title: Structural organization of Weibel-Palade bodies revealed by cryo-EM of vitrified endothelial cells.
abstract: In endothelial cells, the multifunctional blood glycoprotein von Willebrand Factor (VWF) is stored for rapid exocytic release in specialized secretory granules called Weibel-Palade bodies (WPBs). Electron cryomicroscopy at the thin periphery of whole, vitrified human umbilical vein endothelial cells (HUVECs) is used to directly image WPBs and their interaction with a 3D network of closely apposed membranous organelles, membrane tubules, and filaments. Fourier analysis of images and tomographic reconstruction show that VWF is packaged as a helix in WPBs. The helical signature of VWF tubules is used to identify VWF-containing organelles and characterize their paracrystalline order in low dose images. We build a 3D model of a WPB in which individual VWF helices can bend, but in which the paracrystalline packing of VWF tubules, closely wrapped by the WPB membrane, is associated with the rod-like morphology of the granules.
authors.affiliation: Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom.
authors.forename: John A
authors.initials: JA
authors.lastname: Berriman
authors.forename: Sam
authors.initials: S
authors.lastname: Li
authors.forename: Lindsay J
authors.initials: LJ
authors.lastname: Hewlett
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wasilewski
authors.forename: Fedir N
authors.initials: FN
authors.lastname: Kiskin
authors.forename: Tom
authors.initials: T
authors.lastname: Carter
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hannah
authors.forename: Peter B
authors.initials: PB
authors.lastname: Rosenthal
mesh_terms: D002352:Carrier Proteins / Q000097:blood; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D042783:Endothelial Cells / Q000166:cytology* / Q000502:physiology / Q000648:ultrastructure; D005169:Factor VIII / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D014471:Umbilical Veins; D020302:Weibel-Palade Bodies / Q000502:physiology / Q000648:ultrastructure*; D014841:von Willebrand Factor / Q000032:analysis / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D014841:von Willebrand Factor; D005169:Factor VIII