EXPRESSION OF THE D-MEF2 TRANSCRIPTION FACTOR IN THE DROSOPHILA BRAINSUGGESTS A ROLE IN NEURONAL CELL-DIFFERENTIATION

D-MEF2 is a MADS domain transcription factor expressed in the cardiac, somatic, and visceral muscle cell lineages in the Drosophila embryo, Genetic studies have demonstrated that D-mef2 gene function is require d for the proper differentiation of all three of these muscle types, W e show that D-MEF2 is also expressed in a limited number of other cell types during development, including Kenyon cells present in the mushr oom bodies of the Drosophila brain, This finding suggests a role for D -mef2 in neuron differentiation, To investigate D-mef2 expression in m uscle and Kenyon cells, we assayed 26 kb of D-mef2 5'-flanking and int ragenic DNA for regulatory sequences controlling the expression of the gene, Our results show that separable enhancer sequences direct D-mef 2 gene expression in the myogenic and neuronal cell lineages. The iden tification of these regulatory DNAs provides a starting point for the analysis of transcriptional regulators controlling the cell-specific e xpression of D-mef2 and a means to address the function of D-mef2 in K enyon cell differentiation.