Top–DER- and Dpp-dependent requirements for the Drosophila fos/ kayak gene in follicular epithelium morphogenesis

• Published in: Mechanisms of development 2001-08, Vol.106 (1), p.47-60
• Main Authors: Dequier, Emmanuel, Souid, Sami, Pál, Margit, Maróy, Péter, Lepesant, Jean-Antoine, Yanicostas, Constantin
• Format: Article
• Language: English
• Subjects: Animals; Cell Movement; Dfos/ kayak; Dpp/TGFβ signalling; Drosophila Egf receptor; Drosophila melanogaster - genetics; Drosophila melanogaster - physiology; Drosophila Proteins; Epithelial Cells - physiology; ErbB Receptors - metabolism; Female; Follicular epithelium; Gene Expression Regulation, Developmental; Genes, Insect; Insect Proteins - genetics; Insect Proteins - metabolism; Insect Proteins - physiology; Morphogenesis; Oogenesis; Ovarian Follicle - cytology; Ovarian Follicle - metabolism; Ovarian Follicle - physiology; Paracrine Communication; Protein Kinases; Receptors, Invertebrate Peptide - metabolism; Signal Transduction; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Transforming Growth Factor beta - metabolism
• ISSN: 0925-4773; 1872-6356
• DOI: 10.1016/S0925-4773(01)00418-X

The Drosophila fos ( Dfos)/ kayak gene has been previously identified as a key regulator of epithelial cell morphogenesis during dorsal closure of the embryo and fusion of the adult thorax. We show here that it is also required for two morphogenetic movements of the follicular epithelium during oogenesis. Firstly, it is necessary for the proper posteriorward migration of main body follicle cells during stage 9. Secondly, it controls, from stage 11 onwards, the morphogenetic reorganization of the follicle cells that are committed to secrete the respiratory appendages. We demonstrate that DER pathway activation and a critical level of Dpp/TGFβ signalling are required to pattern a high level of transcription of Dfos at the anterior and dorsal edges of the two groups of cells that will give rise to the respiratory appendages. In addition, we provide evidence that, within the dorsal–anterior territory, the level of paracrine Dpp/TGFβ signalling controls the commitment of follicle cells towards either an operculum or an appendage secretion fate. Finally, we show that Dfos is required in follicle cells for the dumping of the nurse cell cytoplasm into the oocyte and the subsequent apoptosis of nurse cells. This suggests that in somatic follicle cells, Dfos controls the expression of one or several factors that are necessary for these processes in underlying germinal nurse cells.