title: Two distinct but convergent groups of cells trigger Torso receptor tyrosine kinase activation by independently expressing torso-like.
abstract: Cell fate determination is often the outcome of specific interactions between adjacent cells. However, cells frequently change positions during development, and thus signaling molecules might be synthesized far from their final site of action. Here, we analyze the regulation of the torso-like gene, which is required to trigger Torso receptor tyrosine kinase activation in the Drosophila embryo. Whereas torso is present in the oocyte, torso-like is expressed in the egg chamber, at the posterior follicle cells and in two separated groups of anterior cells, the border cells and the centripetal cells. We find that JAK/STAT signaling regulates torso-like expression in the posterior follicle cells and border cells but not in the centripetal cells, where torso-like is regulated by a different enhancer. The border and centripetal cells, which are originally apart, converge at the anterior end of the oocyte, and we find that both groups contribute to trigger Torso activation. Our results illustrate how independently acquired expression of a signaling molecule can constitute a mechanism by which distinct groups of cells act together in the activation of a signaling pathway.
authors.affiliation: Institut de Biologia Molecular de Barcelona (Consejo Superior de Investigaciones Científicas), Institut de Recerca Biomèdica de Barcelona, C/Josep Samitier 1-5, 08028 Barcelona, Spain. mfebmc@cid.csic.es
authors.forename: Marc
authors.initials: M
authors.lastname: Furriols
authors.forename: Gemma
authors.initials: G
authors.lastname: Ventura
authors.forename: Jordi
authors.initials: J
authors.lastname: Casanova
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000502:physiology; D029721:Drosophila Proteins / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D004331:Drosophila melanogaster / Q000196:embryology / Q000201:enzymology; D004742:Enhancer Elements, Genetic; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D009866:Oogenesis / Q000502:physiology; D006080:Ovarian Follicle / Q000166:cytology / Q000201:enzymology; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D013997:Time Factors
chemical_list: D029721:Drosophila Proteins; C085211:tsl protein, Drosophila; D020794:Receptor Protein-Tyrosine Kinases; C080148:tor protein, Drosophila