Oxygen-regulated protein-150 prevents calcium homeostasis deregulation and apoptosis induced by oxidized LDL in vascular cells.
Oxidized LDLs (oxLDLs) induce apoptosis, which contributes to the pathogenesis of atherosclerosis. The 150 kDa oxygen-regulated protein (ORP150), an endoplasmic reticulum (ER)-resident chaperone, is upregulated by hypoxia and prevents ischemia-induced cell death. The aim of this work was to investigate whether and how ORP150 can prevent apoptosis induced by oxLDLs in vascular cells. OxLDLs induced ORP150 expression in the ER of human microvascular endothelial cell line (HMEC-1). ORP150 expression was blocked by antioxidants, by the permeant calcium chelator BAPTA-AM, and by inhibitors of the inositol-1,4,5 trisphosphate (IP3) receptors, 2-aminoethyl diphenylborinate (2-APB) and xestospongin C. ORP150 silencing by siRNA-enhanced oxLDL-induced apoptosis, while forced ORP150 expression increased the resistance of cells via an inhibition of the oxLDL-induced calcium rise, and of subsequent calpain activation, cytochrome c release, caspase 3 activation and apoptosis. A similar protective effect was achieved by BAPTA-AM, 2-APB and xestospongin C. Altogether, these data indicate that (i)ORP150 inhibits oxLDL-induced apoptosis by blocking calcium signaling and subsequent apoptosis, (ii)calcium released from ER stores through IP3 channels is involved in the oxLDL-induced calcium rise and apoptosis, and is inhibited by ORP150. Finally, ORP150 is expressed in advanced atherosclerotic lesions, where it may locally participate to reduce the apoptotic effect of oxLDLs and the subsequent risk of plaque rupture.
Sanson
M
M
Inserm U-858, Faculty of Medicine Rangueil, University Toulouse-3, CHU Toulouse, France.
Ingueneau
C
C
Vindis
C
C
Thiers
J-C
JC
Glock
Y
Y
Rousseau
H
H
Sawa
Y
Y
Bando
Y
Y
Mallat
Z
Z
Salvayre
R
R
Nègre-Salvayre
A
A
D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D050197:Atherosclerosis / Q000378:metabolism*; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002340:Carotid Artery Diseases / Q000378:metabolism; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins; D006706:Homeostasis; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D047028:Macrocyclic Compounds / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D034622:RNA Interference
D000975:Antioxidants; D001896:Boron Compounds; D002614:Chelating Agents; D018840:HSP70 Heat-Shock Proteins; D008077:Lipoproteins, LDL; D047028:Macrocyclic Compounds; D010080:Oxazoles; D011506:Proteins; C099252:oxidized low density lipoprotein; C050087:oxygen-regulated proteins; C511704:xestospongin C; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium