Membrane platforms in regulated secretion from endothelial cells
Weibel-Palade Bodies (WPB) are endothelial cell-specific storage granules that participate in the regulation of vascular hemostasis by releasing the platelet adhesion receptor von Willebrand factor (VWF) following endothelial stimulation. The cigar shaped organelles form at the trans-Golgi network (TGN) and further mature upon transport to the cell periphery, where regulated exocytosis can occur upon elevation of intracellular Ca2+ or cAMP levels.
By applying proximity proteomics via the ascorbate peroxidase APEX2 targeted to WPB, we identified several novel WPB associated proteins in human vein endothelial cells (HUVEC). We are especially interested in the newly identified actin-binding proteins localizing to WPB, since both WPB exocytosis and regulated VWF release have been linked to reorganization in the cortical actin cytoskeleton.