FIGURE 3.

Overexpression and rescue of MEF2 in C2C12 myoblasts. A, Western blot analyses of C2C12 cells transduced with MEF2 isoform adenoviruses confirm an increase in MEF2 protein levels, relative to the β-gal control. OE, overexpression. B, overexpression of MEF2A, -C, or -D did not overtly modulate C2C12 myotube formation. Interestingly, overexpression of the MEF2D muscle-specific isoform did not result in enhanced myotube formation, as previously described. C, overexpression of MEF2-VP16, but not overexpression of MEF2C or -D alone or in combination, was able to rescue the differentiation defect observed in MEF2A depleted C2C12 myotubes. D, overexpression of MEF2A was unable to restore MEF2A to wild type levels, because the MEF2A cDNA encoded in this adenovirus is knocked down by shMef2a. E, quantification of MEF2A Western blot analysis. F, Western blot analysis of myosin heavy chain (MHC) expression demonstrates overexpression of MEF2-VP16, but not MEF2C or -D alone or in combination, was able to rescue impaired differentiation in MEF2A deficient cells. G, quantification of the myosin heavy chain expression Western blot analysis. The data are means ± S.E. **, p < 0.01; ***, p < 0.001.