The physiological function of von Willebrand's factor depends on its tubular storage in endothelial Weibel-Palade bodies.
Weibel-Palade bodies are the 1-5 microm long rod-shaped storage organelles of endothelial cells. We have investigated the determinants and functional significance of this shape. We find that the folding of the hemostatic protein von Willebrand's factor (VWF) into tubules underpins the rod-like shape of Weibel-Palade bodies. Further, while the propeptide and the N-terminal domains of mature VWF are sufficient to form tubules, their maintenance relies on a pH-dependent interaction between the two. We show that the tubular conformation of VWF is essential for a rapid unfurling of 100 microm long, platelet-catching VWF filaments when exposed to neutral pH after exocytosis in cell culture and in living blood vessels. If tubules are disassembled prior to exocytosis, then short or tangled filaments are released and platelet recruitment is reduced. Thus, a 100-fold compaction of VWF into tubules determines the unique shape of Weibel-Palade bodies and is critical to this protein's hemostatic function.
Michaux
Grégoire
G
Department of Biochemistry, University College London, Gower Street, London WC1E 6BT, United Kingdom.
Abbitt
Kate B
KB
Collinson
Lucy M
LM
Haberichter
Sandra L
SL
Norman
Keith E
KE
Cutler
Daniel F
DF
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000648:ultrastructure*; D005089:Exocytosis; D006487:Hemostasis / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008985:Monensin / Q000494:pharmacology; D010973:Platelet Adhesiveness; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D014699:Venules / Q000187:drug effects / Q000502:physiology; D020302:Weibel-Palade Bodies / Q000378:metabolism*; D014841:von Willebrand Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D014841:von Willebrand Factor; D004247:DNA; D008985:Monensin