Expression of Mef2 genes in the mouse central nervous system suggests a role in neuronal maturation

Members of the myocyfe enhancer factor 2 (MEF2) gene family are expressed in a dynamic pattern during cievel-opment of the CNS of pre- and postnatal mice. The four MEF2 genes, Mef2A,-B, 4,-0, encode transcription factors belonging to the MADS (MCMl-agamous-deficiens-serum response factor) superfamily of DNA binding proteins. MEF2 factors have previously been shown to be positive regulators of gene expression in terminally differentiated muscle cells. To begin to determine the role of MEF2 fac-tors in CNS development, we used in situ hybridization with gene-specific cRNA probes to define the expression patterns of each of the four Mef2 mRNAs in the developing and mature mouse CNS. Mef2C mRNA was first detected in a ventral portion of the telencephalon at 11.5 d postcoi-turn (p.c.). By 13.5 d p.c., each of the four Mef2 genes wer