Figure 7
A model of the E2F1/miR-17-92/ENH1/Id1 regulatory axis in myogenesis. In the proliferating myoblasts, E2F1 upregulates the transcription of miR-17-92. miR-17, -20a and -92a, sequester Id1 in the nucleus by targeting its cytoplasmic sequestration factor, ENH1. Id1 binds to myogenic regulatory factor (MRF) and E protein, which prevents the heterodimerization of MRF and E protein and subsequently inhibits myogenic differentiation. Upon the stimulation of differentiation, the low expression of miR-17-92 results in a high level of ENH1, which reduces the abundance of Id1 protein in the nucleus, possibly by sequestrating the Id1 into the cytoplasm. The complex of MRF and E protein binds to the promoters of target muscle genes, thereby driving their expressions and inducing myogenic differentiation
