title: Notch regulates numb: integration of conditional and autonomous cell fate specification.
abstract: The Notch cell-cell signaling pathway is used extensively in cell fate specification during metazoan development. In many cell lineages, the conditional role of Notch signaling is integrated with the autonomous action of the Numb protein, a Notch pathway antagonist. During Drosophila sensory bristle development, precursor cells segregate Numb asymmetrically to one of their progeny cells, rendering it unresponsive to reciprocal Notch signaling between the two daughters. This ensures that one daughter adopts a Notch-independent, and the other a Notch-dependent, cell fate. In a genome-wide survey for potential Notch pathway targets, the second intron of the numb gene was found to contain a statistically significant cluster of binding sites for Suppressor of Hairless, the transducing transcription factor for the pathway. We show that this region contains a Notch-responsive cis-regulatory module that directs numb transcription in the pIIa and pIIIb cells of the bristle lineage. These are the two precursor cells that do not inherit Numb, yet must make Numb to segregate to one daughter during their own division. Our findings reveal a new mechanism by which conditional and autonomous modes of fate specification are integrated within cell lineages.
authors.affiliation: Division of Biological Sciences, Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA 92093, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Rebeiz
authors.forename: Steven W
authors.initials: SW
authors.lastname: Miller
authors.forename: James W
authors.initials: JW
authors.lastname: Posakony
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D019070:Cell Lineage / Q000235:genetics / Q000502:physiology; D017931:DNA Primers / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism* / Q000648:ultrastructure; D004742:Enhancer Elements, Genetic; D005260:Female; D017344:Genes, Insect; D007605:Juvenile Hormones / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D009030:Mosaicism; D009154:Mutation; D010641:Phenotype; D034741:RNA, Small Interfering / Q000235:genetics; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D058618:Sensilla / Q000254:growth & development / Q000648:ultrastructure; D015398:Signal Transduction
chemical_list: D017931:DNA Primers; D029721:Drosophila Proteins; D007605:Juvenile Hormones; C497759:N protein, Drosophila; D034741:RNA, Small Interfering; D051880:Receptors, Notch; D012097:Repressor Proteins; C088731:Su(H) protein, Drosophila; C060606:numb protein, Drosophila