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

Abstract

The <italic>Drosophila melanogaster</italic> selector gene <italic>cut </italic> is a hierarchal regulator of external sensory organ identity, and is required to pattern sensory and non-sensory cells of the wing margin. <italic> cut</italic> performs the latter function, in part, by maintaining expression of the secreted morphogen encoded by <italic>wingless</italic>. I find that cut is required for wing margin sensory organ specification in addition to and independent of <italic>wingless</italic> maintenance. In addition, I performed a genetic modifier screen to identify other genes that interact with <italic> cut</italic> 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 <italic> gypsy</italic> retrotransposon-mediated insulation of the <italic>cut</italic> wing margin enhancer. Further genetic characterization identified several subgroups of candidate <italic>cut</italic> interacting loci. One group consists of putative regulators of <italic>gypsy</italic> insulator activity. A second group is potentially required for the regulation of cut expression and/or activity, which includes <italic>longitudinals lacking</italic>, 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 <italic> moira</italic>, affects the level of <italic>cut</italic> expression/activity in two opposing ways, by suppressing <italic>gypsy</italic>-mediated <italic> ct<super>K</super></italic> phenotype and enhancing the non-<italic>gypsy ct<super>53d</super></italic> phenotype. This suggests enhancer controlled transcription and gypsy mediated insulation, at least of the cut locus, may utilize common components to regulate gene expression.