Characterization of the Drosophila insulin receptor promoter

The insulin receptor (InR) signaling pathway is largely conserved in metazoans and it is required for normal growth and development in Drosophila. Despite the importance of this pathway in regulating growth, development and metabolism in Drosophila, little is known about how dInR expression is controlled in flies. Here we report the characterization of the dInR gene promoter and the analysis of its expression during embryo development. Drosophila InR gene has three promoters spanning 40 kb in the genome. These promoters direct the expression of three distinct mRNA transcripts that share common exons downstream of the initiator codon ATG but have different 5′UTRs. All three promoters are differentially regulated, spatially and temporally, contributing to a very complex pattern of expression in the developing embryo. Our results indicate that dInR expression in Drosophila displays an intricate pattern of regulation that assures an adequate control of growth, development and metabolism.