mDUX and myogenic differentiation.

<p>(A) Phase-contrast microscopy of iC2C12-mDUX cells induced with doxycyline through 6 days of differentiation. (B) Immunofluorescence for detection of MyHC (red, upper panels) and MyoD (red, lower panels) in cells induced with low levels of doxycycline. Nuclei were counterstained with DAPI (blue). iC2C12-mDUX cells were in differentiation medium for 6 days when myotube fusion index was calculated (C). Significantly diminished myogenic differentiation was observed in the cells induced with 10 ng/mL doxycyline. (D) Inhibition of differentiation was confirmed by qRT-PCR. Results are presented as fold difference compared to uninduced cells (0 ng/mL) and the error bars represent the STDEV. (E) Immunofluorescence for detection of MyHC (red) in C2C12 and iC2C12 control cells after 6 days of differentiation and treatment with different concentrations of doxycycline. (F) Calculated fusion index and (G) gene expression analyses of differentiated C2C12 and iC2C12 control cells. Doxycycline by itself did not have any significant effect on myoblast (C2C12 and iC2C12) differentiation.