51
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Zhao Y, Pennings M, Vrins CL, Calpe-Berdiel L, Hoekstra M, Kruijt JK, Ottenhoff R, Hildebrand RB, van der Sluis R, Jessup W, Le Goff W, Chapman MJ, Huby T, Groen AK, Van Berkel TJ, Van Eck M. Hypocholesterolemia, foam cell accumulation, but no atherosclerosis in mice lacking ABC-transporter A1 and scavenger receptor BI. Atherosclerosis 2011; 218:314-22. [DOI: 10.1016/j.atherosclerosis.2011.07.096] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 06/23/2011] [Accepted: 07/14/2011] [Indexed: 10/17/2022]
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52
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Abstract
PURPOSE OF REVIEW HDL cholesterol levels have been inversely correlated with thrombosis and HDL has been shown to mediate various antithrombotic effects. However, molecular mechanisms underlying the suppressing effect of HDL on platelet reactivity are not completely understood. The present review summarizes the recent advancements in understanding the role played by scavenger receptor class B type I (SR-BI) - an HDL receptor - in modulating platelet function and mediating platelet-HDL interactions. RECENT FINDINGS SR-BI is expressed on platelet surface and platelets from SR-BI knockout animals are characterized by increased free-to-total cholesterol ratio, abnormal morphology, increased reactivity to strong platelets agonists, enhanced adherence to immobilized fibrinogen, and a propensity to form arterial thrombi. Crossover incubation experiments and a bone marrow transplantation approach reveal increased wild-type platelet reactivity in plasma from SR-BI mice and normal or decreased SR-BI-deficient platelet reactivity in wild-type plasma. A similar functional platelet phenotype has been observed in human carriers of an SR-BI genetic variant. SR-BI ligands interfere with HDL binding to murine platelets and impede the agonist-induced platelet activation as effectively as native HDL. The inhibitory effects of native HDL, moderately oxidized HDL, and SR-BI ligands are abolished in SR-BI-deficient platelets but not in CD36-deficient platelets. SUMMARY SR-BI exerts an indirect influence on platelet reactivity via maintaining normal plasma cholesterol homeostasis. In addition, SR-BI is a functional receptor for native and moderately oxidized HDL on platelets that generates an inhibitory signal for platelet activation.
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Affiliation(s)
- Jerzy-Roch Nofer
- Center for Laboratory Medicine, University Hospital Münster, Münster, Germany.
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53
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Nieland TJ, Xu S, Penman M, Krieger M. Negatively cooperative binding of high-density lipoprotein to the HDL receptor SR-BI. Biochemistry 2011; 50:1818-30. [PMID: 21254782 PMCID: PMC3065119 DOI: 10.1021/bi101657j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Scavenger receptor class B, type I (SR-BI), is a high-density lipoprotein (HDL) receptor, which also binds low-density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a coreceptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high-affinity binding sites (one site model). We have reinvestigated the ligand concentration dependence of (125)I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [(3)H]CE from [(3)H]CE-HDL using an expanded range of ligand concentrations (<1 μg of protein/mL, lower than previously reported). Scatchard and nonlinear least-squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects ("lattice model"). Similar results were observed for LDL. Application of the "infinite dilution" dissociation rate method established that the binding of (125)I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport, and cell signaling.
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Affiliation(s)
- Thomas J.F. Nieland
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
- Broad Institute of Harvard and MIT, 7 Cambridge Center, Cambridge, MA 02142
| | - Shangzhe Xu
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
| | - Marsha Penman
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
| | - Monty Krieger
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, MA 02139
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54
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El Bouhassani M, Gilibert S, Moreau M, Saint-Charles F, Tréguier M, Poti F, Chapman MJ, Le Goff W, Lesnik P, Huby T. Cholesteryl ester transfer protein expression partially attenuates the adverse effects of SR-BI receptor deficiency on cholesterol metabolism and atherosclerosis. J Biol Chem 2011; 286:17227-38. [PMID: 21454568 DOI: 10.1074/jbc.m111.220483] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Scavenger receptor SR-BI significantly contributes to HDL cholesterol metabolism and atherogenesis in mice. However, the role of SR-BI may not be as pronounced in humans due to cholesteryl ester transfer protein (CETP) activity. To address the impact of CETP expression on the adverse effects associated with SR-BI deficiency, we cross-bred our SR-BI conditional knock-out mouse model with CETP transgenic mice. CETP almost completely restored the abnormal HDL-C distribution in SR-BI-deficient mice. However, it did not normalize the elevated plasma free to total cholesterol ratio characteristic of hepatic SR-BI deficiency. Red blood cell and platelet count abnormalities observed in mice liver deficient for SR-BI were partially restored by CETP, but the elevated erythrocyte cholesterol to phospholipid ratio remained unchanged. Complete deletion of SR-BI was associated with diminished adrenal cholesterol stores, whereas hepatic SR-BI deficiency resulted in a significant increase in adrenal gland cholesterol content. In both mouse models, CETP had no impact on adrenal cholesterol metabolism. In diet-induced atherosclerosis studies, hepatic SR-BI deficiency accelerated aortic lipid lesion formation in both CETP-expressing (4-fold) and non-CETP-expressing (8-fold) mice when compared with controls. Impaired macrophage to feces reverse cholesterol transport in mice deficient for SR-BI in liver, which was not corrected by CETP, most likely contributed by such an increase in atherosclerosis susceptibility. Finally, comparison of the atherosclerosis burden in SR-BI liver-deficient and fully deficient mice demonstrated that SR-BI exerted an atheroprotective activity in extra-hepatic tissues whether CETP was present or not. These findings support the contention that the SR-BI pathway contributes in unique ways to cholesterol metabolism and atherosclerosis susceptibility even in the presence of CETP.
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55
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Nieland TJF, Xu S, Penman M, Krieger M. Negatively cooperative binding of high-density lipoprotein to the HDL receptor SR-BI. Biochemistry 2011. [PMID: 21254782 DOI: 10.1021/bi1011657j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Scavenger receptor class B, type I (SR-BI), is a high-density lipoprotein (HDL) receptor, which also binds low-density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a coreceptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high-affinity binding sites (one site model). We have reinvestigated the ligand concentration dependence of (125)I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [(3)H]CE from [(3)H]CE-HDL using an expanded range of ligand concentrations (<1 μg of protein/mL, lower than previously reported). Scatchard and nonlinear least-squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects ("lattice model"). Similar results were observed for LDL. Application of the "infinite dilution" dissociation rate method established that the binding of (125)I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport, and cell signaling.
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Affiliation(s)
- Thomas J F Nieland
- Department of Biology, Massachusetts Institute of Technology, Room 68-483, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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56
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Korporaal SJA, Meurs I, Hauer AD, Hildebrand RB, Hoekstra M, Cate HT, Praticò D, Akkerman JWN, Van Berkel TJC, Kuiper J, Van Eck M. Deletion of the high-density lipoprotein receptor scavenger receptor BI in mice modulates thrombosis susceptibility and indirectly affects platelet function by elevation of plasma free cholesterol. Arterioscler Thromb Vasc Biol 2010; 31:34-42. [PMID: 21051668 DOI: 10.1161/atvbaha.110.210252] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Scavenger receptor BI (SR-BI) is a cell surface receptor that promotes the selective uptake of cholesteryl esters from high-density lipoprotein (HDL) by the liver. In mice, SR-BI deficiency results in increased plasma HDL cholesterol levels and enhanced susceptibility to atherosclerosis. The aim of this study was to investigate the role of SR-BI deficiency on platelet function. METHODS AND RESULTS SR-BI-deficient mice were thrombocytopenic, and their platelets were abnormally large, probably because of an increased cholesterol content. The FeCl(3) acute injury model to study arterial thrombosis susceptibility showed that SR-BI wild-type mice developed total arterial occlusion after 24±2 minutes. In SR-BI-deficient mice, however, the time to occlusion was reduced to 13±1 minutes (P=0.02). Correspondingly, in SR-BI-deficient mice, platelets circulated in an activated state and showed increased adherence to immobilized fibrinogen. In contrast, platelet-specific disruption of SR-BI by bone marrow transplantation in wild-type mice did not alter plasma cholesterol levels or affect platelet count, size, cholesterol content, or reactivity, suggesting that changes in plasma cholesterol levels were responsible for the altered responsiveness of platelets in SR-BI-deficient mice. CONCLUSIONS The function of SR-BI in HDL cholesterol homeostasis and prevention of atherosclerosis is indirectly also essential for maintaining normal platelet function and prevention of thrombosis.
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Affiliation(s)
- Suzanne J A Korporaal
- Leiden/Amsterdam Center for Drug Research, Division of Biopharmaceutics, Gorlaeus Laboratories, Einsteinweg 55, 2333 CC, Leiden, the Netherlands.
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57
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Hildebrand RB, Lammers B, Meurs I, Korporaal SJA, De Haan W, Zhao Y, Kruijt JK, Praticò D, Schimmel AWM, Holleboom AG, Hoekstra M, Kuivenhoven JA, Van Berkel TJC, Rensen PCN, Van Eck M. Restoration of high-density lipoprotein levels by cholesteryl ester transfer protein expression in scavenger receptor class B type I (SR-BI) knockout mice does not normalize pathologies associated with SR-BI deficiency. Arterioscler Thromb Vasc Biol 2010; 30:1439-45. [PMID: 20431066 DOI: 10.1161/atvbaha.110.205153] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Disruption of scavenger receptor class B type I (SR-BI) in mice impairs high-density lipoprotein (HDL)-cholesterol (HDL-C) delivery to the liver and induces susceptibility to atherosclerosis. In this study, it was investigated whether introduction of cholesteryl ester transfer protein (CETP) can normalize HDL-C transport to the liver and reduce atherosclerosis in SR-BI knockout (KO) mice. METHODS AND RESULTS Expression of human CETP in SR-BI(KO) mice resulted in decreased plasma HDL-C levels, both on chow diet (1.8-fold, P<0.001) and on challenge with Western-type diet (1.6-fold, P<0.01). Furthermore, the presence of CETP partially normalized the abnormally large HDL particles observed in SR-BI(KO) mice. Unexpectedly, expression of CETP in SR-BI(KO) mice did not reduce atherosclerotic lesion development, probably because of consequences of SR-BI deficiency, including the persistence of higher VLDL-cholesterol (VLDL-C) levels, unchanged elevated free cholesterol/total cholesterol ratio, and the increased oxidative status of the animals. In addition, CETP expression did not normalize other characteristics of SR-BI deficiency, including female infertility, reticulocytosis, thrombocytopenia, and impaired platelet aggregation. CONCLUSIONS CETP restores HDL-C levels in SR-BI(KO) mice, but it does not change the susceptibility to atherosclerosis and other typical characteristics that are associated with SR-BI disruption. This may indicate that the pathophysiology of SR-BI deficiency is not a direct consequence of changes in the HDL pool.
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Affiliation(s)
- Reeni B Hildebrand
- Leiden/Amsterdam Center for Drug Research, Division of Biopharmaceutics, Leiden, the Netherlands
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58
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Nishiuchi T, Murao K, Imachi H, Yu X, Dobashi H, Haba R, Ishida T. Scavenger receptor class BI mediates the anti-apoptotic effect of erythropoietin. Ann Med 2010; 42:151-60. [PMID: 20156043 DOI: 10.3109/07853891003601556] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A scavenger receptor of the B class (SR-BI)/human homolog of SR-BI, CD36, and LIMP II analogous-1 (CLA-1), has been identified as a receptor for high-density lipoprotein (HDL). Mice lacking SR-B1 develop anemia, plausibly explained by the observation that the erythrocyte life-span in these animals is reduced. Erythropoietin (EPO) is known to promote survival of erythroid cells, in large part through protection from apoptosis. We have examined the role of EPO on hSR-BI/CLA-1 expression and erythrocyte apoptosis. Endogenous expression of hSR-BI/CLA-1 was increased by exposure to EPO. EPO increased transcriptional activity of hSR-BI/CLA-1 promoter. The stimulatory effect of EPO on hSR-BI/CLA-1 promoter activity was abrogated by LY294002, specific inhibitor of phosphatidylinositol-3 kinase (PI3K). Constitutively active Akt stimulates the activity of the hSR-BI/CLA-1 promoter and a dominant-negative mutant of Akt abolished the ability of EPO to stimulate promoter activity. Finally, EPO in combination with HDL protected the cell from apoptosis, which suggests that hSR-BI/CLA-1 induced by EPO might contribute to the erythrocyte life-span.
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Affiliation(s)
- Takamasa Nishiuchi
- Division of Endocrinology & Metabolism and Hematology, Department of Internal Medicine, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe Miki-Cho, Kita-gun, Kagawa, 761-0793, Japan
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59
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Fan J, Rone MB, Papadopoulos V. Translocator protein 2 is involved in cholesterol redistribution during erythropoiesis. J Biol Chem 2009; 284:30484-97. [PMID: 19729679 PMCID: PMC2781603 DOI: 10.1074/jbc.m109.029876] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 08/17/2009] [Indexed: 12/11/2022] Open
Abstract
Translocator protein (TSPO) is an 18-kDa cholesterol- and drug-binding protein conserved from bacteria to humans. While surveying for Tspo-like genes, we identified its paralogous gene, Tspo2, encoding an evolutionarily conserved family of proteins that arose by gene duplications before the divergence of avians and mammals. Comparative analysis of Tspo1 and Tspo2 functions suggested that Tspo2 has become subfunctionalized, typical of duplicated genes, characterized by the loss of diagnostic drug ligand-binding but retention of cholesterol-binding properties, hematopoietic tissue- and erythroid cell-specific distribution, and subcellular endoplasmic reticulum and nuclear membrane localization. Expression of Tspo2 in erythroblasts is strongly correlated with the down-regulation of the enzymes involved in cholesterol biosynthesis. Overexpression of TSPO2 in erythroid cells resulted in the redistribution of intracellular free cholesterol, an essential step in nucleus expulsion during erythrocyte maturation. Taken together, these data identify the TSPO2 family of proteins as mediators of cholesterol redistribution-dependent erythroblast maturation during mammalian erythropoiesis.
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Affiliation(s)
- Jinjiang Fan
- From the Research Institute of the McGill University Health Center and the Departments of Medicine, Biochemistry, and Pharmacology and Therapeutics, McGill University, Montréal, Québec H3A 1A4, Canada
| | - Malena B. Rone
- From the Research Institute of the McGill University Health Center and the Departments of Medicine, Biochemistry, and Pharmacology and Therapeutics, McGill University, Montréal, Québec H3A 1A4, Canada
| | - Vassilios Papadopoulos
- From the Research Institute of the McGill University Health Center and the Departments of Medicine, Biochemistry, and Pharmacology and Therapeutics, McGill University, Montréal, Québec H3A 1A4, Canada
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60
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Fenske SA, Yesilaltay A, Pal R, Daniels K, Rigotti A, Krieger M, Kocher O. Overexpression of the PDZ1 domain of PDZK1 blocks the activity of hepatic scavenger receptor, class B, type I by altering its abundance and cellular localization. J Biol Chem 2008; 283:22097-104. [PMID: 18544532 DOI: 10.1074/jbc.m800029200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PDZK1 is a four-PDZ domain-containing scaffold protein that, via its first PDZ domain (PDZ1), binds to the C terminus of the high density lipoprotein (HDL) receptor scavenger receptor, class B, type I (SR-BI). Abolishing PDZK1 expression in PDZK1 knock-out (KO) mice leads to a post-transcriptional, tissue-specific decrease in SR-BI protein level and an increase in total plasma cholesterol carried in abnormally large HDL particles. Here we show that, although hepatic overexpression of PDZK1 restored normal SR-BI protein abundance and function in PDZK1 KO mice, hepatic overexpression of only the PDZ1 domain was not sufficient to restore normal SR-BI function. In wild-type mice, overexpression of the PDZ1 domain overcame the activity of the endogenous hepatic PDZK1, resulting in a 75% reduction in hepatic SR-BI protein levels and intracellular mislocalization of the remaining SR-BI. As a consequence, the plasma lipoproteins in PDZ1 transgenic mice resembled those in PDZK1 KO mice (hypercholesterolemia due to large HDL). These results indicate that the PDZ1 domain can control the abundance and localization, and therefore the function, of hepatic SR-BI and that structural features of PDZK1 in addition to its SR-BI-binding PDZ1 domain are required for normal hepatic SR-BI regulation.
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Affiliation(s)
- Sara A Fenske
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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61
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Dole VS, Matuskova J, Vasile E, Yesilaltay A, Bergmeier W, Bernimoulin M, Wagner DD, Krieger M. Thrombocytopenia and platelet abnormalities in high-density lipoprotein receptor-deficient mice. Arterioscler Thromb Vasc Biol 2008; 28:1111-6. [PMID: 18436807 DOI: 10.1161/atvbaha.108.162347] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE High-density lipoprotein (HDL) receptor, scavenger receptor class B, type I (SR-BI), mediated cellular uptake of lipoprotein cholesterol controls HDL structure and plasma HDL and biliary cholesterol levels. In SR-BI knockout (KO) mice, an unusually high plasma unesterified-to-total cholesterol ratio (UC:TC) and abnormally large HDL particles apparently contribute to pathology, including female infertility, susceptibility to atherosclerosis and coronary heart disease, and anemia. Here we examined the influence of SR-BI deficiency on platelets. METHODS AND RESULTS The high plasma UC:TC ratio in SR-BI KO mice was correlated with platelet abnormalities, including high cholesterol content, abnormal morphologies, high clearance rates, and thrombocytopenia. One day after platelets from wild-type mice were infused into SR-BI KO mice, they exhibited abnormally high cholesterol content and clearance rates similar to those of endogenous platelets. Platelets from SR-BI KO mice exhibited in vitro a blunted aggregation response to the agonist ADP but a normal response to PAR4. CONCLUSIONS In SR-BI KO mice abnormal circulating lipoproteins, particularly their high UC:TC ratio-rather than the absence of SR-BI in platelets themselves-induce defects in platelet structure and clearance, together with a mild defect in function.
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Affiliation(s)
- Vandana S Dole
- Biology Department, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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62
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Tseng MY, Hutchinson PJ, Turner CL, Czosnyka M, Richards H, Pickard JD, Kirkpatrick PJ. Biological effects of acute pravastatin treatment in patients after aneurysmal subarachnoid hemorrhage: a double-blind, placebo-controlled trial. J Neurosurg 2008; 107:1092-100. [PMID: 18077945 DOI: 10.3171/jns-07/12/1092] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The authors previously demonstrated that acute pravastatin therapy in patients after aneurysmal subarachnoid hemorrhage (SAH) ameliorates vasospasm-related delayed ischemic neurological deficits. The object of this study was to continue to examine potential mechanisms of these beneficial effects. METHODS Eighty patients with aneurysmal SAH (age range 18-84 years; time to onset 1.8 +/- 1.3 days) were enrolled in a double-blind study and randomized to receive 40 mg of oral pravastatin or placebo daily for as long as 14 days. Daily transcranial Doppler ultrasonography and blood tests every 3 days (including full blood cell counts, coagulation profiles, fasting glucose and lipid profiles, and serum biochemistry) were performed during the trial period. RESULTS No significant differences were found in baseline laboratory data between the trial groups. Subsequent measurements during the 14-day trial showed reduced low-density lipoprotein (LDL) cholesterol levels and total/high-density lipoprotein cholesterol ratios between Days 3 and 15 (p < 0.05), and increased D-dimer levels (p < 0.05) on Day 6, in the pravastatin group. Patients who received pravastatin but developed vasospasm had significantly lower baseline LDL cholesterol levels or a less extensive reduction in LDL cholesterol levels (p < 0.05), and greater increases in plasma fibrinogen (p = 0.009) and serum C-reactive protein on Day 3 (p = 0.007), compared with those patients without vasospasm. The reduction in LDL cholesterol levels on Day 3 in the placebo group correlated with the duration of normal cerebral autoregulation on the ipsilateral side of the ruptured aneurysm (p = 0.002). CONCLUSIONS In addition to functioning through a cholesterol-independent pathway, cerebrovascular protection from acute statin therapy following aneurysmal SAH may also function through cholesterol-dependent mechanisms.
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Affiliation(s)
- Ming-Yuan Tseng
- Department of Neurosurgery, Addenbrooke's Hospital, University of Cambridge, United Kingdom
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63
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Van Eck M, Hoekstra M, Hildebrand RB, Yaong Y, Stengel D, Kruijt JK, Sattler W, Tietge UJF, Ninio E, Van Berkel TJC, Praticò D. Increased Oxidative Stress in Scavenger Receptor BI Knockout Mice With Dysfunctional HDL. Arterioscler Thromb Vasc Biol 2007; 27:2413-9. [PMID: 17717299 DOI: 10.1161/atvbaha.107.145474] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Objective—
In the current study the effect of disruption of SR-BI, a prominent regulator of HDL metabolism, on the activity of the HDL-associated antioxidant enzymes PON1 and PAF-AH as well as in vivo oxidative stress were investigated.
Methods and Results—
SR-BI deficiency resulted in 1.4-fold (
P
<0.001) and 1.6-fold (
P
<0.01) lower serum paraoxonase and arylesterase activity of PON1, respectively. Furthermore, a trend to slightly lower PAF-AH activity was observed. In vivo oxidative stress was evaluated by measuring isoprostane F2α-VI (iPF2α-VI) and protein carbonyls. Compared with wild-type animals, SR-BI knockouts had 1.4-fold (
P
<0.05) higher levels of plasma iPF2α-VI, whereas urinary excretion was increased 2-fold (
P
<0.0001). Plasma carbonyls were 1.5-fold (
P
<0.05) higher in SR-BI knockout animals. Furthermore, iPF2α-VI and carbonyl levels were 2.1-fold (
P
<0.01) and 1.4-fold (
P
<0.01), respectively, increased in livers of SR-BI knockout mice, and in reaction to the increased oxidative stress the expression of several endogenous antioxidant systems was upregulated. On challenging the SR-BI knockout mice with an atherogenic Western-type diet, a further increase in oxidative stress in these animals was observed.
Conclusion—
SR-BI deficiency results in a reduced activity of the antioxidant enzyme PON1 and a significant increase in oxidative stress, potentially contributing to the proatherogenic effect of SR-BI deficiency.
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Affiliation(s)
- Miranda Van Eck
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, Leiden University, The Netherlands.
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Coccia R, Spadaccio C, Foppoli C, Perluigi M, Covino E, Lusini M, Chello M. The Effect of Simvastatin on Erythrocyte Membrane Fluidity During Oxidative Stress Induced by Cardiopulmonary Bypass: A Randomized Controlled Study. Clin Ther 2007; 29:1706-17. [DOI: 10.1016/j.clinthera.2007.08.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2007] [Indexed: 10/22/2022]
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65
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Meurs I, Van Berkel TJ, Van Eck M. Response to Comment on “HDL Cholesterol Levels Are An Important Factor For Determining The Life-Span Of Erythrocytes”. Exp Hematol 2006. [DOI: 10.1016/j.exphem.2006.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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66
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Fredericks S, Holt DW. Comment on: HDL cholesterol levels are an important factor for determining the lifespan of erythrocytes. Exp Hematol 2005; 33(11):1309–1319. Exp Hematol 2006; 34:575-6; author reply 577-8. [PMID: 16647561 DOI: 10.1016/j.exphem.2006.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Revised: 01/06/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
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