title: A genome-wide RNAi screen identifies regulators of cholesterol-modified hedgehog secretion in Drosophila.
abstract: Hedgehog (Hh) proteins are secreted molecules that function as organizers in animal development. In addition to being palmitoylated, Hh is the only metazoan protein known to possess a covalently-linked cholesterol moiety. The absence of either modification severely disrupts the organization of numerous tissues during development. It is currently not known how lipid-modified Hh is secreted and released from producing cells. We have performed a genome-wide RNAi screen in Drosophila melanogaster cells to identify regulators of Hh secretion. We found that cholesterol-modified Hh secretion is strongly dependent on coat protein complex I (COPI) but not COPII vesicles, suggesting that cholesterol modification alters the movement of Hh through the early secretory pathway. We provide evidence that both proteolysis and cholesterol modification are necessary for the efficient trafficking of Hh through the ER and Golgi. Finally, we identified several putative regulators of protein secretion and demonstrate a role for some of these genes in Hh and Wingless (Wg) morphogen secretion in vivo. These data open new perspectives for studying how morphogen secretion is regulated, as well as provide insight into regulation of lipid-modified protein secretion.
authors.affiliation: CNRS UMR 7277, Inserm UMR 1091, Institut de Biologie Valrose (iBV), Centre de Biochimie, Nice, France.
authors.forename: Reid
authors.initials: R
authors.lastname: Aikin
authors.forename: Alexandra
authors.initials: A
authors.lastname: Cervantes
authors.forename: Gisela
authors.initials: G
authors.lastname: D'Angelo
authors.forename: Laurent
authors.initials: L
authors.lastname: Ruel
authors.forename: Sandra
authors.initials: S
authors.lastname: Lacas-Gervais
authors.forename: Sébastien
authors.initials: S
authors.lastname: Schaub
authors.forename: Pascal
authors.initials: P
authors.lastname: Thérond
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002784:Cholesterol / Q000494:pharmacology*; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000187:drug effects* / Q000378:metabolism*; D017344:Genes, Insect / Q000235:genetics; D005820:Genetic Testing; D049750:Genome, Insect / Q000235:genetics*; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D053823:Hedgehog Proteins / Q000378:metabolism*; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D049410:Luciferases, Renilla / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D034622:RNA Interference / Q000187:drug effects*; D012330:RNA, Double-Stranded / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015203:Reproducibility of Results; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D051155:Wnt1 Protein / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D053823:Hedgehog Proteins; D012330:RNA, Double-Stranded; D011993:Recombinant Fusion Proteins; D051155:Wnt1 Protein; C074622:wg protein, Drosophila; C077245:hh protein, Drosophila; D002784:Cholesterol; D049410:Luciferases, Renilla