title: Discs large 1 (Dlg1) scaffolding protein participates with clathrin and adaptator protein complex 1 (AP-1) in forming Weibel-Palade bodies of endothelial cells.
abstract: Weibel-Palade bodies (WPBs) are specific cigar-shaped granules that store von Willebrand factor (VWF) for its regulated secretion by endothelial cells. The first steps of the formation of these granules at the trans-Golgi network specifically require VWF aggregation and an external scaffolding complex that contains the adaptator protein complex 1 (AP-1) and clathrin. Discs large 1 (Dlg1) is generally considered to be a modular scaffolding protein implicated in the control of cell polarity in a large variety of cells by specific recruiting of receptors, channels, or signaling proteins to specialized zones of the plasma membrane. We propose here that in endothelial cells, Dlg1, in a complex with AP-1 and clathrin, participates in the biogenesis of WPBs. Supporting data show that Dlg1 colocalizes with microtubules, intermediate filaments, and Golgi markers. Tandem mass spectrometry experiments led to the identification of clathrin as an Dlg1-interacting partner. Interaction was confirmed by in situ proximity ligation assays. Furthermore, AP-1 and VWF immunoprecipitate and colocalize with Dlg1 in the juxtanuclear zone. Finally, Dlg1 depletion by siRNA duplexes disrupts trans-Golgi network morphology and WPB formation. Our results provide the first evidence for an unexpected role of Dlg1 in controlling the formation of specific secretory granules involved in VWF exocytosis in endothelial cells.
authors.affiliation: INSERM U698, Université Paris 7, Hemostasis, Bio-Engineering and Cardiovascular Remodeling, CHU X. Bichat, 75018 Paris, France.
authors.forename: Monique
authors.initials: M
authors.lastname: Philippe
authors.forename: Thibaut
authors.initials: T
authors.lastname: Léger
authors.forename: Raphaëlle
authors.initials: R
authors.lastname: Desvaux
authors.forename: Laurence
authors.initials: L
authors.lastname: Walch
mesh_terms: D033961:Adaptor Protein Complex 1 / Q000235:genetics / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002966:Clathrin / Q000235:genetics / Q000378:metabolism*; D000074288:Discs Large Homolog 1 Protein; D005089:Exocytosis / Q000502:physiology*; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007382:Intermediate Filaments / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D020302:Weibel-Palade Bodies / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism
chemical_list: D033961:Adaptor Protein Complex 1; D048868:Adaptor Proteins, Signal Transducing; D002966:Clathrin; C513314:DLG1 protein, human; D000074288:Discs Large Homolog 1 Protein; D008565:Membrane Proteins
keywords: Adaptator Protein Complex 1; Clathrin; Dlg1; Endothelial Cell; Intracellular Trafficking; Protein Sorting; Scaffold Proteins; Secretion; Weibel-Palade Bodies; von Willebrand Factor