Figure 5.

Progesterone promotes CM proliferation through up‐regulation of YAP expression. Cultured P7 CMs were treated with control (vehicle, DMSO) or progesterone (10⁻⁷ M), alone or in combination with RU486 (A‐C) or YAP siRNAs (D‐F). A, Proliferation regulator mRNA expressions of CM were analysed by quantitative PCR (n = 4). B, Representative immunoblots (B1) and quantification (B2) of YAP protein expression were analysed by Western blotting (GAPDH was used as internal control) (n = 4). C, The mRNA expression of YAP target genes ANKRD1, CYR61 and CTGF was analysed by quantitative real‐time PCR (n = 4). D‐F, CM proliferation was evaluated by Ki67, PH3 and Aurora B immunostaining. Representative images are shown in D1, E1 and F1, and quantification of percentages of Ki67⁺, PH3⁺ or Aurora B⁺ CMs is shown in D2, E2 and F2, respectively (3000‐5000 cells were randomly selected and analysed for each group) (n = 4). Scale bars are 40 µm (^** P < .01, ^*** P < .001) vs Control; (^## P < .01, ^### P < .001) vs Progesterone. CM, cardiomyocyte; YAP, yes‐associated protein