The biogenesis and regulation of Weibel-Palade bodies.
Doctoral thesis, UCL (University College London).
Weibel-Palade Bodies (WPBs) are the regulated storage organelles of endothelial cells that play an important role in haemostasis and the initiation of inflammation through release of their major content protein, von Willebrand Factor (VWF), and other factors present in/on the organelle. Their large size and novel shape – a 1–5 μm long cigar-shape – raises a unique problem as to how they form at the trans-Golgi network (TGN). In this thesis I have examined the way in which these organelles form at and subsequently scission from the TGN, and possible factors involved in their regulated release in response to extracellular stimulus. I have shown that the formation of WPBs at the TGN, which is critically dependent on the presence of clathrin and AP-1, does not appear to follow the standard model of formation of a spherical clathrin-coated vesicle. Rather, the organelle appears to form through maturation of the TGN using clathrin as a scaffold. Consistent with this model, the classic candidate molecule for vesicle scission from a donor membrane, dynamin, does not play a role in the budding of the WPB from the TGN in Human Umbilical Vein Endothelial Cells (HUVECs). However, in HEK293 cells, dynamin appears crucial for scission of heterologously expressed WPBs – an example of different cells using different machinery to form the same organelle. During formation, and also following scission, a variety of factors are recruited to, or help regulate, the maturing organelle. One pair of such factors, the small GTPases Rab10 and Rab8a, play a role in controlling WPB exocytosis in response to endothelial activation, since their removal by siRNA results in a significant reduction in VWF release.
|Title:||The biogenesis and regulation of Weibel-Palade bodies|
|Additional information:||Permission for digitisation not received|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Life Sciences > MRC/UCL Lab for Molecular Cell Biology|
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