Figure 4

Effects of cyclic stretch on myocardin binding activity and promoter activity in VSMCs. Binding activity between myocardin and SRF and genetic transcription activity at SRF binding site of myocardin promoter increase in VSMCs under 20% cyclic stretch. (A) EMSA showed increased binding between myocardin and SRF under 20% cyclic stretch, which was suppressed by losartan and PD98059. Exogenous addition of AngII (10 nM) without cyclic stretch also increased the binding between myocardin and SRF. (B and C) Luciferase reporter assay revealed 20% cyclic stretch increased transcriptional activity at SRF binding sites of myocardin promoter when compared with the myocardin mutant, which was suppressed by PD98059 and losartan. Exogenous addition of AngII (10 nM) without cyclic stretch also increased the transcriptional activity in VSMCs. *P < 0.01 vs.control. ^#P < 0.01 vs. 6 hr (n = 3 per group).