title: Content delivery to newly forming Weibel-Palade bodies is facilitated by multiple connections with the Golgi apparatus.
abstract: Weibel-Palade bodies (WPBs) comprise an on-demand storage organelle within vascular endothelial cells. It's major component, the hemostatic protein von Willebrand factor (VWF), is known to assemble into long helical tubules and is hypothesized to drive WPB biogenesis. However, electron micrographs of WPBs at the Golgi apparatus show that these forming WPBs contain very little tubular VWF compared with mature peripheral WPBs, which raises questions on the mechanisms that increase the VWF content and facilitate vesicle growth. Using correlative light and electron microscopy and electron tomography, we investigated WPB biogenesis in time. We reveal that forming WPBs maintain multiple connections to the Golgi apparatus throughout their biogenesis. Also by volume scanning electron microscopy, we confirmed the presence of these connections linking WPBs and the Golgi apparatus. From electron tomograms, we provided evidence that nontubular VWF is added to WPBs, which suggested that tubule formation occurs in the WPB lumen. During this process, the Golgi membrane and clathrin seem to provide a scaffold to align forming VWF tubules. Overall, our data show that multiple connections with the Golgi facilitate content delivery and indicate that the Golgi appears to provide a framework to determine the overall size and dimensions of newly forming WPBs.
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands;
authors.forename: Marjon J
authors.initials: MJ
authors.lastname: Mourik
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands;
authors.forename: Frank G A
authors.initials: FG
authors.lastname: Faas
authors.affiliation: Carl Zeiss Microscopy GmbH, Munich, Germany;
authors.forename: Hans
authors.initials: H
authors.lastname: Zimmermann
authors.affiliation: Department of Plasma Proteins, Sanquin-AMC Landsteiner Laboratory, Amsterdam, The Netherlands; and.
authors.forename: Jan
authors.initials: J
authors.lastname: Voorberg
authors.affiliation: Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands;
authors.forename: Abraham J
authors.initials: AJ
authors.lastname: Koster
authors.affiliation: Department of Thrombosis and Hemostasis, Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Eikenboom
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008859:Microscopy, Polarization; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D022161:Transport Vesicles / Q000378:metabolism / Q000648:ultrastructure; D020302:Weibel-Palade Bodies / Q000378:metabolism* / Q000648:ultrastructure; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D014841:von Willebrand Factor; D013755:Tetradecanoylphorbol Acetate