Abstract 639: CD36 Recruits Na/K-ATPase/Lyn Complex to Mediate Proatherogenic Phenotypes in Macrophages

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Yiliang Chen ◽  
David Kennedy ◽  
Devi Prasadh Ramakrishnan ◽  
Huang Wenxin ◽  
Zhichuan Li ◽  
...  
Keyword(s):  
Foam Cell ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Null Mouse ◽  
Macrophage Migration ◽  
Lesion Area ◽  
Downstream Signaling ◽  
Lyn Kinase

Atherosclerosis is characterized by accumulation of macrophage foam cells in the arterial wall. We previously showed that CD36, a scavenger receptor highly expressed in macrophages, mediates oxidized-LDL (oxLDL) uptake, contributes to intracellular cholesterol accumulation and foam cell formation, and regulates macrophage migration and pro-inflammatory signaling. Genetic deletion of cd36 in mice is protective against diet-induced atherosclerosis. Mechanistically, we discovered that binding of oxLDL to CD36 activates Lyn kinase and initiates a cascade that is necessary for the pro-atherogenic cellular phenotype. Nevertheless, how CD36 regulates Lyn kinase remains undefined. We previously showed that Na/K-ATPase (NKA) regulates Src family kinases, including Lyn and we now hypothesized that CD36 regulates Lyn kinase via an interaction with NKA. We used co-immunoprecipitation and a novel immunofluorescence-based cell surface cross linking assay to demonstrate that CD36 physically associates with NKA on the macrophage surface. In a NKA α1 subunit heterozygous null mouse model in which ~60% of macrophage NKA expression is downregulated, we demonstrated that recruitment and activation of Lyn and its downstream signaling events in response to oxLDL were abolished. Functionally, we showed that NKA haploinsufficiency significantly blunted oxLDL uptake, foam cell formation and macrophage migration under atherogenic conditions. Importantly NKA α1 heterozygous null mice when bred into an apoe null background developed less atherosclerosis (26.7% lesion area in NKA control mice v.s. 13.4% lesion area in NKA heterozygous null mice) assessed by en face oil red O staining of aortae after 12 weeks on high fat diet. We conclude that by controlling Lyn kinase activity NKA critically regulates oxLDL/CD36 induced pro-atherogenic signaling.

Abstract 333: CD36 Mediates Cholesterol Uptake via Na/K-ATPase/lyn Signaling in Macrophages

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Yiliang Chen ◽  
David Kennedy ◽  
Zhichuan Li ◽  
Zijian Xie ◽  
Roy L Silverstein
Keyword(s):  
Kinase Activity ◽  
Foam Cell ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Developed Countries ◽  
Foam Cell Formation ◽  
Macrophage Foam Cell ◽  
Cholesterol Uptake ◽  
Lyn Kinase

Atherosclerosis, the leading cause of death in the developed countries, is characterized by macrophage foam cell formation. We previously showed that CD36, a scavenger receptor highly expressed in macrophages, mediates oxidized-LDL uptake, contributes to intracellular cholesterol accumulation and foam cell formation, and regulates macrophage migration and pro-inflammatory signaling. Consistently, cd36 deletion in mice protects from diet-induced atherosclerosis. Mechanistically, we discovered a novel signaling pathway, in which oxidized LDL (oxLDL) binding to CD36 activates Lyn kinase and initiates a cascade that is necessary for the pro-atherogenic cellular phenotype. How CD36 regulates Lyn kinase remains undefined. Since we previously showed that the Na/K-ATPase (NKA) regulates Src family kinases, including Lyn, we hypothesized that CD36 regulates Lyn kinase via an interaction with NKA. We used co-immunoprecipitation, FRET, and a novel cross linking assay to demonstrate that CD36 physically associates with NKA on the macrophage surface. Using a Lyn kinase activity assay, we showed that the interaction regulates Lyn kinase activity in response to oxLDL in macrophages. Moreover, a newly developed peptide inhibitor specifically blocked Lyn activation in response to oxLDL and attenuated oxLDL-stimulated cholesterol uptake (135.6±3.4 μM cholesterol/mg protein after 24 hours vs 173.8±7.7 μM cholesterol/mg protein in vehicle treated cells; p=0.0005; n=6). Taken together, we conclude that CD36 signals through NKA to regulate Lyn kinase activity in macrophages, which may be a molecular mechanism underlying cholesterol overloading and foam cell formation.

OxLDL-mediated survival of macrophages does not require LDL internalization or signalling by major pattern recognition receptors

2011 ◽  
Vol 89 (4) ◽  
pp. 387-395 ◽  
Author(s):  
Maziar Riazy ◽  
Johnny H. Chen ◽  
Yasuhiko Yamamato ◽  
Hiroshi Yamamato ◽  
Vincent Duronio ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Foam Cell ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Pi3k Pathway ◽  
Pattern Recognition Receptors ◽  
Foam Cell Formation ◽  
Macrophage Populations ◽  
Phosphoinositide 3 Kinase

Macrophages play a key role in the pathogenesis of atherosclerosis, in part by destabilizing plaques. We and others have shown that low concentrations of oxidized LDL (oxLDL) inhibit macrophage apoptosis. As oxLDL is present in lesions, this may be a mechanism by which macrophage populations in the intima are expanded. We have previously shown that oxLDL activates prosurvival signalling pathways such as the phosphoinositide 3-kinase (PI3K) pathway in bone marrow derived macrophages (BMDMs). However, little is known about more upstream signalling events especially at the receptor level. The endocytic pattern recognition receptors (PRRs), scavenger receptor A (SR-A) and CD36, are the main receptors on macrophages for uptake of oxLDL and are therefore important in foam cell formation. The signalling PRRs such as toll-like receptor (TLR) 2 and 4 also bind some types of oxLDL. This study was done to determine if any of the known PRRs are required for the anti-apoptotic effects of oxLDL in BMDMs. To do this, we tested the effect of oxLDL on viability of BMDMs lacking both SR-A and CD36 or lacking TLR2, TLR4, CD14, FcγRIIb, or RAGE. Our results indicate that none of these receptors are essential for activating the oxLDL prosurvival pathway. Furthermore, we show that the anti-apoptotic effect is not dependent on the uptake of oxLDL.

scholarly journals Chondroitin Sulfate N -acetylgalactosaminyltransferase-2 Impacts Foam Cell Formation and Atherosclerosis by Altering Macrophage Glycosaminoglycan Chain

2021 ◽  
Vol 41 (3) ◽  
pp. 1076-1091
Author(s):  
Imam Manggalya Adhikara ◽  
Keiko Yagi ◽  
Dyah Samti Mayasari ◽  
Yoko Suzuki ◽  
Koji Ikeda ◽  
...  
Keyword(s):  
Chondroitin Sulfate ◽  
Foam Cell ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Peritoneal Macrophages ◽  
Metabolic Phenotype ◽  
Foam Cell Formation ◽  
Macrophage Foam Cell

Objective: Chondroitin sulfate proteoglycans are the primary constituents of the macrophage glycosaminoglycan and extracellular microenvironment. To examine their potential role in atherogenesis, we investigated the biological importance of one of the chondroitin sulfate glycosaminoglycan biosynthesis gene, ChGn-2 (chondroitin sulfate N -acetylgalactosaminyltransferase-2), in macrophage foam cell formation. Approach and Results: ChGn-2-deficient mice showed decreased and shortened glycosaminoglycans. ChGn-2 −/− /LDLr −/− (low-density lipoprotein receptor) mice generated less atherosclerotic plaque after being fed with Western diet despite exhibiting a metabolic phenotype similar to that of the ChGn-2 +/+ /LDLr −/− littermates. We demonstrated that in macrophages, ChGn-2 expression was upregulated in the presence of oxLDL (oxidized LDL), and glycosaminoglycan was substantially increased. Foam cell formation was significantly altered by ChGn-2 in both mouse peritoneal macrophages and the RAW264.7 macrophage cell line. Mechanistically, ChGn-2 enhanced oxLDL binding on the cell surface, and as a consequence, CD36—an important macrophage membrane scavenger receptor—was differentially regulated. Conclusions: ChGn-2 alteration on macrophages conceivably influences LDL accumulation and subsequently accelerates plaque formation. These results collectively suggest that ChGn-2 is a novel therapeutic target amenable to clinical translation in the future. Graphic Abstract: A graphic abstract is available for this article.

Abstract 143: Macropinocytosis Mediates Enzymatically Modified LDL (ELDL)-Induced Murine Smooth Muscle Cell Formation: A Role for RAGE In ELDL Endocytosis and Upregulation of Scavenger Receptor LOX1

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Bijoy Chellan ◽  
Catherine A Reardon ◽  
Marion Hofmann Bowman
Keyword(s):  
Smooth Muscle ◽  
Foam Cell ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Wild Type ◽  
Pi3k Inhibitors ◽  
Atherosclerotic Lesions ◽  
Ldl Particles

Background: ELDL is present in human atherosclerotic lesions and promotes foam cell formation in cultured macrophages and vascular smooth muscle cells (SMC). Here we study mechanism of ELDL uptake and its effects on SMCs. Methods and Results: Incubation of wild type murine aortic SMCs with 10 μg/ml ELDL (trypsin, cholesterol esterase modified) results in enhanced foam cell formation (analyzed by Oil Red O, lipid measurement) compared to SMCs incubated with acetylated LDL (500 μg/ml; -50%, p<0.01) and oxidized LDL (200 μg/ml; -75%, p<0.01). Inhibitors of macropinocytosis (50 μM LY294006, 2 μM wortmannin, and 3 mM amiloride) attenuated ELDL uptake (-50%, -50%, -100% respectively). In contrast, inhibitors of receptor mediated endocytosis (100 μM dynasore, 0.1 M Sucrose), and inhibitors of caveolae /lipid raft mediated endocytosis (5mM MBCD, 5 μM filipin) had no effect on ELDL uptake in SMCs. Moreover, ELDL incubation led to increased expression of scavenger receptor LOX1 (+ 3 fold, p<0.01) in wild type SMC’s, but not in SMC deficient in Receptor for AGE (RAGE-/-), while CD36 and SRA1 remained unchanged in both the SMCs. Importantly, RAGE-/- SMCs upon pretreatment with PI3K inhibitors that only partially inhibited macropinocytosis of ELDL in wild type SMCs, completely prevented ELDL uptake in RAGE-/- SMCs. Mechanistically, ELDL upregulates ROS (detected using H2DCFDA) and down regulates PIP3 (detected by pAkt immunoblotting) in wild type, but not in RAGE-/- SMCs. Since ROS is known to regulate macropinocytosis via increased Ca2+ levels, we tested Ca2+ channel inhibitor lacidipine (30 μM), and found complete inhibition of ELDL uptake in both, wild type and RAGE-/- SMCs. Lastly, we speculate that the fused structure of LDL in the ELDL preparation is preferentially activating RAGE, since oligomerization of ligands are known to increase RAGE signaling, and FPLC analysis demonstrated that ELDL consists mostly of fused LDL particles. Conclusions: ELDL is highly potent in inducing foam cells in aortic SMCs. ELDL endocytosis is mediated by RAGE-regulated, Ca2+ dependent macropinocytosis.

scholarly journals 10: CHOLESTEROL FLUX PATHWAY ABNORMALITIES INDUCED BY PLASMA FROM PATIENTS WITH CHRONIC KIDNEY DISEASE

2016 ◽  
Vol 64 (3) ◽  
pp. 803.1-803
Author(s):  
N Miyawaki ◽  
F Daccueil ◽  
NM Siegart ◽  
J Mattana ◽  
I Voloshyna ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Kidney Disease ◽  
Foam Cell ◽  
Oxidized Ldl ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Pcr Analysis ◽  
Foam Cell Formation ◽  
Cvd Risk ◽  
Healthy Control

Purpose of StudyChronic kidney disease (CKD) is a known risk factor for cardiovascular disease (CVD). Patients with CKD have a high prevalence of atherosclerosis. However, CVD risk associated with CKD is not entirely explained by standard lipid profile or liver handling of cholesterol, as evidenced by the resistance to statin benefits seen in later stages of CKD. This study aims to detect changes in expression of cholesterol transport proteins in the setting of CKD and to determine if such changes adversely affect lipid handling by macrophages leading to cholesterol overload and atheromatous foam cell formation.Methods UsedTHP-1 human macrophages (106/ml) were incubated for 18 h–24 h with plasma obtained from 10 CKD patients (7 male, 3 female) or 10 healthy control subjects (4 male, 6 female). CKD patients were not on dialysis and had not received renal transplant. Following incubation, mRNA was isolated and reverse transcribed. The resulting cDNA was subjected to quantitative real-time PCR using specific primers for ATP binding cassette transporter (ABC)A1 (cholesterol efflux protein) and CD36, (a scavenger receptor with the capacity to endocytose oxidized LDL).Summary of ResultsPCR analysis showed that ABCA1 mRNA was reduced by 23±5% (p<0.0001) while CD36 mRNA was decreased by 36±7% (p<0.0001) in macrophages exposed to CKD plasma as compared to healthy control.ConclusionsThese findings suggest a different mechanism of lipid dysregulation associated with CKD that may explain the pathogenesis of elevated CVD risk in CKD and lack of response to statins. This mechanism, through pro-atherogenic suppression of ABCA1, differs from our finding in autoimmune rheumatic diseases where, in addition to lowering of ABCA1, augmentation of CD36 was also observed. In CKD, a paradoxical decrease in CD36 could compromise macrophage clearance of lipids, increasing vulnerability to lipoprotein thrombi in kidney. Further lowering of monocyte CD36 with statins would be of little benefit if CD36 is already low in CKD. Defining changes in lipid handling in CKD could lead to novel, targeted CVD treatment approaches in the CKD population.

L-theanine inhibits foam cell formation via promoting the scavenger receptor A degradation

2021 ◽  
pp. 174181
Author(s):  
Jianzhen Lei ◽  
Jingheng Ye ◽  
Rong She ◽  
Ruyi Zhang ◽  
Yanan Wang ◽  
...  
Keyword(s):  
Foam Cell ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Scavenger Receptor A

Abstract 450: Modification of HDL by Reactive Aldehydes Impairs HDL's Athero-protective Functions

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Rebecca L Holme ◽  
Alexandra C Chadwick ◽  
Sarah C Proudfoot ◽  
Yiliang Chen ◽  
Devi Prasadh Ramakrishnan ◽  
...  
Keyword(s):  
Foam Cell ◽  
Cell Formation ◽  
Oxidative Modification ◽  
High Density Lipoproteins ◽  
Foam Cell Formation ◽  
Macrophage Migration ◽  
Mrna Levels ◽  
Protective Effects ◽  
Impaired Ability ◽  
Reactive Aldehydes

High density lipoproteins (HDL) are athero-protective particles that promote the removal of excess cholesterol from lipid-loaded macrophages and stimulate their migration in order to protect against foam cell formation, a precursor to atherosclerotic plaque build-up. Recently, studies have shown that oxidative modification of HDL prevents HDL from protecting against atherosclerosis; however, the exact mechanisms by which this occurs are not well defined. We hypothesize that oxidative modification of HDL by reactive aldehydes such as acrolein (a major component of cigarette smoke) and 4-hydroxynonenal (HNE; a product of lipid peroxidation) impairs HDL’s athero-protective effects in macrophages. We tested our hypothesis using three different assays. First, we determined that modified forms of HDL upregulate mRNA levels of pro-atherogenic scavenger receptors such as cluster of differentiation 36 (CD36), a known oxidized LDL receptor. Incubation of macrophages with native HDL did not exert similar effects. Second, we tested the ability of oxidized HDL to prevent foam cell formation. Peritoneal macrophages isolated from WT C57Bl/J mice were cholesterol-loaded and incubated with native HDL, acrolein-modified HDL (acro-HDL), or HNE-modified HDL (HNE-HDL). Oil Red-O staining demonstrated that 24% of macrophages had foam cell formation upon incubation with native HDL, whereas 61% and 49% foam cell formation was observed for acro- and HNE-HDL, respectively. Preliminary data suggests this may be CD36-dependent. Finally, using a Boyden chamber assay, we demonstrated that both acro- and HNE-HDL, but not native HDL, had an impaired ability to promote macrophage migration (43% and 72% of HDL cell migration levels, respectively). We determined that the inability of acro- and/or HNE-HDL to stimulate macrophage migration may be due to an impaired ability of these modified lipoproteins to activate the PI3K pathway, as shown by decreased levels of phosphorylated protein kinase B (Akt). In conclusion, we have identified three independent mechanisms by which modification of HDL with acrolein or HNE impairs HDL’s cardio-protective effects and, instead, generates a particle that promotes pathways that lead to atherosclerosis.

scholarly journals Anti-Atherosclerotic Activity of (3R)-5-Hydroxymellein from an Endophytic Fungus Neofusicoccum parvum JS-0968 Derived from Vitex rotundifolia through the Inhibition of Lipoproteins Oxidation and Foam Cell Formation

Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 715
Author(s):  
Jae-Yong Kim ◽  
Soonok Kim ◽  
Sang Hee Shim
Keyword(s):  
Conformational Changes ◽  
Endophytic Fungus ◽  
Foam Cell ◽  
Oxidized Ldl ◽  
Cell Formation ◽  
Density Lipoprotein ◽  
Ldl Oxidation ◽  
Foam Cell Formation ◽  
Macrophage Foam Cell ◽  
Neofusicoccum Parvum

An endophytic fungus, Neofusicoccum parvum JS-0968, was isolated from a plant, Vitex rotundifolia. The chemical investigation of its cultures led to the isolation of a secondary metabolite, (3R)-5-hydroxymellein. It has been reported to have antifungal, antibacterial, and antioxidant activity, but there have been no previous reports on the effects of (3R)-5-hydroxymellein on atherosclerosis. The oxidation of lipoproteins and foam cell formation have been known to be significant in the development of atherosclerosis. Therefore, we investigated the inhibitory effects of (3R)-5-hydroxymellein on atherosclerosis through low-density lipoprotein (LDL) and high-density lipoprotein (HDL) oxidation and macrophage foam cell formation. LDL and HDL oxidation were determined by measuring the production of conjugated dienes and malondialdehyde, the amount of hyperchromicity and carbonyl content, conformational changes, and anti-LDL oxidation. In addition, the inhibition of foam cell formation was measured by Oil red O staining. As a result, (3R)-5-hydroxymellein suppressed the oxidation of LDL and HDL through the inhibition of lipid peroxidation, the decrease of negative charges, the reduction of hyperchromicity and carbonyl contents, and the prevention of apolipoprotein A-I (ApoA-I) aggregation and apoB-100 fragmentation. Furthermore, (3R)-5-hydroxymellein significantly reduced foam cell formation induced by oxidized LDL (oxLDL). Taken together, our data show that (3R)-5-hydroxymellein could be a potential preventive agent for atherosclerosis via obvious anti-LDL and HDL oxidation and the inhibition of foam cell formation.

scholarly journals A Growth Hormone-Releasing Peptide Promotes Mitochondrial Biogenesis and a Fat Burning-Like Phenotype through Scavenger Receptor CD36 in White Adipocytes

Endocrinology ◽  
2007 ◽  
Vol 148 (3) ◽  
pp. 1009-1018 ◽  
Author(s):  
Amélie Rodrigue-Way ◽  
Annie Demers ◽  
Huy Ong ◽  
André Tremblay
Keyword(s):  
Mitochondrial Biogenesis ◽  
Foam Cell ◽  
Uncoupling Protein ◽  
Scavenger Receptor ◽  
Cell Formation ◽  
Foam Cell Formation ◽  
Ppar Γ ◽  
Cd36 Expression ◽  
White Fat

Whereas the uptake of oxidized lipoproteins by scavenger receptor CD36 in macrophages has been associated with foam cell formation and atherogenesis, little is known about the role of CD36 in regulating lipid metabolism in adipocytes. Here we report that treatment of 3T3-L1 adipocytes with hexarelin, a GH-releasing peptide that interacts with CD36, resulted in a depletion of intracellular lipid content with no significant change in CD36 expression. Microarray analysis revealed an increased pattern in several genes involved in fatty acid mobilization toward the mitochondrial oxidative phosphorylation process in response to hexarelin. Interestingly, many of these up-regulated genes are known targets of peroxisomal proliferator-activated receptor (PPAR)-γ, such as FATP, CPT-1, and F1-ATPase, suggesting that adipocyte response to hexarelin may involve PPARγ activation. Expression studies also indicate an increase in thermogenic markers PPARγ coactivator 1α and uncoupling protein-1, which are normally expressed in brown adipocytes. Electron microscopy of hexarelin-treated 3T3-L1 adipocytes showed an intense and highly organized cristae formation that spans the entire width of mitochondria, compared with untreated cells, and cytochrome c oxidase activity was enhanced by hexarelin, two features characteristic of highly oxidative tissues. A similar mitochondrial phenotype was detected in epididymal white fat of mice treated with hexarelin, along with an increased expression of thermogenic markers that was lost in treated CD36-null mice, suggesting that the ability of hexarelin to promote a brown fat-like phenotype also occurs in vivo and is dependent on CD36. These results provide a potential role for CD36 to impact the overall metabolic activity of fat usage and mitochondrial biogenesis in adipocytes.

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