FIGURE 6.

Mef2A activates costamere target gene expression. A, luciferase reporter assays of cloned costamere promoters display significant activation with transiently transfected Mef2A in COS1 cells. Fold change was calculated using normalized luciferase readings. B, functional Mef2 sites in costamere promoters. Mutant Mef2 sites in costamere promoters reduces the ability of Mef2A to activate reporter in cells co-transfected with Mef2A. C, analysis of costamere gene expression in NRVMs overexpressing Mef2A. Total RNA was harvested from four NRVM cultures transduced with LacZ (O/E LacZ, black bars) or Mef2A (O/E Mef2A, white bars) adenovirus for overexpression. Total RNA was harvested from NRVMs 72 h after transduction and subjected to qRT-PCR analysis. A subset of costamere target genes (ANKB, DYSB, PDLIM1, PDLIM5, SGCA, and SGCB) are activated with acute expression of Mef2A (n = 4). *, p ≤ 0.05; #, p ≤ 0.008.