are significant with respect to the Me2SO-nonstimulated group. B, rVSMCs were transfected with siRNA for β-arr2 and subjected to pMnk1 analysis as in A at 96 h post-transfection. Graph depicts results from six experiments ± S.E. Statistical significance was calculated using a one-way ANOVA with post test. CTL-nonstimulated was compared with CTL AngII (***, p < 0.001) and CTL SII (**, p < 0.01). CTL AngII was compared with βarr2 AngII (**, p < 0.01). No other comparisons are significant. C, rat vascular smooth muscle cells (rVSMC) were serum-starved and stimulated with AngII or SII in the presence of [3H]leucine for 24 h. Radiolabeled proteins were quantitated as described under “Experimental Procedures.” Data are normalized such that nonstimulated cells are set to 100%. Results depicted are representative of four experiments (means ± S.E.). Statistical significance was calculated using a one-way ANOVA with post test: N.S. versus AngII was *, p < 0.01 and N.S. versus SII was **, p < 0.05. D, rVSMC were transfected with siRNAs for β-arrestin2 or Mnk1 and subjected to protein synthesis analysis as in C at 96 h post-transfection. Results depicted are representative of six experiments (means ± S.E.). Statistical significance was calculated using a one-way ANOVA with post test. CTL N.S. compared with CTL AngII was *, p < 0.05. CTL AngII compared with βarr2 AngII and Mnk1 AngII were both **, p < 0.01.