Membrane Cholesterol Modulates LOX-1 Shedding in Endothelial Cells.
The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a scavenger receptor responsible for ox-LDL recognition, binding and internalization, which is up-regulated during atherogenesis. Its activation triggers endothelium dysfunction and induces inflammation. A soluble form of LOX-1 has been identified in the human blood and its presence considered a biomarker of cardiovascular diseases. We recently showed that cholesterol-lowering drugs inhibit ox-LDL binding and internalization, rescuing the ox-LDL induced apoptotic phenotype in primary endothelial cells. Here we have investigated the molecular bases of human LOX-1 shedding by metalloproteinases and the role of cell membrane cholesterol on the regulation of this event by modulating its level with MβCD and statins. We report that membrane cholesterol affects the release of different forms of LOX-1 in cells transiently and stably expressing human LOX-1 and in a human endothelial cell line (EA.hy926). In particular, our data show that i) cholesterol depletion triggers the release of LOX-1 in exosomes as a full-length transmembrane isoform and as a truncated ectodomain soluble fragment (sLOX-1); ii) endothelial cells secrete a soluble metalloproteinase which induces LOX-1 ectodomain shedding and iii) long term statins treatment enhances sLOX-1 proteolytic shedding.
Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata, Via Montpellier 1, 00133, Rome, Italy.
Magda
M
Gioia
Department of Systems Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133, Rome, Italy.
Giulia
G
Vindigni
Department of Systems Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133, Rome, Italy.
Barbara
B
Testa
Department of Systems Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133, Rome, Italy.
Sofia
S
Raniolo
Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata, Via Montpellier 1, 00133, Rome, Italy.
Giovanni Francesco
GF
Fasciglione
Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata, Via Montpellier 1, 00133, Rome, Italy.
Massimiliano
M
Coletta
Department of Systems Medicine, University of Rome "Tor Vergata", Via Montpellier 1, 00133, Rome, Italy.
Silvia
S
Biocca
D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D002522:Chlorocebus aethiops; D002784:Cholesterol / Q000502:physiology*; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000378:metabolism*; D055354:Exosomes / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008077:Lipoproteins, LDL; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D059748:Proteolysis; D051127:Scavenger Receptors, Class E / Q000378:metabolism*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism
D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D051127:Scavenger Receptors, Class E; C560822:TIMP1 protein, human; D019715:Tissue Inhibitor of Metalloproteinase-1; C099252:oxidized low density lipoprotein; D002784:Cholesterol; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; C522360:MMP1 protein, human; D020781:Matrix Metalloproteinase 1