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Regulation of Epithelial Morphogenesis

Epithelial morphogenesis underlies tissue and organ formation during animal development as well as during tissue regeneration. The best-known examples in Drosophila include the embryonic dorsal closure, formation of the adult thorax, and wound healing. We are interested in the less-well characterized process of fly abdominal morphogenesis, which involves replacement of larval epidermal cells (LECs) with adult histoblasts during metamorphosis. We have implicated the Drosophila basic leucine zipper (bZIP) protein Activating transcription factor 3 (Atf3) in abdominal morphogenesis. During the process of epithelial cell replacement, transcription of atf3 sharply declines. This down-regulation is critical, as sustained atf3 expression in the LECs leads to increased cell adhesion, thus preventing LECs extrusion and their replacement by histoblasts leaving the process of abdominal closure incomplete. Atf3 genetically interacts with Rho1 signaling. To elicit its effect, ectopic Atf3 specifically requires its binding partner dJun. Our data thus identify Atf3 as a new functional partner of Drosophila Jun during development (Sekyrova et al., 2010, Development).