Regulation of Myf5 Early Enhancer by Histone Acetyltransferase p300 during Stem Cell Differentiation

Skeletal myogenesis is an intricate process coordinated temporally by multiple myogenic regulatory factors (MRF) including Myf5, which is the first MRF expressed and marks the commitment of skeletal muscle lineage. The expression of Myf5 gene during early embryogenesis is controlled by a set of enhancer elements, and requires the histone acetyltransferase (HAT) activity of transcriptional coactivator p300. However, it is unclear as to how different regulatory signals converge at enhancer elements to regulate early Myf5 gene expression, and if p300 is directly involved. We show here that p300 associates with the Myf5 early enhancer at the early stage of stem cell differentiation, and its HAT activity is important for the recruitment of β-catenin to this early enhancer. In addition, histone H3-K27 acetylation, but not H3-K9/14, is intimately connected to the p300 HAT activity. Thus, p300 is directly involved in the regulation of the Myf5 early enhancer, and is important for specific histone acetylation and transcription factor recruitment. This connection of p300 HAT activity with H3-K27 acetylation and β-catenin signalling during myogenic differentiation in vitro offers a molecular insight into the enhancer-elements participation observed in embryonic development. In addition, pluripotent stem cell differentiation is a valuable system to dissect the signal-dependent regulation of specific enhancer element during cell fate determinations.