FIGURE 3.

β-Catenin is required for smooth muscle contraction. A, human bronchial rings were transduced with lentiviruses encoding control shRNA or β-catenin shRNA. These tissues were then incubated in serum-free medium for 3 days. Immunoblot analysis was used to assess protein expression in tissues. UI, uninfected; Ctrl, control shRNA; β-Cat, β-catenin shRNA. *, p < 0.05 (significantly lower protein ratios of β-catenin/GAPDH in tissues transduced with virus encoding β-catenin shRNA than in uninfected tissues and tissues expressing control shRNA). Data are mean ± S.E. of three independent experiments. B, the contraction of human bronchial rings was evaluated, after which they were transduced with lentiviruses as described above. Contractile responses were compared before and after incubation. *, p < 0.05 (significantly lower contractile force in bronchial rings treated with β-catenin shRNA compared with uninfected tissues or tissues infected with viruses encoding control shRNA). Data are mean ± S.E. of three independent experiments. C, uninfected cells and cells expressing control shRNA or β-catenin shRNA were stimulated with ACh (10⁻⁴ m, 5 min) or left unstimulated. F/G-actin ratios in the cells were evaluated using a fractionation assay. Data are mean ± S.E. of four independent experiments. (p > 0.05). S, supernatant; P, pellet. D, myosin light chain (MLC) phosphorylation at Ser-19 in uninfected cells and cells transduced with lentivirus encoding control or β-catenin shRNA was assessed by immunoblot analysis. Myosin phosphorylation was similar in uninfected cells, cells expressing control shRNA, or β-catenin shRNA (p > 0.05). Data are mean ± S.E. of four to five independent experiments.