Myocyte enhancer factor (MEF) 2C: A tissue-restricted member of the MEF-2 family of transcription factors

MEF-2 is a muscle-specific DNA binding activity that recognizes an A+T-rich sequence found in the control regions of numerous muscle-specific genes. The recent cloning of MEF-2 showed that it belongs to the MADS (MCM1, Agamous, Deficiens, and serum-response factor) box family of transcription factors and that MEF-2 mRNA is expressed ubiquitously. Here we describe the cloning of a member of the MEF-2 gene family, referred to as MEF-2C, that is nearly identical to other MEF-2 gene products in the MADS box but diverges from other members of the family outside of this domain. MEF-2C binds the MEF-2 site with high affinity and can activate transcription of a reporter gene linked to tandem copies of that site. In contrast to previously described members of the MEF-2 family, MEF-2C transcripts are highly enriched in skeletal muscle, spleen, and brain of adult mice and are upregulated during myoblast differentiation. These results suggest that the MEF-2 site is a target for a diverse family of proteins that regulates transcription in a variety of cell types.