Efficiency of von Willebrand factor-mediated targeting of interleukin-8 into Weibel-Palade bodies.
BACKGROUND
After de novo synthesis in endothelial cells, the chemokine interleukin-8 (IL-8) is targeted to endothelial cell-specific storage vesicles, the Weibel-Palade bodies (WPBs), where it colocalizes with von Willebrand factor (VWF).


OBJECTIVE
In this study we investigated a putative regulator function for VWF in the recruitment of IL-8 to WPBs.


METHODS
We performed a quantitative analysis of the entry of IL-8 into the storage system of the endothelium using pulse-chase analysis and subcellular fractionation studies.


RESULTS
Using pulse-chase analysis of IL-1beta-stimulated human umbilical vein endothelial cells, we found that a small part of de novo synthesized IL-8 was retained in endothelial cells after 4 h. In density gradients of endothelial cell homogenates nearly equimolar amounts of VWF and IL-8 were present in subcellular fractions that contained WPBs. Furthermore, we found that IL-8 binds to immobilized VWF under the slightly acidic conditions thought to prevail in the lumen of the late secretory pathway.


CONCLUSIONS
These observations indicate that the sorting efficiency of IL-8 into the regulated secretory pathway of the endothelium is tightly controlled by the entry of VWF into WPBs.
Bierings
R
R
Department of Plasma Proteins, Sanquin Research and Landsteiner Laboratory AMC, University of Amsterdam, Plesmanlaan 125, Amsterdam, The Netherlands.
van den Biggelaar
M
M
Kragt
A
A
Mertens
K
K
Voorberg
J
J
van Mourik
J A
JA
D001665:Binding Sites; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism*; D007700:Kinetics; D011485:Protein Binding; D021381:Protein Transport; D013347:Subcellular Fractions / Q000378:metabolism; D013917:Thrombin / Q000378:metabolism; D020302:Weibel-Palade Bodies / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism*
D053583:Interleukin-1beta; D016209:Interleukin-8; D014841:von Willebrand Factor; D013917:Thrombin