Essential roles for stat92E in patterning the proximodistal axis of the Drosophila wing imaginal disc. Victor Hatini, Ela Kula, David Nusinow, Steven DelSignore. Dept Anatomy & Cellular Biol, Tufts Univ, Boston, MA.

   The Drosophila wing imaginal disc is subdivided along the proximodistal axis into the distal pouch, the hinge, the surrounding pleura, and the notum. The mechanisms that subdivide the wing proximodistal axis into smaller domains and regulate their scope and limits are incompletely understood. Here we investigated the role of the stat92E signal transducer and activator of transcription in wing proximodistal patterning. We mapped Stat92E activity from early stages and employed genetic loss- and gain-of-function analysis to investigate the role of stat92E in wing proximodistal axis patterning. We find that Stat92E is active ubiquitously in early wing imaginal discs where it acts to inhibit the induction of ectopic wing fields. As development proceeds, Stat92E activity is downregulated in the notum and distal pouch. This downregulation coincides with and contributes to the expansion and patterning of these structures. At late stages, Stat92E activity is progressively restricted to the lateral border of the notum, the pleura and hinge. During this period, stat92E specifies dorsal pleura identity and inhibits notum identity. Additionally, stat92E contributes to the expansion of gene expression domains along the hinge proximodistal axis. Overall, we find important roles for stat92E in wing proximodistal patterning and in controlling the scope and limits of gene expression domains along the wing proximodistal axis.