Interaction between JAK STAT pathway and axial patterning genes in Drosophila eye development

Axial patterning is the fundamental process of organogenesis, which entails delineation of three distinct axes: Antero-Posterior (AP), Dorso-Ventral (DV) and Proximo-Distal (PD) axes. Any impairment in the axis formation may lead to developmental birth defects in humans and therefore, getting insight of the mechanism of axis determination is crucial for better understanding of organogenesis. In Drosophila eye model, DV patterning is the primary lineage restriction event. A new member of DV patterning gene, defective proventriculus (dve, a Homeobox gene), an ortholog of SATB homeobox 1 (special AT-rich sequence binding protein 1) has been identified which acts downstream of a GATA-1 transcription factor pannier (pnr), and upstream of wingless (wg) in the dorsal gene hierarchy. Unpaired (Upd), a long range secreted ligand for JAK STAT pathway, is known to promote eye development by negatively regulating Wg expression. Here we present that Upd interacts with dve, to regulate the patterning and growth of the developing Drosophila eye. We found that activation of JAK STAT pathway in dve expression domain results in dorsal eye enlargement and downregulation of Wg expression whereas its inactivation in Dve domain results in eye suppression phenotype and upregulating Wg expression. Our data strongly imply that Upd plays a crucial role in defining the functional domain of Dve during DV axis formation of developing eye. We will present the complex interactions between these two highly conserved pathways, viz., JAK-STAT and dorsal eye fate selectors in growth and patterning of the eye