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-specifi c genes. The recent cloning of MEF-2 showed that it belongs to the MAD S (MCM1, Agamous, Deficiens, and serum-response factor) box family of transcription factors and that MEF-2 mRNA is expressed ubiquitously. H ere we describe the cloning of a member of the MEF-2 gene family, refe rred to as MEF-2C, that is nearly identical to other MEF-2 gene produc ts in the MADS box but diverges from other members of the family outsi de 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, sp leen, and brain of adult mice and are upregulated during myoblast diff erentiation. These results suggest that the MEF-2 site is a target for a diverse family of proteins that regulates transcription in a variet y of cell types.