scholarly journals Cellular Uptake and Clearance of Oxidatively-modified Apolipoprotein E3 by Cerebral Cortex Endothelial Cells

2019 ◽  
Vol 20 (18) ◽  
pp. 4582 ◽  
Author(s):  
Siobanth Cruz ◽  
Vasanthy Narayanaswami
Keyword(s):  
Endothelial Cells ◽  
Cellular Uptake ◽  
Hot Spot ◽  
Oxidized Ldl ◽  
Critical Role ◽  
Density Lipoprotein ◽  
Oxidative Modification ◽  
Alternative Mechanism ◽  
Type I ◽  
Western Blots

Apolipoprotein E3 (apoE3) plays a critical role in the metabolism of lipoproteins and lowers plasma lipid levels by serving as a ligand for the low-density lipoprotein receptor (LDLr) family of proteins and by promoting macrophage cholesterol efflux. The current study examines the effect of acrolein (an endogenously generated metabolite and an environmental pollutant) modification on the structure and function of apoE3. Acrolein modification was confirmed in Western blots by reactivity with acrolein–lysine-specific antibody and by the presence of oligomeric species due to cross-linking. LC-MS/MS analysis revealed modification of 10 out of 12 lysines in apoE3, with Nε-(3-methylpyridinium)-lysine being the predominant form of modification, and Lys75 being a ‘hot spot’ in terms of susceptibility to oxidation. Circular dichroism spectroscopy showed no major change in overall secondary structure compared to unmodified apoE3. Reconstituted high density lipoprotein (HDL) bearing acrolein modified apoE3 showed loss of binding to soluble LDLr; however, incubation with mouse endothelioma bEnd.3 cells showed that it was internalized. Incubation with excess LDL did not abolish cellular uptake of acrolein modified apoE3, suggesting alternative mechanism(s) not involving LDLr. Incubation with anti-CD36 antibody did not show a decrease in internalization while incubation with anti- lectin-like oxidized LDL receptor 1 (LOX1) showed partial internalization. However, incubation with anti-scavenger receptor class B type I (SRB1) antibody abolished internalization of acrolein modified apoE3. Taken together, our studies suggest that acrolein modification of apoE3 at lysine residues leads to increase in net negative charge, and as a consequence, results in clearance by LOX1 and SRB1 on endothelial cells. Overall, oxidative modification of apoE3 likely impairs its role in regulating plasma cholesterol homeostasis, eventually leading to lipid disorders.

Prior exposure to oxidized low-density lipoprotein limits apoptosis in subsequent generations of endothelial cells by altering promoter methylation

2011 ◽  
Vol 301 (2) ◽  
pp. H506-H513 ◽  
Author(s):  
Sona Mitra ◽  
Magomed Khaidakov ◽  
Jingjun Lu ◽  
Srinivas Ayyadevara ◽  
Jackob Szwedo ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Promoter Methylation ◽  
Umbilical Vein ◽  
Oxidized Ldl ◽  
Critical Role ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Continuous Exposure ◽  
Epigenetic Changes ◽  
Apoptotic Response

Oxidized LDL (ox-LDL) plays a critical role in atherogenesis, including apoptosis. As hypercholesterolemia causes epigenetic changes resulting in long-term phenotypic consequences, we hypothesized that repeated and continuous exposure to ox-LDL may alter the pattern of apoptosis in human umbilical vein endothelial cells (HUVECs). We also analyzed global and promoter-specific methylation of apoptosis-related genes. As expected, ox-LDL evoked a dose-dependent increase in apoptosis in the first passage HUVECs that was completely abrogated by lectin-like ox-LDL receptor (LOX-1)-neutralizing antibody. Ox-LDL-induced apoptosis was associated with upregulation of proapoptotic LOX-1, ANXA5, BAX, and CASP3 and inhibition of antiapoptotic BCL2 and cIAP-1 genes accompanied with reciprocal changes in the methylation of promoter regions of these genes. Subsequent passages of cells displayed attenuated apoptotic response to repeat ox-LDL challenge with blunted gene expression and exaggerated methylation of LOX-1, BAX, ANXA5, and CASP3 genes (all P < 0.05 vs. first exposure to ox-LDL). Treatment of cells with LOX-1 antibody before initial ox-LDL treatment prevented both gene-specific promoter methylation and expression changes and reduction of apoptotic response to repeat ox-LDL challenge. Based on these data, we conclude that exposure of HUVECs to ox-LDL induces epigenetic changes leading to resistance to apoptosis in subsequent generations and that this effect may be related to the LOX-1-mediated increase in DNA methylation.

scholarly journals The Osteoclast-Associated Receptor (OSCAR) Is a Novel Receptor Regulated by Oxidized Low-Density Lipoprotein in Human Endothelial Cells

Endocrinology ◽  
2011 ◽  
Vol 152 (12) ◽  
pp. 4915-4926 ◽  
Author(s):  
Claudia Goettsch ◽  
Martina Rauner ◽  
Kathrin Sinningen ◽  
Susann Helas ◽  
Nadia Al-Fakhri ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Critical Role ◽  
Osteoclast Differentiation ◽  
Density Lipoprotein ◽  
Low Density ◽  
Oxidized Low Density Lipoprotein ◽  
Human Endothelial Cells ◽  
Apolipoprotein E Knockout Mice

Cross talks between the vascular and immune system play a critical role in vascular diseases, in particular in atherosclerosis. The osteoclast-associated receptor (OSCAR) is a regulator of osteoclast differentiation and dendritic cell maturation. Whether OSCAR plays a role in vascular biology and has an impact on atherogenic processes provoked by proinflammatory stimuli is yet unknown. We identified OSCAR on the surface of human primary endothelial cells. Stimulation of endothelial cells with oxidized low-density lipoprotein (oxLDL) caused a time- and dose-dependent induction of OSCAR, which was lectin-like oxidized LDL receptor 1 and Ca2+ dependent. OSCAR was transcriptionally regulated by oxLDL as shown by OSCAR promoter analysis. Specific inhibition of the nuclear factor of activated T cells (NFAT) pathway prevented the oxLDL-mediated increase of endothelial OSCAR expression. As assessed by EMSA, oxLDL induced binding of NFATc1 to the OSCAR promoter. Notably, in vivo-modified LDL from patients with diabetes mellitus stimulated OSCAR mRNA expression in human endothelial cells. Furthermore, apolipoprotein E knockout mice fed a high-fat diet showed an enhanced aortic OSCAR expression associated with increased expression of NFATc1. In summary, OSCAR is expressed in vascular endothelial cells and is regulated by oxLDL involving NFATc1. Our data suggest that OSCAR, originally described in bone as immunological mediator and regulator of osteoclast differentiation, may be involved in cell activation and inflammation during atherosclerosis.

scholarly journals Paraoxonase-1 Inhibits Oxidized Low-Density Lipoprotein-Induced Metabolic Alterations and Apoptosis in Endothelial Cells: A Nondirected Metabolomic Study

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Anabel García-Heredia ◽  
Judit Marsillach ◽  
Anna Rull ◽  
Iris Triguero ◽  
Isabel Fort ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Current Knowledge ◽  
Oxidized Ldl ◽  
Density Lipoprotein ◽  
Wild Type Mouse ◽  
Protective Role ◽  
Paraoxonase 1 ◽  
Wild Type ◽  
Metabolic Alterations ◽  
Deficient Mice

We studied the influence of PON1 on metabolic alterations induced by oxidized LDL when incubated with endothelial cells. HUVEC cells were incubated with native LDL, oxidized LDL, oxidized LDL plus HDL from wild type mice, and oxidized LDL plus HDL from PON1-deficient mice. Results showed alterations in carbohydrate and phospholipid metabolism and increased apoptosis in cells incubated with oxidized LDL. These changes were partially prevented by wild type mouse HDL, but the effects were less effective with HDL from PON1-deficient mice. Our results suggest that PON1 may play a significant role in endothelial cell survival by protecting cells from alterations in the respiratory chain induced by oxidized LDL. These results extend current knowledge on the protective role of HDL and PON1 against oxidation and apoptosis in endothelial cells.

Abstract 624: Endothelial Scavenger Receptor Class B, Type I (SR-BI) Mediates LDL Uptake by the Artery Wall and Promotes Atherosclerosis in Hypercholesterolemic Mice

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Linzhang Huang ◽  
Ken Chambliss ◽  
Mohamed Ahmed ◽  
Chieko Mineo ◽  
Philip W Shaul
Keyword(s):  
Endothelial Cells ◽  
Scavenger Receptor ◽  
Plasma Lipid ◽  
Density Lipoprotein ◽  
Type I ◽  
Artery Wall ◽  
Blocking Antibody ◽  
Scavenger Receptor Class ◽  
Class B ◽  
Ldl Uptake

In endothelial cells, high density lipoprotein cholesterol (HDL) binding to scavenger receptor class B, type I (SR-BI) promotes the production of the antiatherogenic signaling molecule nitric oxide (NO) and also endothelial repair. To study how SR-BI in endothelium impacts atherosclerosis, we bred newly-created floxed SR-BI mice, vascular endothelial cadherin promoter-driven Cre recombinase transgenic (VECad-Cre), and apoE -/- mice to generate apoE -/- with normal endothelial SR-BI expression (SR-BI ECIN ;apoE -/- ) or selective deletion of SR-BI from endothelium (SR-BI ECOUT ;apoE -/- ). At weaning all mice were placed on an atherogenic diet (20% fat, 1.25% cholesterol), and plasma lipid profiles and atherosclerosis were evaluated 8 weeks later. Endothelial deletion of SR-BI did not alter the plasma lipid profile. Surprisingly, male SR-BI ECOUT ;apoE -/- mice displayed 63% less atherosclerosis in the en face aorta than male SR-BI ECIN ;apoE -/- mice, aortic root lesions were comparably affected, and similar findings were obtained in females. Recognizing that SR-BI binds both HDL and low density lipoprotein cholesterol (LDL), to then discern how endothelial SR-BI promotes atherosclerosis we determined using Di-I-labeled oxidized LDL (oxLDL) if SR-BI influences oxLDL uptake by endothelial cells. Such uptake is the first step in the endothelial transcytosis that delivers LDL to the artery wall to initiate atherogenesis. OxLDL uptake by primary human aortic endothelial cells was blunted by 87% by SR-BI blocking antibody, and it was also decreased by SR-BI deletion via siRNA, and by the chemical inhibitor of SR-BI BLT-1. Furthermore, SR-BI blocking antibody and BLT-1 caused marked declines in endothelial oxLDL transcytosis. Moreover, 4 hours following IV administration, oxLDL uptake in aorta was decreased by 84% in SR-BI ECOUT ;apoE -/- versus SR-BI ECIN ;apoE -/- mice. These collective findings indicate that endothelial SR-BI plays an important role in atherogenesis, and that it likely does so by mediating LDL uptake into the artery wall. They further suggest that there are mechanisms that govern LDL transport across endothelium that may be targeted to provide novel means to combat atherosclerosis.

scholarly journals Treatment of macrophages with oxidized low-density lipoprotein increases their intracellular glutathione content

1991 ◽  
Vol 278 (2) ◽  
pp. 429-434 ◽  
Author(s):  
V M Darley-Usmar ◽  
A Severn ◽  
V J O'Leary ◽  
M Rogers
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Human Monocyte ◽  
Cell Types ◽  
Oxidative Modification ◽  
Glutathione Depletion ◽  
Lipid Phase ◽  
Low Density ◽  
Oxidized Low Density Lipoprotein

Macrophages derived from the human monocyte cell line THP-1 or isolated from the peritoneum of C3H/HEJ mice were incubated with oxidized low-density lipoprotein (LDL) and the total glutathione content (oxidized plus reduced) was measured. An initial depletion of glutathione was followed by an increase, such that after a period of 24 h the glutathione content has approximately doubled. This response required the oxidation of the lipid phase of the LDL molecule, since both native LDL and acetylated LDL had little effect on glutathione levels. The response of the cells to oxidized LDL was dependent on the extent of oxidative modification of the protein. It was also found that 4-hydroxynonenal had a similar effect on THP-1 cells, and we suggest that this or other aldehydes present in oxidized LDL causes the induction of glutathione synthesis in response to an initial oxidative stress and consequent glutathione depletion. In addition, we found that both cell types possess transferases and peroxidases capable of detoxifying aldehydes and peroxides. However, treatment of cells with oxidized LDL or 4-hydroxynonenal for a period of 24 h had no effect on the activities of these enzymes.

Protective Effects of Berberine against Low-Density Lipoprotein (LDL) Oxidation and Oxidized LDL-Induced Cytotoxicity on Endothelial Cells

2007 ◽  
Vol 55 (25) ◽  
pp. 10437-10445 ◽  
Author(s):  
Yih-Shou Hsieh ◽  
Wu-Hsien Kuo ◽  
Ta-Wei Lin ◽  
Horng-Rong Chang ◽  
Teseng-His Lin ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Ldl Oxidation ◽  
Low Density ◽  
Protective Effects

Hydrogen sulfide destroys lipid hydroperoxides in oxidized LDL

2009 ◽  
Vol 420 (2) ◽  
pp. 277-281 ◽  
Author(s):  
Markus K. Muellner ◽  
Sabine M. Schreier ◽  
Hilde Laggner ◽  
Marcela Hermann ◽  
Harald Esterbauer ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Hplc Analysis ◽  
Octadecadienoic Acid ◽  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Lipid Hydroperoxides ◽  
Low Density ◽  
The Third ◽  
Haem Oxygenase

LOOHs (lipid hydroperoxides) in oxLDL [oxidized LDL (low-density lipoprotein)] are potentially atherogenic compounds. Recently, H2S was identified as the third endogenous gasotransmitter in the vasculature. H2O2 is known to be destroyed by H2S. Assuming that H2S may also react with LOOHs, the results show that H2S can destroy LOOHs in oxLDL. The ability of LOOH-enriched LDL to induce HO-1 (haem oxygenase 1) in endothelial cells was abolished by H2S pretreatment. HPLC analysis showed that 9-HPODE [(9S)-hydroperoxy-(10E,12Z)-octadecadienoic acid], a compound found in oxLDL, was reduced to 9-HODE [(9S)-hydroxy-(10E,12Z)-octadecadienoic acid] in the presence of H2S. Thus H2S may act as an antiatherogenic agent by reducing LOOHs to the less reactive LOHs and could abrogate the pathobiological activity of oxLDL.

Scavenger receptors: targets for antiplatelet therapies?

Blood ◽  
2008 ◽  
Vol 111 (4) ◽  
pp. 1749-1750 ◽  
Author(s):  
Meinrad Gawaz
Keyword(s):  
High Density Lipoprotein ◽  
Critical Role ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
High Density ◽  
Scavenger Receptors ◽  
Type I ◽  
Antiplatelet Activity ◽  
Oxidatively Modified

Scavenger receptors are increasingly recognized as playing a critical role in atherothrombosis.1 A new study presented by Valiyaveettil and colleagues in this issue of Blood demonstrates that oxidatively modified high-density lipoprotein (OxHDL) exhibits potent antiplatelet activity via the platelet scavenger receptor B type I (SR-BI).

Lipoproteins in heart disease

Perfusion ◽  
1996 ◽  
Vol 11 (4) ◽  
pp. 338-345 ◽  
Author(s):  
Annette Basile-Borgia ◽  
John H Abel
Keyword(s):  
Oxidized Ldl ◽  
Low Density Lipoprotein ◽  
Critical Role ◽  
Lipoprotein Metabolism ◽  
Density Lipoprotein ◽  
Acute Phase Reactant ◽  
Essential Elements ◽  
Current Data ◽  
Atherosclerotic Cardiovascular Disease ◽  
Key Steps

Most lipids are carried in the circulation by lipoproteins. Liproproteins and their associated proteins, called apolipoproteins, are currently being studied in an effort to further our understanding of atherosclerotic cardiovascular disease. Lipoprotein assembly, secretion, transportation, modification and clearance are essential elements of healthy lipid metabolism. When one or more of these key steps becomes altered, various disease states are induced. Current data suggest that lipoprotein(a), a low density lipoprotein (LDL)-like particle, is an acute phase reactant that plays a critical role in the modulation of fibrinolysis. Several aspects of lipoproteins and lipoprotein metabolism will be examined. Emphasis will be placed on the proatherogenic and thrombogenic effects of oxidized LDL.

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