Jian Wang et al. npg 519 2E). Conversely, knockdown of miR-27b partially res- cued the hypertrophic effects of PE treatment and miR- 27b overexpression (Figure 2F-2I). Cardiac hypertrophy is always accompanied by upregulation of fetal genes, such as atrial natriuretic factor (ANF) and skeletal mus- cle and cardiac actin (SKA). Real-time PCR showed that miR-27b overexpression could significantly upregulate ANF and SKA transcripts, while miR-27b knockdown could partially rescue the upregulation of these genes in the cardiomyocytes treated with PE or cardiomyocytes overexpressing miR-27b (Figure 2J and 2K). Quantita- tive assessment of cardiomyocyte proliferation by using Figure 2 Overexpression of miR-27b promoted hypertrophic growth of cardiomyocytes. (A) Real-time PCR showed that miR- 27b adenovirus effectively increased the expression level of pre-miR-27b. (B) Northern blot and quantification results showed that miR-27b adenovirus increased the miR-27b level in cardiomyocytes, while anti-miR-27b adenovirus decreased the en- dogenous expression level of miR-27b. (C-H) Isolated rat neonatal cardiomyocytes were infected with Ad-miR-27b, Ad-anti- miR-27b or control adenoviruses, and treated with or without PE. Cardiomyocytes were stained for GFP (green) and α-actinin (red). DAPI staining was done to visualize the nuclei (blue). Scale bar, 15 µm. (I) Fold change in mean cell surface area of α-actinin-immunostained cardiomyocytes (n = 120 cells/condition). (J, K) ANF and SKA transcripts were examined by real- time PCR. *P < 0.05 relative to respective controls. aP < 0.05 vs Ad-GFP treated with PE. bP < 0.05 vs miR-27b overexpres- sion. www.cell-research.com | Cell Research