A specific role for the splice variants of the transcription factor NF-Y in modulating the transcriptional activity of the myogenic program

Cell proliferation and differentiation programs are highly regulated transcriptional processes essential for myogenesis. The transcription factor NF-Y has been long considered a fundamental player of cell growth by supporting the basal transcription of various cell cycle genes. It is composed by the NF-YB/NF-YC heterodimer and NF-YA, which interacts with the other two subunits and confers the strict sequence specificity to the complex. The NF-YA gene encodes two alternatively splice transcripts (NF-YAs and NF-YAl), which differently regulate cell proliferation and differentiation, as shown in haematopoietic and mouse embryonic stem cells. NF-YAl expression is down-regulated in terminally differentiated muscle cells and in skeletal and cardiac muscle tissues. Its forced expression in muscle cells committed to differentiate impairs their exit from the cell cycle and indirectly interferes with the differentiation program. Here we show that the two NF-YA isoforms play a different role in the transcriptional activity of the myogenic program and may regulate the activity of muscle satellite cells.