aaquetzalli is required for epithelial cell polarity and neural tissue formation in Drosophila

Morphogenetic movements during embryogenesis require dynamic changes in epithelial cell polarity and cytoskeletal reorganization. Such changes involve, among others, rearrangements of cell-cell contacts and protein traffic. In , neuroblast delamination during early neurogenesis is a well-characterized process requiring a polarized neuroepithelium, regulated by the Notch signaling pathway. Maintenance of epithelial cell polarity ensues proper Notch pathway activation during neurogenesis. We characterize here ( ), a gene whose mutations affect cell polarity and nervous system specification. The locus encodes a protein that harbors a domain with significant homology to a proline-rich conserved domain of nuclear receptor co-activators. expression occurs at all stages of the fly life cycle, and is dynamic. mutants are lethal, showing a disruption of cell polarity during embryonic ventral neuroepithelium differentiation resulting in loss of epithelial integrity and mislocalization of membrane proteins (shown by mislocalization of Crumbs, DE-Cadherin, and Delta). As a consequence, mutant embryos with compromised apical-basal cell polarity develop spotty changes of neuronal and epithelial numbers of cells.