FIGURE 5.

Exercise-stimulated Wnt signaling directly triggered the expression of Myf5 and MyoD transcripts in adult/aged skeletal muscle. A, schematic representation of Wnt/β-catenin regulatory sites on the mouse, rat, and human Myf5 promoters. The region about 5 kb upstream of the Myf5 gene is shown with the TCF/LEF consensus sequence. Each yellow square box represents a TCF/LEF regulatory element. A highly conserved sequence within species (* indicates the location), AACAAACAAA, was located 2.5 kb upstream of the Myf5 gene, and the conserved sequence contained multiple TCF/LEF regulatory elements. B, schematic representation of Wnt/β-catenin regulatory sites on the mouse, rat, and human MyoD promoters. The region about 5 kb upstream of the MyoD gene is shown with the TCF/LEF consensus sequence. A highly conserved sequence within species (* indicates the location), ATTTCAAATTTTGC, was located 2.7 kb upstream of the MyoD gene, and the conserved sequence involved the TCF/LEF regulatory element. C, ChIP analysis of the mouse Myf5 promoter in adult/aged skeletal muscle after voluntary wheel running. PCR primers were designed to surround the TCF/LEF regulatory elements that are conserved within species at 2.5 kb upstream of the Myf5 gene. ChIP results obtained by independent replicate experiments are represented as percentages of the input signal (signal relative to input (%)). Signals are represented by white bars (controls in adult and aged mice), gray bars (adult runner mice), and black bars (aged runner mice). D, ChIP analysis of the mouse MyoD promoter in adult/aged skeletal muscle after voluntary exercise. PCR primers were designed to surround the TCF/LEF regulatory element contained within the conserved sequence among mouse, rat, and human MyoD promoters at the 2.7-kb upstream locus.