Weibel-Palade body size modulates the adhesive activity of its von Willebrand Factor cargo in cultured endothelial cells

Abstract

Changes in the size of cellular organelles are often linked to modifications in their function. Endothelial cells store von Willebrand Factor (vWF), a glycoprotein essential to haemostasis in Weibel-Palade bodies (WPBs), cigar-shaped secretory granules that are generated in a wide range of sizes. We recently showed that forcing changes in the size of WPBs modifies the activity of this cargo. We now find that endothelial cells treated with statins produce shorter WPBs and that the vWF they release at exocytosis displays a reduced capability to recruit platelets to the endothelial cell surface. Investigating other functional consequences of size changes of WPBs, we also report that the endothelial surface-associated vWF formed at exocytosis recruits soluble plasma vWF and that this process is reduced by treatments that shorten WPBs, statins included. These results indicate that the post-exocytic adhesive activity of vWF towards platelets and plasma vWF at the endothelial surface reflects the size of their storage organelle. Our findings therefore show that changes in WPB size, by influencing the adhesive activity of its vWF cargo, may represent a novel mode of regulation of platelet aggregation at the vascular wall.

Meeting report – Emerging Concepts in Cell Organization

“…This approach revealed that trafficking fellows are transported together as subpools of cargos through the Golgi complex. He further showed that (Ferraro et al, 2016). Changes in Golgi organization, in particular its disassembly in early mitosis, also appear to have a role in controlling mitotic spindle assembly, as shown by Joachim Seemann (UT Southwestern, Dallas, USA) (Guizzunti and Seemann, 2016).…”

Modulation of endothelial organelle size as an antithrombotic strategy

“…A quantitative high-throughput microscopy-based workflow, dubbed highthroughput morphometry (HTM), allows rapid quantification of the size of tens to hundreds of thousands of WPBs within thousands of endothelial cells (Ferraro et al, 2014). HTM has been applied for analytical purposes and in phenotypic screens (Ferraro et al, 2014;Ferraro et al, 2016;Ketteler et al, 2017;Lopes-da-Silva et al, 2019;Stevenson et al, 2014). In the present report, HTM was deployed to identify compounds that can induce a reduction of WPB size in Human Umbilical Vein Endothelial Cells (HUVECs).…”

“…Their size depends on the structural status of the endothelial Golgi apparatus where they form, and experimental manipulations causing Golgi fragmentation consistently result in the formation of only short WPBs (Ferraro et al, 2014). Short WPBs also form when VWF biosynthesis by endothelial cells is reduced, or following statin treatment, via Golgi fragmentation-independent and -dependent mechanisms, respectively (Ferraro et al, 2014;Ferraro et al, 2016). The metabolic status of endothelial cells also regulates WPB size through an AMPK-mediated signalling pathway (Lopes-da-Silva et al, 2019).…”

“…The metabolic status of endothelial cells also regulates WPB size through an AMPK-mediated signalling pathway (Lopes-da-Silva et al, 2019). Importantly, in vitro experiments have revealed that reducing WPB size results in the shortening of the VWF strings they generate and in much-reduced recruitment of platelets and soluble circulating VWF to the endothelial surface (Ferraro et al, 2014;Ferraro et al, 2016). Conversely, endothelial cells respond to raised glucose levels (mimicking hyperglycemia) by producing longer WPBs, suggesting a link between long VWF strings and thrombotic manifestations in diabetes (Lopes-da-Silva et al, 2019), which is often associated with high levels of plasma VWF and microangiopathy (Westein et al, 2017).…”

Golgi ribbon disassembly during mitosis, differentiation and disease progression

“…The homotypic connections between adjacent cisternae of the stacks enlarge the membrane compartment such that large cargos as collagen can be readily accommodated [10,11*]. Similarly, a continuous ribbon allows proper packing of the von Willebrand factor into larger Weibel-Palade bodies, which impacts platelet aggregation [12**,13]. Furthermore, by laterally linking stacks, the Golgi apparatus is consolidated into one single entity that in most cases is asymmetrically positioned in the juxtanuclear region and in close proximity to centrosomes, the primary microtubule-organizing center (MTOC) in proliferating cells [6].…”