Generation of miR-133a transgenic mice. (A) Diagram of transgenic construct used in this study to overexpress miR-133a in the skeletal muscle of transgenic mice. Two arrows represent PCR primers used for genotyping. MCK: muscle creatine kinase; hGH: human growth hormone. (B) PCR genotyping of miR-133a transgenic founder mice. * indicated genotyping positive founder lines; M: DNA size marker; +: Positive control; -: Negative control. (C) Northern blot analyses of miR-133a expression in the heart, skeletal muscle and liver tissues of the wild type and transgenic mice. tRNAs were used as a loading control. (D) The intensity of skeletal muscle expressed miR-133a from Northern blot was quantified using the Photoshop Histogram Analysis and was plotted using Microsoft excel and is shown as relative expression level after normalized by tRNA. Statistical differences were determined using the Student's t-test; (*) P < 0.05.