The identification of genetic loci that interact with the neural selector gene cut during wing margin development in Drosophila melanogaster

The Drosophila melanogaster selector gene cut is a hierarchal regulator of external sensory organ identity, and is required to pattern sensory and non-sensory cells of the wing margin. cut performs the latter function, in part, by maintaining expression of the secreted morphogen encoded by wingless. I find that cut is required for wing margin sensory organ specification in addition to and independent of wingless maintenance. In addition, I performed a genetic modifier screen to identify other genes that interact with cut in the regulation of wing margin patterning. In total, 45 genetic loci (35 gain-of-function and 10 loss-of-function) were identified by virtue of their ability to suppress the wing margin defects resulting from gypsy retrotransposon-mediated insulation of the cut wing margin enhancer. Further genetic characterization identified several subgroups of candidate cut interacting loci. One group consists of putative regulators of gypsy insulator activity. A second group is potentially required for the regulation of cut expression and/or activity, which includes longitudinals lacking, a gene encoding for a BTB-domain zinc-finger transcription factor. A third group, which includes a component of the Brahma chromatin remodeling complex encoded by moira, affects the level of cut expression/activity in two opposing ways, by suppressing gypsy-mediated ctK phenotype and enhancing the non-gypsy ct53d phenotype. This suggests enhancer controlled transcription and gypsy mediated insulation, at least of the cut locus, may utilize common components to regulate gene expression.