Figure 7

Recovery of myogenic gene expression in C2A1a cells after siRNA mediated HMGA1 depletion. (A) RT-PCR to analyze myogenic gene expression after HMGA1 knock-down in C2A1a cells. RT-PCR was as described in Fig. 1. Days of analyses are indicated. Gapdh expression was used as a control. Note the recovery of MyoD, myogenin, myosin lc and α-actin expression on day 3 of differentiation after HMGA1 knock-down in C2A1a cells. (B) Immunofluorescence localizations of myosin (red) in C2C12 and C2A1a control cells (a, b) and C2C12 and C2A1a cells treated with HMGA1 siRNA (a', b') on day 6 after induction. DNA was stained with Hoechst (blue). The siRNA treated C2C12 cells (a') differentiate as control treated C2C12 cells (a). Knock-down of HMGA1 in C2A1a cells recovers myotube formation and myosin expression (b'). Note that the number of chromocenters is reduced in these cells indicating chromocenter clustering (arrows). Bar represents 100 μm. (C) Chromocenter clustering occurs after HMGA1a knock-down in C2A1a cells. Comparison of chromocenter numbers on day 6 of differentiation in terminal differentiated C2C12 cells (grey columns), C2A1a on day 6 throughout induction of myogenesis (green columns) and myosin positive C2A1a cells after knock-down of HMGA1a on day 6 of differentiation (red columns). The evaluation of chromocenter numbers was as described in Fig. 4C.