Figure 7.

GABPα/β activates the utrophin promoter in muscle cell cultures. (A) The utrophin promoter–luciferase reporter construct PUBF was cotransfected into L6 muscle cell lines along with expression constructs pGABPα, pGABPβ, and pCAGGS (empty vector) along with transfection control pRL and assayed after 24 h of incubation. PUBF-derived firefly luciferase activity is normalized to pRL-derived renilla luciferase activity (internal control) in control transfectants as 100% and expressed as luciferase activity (normalized). The stippled bars represent utrophin promoter activity in cells transfected with empty vector pCAGGS, and cross-hatched bars represent the levels in cultures transfected with pGABPα and pGABPβ. (B) L6 muscle cell lines were transfected with expression constructs pGABPα, pGABPβ, and pCAGGS (empty vector) as control. RNA was extracted, and quantitative RT-PCR was performed for estimating the level of utrophin mRNA. The graph shows the results of quantification of five individual experiments. The stippled bars represent utrophin mRNA levels in control cultures, and cross-hatched bars represent the levels in cultures transfected withpGABPα and pGABPβ. GABPα and GABPβ cotransfection increases de novo utrophin transcription in muscle cell cultures to 238% of control levels (error bars indicate SEM; n = 24) and increases endogenous utrophin mRNA by 189% of control levels (error bars indicate SD; n = 5). Asterisks denote the results were statistically highly significant at p < 0.001.