ISOLATION AND CHARACTERIZATION OF MAMMALIAN HOMOLOGS OF THE DROSOPHILA GENE GLIAL-CELLS MISSING

The glial cells missing (gcm) gene in Drosophila encodes a transcripti on factor that determines the choice between glial and neuronal fates. We report here the isolation of two mammalian gem homologs, Gcm1 and Gcm2, and the characterization of their expression patterns during emb ryonic development. Although Gcm2 Is expressed in neural tissues at a low level, the major sites of expression for both of the mammalian gen es are nonneural, suggesting that the functions of the mammalian homol ogs have diverged and diversified. However, when expressed ectopically , Gcm1 can substitute functionally for Drosophila gem by transforming presumptive neurons into glia, Thus, certain biochemical properties, a lthough not the specificity of the tissue in which the gene is express ed, have been conserved through the evolution of the Gcm gene family.