title: Cleavage and secretion is not required for Four-jointed function in Drosophila patterning.
abstract: Four-jointed (fj) is required for proximodistal growth and planar polarity in Drosophila tissues. It encodes a predicted type II transmembrane protein with putative signal peptidase sites in its transmembrane domain, and its C terminus is secreted. Fj has therefore been proposed to act as a secreted signalling molecule. We show that Fj protein has a graded distribution in eye and wing imaginal discs, and is largely localised to the Golgi in vivo and in transfected cells. Forms of Fj that are constitutively secreted or anchored in the Golgi were assayed for function in vivo. We find that cleavage and secretion of Fj is not necessary for activity, and that Golgi-anchored Fj has increased activity over wild type. fj has similar phenotypes to those caused by mutations in the cadherin-encoding genes fat (ft) and dachsous (ds). We show that fj interacts genetically with ft and ds in planar polarity and proximodistal patterning. We propose that Fj may act in the Golgi to regulate the activity of Ft and Ds.
authors.affiliation: Centre for Developmental Genetics, Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Strutt
authors.forename: Jenifer
authors.initials: J
authors.lastname: Mundy
authors.forename: Katrina
authors.initials: K
authors.lastname: Hofstra
authors.forename: David
authors.initials: D
authors.lastname: Strutt
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D015820:Cadherins / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D004330:Drosophila / Q000254:growth & development*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006056:Golgi Apparatus / Q000378:metabolism; D007814:Larva / Q000254:growth & development*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D018613:Microscopy, Confocal; D014921:Wings, Animal / Q000254:growth & development
chemical_list: D015820:Cadherins; D015815:Cell Adhesion Molecules; D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; C094449:ds protein, Drosophila; C095900:fj protein, Drosophila; C472307:ft protein, Drosophila