Drosophila Med6 is required for elevated expression of a large but distinct set of developmentally regulated genes

Mediator is the evolutionarily conserved coactivator required for the integ ration and recruitment of diverse regulatory signals to basal transcription machinery. To elucidate the functions of metazoan Mediator, we isolated Dr osophila melanogaster Med6 mutants, dMed6 is essential for viability and/or proliferation of most cells. dMed6 mutants faded to pupate and died in the third larval instar with severe proliferation defects in imaginal discs an d other larval mitotic cells, cDNA microarray, quantitative reverse transcr iption-PCR, and in situ expression analyses of developmentally regulated ge nes in dMed6 mutants showed that transcriptional activation of many, but no t all, genes was affected. Among the genes found to be affected were some t hat play a role in cell proliferation and metabolism. Therefore, dMed6 is r equired in most cells for transcriptional regulation of many genes importan t for diverse aspects of Drosophila development.