Proximity proteomics of endothelial Weibel-Palade bodies identifies novel regulator of VWF secretion

ABSTRACT: Weibel-Palade bodies (WPB) are unique secretory organelles of endothelial cells that store factors regulating vascular haemostasis and local inflammation. Endothelial activation triggers the acute exocytosis of WPB, leading to the surface presentation of adhesion molecules relevant for leukocyte rolling (P-selectin) and platelet plug formation (von-Willebrand factor, VWF). Despite its role as an important secretory organelle, a comprehensive compilation of WPB-associated factors has not been carried out. We addressed this by a proximity proteomics approach employing the peroxidase APEX2 coupled to two known WPB-associated proteins, the RabGTPases Rab3b and Rab27a. We show that APEX2-Rab3b/27a fusion constructs are correctly targeted to WPB and that proteins in their close proximity can be biotinylated through the WPB-recruited APEX2. Mass spectrometry analysis of the biotinylated proteins identified 183 WPB-associated proteins. While some of the factors identified have been reported before to localize to WPB, the majority comprises proteins not previously associated with WPB biology. These include the SNARE-interacting protein Munc13-2, which specifically localizes to WPB and serves as a novel factor promoting histamine-evoked WPB exocytosis and VWF secretion.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Endothelial Cell Of Umbilical Vein

SUBMITTER: Hannes Drexler  

LAB HEAD: Hannes C. A. Drexle5r

PROVIDER: PXD013194 | Pride | 2019-07-11

REPOSITORIES: Pride