MEF2Cα2 robustly enhances MRF activity, whereas MEF2Cα1 does not.
A, MEF2Cα2 stimulates the activity of MyoD on a muscle-specific luciferase reporter construct. 10T1/2 cells were transfected with the indicated constructs. Values are represented with respect to a luciferase vector with no promoter (pGL3 basic). pGL3 (+), luciferase vector with the constitutive CMV promoter; Lmod2-luc, luciferase vector with a ∼300-bp Leiomodin 2 (Lmod2) promoter. Error bars show mean ± S.D. **, p < 0.01; ***, p < 0.001. B, confirmation of the expression of MEF2Cα1 and MEF2Cα2. 10T1/2 cells were transfected with expression constructs for MyoD, MEF2Cα1, and MEF2Cα2 as indicated, and gene expression was determined by qRT-PCR for the indicated genes. Vector, vector-only transfection where the expression level was set to 1. Error bars show mean ± S.D. ***, p < 0.001. C, MEF2Cα2 activates endogenous MRF target gene expression. 10T1/2 cells were transfected with expression constructs for MyoD, MEF2Cα1, and MEF2Cα2 and analyzed for the indicated genes as in B.