Figure 1

The expression of myogenic late marker genes correlates with chromatin remodeling on the promoters of myogenic late marker genes in developing embryos. (A) Time course of late myogenic marker gene expression during embryogenesis. mRNA levels of each gene were examined at the indicated stage by quantitative RT–PCR. Late marker genes: MCK, desmin, and -skeletal actin. Fold induction was standardized to the E10.5 stage point of myogenic tissue, which was defined as 1. (B) Chromatin accessibility at the endogenous late marker genes correlates with the onset of gene expression. Nuclei were isolated from each indicated embryonic tissue. A modified LM–PCR protocol (de la Serna et al, 2005) was utilized to visualize digested genomic DNA. The PCR product is shown as an inverse image (top panel). Relative accessibility was standardized to accessibility of the E10.5 sample, which was defined as 1. Quantification represents the average of two independent experiments. Variation between experiments did not exceed 20% for any sample. (C) Time course of regulatory protein gene expression during embryogenesis. mRNA levels of each gene were examined at the indicated stage by quantitative RT–PCR and quantified as described above. MRF family: MyoD, Myogenin, and Myf5. Mef2 family: Mef2A, Mef2C, and Mef2D. SWI/SNF enzyme subunits: Brg1 and Ini1.