title: Extracellular signals responsible for spatially regulated proliferation in the differentiating Drosophila eye.
abstract: Spatially and temporally choreographed cell cycles accompany the differentiation of the Drosophila retina. The extracellular signals that control these patterns have been identified through mosaic analysis of mutations in signal transduction pathways. All cells arrest in G1 prior to the start of neurogenesis. Arrest depends on Dpp and Hh, acting redundantly. Most cells then go through a synchronous round of cell division before fate specification and terminal cell cycle exit. Cell cycle entry is induced by Notch signaling and opposed in subsets of cells by EGF receptor activity. Unusually, Cyclin E levels are not limiting for retinal cell cycles. Rbf/E2F and the Cyclin E antagonist Dacapo are important, however. All retinal cells, including the postmitotic photoreceptor neurons, continue dividing when rbf and dacapo are mutated simultaneously. These studies identify the specific extracellular signals that pattern the retinal cell cycles and show how differentiation can be uncoupled from cell cycle exit.
authors.affiliation: Department of Molecular Genetics, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
authors.forename: Lucy C
authors.initials: LC
authors.lastname: Firth
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Baker
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000502:physiology*; D002454:Cell Differentiation; D049109:Cell Proliferation; D019927:Cyclin E / Q000037:antagonists & inhibitors / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000166:cytology* / Q000254:growth & development; D066246:ErbB Receptors / Q000378:metabolism; D053823:Hedgehog Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009024:Morphogenesis; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology / Q000254:growth & development; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch; D012160:Retina / Q000166:cytology / Q000254:growth & development; D016160:Retinoblastoma Protein; D015398:Signal Transduction / Q000502:physiology*; D000072086:Smoothened Receptor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D019927:Cyclin E; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D053823:Hedgehog Proteins; C112506:MAD protein, Drosophila; D008565:Membrane Proteins; C497759:N protein, Drosophila; D009687:Nuclear Proteins; C099965:Rbf protein, Drosophila; D043562:Receptors, G-Protein-Coupled; D051880:Receptors, Notch; D016160:Retinoblastoma Protein; D000072086:Smoothened Receptor; D014157:Transcription Factors; C103336:dap protein, Drosophila; C064196:dpp protein, Drosophila; C100664:smo protein, Drosophila; C077245:hh protein, Drosophila; D066246:ErbB Receptors