Structural organization of Weibel-Palade bodies revealed by cryo-EM of vitrified endothelial cells.
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.
Berriman
John A
JA
Division of Physical Biochemistry, MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, United Kingdom.
Li
Sam
S
Hewlett
Lindsay J
LJ
Wasilewski
Sebastian
S
Kiskin
Fedir N
FN
Carter
Tom
T
Hannah
Matthew J
MJ
Rosenthal
Peter B
PB
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*
D002352:Carrier Proteins; D014841:von Willebrand Factor; D005169:Factor VIII