FIGURE 2.

Myocardin participates in mediating the hypertrophic signals of Iso and Aldo. A, knockdown of myocardin expression. Cardiomyocytes were infected with adenoviral myocardin-RNAi-A (myo-RNAi-A) or its scramble form (myo-S-RNAi-A) at a moi of 80. 48 h after infection the cells were harvested for the analysis of myocardin levels by immunoblot. B, knockdown of myocardin reduces hypertrophic responses induced by Iso. Cardiomyocytes were infected with adenoviral myocardin-RNAi-A or its scramble form (myocardin-S-RNAi-A) at a moi of 80. 24 h after infection the cells were treated with Iso. Analysis of myocardin levels by immunoblot was performed 1 h after Iso treatment (top panels). Hypertrophy was assessed by cell surface area measurement, protein/DNA ratio and β-MHC levels analyzed by qRT-PCR. *, p < 0.05 versus control; #, p < 0.05 versus Iso alone. C, myocardin is necessary for Aldo to induce hypertrophy. Cardiomyocytes were treated as described for B, except that Aldo was employed. *, p < 0.05 versus control; #, p < 0.05 versus Aldo alone. D, representative photos show sarcomere organization. Cardiomyocytes were treated as described for B or C. Bar, 20 μm. E, knockdown of myocardin expression. Cardiomyocytes were infected with adenoviral myocardin-RNAi-B (myo-RNAi-B) or its scramble form (myo-S-RNAi-B) at a moi of 100. 48 h after infection the cells were harvested for the analysis of myocardin levels by immunoblot. F, knockdown of myocardin reduces cell surface area induced by Iso. Cardiomyocytes were infected with adenoviral myocardin-RNAi-B or its scramble form (myocardin-S-RNAi-B) at a moi of 100. 24 h after infection cells were treated with Iso. Analysis of myocardin levels by immunoblot was performed 1 h after Iso treatment (top panels). Hypertrophy was assessed by cell surface area measurement (bottom panel). *, p < 0.05 versus control; #, p < 0.05 versus Iso alone. The data are expressed as the means ± S.E. of three independent experiments.