Bunched sets a boundary for Notch signaling to pattern anterior eggshell structures during Drosophila oogenesis.
Organized boundaries between different cell fates are critical in patterning and organogenesis. In some tissues, long-range signals position a boundary, and local Notch signaling maintains it. How Notch activity is restricted to boundary regions is not well understood. During Drosophila oogenesis, the long-range signals EGF and Dpp regulate expression of bunched (bun), which encodes a homolog of mammalian transcription factors TSC-22 and GILZ. Here, we show that bun establishes a boundary for Notch signaling in the follicle cell epithelium. Notch signaling is active in anterior follicle cells and is required for concurrent follicle cell reorganizations including centripetal migration and operculum formation. bun is required in posterior columnar follicle cells to repress the centripetal migration fate, including gene expression, cell shape changes and accumulation of cytoskeletal components. bun mutant clones adjacent to the centripetally migrating follicle cells showed ectopic Notch responses. bun is necessary, but not sufficient, to down-regulate Serrate protein levels throughout the follicular epithelium. These data indicate that Notch signaling is necessary, but not sufficient, for centripetal migration and that bun regulates the level of Notch stimulation to position the boundary between centripetally migrating and stationary columnar follicle cells.
Dobens
Leonard
L
Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Bldg. 149 13th Street, Charlestown, MA 02129, USA.
Jaeger
Alejandra
A
Peterson
Jeanne S
JS
Raftery
Laurel A
LA
D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002465:Cell Movement; D048430:Cell Shape; D004330:Drosophila / Q000196:embryology / Q000378:metabolism / Q000502:physiology*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009866:Oogenesis; D006080:Ovarian Follicle / Q000378:metabolism / Q000502:physiology*; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D000072099:Serrate-Jagged Proteins; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch; C000606278:Ser protein, Drosophila; D000072099:Serrate-Jagged Proteins; D014157:Transcription Factors