title: Interaction between Drosophila bZIP proteins Atf3 and Jun prevents replacement of epithelial cells during metamorphosis.
abstract: Epithelial sheet spreading and fusion underlie important developmental processes. Well-characterized examples of such epithelial morphogenetic events have been provided by studies in Drosophila, and include embryonic dorsal closure, formation of the adult thorax and wound healing. All of these processes require the basic region-leucine zipper (bZIP) transcription factors Jun and Fos. Much less is known about morphogenesis of the fly abdomen, which involves replacement of larval epidermal cells (LECs) with adult histoblasts that divide, migrate and finally fuse to form the adult epidermis during metamorphosis. Here, we implicate Drosophila Activating transcription factor 3 (Atf3), the single ortholog of human ATF3 and JDP2 bZIP proteins, in abdominal morphogenesis. During the process of the epithelial cell replacement, transcription of the atf3 gene declines. When this downregulation is experimentally prevented, the affected LECs accumulate cell-adhesion proteins and their extrusion and replacement with histoblasts are blocked. The abnormally adhering LECs consequently obstruct the closure of the adult abdominal epithelium. This closure defect can be either mimicked and further enhanced by knockdown of the small GTPase Rho1 or, conversely, alleviated by stimulating ecdysone steroid hormone signaling. Both Rho and ecdysone pathways have been previously identified as effectors of the LEC replacement. To elicit the gain-of-function effect, Atf3 specifically requires its binding partner Jun. Our data thus identify Atf3 as a new functional partner of Drosophila Jun during development.
authors.affiliation: Biology Center, Czech Academy of Sciences and Department of Molecular Biology, University of South Bohemia, Ceske Budejovice 37005, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Sekyrova
authors.forename: Dirk
authors.initials: D
authors.lastname: Bohmann
authors.forename: Marek
authors.initials: M
authors.lastname: Jindra
authors.forename: Mirka
authors.initials: M
authors.lastname: Uhlirova
mesh_terms: D051700:Activating Transcription Factor 3 / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D004330:Drosophila / Q000254:growth & development* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D047468:Immunoprecipitation; D018613:Microscopy, Confocal; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*
chemical_list: D051700:Activating Transcription Factor 3; D029721:Drosophila Proteins; D016755:Proto-Oncogene Proteins c-jun