MEF2C exon α: role in gene activation and differentiation.

Myocyte enhancer factor 2C (MEF2C) belongs to the MEF2 transcription factors. All products of MEF2 genes have a common amino-terminal DNA binding and dimerization domain. All four vertebrate MEF2 gene transcripts are also alternatively spliced. In the present study we identify two novel MEF2C splice variants, named VP and VP2. These variants are generated by the skipping of exon α. The identified α- variants are ubiquitously expressed, although at very low levels compared to the α+ variants. The existence of MEF2C α- variants gave us the opportunity to study for the first time the function of exon α. Transactivation experiments show that the presence of exon α induces a reduction of transcription levels. Moreover, α- variants are significantly expressed during neuronal cell differentiation, indicating a putative role of these variants in development.