Low density lipoprotein receptor-related protein 1 expression correlates with cholesteryl ester accumulation in the myocardium of ischemic cardiomyopathy patients

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Cal Roi

2012-08-01

Full Text Available Abstract Our hypothesis was that overexpression of certain lipoprotein receptors might be related to lipid accumulation in the human ischemic myocardium. Intramyocardial lipid overload contributes to contractile dysfunction and arrhythmias in cardiomyopathy. Thus, the purpose of this study was to assess the effect of hypercholesterolemic LDL and hypertrigliceridemic VLDL dose on LRP1 expression in cardiomyocytes, as well as the potential correlation between LRP1 expression and neutral lipid accumulation in the left ventricle tissue from ischemic cardiomyopathy patients. Cell culture experiments include control and LRP1-deficient cardiomyocytes exposed to lipoproteins under normoxic and hypoxic conditions. Explanted hearts from 18 ICM patients and eight non-diseased hearts (CNT were included. Low density lipoprotein receptor-related protein 1 (LRP1, very low density lipoprotein receptor (VLDLR and low density lipoprotein receptor (LDLR expression was analyzed by real time PCR and Western blotting. Cholesteryl ester (CE, triglyceride (TG and free cholesterol (FC content was assess by thin layer chromatography following lipid extraction. Western blotting experiments showed that protein levels of LRP1, VLDLR and HIF-1α were significantly upregulated in ischemic hearts. Immunohistochemistry and confocal microscopy analysis showed that LRP1 and HIF-1α were upregulated in cardiomyocytes of ICM patients. In vitro studies showed that VLDL, LDL and hypoxia exerted an upregulatory effect on LRP1 expression and that LRP1 played a major role in cholesteryl ester accumulation from lipoproteins in cardiomyocytes. Myocardial CE accumulation strongly correlated with LRP1 levels in ischemic hearts. Taken together, our results suggest that LRP1 upregulation is key for myocardial cholesterol ester accumulation in ischemic human hearts and that LRP1 may be a target to prevent the deleterious effects of myocardial cholesterol accumulation in ischemic cardiomyopathy.

α-Tocopherol modulates the low density lipoprotein receptor of human HepG2 cells

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Bottema Cynthia DK

2003-05-01

Full Text Available Abstract The aim of this study was to determine the effects of vitamin E (α-tocopherol on the low density lipoprotein (LDL receptor, a cell surface protein which plays an important role in controlling blood cholesterol. Human HepG2 hepatoma cells were incubated for 24 hours with increasing amounts of α, δ, or γ-tocopherol. The LDL receptor binding activity, protein and mRNA, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA reductase mRNA, cell cholesterol and cell lathosterol were measured. The effect of α-tocopherol was biphasic. Up to a concentration of 50 μM, α-tocopherol progressively increased LDL receptor binding activity, protein and mRNA to maximum levels 2, 4 and 6-fold higher than control, respectively. The HMG-CoA reductase mRNA and the cell lathosterol concentration, indices of cholesterol synthesis, were also increased by 40% over control by treatment with 50 μM α-tocopherol. The cell cholesterol concentration was decreased by 20% compared to control at 50 μM α-tocopherol. However, at α-tocopherol concentrations higher than 50 μM, the LDL receptor binding activity, protein and mRNA, the HMG-CoA reductase mRNA and the cell lathosterol and cholesterol concentrations all returned to control levels. The biphasic effect on the LDL receptor was specific for α-tocopherol in that δ and γ-tocopherol suppressed LDL receptor binding activity, protein and mRNA at all concentrations tested despite the cells incorporating similar amounts of the three homologues. In conclusion, α-tocopherol, exhibits a specific, concentration-dependent and biphasic "up then down" effect on the LDL receptor of HepG2 cells which appears to be at the level of gene transcription. Cholesterol synthesis appears to be similarly affected and the cell cholesterol concentration may mediate these effects.

Boronated protoporphyrin (BOPP): localization in lysosomes of the human glioma cell line SF-767 with uptake modulated by lipoprotein levels

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Callahan, Daniel E.; Forte, Trudy M.; Javed Afzal, S.M.; Deen, Dennis F.; Kahl, Stephen B.; Bjornstad, Kathleen A.; Bauer, William F.; Blakely, Eleanor A.

1999-01-01

Purpose: Boronated protoporphyrin (BOPP) is a candidate for use in both boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) of glioblastoma multiforme (GBM). Our objectives are to identify factors that influence the uptake and retention of BOPP in vitro and to determine BOPP distribution in a human glioma cell line in vitro. This information will aid the development of compounds and treatment strategies that increase the effectiveness of BNCT therapy for GBM. Methods and Materials: The amount, distribution pattern, and site of internalization of BOPP were assessed using fluorescence microscopy. Living human glioma (SF-767) cells were imaged after a 24-h exposure to BOPP (20-135.6 μg/ml, normal serum). Dose-dependent uptake of BOPP was determined using both fluorescence microscopy of individual living cells and inductively-coupled plasma-atomic emission spectroscopy (ICP-AES) analysis of cell pellets. Lysosome- or mitochondria-specific fluorescent probes were used to identify the cellular compartment containing BOPP. Two human fibroblast cell lines, AG-1522 (LDL receptor-positive) and GM019-15C (LDL receptor-deficient), were used to investigate LDL receptor-dependent BOPP uptake. The dependence of BOPP uptake on lipoproteins in the media was determined by exposing each of the three cell types to BOPP in medium containing either normal (NS) or lipoprotein deficient serum (LPDS). Results: BOPP accumulated in the lysosomes of human glioma cells in vitro, and not in the mitochondria, as reported for C6 rat glioma cells in vitro. BOPP uptake was concentration-dependent and was also dependent on the amount of lipoproteins in the medium. Over the range of incubation concentrations studied and at the single exposure duration time point investigated (24 h), all cells retained a similar amount of BOPP. At the lowest incubation concentration (20 μg/ml, NS), the amount of boron retained was near 10 9 atoms per cell (15 μg B/g cells). Lysosomes containing high

CRISPR Correction of a Homozygous Low-Density Lipoprotein Receptor Mutation in Familial Hypercholesterolemia Induced Pluripotent Stem Cells.

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Omer, Linda; Hudson, Elizabeth A; Zheng, Shirong; Hoying, James B; Shan, Yuan; Boyd, Nolan L

2017-11-01

Familial hypercholesterolemia (FH) is a hereditary disease primarily due to mutations in the low-density lipoprotein receptor (LDLR) that lead to elevated cholesterol and premature development of cardiovascular disease. Homozygous FH patients (HoFH) with two dysfunctional LDLR alleles are not as successfully treated with standard hypercholesterol therapies, and more aggressive therapeutic approaches to control cholesterol levels must be considered. Liver transplant can resolve HoFH, and hepatocyte transplantation has shown promising results in animals and humans. However, demand for donated livers and high-quality hepatocytes overwhelm the supply. Human pluripotent stem cells can differentiate to hepatocyte-like cells (HLCs) with the potential for experimental and clinical use. To be of future clinical use as autologous cells, LDLR genetic mutations in derived FH-HLCs need to be corrected. Genome editing technology clustered-regularly-interspaced-short-palindromic-repeats/CRISPR-associated 9 (CRISPR/Cas9) can repair pathologic genetic mutations in human induced pluripotent stem cells. We used CRISPR/Cas9 genome editing to permanently correct a 3-base pair homozygous deletion in LDLR exon 4 of patient-derived HoFH induced pluripotent stem cells. The genetic correction restored LDLR-mediated endocytosis in FH-HLCs and demonstrates the proof-of-principle that CRISPR-mediated genetic modification can be successfully used to normalize HoFH cholesterol metabolism deficiency at the cellular level.

Serum lipoproteins attenuate macrophage activation and Toll-Like Receptor stimulation by bacterial lipoproteins

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James Richard W

2010-09-01

Full Text Available Abstract Background Chlamydia trachomatis was previously shown to express a lipoprotein, the macrophage infectivity potentiator (Mip, exposed at the bacterial surface, and able to stimulate human primary monocytes/macrophages through Toll Like Receptor (TLR2/TLR1/TLR6, and CD14. In PMA-differentiated THP-1 cells the proinflammatory activity of Mip was significantly higher in the absence than in the presence of serum. The present study aims to investigate the ability of different serum factors to attenuate Mip proinflammatory activity in PMA-differentiated THP-1 cells and in primary human differentiated macrophages. The study was also extend to another lipoprotein, the Borrelia burgdorferi outer surface protein (OspA. The proinflammatory activity was studied through Tumor Necrosis Factor alpha (TNF-α and Interleukin (IL-8 release. Finally, TLR1/2 human embryonic kidney-293 (HEK-293 transfected cells were used to test the ability of the serum factors to inhibit Mip and OspA proinflammatory activity. Results In the absence of any serum and in the presence of 10% delipidated FBS, production of Mip-induced TNF-α and IL-8 in PMA-differentiated THP-1 cells were similar whereas they were significantly decreased in the presence of 10% FBS suggesting an inhibiting role of lipids present in FBS. In the presence of 10% human serum, the concentrations of TNF-α and IL-8 were 2 to 5 times lower than in the presence of 10% FBS suggesting the presence of more potent inhibitor(s in human serum than in FBS. Similar results were obtained in primary human differentiated macrophages. Different lipid components of human serum were then tested (total lipoproteins, HDL, LDL, VLDL, triglyceride emulsion, apolipoprotein (apoA-I, B, E2, and E3. The most efficient inhibitors were LDL, VLDL, and apoB that reduced the mean concentration of TNF-α release in Mip-induced macrophages to 24, 20, and 2%, respectively (p Conclusions These results demonstrated the ability of

Lipoprotein lipase deficiency with visceral xanthomas

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Servaes, Sabah; Bellah, Richard [Department of Radiology, Philadelphia, PA (United States); Verma, Ritu [Department of Gastroenterology, Philadelphia, PA (United States); Pawel, Bruce [Department of Pathology, Philadelphia, PA (United States)

2010-08-15

Lipoprotein lipase deficiency (LLD) is a rare metabolic disorder that typically presents with skin xanthomas and pancreatitis in childhood. We report a case of LLD in an infant who presented with jaundice caused by a pancreatic head mass. Abdominal imaging also incidentally revealed hyperechoic renal masses caused by renal xanthomas. This appearance of the multiple abdominal masses makes this a unique infantile presentation of LLD. (orig.)

Radiochemical and immunohistochemical detection of low density lipoprotein surface binding by lymphocytes

International Nuclear Information System (INIS)

Melzner, I.; Hambitzer, R.; Haferkamp, O.

1983-01-01

Human peripheral blood lymphocytes bind and take up low density lipoprotein (LDL) by receptor-mediated endocytosis. The binding of LDL was determiend by incubation with 125 I-LDL and an immunohistochemical assay. By both techniques a diminished rate of binding was found when cells were freshly isolated from the blood, but increased 5 to 10 fold when lymphocytes were incubated in lipoprotein-deficient medium for 72 hours. In addition, it was shown immunohistochemically that only few ceels showed an LDL-dependent fluorescent labelling: approximately 5 to 10 % of the freshly isolated lymphocytes and 40 to 50 % of the cells incubated for 72 hours under lipoprotein-free conditions. The present data indicate that not only the high affinity LDL receptor described by Goldstein and Braun may be involved in the uptake of cholesterol by lymphocytes, but also other binding sites, which may have immunological function in some lymphocyte subpopulations. (author)

Low density lipoprotein uptake by an endothelial-smooth muscle cell bilayer

International Nuclear Information System (INIS)

Alexander, J.J.; Miguel, R.; Graham, D.

1991-01-01

To study the interaction of endothelial and smooth muscle cells, and the means by which such interaction may affect lipid permeability of the arterial wall, cell bilayers were established by use of a transwell culture system. After confluent growth of both cell types had been achieved, iodine 125 bound to low-density lipoprotein (10 ng protein/ml) was added to the media of the upper well. After a 3-hour incubation period, the iodine 125-bound low-density lipoprotein content of the upper and lower media demonstrated an impedance to lipoprotein movement across the endothelial cell monolayer as compared to the bare porous polycarbonate filter of the transwell (p less than 10(-6)). The presence of smooth muscle cells in the bottom well significantly enhanced the permeability of the endothelial cell layer (p less than 10(-60)). This effect remained unchanged over a 9-day time course. Membrane binding and cellular uptake of low-density lipoprotein by endothelial cells was not altered by smooth muscle cells, indicating that this change in permeability could not be easily attributed to changes in receptor-mediated transport or transcytosis. Membrane binding (p less than 0.02) and cellular uptake (p less than 10(-6)) of low-density lipoprotein by smooth muscle cells in the bilayer, when adjusted for counts available in the smooth muscle cell media, were both reduced in the early incubation period as compared to isolated smooth muscle cells. The disproportionate reduction in uptake as compared to binding would suggest that this was not entirely a receptor-dependent process

Potential of essential fatty acid deficiency with extremely low fat diet in lipoprotein lipase deficiency during pregnancy: A case report

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Anderson Gregory J

2004-12-01

Full Text Available Abstract Background Pregnancy in patients with lipoprotein lipase deficiency is associated with high risk of maternal pancreatitis and fetal death. A very low fat diet ( Case presentation A 23 year-old gravida 1 woman with primary lipoprotein lipase deficiency was seen at 7 weeks of gestation in the Lipid Clinic for management of severe hypertriglyceridemia that had worsened with pregnancy. While on her habitual fat intake of 10% of total calories, her pregnancy resulted in an exacerbation of the hypertriglyceridemia, which prompted further restriction of fat intake to Conclusions An extremely low fat diet in combination with topical sunflower oil and gemfibrozil administration was safely implemented in pregnancy associated with the severe hypertriglyceridemia of lipoprotein lipase deficiency.

Analysis of glomerulosclerosis and atherosclerosis in lecithin cholesterol acyltransferase-deficient mice.

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Lambert, G; Sakai, N; Vaisman, B L; Neufeld, E B; Marteyn, B; Chan, C C; Paigen, B; Lupia, E; Thomas, A; Striker, L J; Blanchette-Mackie, J; Csako, G; Brady, J N; Costello, R; Striker, G E; Remaley, A T; Brewer, H B; Santamarina-Fojo, S

2001-05-04

To evaluate the biochemical and molecular mechanisms leading to glomerulosclerosis and the variable development of atherosclerosis in patients with familial lecithin cholesterol acyl transferase (LCAT) deficiency, we generated LCAT knockout (KO) mice and cross-bred them with apolipoprotein (apo) E KO, low density lipoprotein receptor (LDLr) KO, and cholesteryl ester transfer protein transgenic mice. LCAT-KO mice had normochromic normocytic anemia with increased reticulocyte and target cell counts as well as decreased red blood cell osmotic fragility. A subset of LCAT-KO mice accumulated lipoprotein X and developed proteinuria and glomerulosclerosis characterized by mesangial cell proliferation, sclerosis, lipid accumulation, and deposition of electron dense material throughout the glomeruli. LCAT deficiency reduced the plasma high density lipoprotein (HDL) cholesterol (-70 to -94%) and non-HDL cholesterol (-48 to -85%) levels in control, apoE-KO, LDLr-KO, and cholesteryl ester transfer protein-Tg mice. Transcriptome and Western blot analysis demonstrated up-regulation of hepatic LDLr and apoE expression in LCAT-KO mice. Despite decreased HDL, aortic atherosclerosis was significantly reduced (-35% to -99%) in all mouse models with LCAT deficiency. Our studies indicate (i) that the plasma levels of apoB containing lipoproteins rather than HDL may determine the atherogenic risk of patients with hypoalphalipoproteinemia due to LCAT deficiency and (ii) a potential etiological role for lipoproteins X in the development of glomerulosclerosis in LCAT deficiency. The availability of LCAT-KO mice characterized by lipid, hematologic, and renal abnormalities similar to familial LCAT deficiency patients will permit future evaluation of LCAT gene transfer as a possible treatment for glomerulosclerosis in LCAT-deficient states.

Bilirubin Prevents Atherosclerotic Lesion Formation in Low-Density Lipoprotein Receptor-Deficient Mice by Inhibiting Endothelial VCAM-1 and ICAM-1 Signaling.

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Vogel, Megan E; Idelman, Gila; Konaniah, Eddy S; Zucker, Stephen D

2017-04-01

Numerous epidemiological studies support an inverse association between serum bilirubin levels and the incidence of cardiovascular disease; however, the mechanism(s) by which bilirubin may protect against atherosclerosis is undefined. The goals of the present investigations were to assess the ability of bilirubin to prevent atherosclerotic plaque formation in low-density lipoprotein receptor-deficient ( Ldlr -/- ) mice and elucidate the molecular processes underlying this effect. Bilirubin, at physiological concentrations (≤20 μmol/L), dose-dependently inhibits THP-1 monocyte migration across tumor necrosis factor α-activated human umbilical vein endothelial cell monolayers without altering leukocyte binding or cytokine production. A potent antioxidant, bilirubin effectively blocks the generation of cellular reactive oxygen species induced by the cross-linking of endothelial vascular cell adhesion molecule 1 (VCAM-1) or intercellular adhesion molecule 1 (ICAM-1). These findings were validated by treating cells with blocking antibodies or with specific inhibitors of VCAM-1 and ICAM-1 signaling. When administered to Ldlr -/- mice on a Western diet, bilirubin (30 mg/kg intraperitoneally) prevents atherosclerotic plaque formation, but does not alter circulating cholesterol or chemokine levels. Aortic roots from bilirubin-treated animals exhibit reduced lipid and collagen deposition, decreased infiltration of monocytes and lymphocytes, fewer smooth muscle cells, and diminished levels of chlorotyrosine and nitrotyrosine, without changes in VCAM-1 or ICAM-1 expression. Bilirubin suppresses atherosclerotic plaque formation in Ldlr -/- mice by disrupting endothelial VCAM-1- and ICAM-1-mediated leukocyte migration through the scavenging of reactive oxygen species signaling intermediaries. These findings suggest a potential mechanism for the apparent cardioprotective effects of bilirubin. © 2017 The Authors. Published on behalf of the American Heart Association, Inc

An update on gene therapy for the treatment of lipoprotein lipase deficiency

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Libby AE

2014-05-01

Full Text Available Andrew E Libby, Hong Wang Division of Endocrinology, Metabolism, and Diabetes, School of Medicine, University of Colorado at Denver, Aurora, CO, USA Abstract: Lipoprotein lipase (LPL is responsible for clearance of triglyceride-rich lipoproteins from the blood. Deficiency or defects in this enzyme result in profound hypertriglyceridemia and susceptibility to chronic, life-threatening pancreatitis. Management of LPL deficiency has traditionally been restricted to palliative care and strategies to reduce the risk of pancreatitis, including severe dietary restrictions of fat. Recently, the European Commission approved the first gene therapy treatment in the West to treat this rare disease. Alipogene tiparvovec (Glybera® was granted marketing authorization in November 2012 to treat LPL deficiency in a subset of patients that are at increased risk for pancreatitis. Designed as a one-time treatment, the drug uses adeno-associated virus (AAV1 delivery of transgenic LPL to muscle in patients lacking functional enzyme. Although statistically significant reduction of serum triglycerides was initially observed in trial subjects, this effect was found to be transient, with triglyceride levels eventually rebounding to basal levels by 26 weeks in all participants. Nevertheless, despite the return of triglycerides to pretreatment levels, alipogene tiparvovec was found to have a long-term impact on postprandial chylomicron metabolism by lowering the fraction of triglyceride found in this subset of lipoproteins. Furthermore, the drug led to a clinically significant reduction in the incidence of pancreatitis in LPL-deficient patients. The regulatory approval of alipogene tiparvovec was a historic process and serves as an example of the challenges that future orphan drugs will face. Keywords: lipoprotein lipase deficiency, gene therapy, AAV, chylomicron, pancreatitis

Cellular uptake of lipoproteins and persistent organic compounds-An update and new data

International Nuclear Information System (INIS)

Hjelmborg, Philip Sebastian; Andreassen, Thomas Kjaergaard; Bonefeld-Jorgensen, Eva Cecilie

2008-01-01

There are a number of interactions related to the transport of lipophilic xenobiotic compounds in the blood stream of mammals. This paper will focus on the interactions between lipoproteins and persistent organic pollutants (POPs) and how these particles are taken up by cells. A number of POPs including the pesticide p,p'-dichlorodiphenyltrichloroethane (DDT), and especially its metabolite p,p'-dichlorodiphenyldichloroethene (DDE), interacts with nuclear hormone receptors causing these to malfunction, which in turn results in a range of deleterious health effects in humans. The aim of the present study was to determine the role of lipoprotein receptors in mouse embryonic fibroblast (MEF) cells in conjunction with uptake of DDT-lipoprotein complexes from supplemented media in vitro. Uptake of DDT by MEF cells was investigated using MEF1 cells carrying the receptors low-density lipoprotein receptor-related protein (LRP) and low-density lipoprotein receptor (LDLR) present and MEF4 cells with no LRP and LDLR expression. Cells were incubated together with the complex of low-density lipoproteins (LDL) and [ 14 C]DDT. The receptor function was further evaluated by adding the 40 kDa receptor-associated protein (RAP) which blocks receptor activity. The results showed that [ 14 C]DDT uptake was decreasing when the LDL concentration was increasing. There was no strong evidence for a receptor-mediated uptake of the [ 14 C]DDT-lipoprotein complex. To conclude, DDT travels in the blood stream and can cross cell membranes while being transported as a DDT-lipoprotein complex. The lipoproteins do not need receptors to cross cell membranes since passive diffusion constitutes a major passageway

The Human Pathogen Streptococcus pyogenes Releases Lipoproteins as Lipoprotein-rich Membrane Vesicles.

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Biagini, Massimiliano; Garibaldi, Manuela; Aprea, Susanna; Pezzicoli, Alfredo; Doro, Francesco; Becherelli, Marco; Taddei, Anna Rita; Tani, Chiara; Tavarini, Simona; Mora, Marirosa; Teti, Giuseppe; D'Oro, Ugo; Nuti, Sandra; Soriani, Marco; Margarit, Immaculada; Rappuoli, Rino; Grandi, Guido; Norais, Nathalie

2015-08-01

Bacterial lipoproteins are attractive vaccine candidates because they represent a major class of cell surface-exposed proteins in many bacteria and are considered as potential pathogen-associated molecular patterns sensed by Toll-like receptors with built-in adjuvanticity. Although Gram-negative lipoproteins have been extensively characterized, little is known about Gram-positive lipoproteins. We isolated from Streptococcus pyogenes a large amount of lipoproteins organized in vesicles. These vesicles were obtained by weakening the bacterial cell wall with a sublethal concentration of penicillin. Lipid and proteomic analysis of the vesicles revealed that they were enriched in phosphatidylglycerol and almost exclusively composed of lipoproteins. In association with lipoproteins, a few hypothetical proteins, penicillin-binding proteins, and several members of the ExPortal, a membrane microdomain responsible for the maturation of secreted proteins, were identified. The typical lipidic moiety was apparently not necessary for lipoprotein insertion in the vesicle bilayer because they were also recovered from the isogenic diacylglyceryl transferase deletion mutant. The vesicles were not able to activate specific Toll-like receptor 2, indicating that lipoproteins organized in these vesicular structures do not act as pathogen-associated molecular patterns. In light of these findings, we propose to name these new structures Lipoprotein-rich Membrane Vesicles. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Alterations in plasma lipoproteins and apolipoproteins before the age of 40 in heterozygotes for lipoprotein lipase deficiency

NARCIS (Netherlands)

Bijvoet, S.; Gagné, S. E.; Moorjani, S.; Gagné, C.; Henderson, H. E.; Fruchart, J. C.; Dallongeville, J.; Alaupovic, P.; Prins, M. [=Martin H.; Kastelein, J. J.; Hayden, M. R.

1996-01-01

We have assessed the expression of heterozygosity for lipoprotein lipase (LPL) deficiency by studying a single large French Canadian family comprising 92 persons including 21 carriers of the catalytically defective P207L mutation. Phenotypic changes distinguishing heterozygotes from controls were

Impaired LDL receptor-related protein 1 translocation correlates with improved dyslipidemia and atherosclerosis in apoE-deficient mice.

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Philip L S M Gordts

Full Text Available OBJECTIVE: Determination of the in vivo significance of LDL receptor-related protein 1 (LRP1 dysfunction on lipid metabolism and atherosclerosis development in absence of its main ligand apoE. METHODS AND RESULTS: LRP1 knock-in mice carrying an inactivating mutation in the NPxYxxL motif were crossed with apoE-deficient mice. In the absence of apoE, relative to LRP1 wild-type animals, LRP1 mutated mice showed an increased clearance of postprandial lipids despite a compromised LRP1 endocytosis rate and inefficient insulin-mediated translocation of the receptor to the plasma membrane, likely due to inefficient slow recycling of the mutated receptor. Postprandial lipoprotein improvement was explained by increased hepatic clearance of triglyceride-rich remnant lipoproteins and accompanied by a compensatory 1.6-fold upregulation of LDLR expression in hepatocytes. One year-old apoE-deficient mice having the dysfunctional LRP1 revealed a 3-fold decrease in spontaneous atherosclerosis development and a 2-fold reduction in LDL-cholesterol levels. CONCLUSION: These findings demonstrate that the NPxYxxL motif in LRP1 is important for insulin-mediated translocation and slow perinuclear endosomal recycling. These LRP1 impairments correlated with reduced atherogenesis and cholesterol levels in apoE-deficient mice, likely via compensatory LDLR upregulation.

Receptor-mediated endocytosis and intracellular trafficking of insulin and low-density lipoprotein by retinal vascular endothelial cells.

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Stitt, A W; Anderson, H R; Gardiner, T A; Bailie, J R; Archer, D B

1994-08-01

The authors investigated the receptor-mediated endocytosis (RME) and intracellular trafficking of insulin and low-density lipoprotein (LDL) in cultured retinal vascular endothelial cells (RVECs). Low-density lipoprotein and insulin were conjugated to 10 nm colloidal gold, and these ligands were added to cultured bovine RVECs for 20 minutes at 4 degrees C. The cultures were then warmed to 37 degrees C and fixed after incubation times between 30 seconds and 1 hour. Control cells were incubated with unconjugated gold colloid at times and concentrations similar to those of the ligands. Additional control cells were exposed to several concentrations of anti-insulin receptor antibody or a saturating solution of unconjugated insulin before incubation with gold insulin. Using transmission electron microscopy, insulin gold and LDL gold were both observed at various stages of RME. Insulin-gold particles were first seen to bind to the apical plasma membrane (PM) before clustering in clathrin-coated pits and internalization in coated vesicles. Gold was later visualized in uncoated cytoplasmic vesicles, corresponding to early endosomes and multivesicular bodies (MVBs) or late endosomes. In several instances, localized regions of the limiting membrane of the MVBs appeared coated, a feature of endosomal membranes not previously described. After RME at the apical PM and passage through the endosomal system, the greater part of both insulin- and LDL-gold conjugates was seen to accumulate in large lysosome-like compartments. However, a small but significant proportion of the internalized ligands was transcytosed and released as discrete membrane-associated quanta at the basal cell surface. The uptake of LDL gold was greatly increased in highly vacuolated, late-passage RVECs. In controls, anti-insulin receptor antibody and excess unconjugated insulin caused up to 89% inhibition in gold-insulin binding and internalization. These results illustrate the internalization and intracellular

Sex differences in obesity development in pair-fed neuronal lipoprotein lipase deficient mice

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Hong Wang

2016-10-01

Full Text Available Objective: Compared to men, postmenopausal women suffer from a disproportionate burden of many co-morbidities associated with obesity, e.g. cardiovascular disease, cancer, and dementia. The underlying mechanism for this sex difference is not well understood but is believed to relate to absence of the protective effect of estrogen through the action of estrogen receptor alpha (ERα in the central nervous system. With the recently developed neuron-specific lipoprotein lipase deficient mice (NEXLPL−/− (Wang et al., Cell Metabolism, 2011 [15], we set to explore the possible role of lipid sensing in sex differences in obesity development. Methods: Both male and female NEXLPL−/− mice and littermate WT controls were subjected to pair feeding (pf where daily food amount given was adjusted according to body weight to match the food intake of ad libitum (ad fed control WT mice. Food intake and body weight were measured daily, and pair feeding was maintained to 42 wk in male mice and to 38 wk in female mice. Various brain regions of the mice were harvested, and ERα gene expression was examined in both male and female NEXLPL−/− and WT control mice under both ad- and pf-fed conditions. Results: Although both male and female NEXLPL−/− mice developed obesity similarly on standard chow, male NEXLPL−/− mice still developed obesity under with pair feeding, but on a much delayed time course, while female NEXLPL−/− mice were protected from extra body weight and fat mass gain compared to pair-fed WT control mice. Pair feeding alone induced extra fat mass gain in both male and female WT mice, and this was mostly driven by the reduction in physical activity. LPL deficiency resulted in an increase in ERα mRNA in the hypothalamus of ad-fed female mice, while pair feeding alone also resulted in an increase of ERα in both female WT control and NEXLPL−/− mice. The effect on increasing ERα by pair feeding and LPL deficiency was additive in

Oxidized Lipoprotein as a Major Vessel Cell Proliferator in Oxidized Human Serum.

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Yoshiro Saito

Full Text Available Oxidative stress is correlated with the incidence of several diseases such as atherosclerosis and cancer, and oxidized biomolecules have been determined as biomarkers of oxidative stress; however, the detailed molecular relationship between generated oxidation products and the promotion of diseases has not been fully elucidated. In the present study, to clarify the role of serum oxidation products in vessel cell proliferation, which is related to the incidence of atherosclerosis and cancer, the major vessel cell proliferator in oxidized human serum was investigated. Oxidized human serum was prepared by free radical exposure, separated using gel chromatography, and then each fraction was added to several kinds of vessel cells including endothelial cells and smooth muscle cells. It was found that a high molecular weight fraction in oxidized human serum specifically induced vessel cell proliferation. Oxidized lipids were contained in this high molecular weight fraction, while cell proliferation activity was not observed in oxidized lipoprotein-deficient serum. Oxidized low-density lipoproteins induced vessel cell proliferation in a concentration-dependent manner. Taken together, these results indicate that oxidized lipoproteins containing lipid oxidation products function as a major vessel cell proliferator in oxidized human serum. These findings strongly indicate the relevance of determination of oxidized lipoproteins and lipid oxidation products in the diagnosis of vessel cell proliferation-related diseases such as atherosclerosis and cancer.

Electronegative Low-Density Lipoprotein Increases C-Reactive Protein Expression in Vascular Endothelial Cells through the LOX-1 Receptor

OpenAIRE

Chu, Chih-Sheng; Wang, Yu-Chen; Lu, Long-Sheng; Walton, Brian; Yilmaz, H. Ramazan; Huang, Roger Y.; Sawamura, Tatsuya; Dixon, Richard A. F.; Lai, Wen-Ter; Chen, Chu-Huang; Lu, Jonathan

2013-01-01

Objectives Increased plasma C-reactive protein (CRP) levels are associated with the occurrence and severity of acute coronary syndrome. We investigated whether CRP can be generated in vascular endothelial cells (ECs) after exposure to the most electronegative subfraction of low-density lipoprotein (LDL), L5, which is atherogenic to ECs. Because L5 and CRP are both ligands for the lectin-like oxidized LDL receptor-1 (LOX-1), we also examined the role of LOX-1. Methods and Results Plasma LDL sa...

Demonstration of functional low-density lipoprotein receptors by protein blotting in fibroblasts from a subject with homozygous receptor-negative familial hypercholesterolemia

International Nuclear Information System (INIS)

Semenkovich, C.F.; Ostlund, R.E. Jr.; Yang, J.; Reaban, M.E.

1985-01-01

We report the detection of low-density lipoprotein (LDL) receptors by the technique of receptor blotting in fibroblasts from a patient with homozygous familial hypercholesterolemia (FHC) previously classified as ''receptor negative.'' Solubilized receptors were electrophoresed, transferred to nitrocellulose paper, treated with LDL followed by radiolabeled antibody to LDL, and visualized by autoradiography. GM 2000 FHC fibroblasts revealed LDL receptors with an apparent molecular weight of approximately 140,000, the same as in normal cells. LDL receptor activity by blotting in GM 2000 cells was greatly diminished in comparison with normal cells, but was calcium dependent. Receptor activity was also detectable by conventional monolayer binding and degradation assays. Thus, GM 2000 cells have profoundly diminished LDL receptor activity, but retain the genetic capacity to make LDL receptor material of normal molecular weight that is capable of binding LDL. Previous studies have demonstrated the presence of trace amounts of immunoreactive LDL receptor protein in fibroblasts from some receptor-negative FHC homozygotes. These studies are extended by demonstrating the ability of this material to bind LDL

β-Amyloid promotes accumulation of lipid peroxides by inhibiting CD36-mediated clearance of oxidized lipoproteins

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Khan Tayeba

2004-11-01

Full Text Available Abstract Background Recent studies suggest that hypercholesterolemia, an established risk factor for atherosclerosis, is also a risk factor for Alzheimer's disease. The myeloid scavenger receptor CD36 binds oxidized lipoproteins that accumulate with hypercholesterolemia and mediates their clearance from the circulation and peripheral tissues. Recently, we demonstrated that CD36 also binds fibrillar β-amyloid and initiates a signaling cascade that regulates microglial recruitment and activation. As increased lipoprotein oxidation and accumulation of lipid peroxidation products have been reported in Alzheimer's disease, we investigated whether β-amyloid altered oxidized lipoprotein clearance via CD36. Methods The availability of mice genetically deficient in class A (SRAI & II and class B (CD36 scavenger receptors has facilitated studies to discriminate their individual actions. Using primary microglia and macrophages, we assessed the impact of Aβ on: (a cholesterol ester accumulation by GC-MS and neutral lipid staining, (b binding, uptake and degradation of 125I-labeled oxidized lipoproteins via CD36, SR-A and CD36/SR-A-independent pathways, (c expression of SR-A and CD36. In addition, using mice with targeted deletions in essential kinases in the CD36-signaling cascade, we investigated whether Aβ-CD36 signaling altered metabolism of oxidized lipoproteins. Results In primary microglia and macrophages, Aβ inhibited binding, uptake and degradation of oxidized low density lipoprotein (oxLDL in a dose-dependent manner. While untreated cells accumulated abundant cholesterol ester in the presence of oxLDL, cells treated with Aβ were devoid of cholesterol ester. Pretreatment of cells with Aβ did not affect subsequent degradation of oxidized lipoproteins, indicating that lysosomal accumulation of Aβ did not disrupt this degradation pathway. Using mice with targeted deletions of the scavenger receptors, we demonstrated that Aβ inhibited oxidized

Cellular uptake of lipoproteins and Persistent Organic Compounds - An update and new data

DEFF Research Database (Denmark)

Hjelmborg, Philip Sebastian; Andreassen, Thomas Kjærgaard; Bonefeld-Jørgensen, Eva Cecilie

2008-01-01

including the pesticide DDT (p,p'-dichlorodiphenyltrichloroethane), and especially its metabolite DDE (p,p'-dichlorodiphenyldichloroethene), interacts with nuclear hormone receptors causing these to malfunction, which in turn results in a range of deleterious health effects in humans. The aim of the present...... study was to determine the role of lipoprotein receptors in mouse embryonic fibroblast (MEF) cells in conjunction with uptake of DDT-lipoprotein complexes from supplemented media in vitro. Uptake of DDT by MEF cells was investigated using MEF1 cells carrying the receptors LRP (low-density lipoprotein...... receptor-related protein) and LDLR (low density lipoprotein receptor) present and MEF4 cells with no LRP and LDLR expression. Cells were incubated together with the complex of LDL and [14C]DDT. The receptor function was further evaluated by adding the 40 kDa receptor-associated protein (RAP) which blocks...

Experimental hypothyroidism modulates the expression of the low density lipoprotein receptor by the liver

International Nuclear Information System (INIS)

Scarabottolo, Lia; Trezzi, Ermanno; Roma, Paola; Catapano, A.L.

1986-01-01

The effect of exprimental hypothyroidism of the catabolism of plasma lipoproteins and on the expression of low density lipoprotein receptors by the liver was investigated in rats made hypothyroid by surgery. The animals developed mild hypercholesterolemia, mainly due to an increase of plasma low density lipoprotein, while other lipoprotein classes were only marginally affected. Kinetic studies using ( 125 I)LDL indicated that a decreased fractional catabolic rate of the lipoprotein was responsible for this finding in agreement with the in vitro observation of a reduced binding of lipoproteins to liver membranes from hyperthyroid rats and with the demonstrations, by ligand blotting analysis, of a decreasd expression of lipoprotein receptors in liver membranes. These data suggest that hypothyroidism affects lipoprotein distribution also by decreasing the catabolism of low density lipoproteins by the liver (author)

In vivo regulation of scavenger receptor BI and the selective uptake of high density lipoprotein cholesteryl esters in rat liver parenchymal and Kupffer cells

NARCIS (Netherlands)

Fluiter, K.; van der Westhuijzen, D. R.; van Berkel, T. J.

1998-01-01

High density lipoprotein cholesteryl esters (HDL-CE) are selectively taken up by liver parenchymal cells without parallel apolipoprotein uptake. This selective uptake route forms an important step in the so-called reverse cholesterol transport. Scavenger receptor BI (SR-BI) is the only known HDL

Uptake and metabolism of structured triglyceride by Caco-2 cells: reversal of essential fatty acid deficiency.

Science.gov (United States)

Spalinger, J H; Seidman, E G; Lepage, G; Ménard, D; Gavino, V; Levy, E

1998-10-01

Structured lipids have been proposed as efficient vehicles for the supplementation of essential fatty acids (EFA) to patients with malabsorption. We investigated how a novel structured triglyceride (STG), containing purely octanoic acid in the sn-1/sn-3 and [14C]linoleic acid in the sn-2 positions, was incorporated into different lipid classes in Caco-2 cells. We also evaluated the contribution of gastric lipase in the uptake and metabolism of [14C]linoleic acid from the STG. We furthermore determined the potential of the STG to correct EFA deficiency induced in Caco-2 cells. The absorption of STG by Caco-2 cells was significantly greater compared with that of triolein. The addition of human gastric lipase significantly enhanced cellular uptake of the labeled substrate, reflecting the stereoselectivity of gastric lipase to hydrolyze medium chain FA. Analysis of the intracellular lipids synthesized revealed a predominance of phospholipids-monoglycerides. Most of the radioactivity in the lipoproteins isolated from Caco-2 cells was recovered in TG-rich lipoproteins (45%) and to a lesser extent in the high-density lipoprotein (36%) and low-density lipoprotein (17%) fractions. The administration of STG to Caco-2 cells rendered EFA deficient produced a marked increase of the cellular level of linoleic and arachidonic acids. This resulted in a lower ratio of 20:3(n-9) to 20:4(n-6), reflecting the correction of EFA deficiency in Caco-2 cells. Our data demonstrate that STG, in the presence of gastric lipase, have beneficial effects on lipid incorporation, lipoprotein production, and EFA status, utilizing Caco-2 cells as a model of EFA deficiency.

Plant sterol or stanol esters retard lesion formation in LDL receptor-deficient mice independent of changes in serum plant sterols

NARCIS (Netherlands)

Plat, Jogchum; Beugels, Ilona; Gijbels, Marion J. J.; de Winther, Menno P. J.; Mensink, Ronald P.

2006-01-01

Statins do not always decrease coronary heart disease mortality, which was speculated based on increased serum plant sterols observed during statin treatment. To evaluate plant sterol atherogenicity, we fed low density lipoprotein-receptor deficient (LDLr(+/-)) mice for 35 weeks with Western diets

Deletion of the NR4A nuclear receptor NOR1 in hematopoietic stem cells reduces inflammation but not abdominal aortic aneurysm formation.

Science.gov (United States)

Qing, Hua; Jones, Karrie L; Heywood, Elizabeth B; Lu, Hong; Daugherty, Alan; Bruemmer, Dennis

2017-10-18

The NR4A3 orphan nuclear hormone receptor, NOR1, functions as a constitutively active transcription factor to regulate inflammation, proliferation, and cell survival during pathological vascular remodeling. Inflammatory processes represent key mechanisms leading to abdominal aortic aneurysm (AAA) formation. However, a role of NOR1 in AAA formation has not been investigated previously. Inflammatory gene expression was analyzed in bone marrow-derived macrophages isolated from NOR1-deficient mice. Low-density lipoprotein receptor-deficient (LDLr -/- ) mice were irradiated and reconstituted with hematopoietic stem cells obtained from NOR1-/- or wild-type littermate mice. Animals were infused with angiotensin II and fed a diet enriched in saturated fat to induce AAA formation. Quantification of AAA formation was performed by ultrasound and ex vivo measurements. Among 184 inflammatory genes that were analyzed, 36 genes were differentially regulated in LPS-treated NOR1-deficient macrophages. Albeit this difference in gene regulation, NOR1-deficiency in hematopoietic stem cells did not affect development of AAA formation in bone marrow-derived stem cell transplanted LDLr-deficient mice. NOR1 deletion induced differential inflammatory gene transcription in macrophages but did not influence AAA formation in mice.

Antagonism of Secreted PCSK9 Increases Low Density Lipoprotein Receptor Expression in HepG2 Cells

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McNutt, Markey C.; Kwon, Hyock Joo; Chen, Chiyuan; Chen, Justin R.; Horton, Jay D.; Lagace, Thomas A.; (USMC); (UTSMC)

2009-07-10

PCSK9 is a secreted protein that degrades low density lipoprotein receptors (LDLRs) in liver by binding to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. It is not known whether PCSK9 causes degradation of LDLRs within the secretory pathway or following secretion and reuptake via endocytosis. Here we show that a mutation in the LDLR EGF-A domain associated with familial hypercholesterolemia, H306Y, results in increased sensitivity to exogenous PCSK9-mediated cellular degradation because of enhanced PCSK9 binding affinity. The crystal structure of the PCSK9-EGF-A(H306Y) complex shows that Tyr-306 forms a hydrogen bond with Asp-374 in PCSK9 at neutral pH, which strengthens the interaction with PCSK9. To block secreted PCSK9 activity, LDLR (H306Y) subfragments were added to the medium of HepG2 cells stably overexpressing wild-type PCSK9 or gain-of-function PCSK9 mutants associated with hypercholesterolemia (D374Y or S127R). These subfragments blocked secreted PCSK9 binding to cell surface LDLRs and resulted in the recovery of LDLR levels to those of control cells. We conclude that PCSK9 acts primarily as a secreted factor to cause LDLR degradation. These studies support the concept that pharmacological inhibition of the PCSK9-LDLR interaction extracellularly will increase hepatic LDLR expression and lower plasma low density lipoprotein levels.

Deficiency of leptin receptor in myeloid cells disrupts hypothalamic metabolic circuits and causes body weight increase

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Yuanqing Gao

2018-01-01

Conclusions: Myeloid cell leptin receptor deficient mice partially replicate the db/db phenotype. Leptin signaling in hypothalamic microglia is important for microglial function and a correct formation of the hypothalamic neuronal circuit regulating metabolism.

Surface-Associated Lipoproteins Link Enterococcus faecalis Virulence to Colitogenic Activity in IL-10-Deficient Mice Independent of Their Expression Levels.

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Soeren Ocvirk

2015-06-01

Full Text Available The commensal Enterococcus faecalis is among the most common causes of nosocomial infections. Recent findings regarding increased abundance of enterococci in the intestinal microbiota of patients with inflammatory bowel diseases and induction of colitis in IL-10-deficient (IL-10-/- mice put a new perspective on the contribution of E. faecalis to chronic intestinal inflammation. Based on the expression of virulence-related genes in the inflammatory milieu of IL-10-/- mice using RNA-sequencing analysis, we characterized the colitogenic role of two bacterial structures that substantially impact on E. faecalis virulence by different mechanisms: the enterococcal polysaccharide antigen and cell surface-associated lipoproteins. Germ-free wild type and IL-10-/- mice were monoassociated with E. faecalis wild type OG1RF or the respective isogenic mutants for 16 weeks. Intestinal tissue and mesenteric lymph nodes (MLN were collected to characterize tissue pathology, loss of intestinal barrier function, bacterial adhesion to intestinal epithelium and immune cell activation. Bone marrow-derived dendritic cells (BMDC were stimulated with bacterial lysates and E. faecalis virulence was additionally investigated in three invertebrate models. Colitogenic activity of wild type E. faecalis (OG1RF score: 7.2±1.2 in monoassociated IL-10-/- mice was partially impaired in E. faecalis lacking enterococcal polysaccharide antigen (ΔepaB score: 4.7±2.3; p<0.05 and was almost completely abrogated in E. faecalis deficient for lipoproteins (Δlgt score: 2.3±2.3; p<0.0001. Consistently both E. faecalis mutants showed significantly impaired virulence in Galleria mellonella and Caenorhabditis elegans. Loss of E-cadherin in the epithelium was shown for all bacterial strains in inflamed IL-10-/- but not wild type mice. Inactivation of epaB in E. faecalis reduced microcolony and biofilm formation in vitro, altered bacterial adhesion to intestinal epithelium of germ

Release of endothelial cell lipoprotein lipase by plasma lipoproteins and free fatty acids

International Nuclear Information System (INIS)

Saxena, U.; Witte, L.D.; Goldberg, I.J.

1989-01-01

Lipoprotein lipase (LPL) bound to the lumenal surface of vascular endothelial cells is responsible for the hydrolysis of triglycerides in plasma lipoproteins. Studies were performed to investigate whether human plasma lipoproteins and/or free fatty acids would release LPL which was bound to endothelial cells. Purified bovine milk LPL was incubated with cultured porcine aortic endothelial cells resulting in the association of enzyme activity with the cells. When the cells were then incubated with media containing chylomicrons or very low density lipoproteins (VLDL), a concentration-dependent decrease in the cell-associated LPL enzymatic activity was observed. In contrast, incubation with media containing low density lipoproteins or high density lipoproteins produced a much smaller decrease in the cell-associated enzymatic activity. The addition of increasing molar ratios of oleic acid:bovine serum albumin to the media also reduced enzyme activity associated with the endothelial cells. To determine whether the decrease in LPL activity was due to release of the enzyme from the cells or inactivation of the enzyme, studies were performed utilizing radioiodinated bovine LPL. Radiolabeled LPL protein was released from endothelial cells by chylomicrons, VLDL, and by free fatty acids (i.e. oleic acid bound to bovine serum albumin). The release of radiolabeled LPL by VLDL correlated with the generation of free fatty acids from the hydrolysis of VLDL triglyceride by LPL bound to the cells. Inhibition of LPL enzymatic activity by use of a specific monoclonal antibody, reduced the extent of release of 125 I-LPL from the endothelial cells by the added VLDL. These results demonstrated that LPL enzymatic activity and protein were removed from endothelial cells by triglyceride-rich lipoproteins (chylomicrons and VLDL) and oleic acid

Potential cellular receptors involved in hepatitis C virus entry into cells

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Muellhaupt Beat

2005-04-01

Full Text Available Abstract Hepatitis C virus (HCV infects hepatocytes and leads to permanent, severe liver damage. Since the genomic sequence of HCV was determined, progress has been made towards understanding the functions of the HCV-encoded proteins and identifying the cellular receptor(s responsible for adsorption and penetration of the virus particle into the target cells. Several cellular receptors for HCV have been proposed, all of which are associated with lipid and lipoprotein metabolism. This article reviews the cellular receptors for HCV and suggests a general model for HCV entry into cells, in which lipoproteins play a crucial role.

The effect of insulin deficiency on the plasma clearance and exchange of high-density-lipoprotein phosphatidylcholine in rats.

Science.gov (United States)

Martins, I J; Redgrave, T G

1992-01-01

Triolein/cholesteryl oleate/cholesterol/phosphatidylcholine emulsions designed to model the lipid composition of chylomicrons were injected intravenously into control and streptozotocin-treated insulin-deficient rats. As previously described for lymph chylomicrons, the emulsion triolein was hydrolysed and phosphatidylcholine was transferred to the plasma high-density lipoproteins (HDL). This mechanism was used to introduce a phospholipid label into HDL in vivo. The subsequent clearance of phospholipid radioactivity from the plasma of insulin-deficient rats was significantly slower than in controls (P less than 0.025). Plasma clearance was similarly slower in insulin-deficient rats after injection of HDL that was previously labelled with radioactive phospholipids. After injection, the phospholipid label redistributed rapidly between the large-particle fraction of plasma lipoproteins (very-low- and low-density lipoproteins), and the lighter and heavier fractions of HDL. Compared with control rats, in insulin-deficient rats less of the phospholipid label was distributed to the lighter HDL fraction and more to the heavier HDL fraction, and this difference was not due to changes in activity of lecithin: cholesterol acyltransferase or in the apparent activity of phospholipid transfer protein. In insulin-deficient rats the changes in HDL phospholipid clearance and exchange appeared to be secondary to the associated hypertriglyceridaemia and the related changes in distribution of phospholipids between classes of plasma lipoproteins. PMID:1536661

Activation of lipoprotein lipase by lipoprotein fractions of human serum.

Science.gov (United States)

Bier, D M; Havel, R J

1970-11-01

Triglycerides in fat emulsions are hydrolyzed by lipoprotein lipase only when they are "activated" by serum lipoproteins. The contribution of different lipoprotein fractions to hydrolysis of triglycerides in soybean oil emulsion was assessed by determining the quantity of lipoprotein fraction required to give half-maximal hydrolysis. Most of the activator property of whole serum from normolipidemic, postabsorptive subjects was in high density lipoproteins. Low density lipoproteins and serum from which all lipoprotein classes were removed had little or no activity. Also, little activator was present in guinea pig serum or in very low density poor serum from an individual with lecithin:cholesterol acyltransferase deficiency, both of which are deficient in high density lipoproteins. Human very low density lipoproteins are potent activators and are much more active than predicted from their content of high density lipoprotein-protein. Per unit weight of protein, very low density lipoproteins had 13 times the activity of high density lipoproteins. These observations suggest that one or more of the major apoproteins of very low density lipoproteins, present as a minor constituent of high density lipoproteins, may be required for the activation process.

LDL Receptor-Related Protein-1 (LRP1 Regulates Cholesterol Accumulation in Macrophages.

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Anna P Lillis

Full Text Available Within the circulation, cholesterol is transported by lipoprotein particles and is taken up by cells when these particles associate with cellular receptors. In macrophages, excessive lipoprotein particle uptake leads to foam cell formation, which is an early event in the development of atherosclerosis. Currently, mechanisms responsible for foam cell formation are incompletely understood. To date, several macrophage receptors have been identified that contribute to the uptake of modified forms of lipoproteins leading to foam cell formation, but the in vivo contribution of the LDL receptor-related protein 1 (LRP1 to this process is not known [corrected]. To investigate the role of LRP1 in cholesterol accumulation in macrophages, we generated mice with a selective deletion of LRP1 in macrophages on an LDL receptor (LDLR-deficient background (macLRP1-/-. After feeding mice a high fat diet for 11 weeks, peritoneal macrophages isolated from Lrp+/+ mice contained significantly higher levels of total cholesterol than those from macLRP1-/- mice. Further analysis revealed that this was due to increased levels of cholesterol esters. Interestingly, macLRP1-/- mice displayed elevated plasma cholesterol and triglyceride levels resulting from accumulation of large, triglyceride-rich lipoprotein particles in the circulation. This increase did not result from an increase in hepatic VLDL biosynthesis, but rather results from a defect in catabolism of triglyceride-rich lipoprotein particles in macLRP1-/- mice. These studies reveal an important in vivo contribution of macrophage LRP1 to cholesterol homeostasis.

Intermittent hypoxia and hypercapnia induce pulmonary artery atherosclerosis and ventricular dysfunction in low density lipoprotein receptor deficient mice.

Science.gov (United States)

Douglas, Robert M; Bowden, Karen; Pattison, Jennifer; Peterson, Alexander B; Juliano, Joseph; Dalton, Nancy D; Gu, Yusu; Alvarez, Erika; Imamura, Toshihiro; Peterson, Kirk L; Witztum, Joseph L; Haddad, Gabriel G; Li, Andrew C

2013-12-01

Patients with obstructive sleep apnea, who experience episodic hypoxia and hypercapnia during sleep, often demonstrate increased inflammation, oxidative stress, and dyslipidemia. We hypothesized that sleep apnea patients would be predisposed to the development of atherosclerosis. To dissect the mechanisms involved, we developed an animal model in mice whereby we expose mice to intermittent hypoxia/hypercapnia (IHH) in normobaric environments. Two- to three-month-old low-density lipoprotein receptor deficient (Ldlr(-/-)) mice were fed a high-fat diet for 8 or 16 wk while being exposed to IHH for either 10 h/day or 24 h/day. Plasma lipid levels, pulmonary artery and aortic atherosclerotic lesions, and cardiac function were then assayed. Surprisingly, atherosclerosis in the aorta of IHH mice was similar compared with controls. However, in IHH mice, atherosclerosis was markedly increased in the trunk and proximal branches of the pulmonary artery of exposed mice; even though plasma cholesterol and triglycerides were lower than in controls. Hemodynamic analysis revealed that right ventricular maximum pressure and isovolumic relaxation constant were significantly increased in IHH exposed mice and left ventricular % fractional shortening was reduced. In conclusion, 1) Intermittent hypoxia/hypercapnia remarkably accelerated atherosclerotic lesions in the pulmonary artery of Ldlr(-/-) mice and 2) increased lesion formation in the pulmonary artery was associated with right and left ventricular dysfunction. These findings raise the possibility that patients with obstructive sleep apnea may be susceptible to atherosclerotic disease in the pulmonary vasculature, an observation that has not been previously recognized.

Increased cell motility and invasion upon knockdown of lipolysis stimulated lipoprotein receptor (LSR) in SW780 bladder cancer cells

DEFF Research Database (Denmark)

Herbsleb, Malene; Birkenkamp-Demtroder, Karin; Thykjaer, Thomas

2008-01-01

Mechanisms underlying the malignant development in bladder cancer are still not well understood. Lipolysis stimulated lipoprotein receptor (LSR) has previously been found to be upregulated by P53. Furthermore, we have previously found LSR to be differentially expressed in bladder cancer. Here we...... investigated the role of LSR in bladder cancer....

The multiligand α₂-macroglobulin receptor/low density lipoprotein receptor-related protein

DEFF Research Database (Denmark)

Gliemann, Jørgen; Nykjær, Anders; Petersen, Claus Munck

1994-01-01

The fusion of separate lines of research has greatly helped in elucidating the function of the giant members of the low density lipoprotein (LDL) receptor (LDLR) supergene family. The cDNA encoding a large protein structurally closely related to LDLR, and hence named LDLR-related protein (LRP......), was cloned by Herz et al. in 1988.'Evidence was provided demonstrating that LRP can function as a receptor for chylomicron remnants@-migrating very low density lipoproteins (P-VLDL) rich in apolipoprotein E (apoE)?' The a2-macroglobulin (a2M) receptor (a2MR) was purified from rat livep and human p l a~e n t...... from the observation that affinity-purified a2MR/LRP contains a 40-kDa5.8 or 39-kDa6.' protein, designated a2MRAP, in addition to the a2MFULRP a- and P-chains. cDNA cloning" disclosed the 323-residue protein as both the human homologue of mouse heparin binding protein 44 (see reference 11) and...

Site-specific O-glycosylation of members of the low-density lipoprotein receptor superfamily enhances ligand interactions.

Science.gov (United States)

Wang, Shengjun; Mao, Yang; Narimatsu, Yoshiki; Ye, Zilu; Tian, Weihua; Goth, Christoffer K; Lira-Navarrete, Erandi; Pedersen, Nis B; Benito-Vicente, Asier; Martin, Cesar; Uribe, Kepa B; Hurtado-Guerrero, Ramon; Christoffersen, Christina; Seidah, Nabil G; Nielsen, Rikke; Christensen, Erik I; Hansen, Lars; Bennett, Eric P; Vakhrushev, Sergey Y; Schjoldager, Katrine T; Clausen, Henrik

2018-05-11

The low-density lipoprotein receptor (LDLR) and related receptors are important for the transport of diverse biomolecules across cell membranes and barriers. Their functions are especially relevant for cholesterol homeostasis and diseases, including neurodegenerative and kidney disorders. Members of the LDLR-related protein family share LDLR class A (LA) repeats providing binding properties for lipoproteins and other biomolecules. We previously demonstrated that short linker regions between these LA repeats contain conserved O -glycan sites. Moreover, we found that O -glycan modifications at these sites are selectively controlled by the GalNAc-transferase isoform, GalNAc-T11. However, the effects of GalNAc-T11-mediated O -glycosylation on LDLR and related receptor localization and function are unknown. Here, we characterized O -glycosylation of LDLR-related proteins and identified conserved O -glycosylation sites in the LA linker regions of VLDLR, LRP1, and LRP2 (Megalin) from both cell lines and rat organs. Using a panel of gene-edited isogenic cell line models, we demonstrate that GalNAc-T11-mediated LDLR and VLDLR O -glycosylation is not required for transport and cell-surface expression and stability of these receptors but markedly enhances LDL and VLDL binding and uptake. Direct ELISA-based binding assays with truncated LDLR constructs revealed that O -glycosylation increased affinity for LDL by ∼5-fold. The molecular basis for this observation is currently unknown, but these findings open up new avenues for exploring the roles of LDLR-related proteins in disease. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

An extrahepatic receptor-associated protein-sensitive mechanism is involved in the metabolism of triglyceride-rich lipoproteins

NARCIS (Netherlands)

Vlijmen, B.J.M. van; Rohlmann, A.; Page, S.T.; Bensadoun, A.; Bos, I.S.T.; Berkel, T.J.C. van; Havekes, L.M.; Herz, J.

1999-01-01

We have used adenovirus-mediated gene transfer in mice to investigate low density lipoprotein receptor (LDLR) and LDLR-related protein (LRP)- independent mechanisms that control the metabolism of chylomicron and very low density lipoprotein (VLDL) remnants in vivo. Overexpression of receptor-

Telomerase deficiency in bone marrow-derived cells attenuates angiotensin II-induced abdominal aortic aneurysm formation.

Science.gov (United States)

Findeisen, Hannes M; Gizard, Florence; Zhao, Yue; Cohn, Dianne; Heywood, Elizabeth B; Jones, Karrie L; Lovett, David H; Howatt, Deborah A; Daugherty, Alan; Bruemmer, Dennis

2011-02-01

Abdominal aortic aneurysms (AAA) are an age-related vascular disease and an important cause of morbidity and mortality. In this study, we sought to determine whether the catalytic component of telomerase, telomerase reverse transcriptase (TERT), modulates angiotensin (Ang) II-induced AAA formation. Low-density lipoprotein receptor-deficient (LDLr-/-) mice were lethally irradiated and reconstituted with bone marrow-derived cells from TERT-deficient (TERT-/-) mice or littermate wild-type mice. Mice were placed on a diet enriched in cholesterol, and AAA formation was quantified after 4 weeks of Ang II infusion. Repopulation of LDLr-/- mice with TERT-/- bone marrow-derived cells attenuated Ang II-induced AAA formation. TERT-deficient recipient mice revealed modest telomere attrition in circulating leukocytes at the study end point without any overt effect of the donor genotype on white blood cell counts. In mice repopulated with TERT-/- bone marrow, aortic matrix metalloproteinase-2 (MMP-2) activity was reduced, and TERT-/- macrophages exhibited decreased expression and activity of MMP-2 in response to stimulation with Ang II. Finally, we demonstrated in transient transfection studies that TERT overexpression activates the MMP-2 promoter in macrophages. TERT deficiency in bone marrow-derived macrophages attenuates Ang II-induced AAA formation in LDLr-/- mice and decreases MMP-2 expression. These results point to a previously unrecognized role of TERT in the pathogenesis of AAA.

Apolipoprotein A-V Deficiency Results in MarkedHypertriglyceridemia Attributable to Decreased Lipolysis ofTriglyceride-Rich Lipoproteins and Removal of Their Remnants

Energy Technology Data Exchange (ETDEWEB)

Grosskopf, Itamar; Baroukh, Nadine; Lee, Sung-Joon; Kamari,Yehuda; Harats, Dror; Rubin, Edward M.; Pennacchio, Len A.; Cooper, AllenD.

2005-09-01

Objective--ApoAV, a newly discovered apoprotein, affectsplasma triglyceride level. To determine how this occurs, we studiedtriglyceride-rich lipoprotein (TRL) metabolism in mice deficient inapoAV. Methods and Results No significant difference in triglycerideproduction rate was found between apoa5_/_ mice and controls. Thepresence or absence of apoAV affected TRL catabolism. After the injectionof 14C-palmitate and 3H-cholesterol labeled chylomicrons and 125I-labeledchylomicron remnants, the disappearance of 14C, 3H, and 125I wassignificantly slower in apoa5_/_ mice relative to controls. This wasbecause of diminished lipolysis of TRL and the reduced rate of uptake oftheir remnants in apoa5_/_ mice. Observed elevated cholesterol level wascaused by increased high-density lipoprotein (HDL) cholesterol inapoa5_/_ mice. VLDL from apoa5_/_ mice were poor substrate forlipoprotein lipase, and did not bind to the low-density lipoprotein (LDL)receptor as well as normal very-low-density lipoprotein (VLDL). LDLreceptor levels were slightly elevated in apoa5_/_ mice consistent withlower remnant uptake rates. These alterations may be the result of thelower apoE-to-apoC ratio found in VLDL isolated from apoa5_/_mice.Conclusions These results support the hypothesis that the absence ofapoAV slows lipolysis of TRL and the removal of their remnants byregulating their apoproteins content after secretion.

Involvement of microtubules in lipoprotein degradation and utilization for steroidogenesis in cultured rat luteal cells

International Nuclear Information System (INIS)

Rajan, V.P.; Menon, K.M.

1985-01-01

Cells isolated from superovulated rat ovaries metabolize low density lipoprotein (LDL) and high density lipoprotein (HDL) of human or rat origin and use the lipoprotein-derived cholesterol as a precursor for progesterone production. Under in vitro conditions, both lipoproteins are internalized and degraded in the lysosomes, although degradation of HDL is of lower magnitude than that of LDL. In this report we have examined the role of cellular microtubules in the internalization and degradation of human LDL and HDL in cultured rat luteal cells. The microtubule depolymerizing agents colchicine, podophyllotoxin, vinblastine, and nocodazole as well as taxol, deuterium oxide, and dimethyl sulfoxide, which are known to rapidly polymerize cellular tubulin into microtubules, were used to block the function of microtubules. When these antimicrotubule agents were included in the incubations, degradation of the apolipoproteins of [ 125 I]iodo-LDL and [ 125 I]iodo-HDL by the luteal cells was inhibited by 50-85% compared to untreated control values. Maximum inhibitory effects were observed when the cells were preincubated with the inhibitor for at least 4 h at 37 C before treatment with the labeled lipoprotein. Lipoprotein-stimulated progesterone production by luteal cells was also inhibited by 50% or more in the presence of antimicrotubule agents. However, basal and hCG-stimulated progesterone production were unaffected by these inhibitors. The binding of [ 125 I]iodo-LDL and [ 125 I]iodo-HDL to luteal cell plasma membrane receptors was not affected by the microtubule inhibitors. Although binding was unaffected and degradation was impaired in the presence of the inhibitors, there was no detectable accumulation of undegraded lipoprotein within the cells during the 24 h of study

Intermittent hypoxia and hypercapnia induce pulmonary artery atherosclerosis and ventricular dysfunction in low density lipoprotein receptor deficient mice

Science.gov (United States)

Bowden, Karen; Pattison, Jennifer; Peterson, Alexander B.; Juliano, Joseph; Dalton, Nancy D.; Gu, Yusu; Alvarez, Erika; Imamura, Toshihiro; Peterson, Kirk L.; Witztum, Joseph L.; Haddad, Gabriel G.; Li, Andrew C.

2013-01-01

Patients with obstructive sleep apnea, who experience episodic hypoxia and hypercapnia during sleep, often demonstrate increased inflammation, oxidative stress, and dyslipidemia. We hypothesized that sleep apnea patients would be predisposed to the development of atherosclerosis. To dissect the mechanisms involved, we developed an animal model in mice whereby we expose mice to intermittent hypoxia/hypercapnia (IHH) in normobaric environments. Two- to three-month-old low-density lipoprotein receptor deficient (Ldlr−/−) mice were fed a high-fat diet for 8 or 16 wk while being exposed to IHH for either 10 h/day or 24 h/day. Plasma lipid levels, pulmonary artery and aortic atherosclerotic lesions, and cardiac function were then assayed. Surprisingly, atherosclerosis in the aorta of IHH mice was similar compared with controls. However, in IHH mice, atherosclerosis was markedly increased in the trunk and proximal branches of the pulmonary artery of exposed mice; even though plasma cholesterol and triglycerides were lower than in controls. Hemodynamic analysis revealed that right ventricular maximum pressure and isovolumic relaxation constant were significantly increased in IHH exposed mice and left ventricular % fractional shortening was reduced. In conclusion, 1) Intermittent hypoxia/hypercapnia remarkably accelerated atherosclerotic lesions in the pulmonary artery of Ldlr−/− mice and 2) increased lesion formation in the pulmonary artery was associated with right and left ventricular dysfunction. These findings raise the possibility that patients with obstructive sleep apnea may be susceptible to atherosclerotic disease in the pulmonary vasculature, an observation that has not been previously recognized. PMID:23990245

Sort1, encoded by the cardiovascular risk locus 1p13.3, is a regulator of hepatic lipoprotein export

DEFF Research Database (Denmark)

Kjølby, Mads Fuglsang; Andersen, Olav Michael; Breiderhoff, Tilman

2010-01-01

of lipoproteins from the liver and ameliorates hypercholesterolemia and atherosclerotic lesion formation in LDL receptor-deficient animals. In contrast, sortilin overexpression stimulates hepatic release of lipoproteins and increases plasma LDL levels. Our data have uncovered a regulatory pathway in hepatic...... lipoprotein export and suggest a molecular explanation for the cardiovascular risk being associated with 1p13.3. Udgivelsesdato: september 8...

The Natural Compound Dansameum Reduces foam Cell Formation by Downregulating CD36 and Peroxisome Proliferator-activated Receptor-gamma; Expression.

Science.gov (United States)

Park, Kang-Seo; Ahn, Sang Hyun; Lee, Kang Pa; Park, Sun-Young; Cheon, Jin Hong; Choi, Jun-Yong; Kim, Kibong

2018-01-01

Atherosclerosis-induced vascular disorders are major causes of death in most western countries. During the development of atherosclerotic lesions, foam cell formation is essential and formed through the expression of CD36 and the peroxisome proliferator-activated receptor gamma (PPAR-γ). To investigate whether dansameum extract (DSE) could show anti-atherosclerotic effect through down-regulating cellular redox state including CD36 and PARP-γ expression in oxidative low-density lipoprotein (oxLDL)-treated RAW264.7 cells and on differentiated foam cells in ApoE Knockout (ApoE-/-) mice. The Korean polyherbal medicine DSE was prepared from three plants in the following proportions: 40 g of Salvia miltiorrhiza root, 4 g of Amomumxanthioides fruit, and 4 g of Santalum album lignum. The immunohistochemistry and reverse transcription-polymerase chain reaction was used for analysis of protein and mRNA involved in foam cell formation. We first showed that effects of DSE on foam cell formation in both oxLDL-induced RAW264.7 cells and in blood vessels from apolipoprotein E deficientApoE-/- mice with high fat diet-fed. DSE treatment significantly reduced the expression of CD36 and PPAR-γ in oxLDL-stimulated RAW264.7 cells and ApoE-/-mice, in the latter case by regulating heme oxygenase-1. Furthermore, DSE treatment also reduced cellular lipid content in vitro and in vivo experiments. Our data suggest that DSE may have anti-atherosclerotic properties through regulating foam cell formation. Dansameum extract (DSE) Regulates the expression of CD36 and peroxisome proliferator-activated receptor gamma in oxidative low-density lipoprotein-stimulated RAW264.7 Cells and ApoE Knockout (ApoE Knockout [ApoE-/-]) miceDSE Regulates Cholesterol Levels in the Serum of ApoE-deficient (ApoE-/-) miceDSE Reduced the Formation of Foam Cells by Regulating heme oxygenase-1 in ApoE-/- mice with high fat diet-fed. Abbreviations used: DSE: Dansameum extract, PPAR-γ: Peroxisome proliferator

Low density lipoprotein induces upregulation of vasoconstrictive endothelin type B receptor expression

DEFF Research Database (Denmark)

Xu, Cang-Bao; Zheng, Jian-Pu; Zhang, Wei

2014-01-01

Vasoconstrictive endothelin type B (ET(B)) receptors promote vasospasm and ischemic cerebro- and cardiovascular diseases. The present study was designed to examine if low density lipoprotein (LDL) induces upregulation of vasoconstrictive ET(B) receptor expression and if extracellular signal...

Effect of neoadjuvant chemotherapy on low-density lipoprotein (LDL) receptor and LDL receptor-related protein 1 (LRP-1) receptor in locally advanced breast cancer

International Nuclear Information System (INIS)

Pires, L.A.; Hegg, R.; Freitas, F.R.; Tavares, E.R.; Almeida, C.P.; Baracat, E.C.; Maranhão, R.C.

2012-01-01

Low-density lipoprotein (LDL) receptors are overexpressed in most neoplastic cell lines and provide a mechanism for the internalization and concentration of drug-laden nanoemulsions that bind to these receptors. The aim of the present study was to determine whether the administration of standard chemotherapeutic schemes can alter the expression of LDL and LDL receptor-related protein 1 (LRP-1) receptors in breast carcinoma. Fragments of tumoral and normal breast tissue from 16 consecutive volunteer women with breast cancer in stage II or III were obtained from biopsies before the beginning of neoadjuvant chemotherapy and after chemotherapy, from fragments excised during mastectomy. Tissues were analyzed by immunohistochemistry for both receptors. Because complete response to treatment was achieved in 4 patients, only the tumors from 12 were analyzed. Before chemotherapy, there was overexpression of LDL receptor in the tumoral tissue compared to normal breast tissue in 8 of these patients. LRP-1 receptor overexpression was observed in tumors of 4 patients. After chemotherapy, expression of both receptors decreased in the tumors of 6 patients, increased in 4 and was unchanged in 2. Nonetheless, even when chemotherapy reduced receptors expression, the expression was still above normal. The fact that chemotherapy does not impair LDL receptors expression supports the use of drug carrier systems that target neoplastic cells by the LDL receptor endocytic pathway in patients on conventional chemotherapy

Tissue-type plasminogen activator-binding RNA aptamers inhibiting low-density lipoprotein receptor family-mediated internalisation.

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Bjerregaard, Nils; Bøtkjær, Kenneth A; Helsen, Nicky; Andreasen, Peter A; Dupont, Daniel M

2015-07-01

Recombinant tissue-type plasminogen activator (tPA, trade name Alteplase), currently the only drug approved by the US Food and Drug Administration and the European Medicines Agency for the treatment of cerebral ischaemic stroke, has been implicated in a number of adverse effects reportedly mediated by interactions with the low-density lipoprotein (LDL) family receptors, including neuronal cell death and an increased risk of cerebral haemorrhage. The tissue-type plasminogen activator is the principal initiator of thrombolysis in human physiology, an effect that is mediated directly via localised activation of the plasmin zymogen plasminogen at the surface of fibrin clots in the vascular lumen. Here, we sought to identify a ligand to tPA capable of inhibiting the relevant LDL family receptors without interfering with the fibrinolytic activity of tPA. Systematic evolution of ligands by exponential enrichment (SELEX) was employed to isolate tPA-binding RNA aptamers, which were characterised in biochemical assays of tPA association to low density lipoprotein receptor-related protein-1 (LRP-1, an LDL receptor family member); tPA-mediated in vitro and ex vivo clot lysis; and tPA-mediated plasminogen activation in the absence and presence of a stimulating soluble fibrin fragment. Two aptamers, K18 and K32, had minimal effects on clot lysis, but were able to efficiently inhibit tPA-LRP-1 association and LDL receptor family-mediated endocytosis in human vascular endothelial cells and astrocytes. These observations suggest that coadministration alongside tPA may be a viable strategy to improve the safety of thrombolytic treatment of cerebral ischaemic stroke by restricting tPA activity to the vascular lumen.

Increased cell motility and invasion upon knockdown of lipolysis stimulated lipoprotein receptor (LSR in SW780 bladder cancer cells

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Ørntoft Torben F

2008-07-01

Full Text Available Abstract Background Mechanisms underlying the malignant development in bladder cancer are still not well understood. Lipolysis stimulated lipoprotein receptor (LSR has previously been found to be upregulated by P53. Furthermore, we have previously found LSR to be differentially expressed in bladder cancer. Here we investigated the role of LSR in bladder cancer. Methods A time course siRNA knock down experiment was performed to investigate the functional role of LSR in SW780 bladder cancer cells. Since LSR was previously shown to be regulated by P53, siRNA against TP53 was included in the experimental setup. We used Affymetrix GeneChips for measuring gene expression changes and we used Ingenuity Pathway Analysis to investigate the relationship among differentially expressed genes upon siRNA knockdown. Results By Ingenuity Pathway analysis of the microarray data from the different timepoints we identified six gene networks containing genes mainly related to the functional categories "cancer", "cell death", and "cellular movement". We determined that genes annotated to the functional category "cellular movement" including "invasion" and "cell motility" were highly significantly overrepresented. A matrigel assay showed that 24 h after transfection the invasion capacity was significantly increased 3-fold (p Conclusion We conclude that LSR may impair bladder cancer cells from gaining invasive properties.

TLR2-Modulating Lipoproteins of the Mycobacterium tuberculosis Complex Enhance the HIV Infectivity of CD4+ T Cells.

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Ciaran Skerry

Full Text Available Co-infection with Mycobacterium tuberculosis accelerates progression from HIV to AIDS. Our previous studies showed that M. tuberculosis complex, unlike M. smegmatis, enhances TLR2-dependent susceptibility of CD4+ T cells to HIV. The M. tuberculosis complex produces multiple TLR2-stimulating lipoproteins, which are absent in M. smegmatis. M. tuberculosis production of mature lipoproteins and TLR2 stimulation is dependent on cleavage by lipoprotein signal peptidase A (LspA. In order to determine the role of potential TLR2-stimulating lipoproteins on mycobacterial-mediated HIV infectivity of CD4+ T cells, we generated M. smegmatis recombinant strains overexpressing genes encoding various M. bovis BCG lipoproteins, as well as a Mycobacterium bovis BCG strain deficient in LspA (ΔlspA. Exposure of human peripheral blood mononuclear cells (PBMC to M. smegmatis strains overexpressing the BCG lipoproteins, LprF (p<0.01, LprH (p<0.05, LprI (p<0.05, LprP (p<0.001, LprQ (p<0.005, MPT83 (p<0.005, or PhoS1 (p<0.05, resulted in increased HIV infectivity of CD4+ T cells isolated from these PBMC. Conversely, infection of PBMC with ΔlspA reduced HIV infectivity of CD4+ T cells by 40% relative to BCG-infected cells (p<0.05. These results may have important implications for TB vaccination programs in areas with high mother-to-child HIV transmission.

TLR2-Modulating Lipoproteins of the Mycobacterium tuberculosis Complex Enhance the HIV Infectivity of CD4+ T Cells.

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Skerry, Ciaran; Klinkenberg, Lee G; Page, Kathleen R; Karakousis, Petros C

2016-01-01

Co-infection with Mycobacterium tuberculosis accelerates progression from HIV to AIDS. Our previous studies showed that M. tuberculosis complex, unlike M. smegmatis, enhances TLR2-dependent susceptibility of CD4+ T cells to HIV. The M. tuberculosis complex produces multiple TLR2-stimulating lipoproteins, which are absent in M. smegmatis. M. tuberculosis production of mature lipoproteins and TLR2 stimulation is dependent on cleavage by lipoprotein signal peptidase A (LspA). In order to determine the role of potential TLR2-stimulating lipoproteins on mycobacterial-mediated HIV infectivity of CD4+ T cells, we generated M. smegmatis recombinant strains overexpressing genes encoding various M. bovis BCG lipoproteins, as well as a Mycobacterium bovis BCG strain deficient in LspA (ΔlspA). Exposure of human peripheral blood mononuclear cells (PBMC) to M. smegmatis strains overexpressing the BCG lipoproteins, LprF (p<0.01), LprH (p<0.05), LprI (p<0.05), LprP (p<0.001), LprQ (p<0.005), MPT83 (p<0.005), or PhoS1 (p<0.05), resulted in increased HIV infectivity of CD4+ T cells isolated from these PBMC. Conversely, infection of PBMC with ΔlspA reduced HIV infectivity of CD4+ T cells by 40% relative to BCG-infected cells (p<0.05). These results may have important implications for TB vaccination programs in areas with high mother-to-child HIV transmission.

Deficiency of lipoprotein lipase in neurons modifies the regulation of energy balance and leads to obesity

OpenAIRE

Wang, H; Astarita, G; Taussig, MD; Bharadwaj, KG; Dipatrizio, NV; Nave, KA; Piomelli, D; Goldberg, IJ; Eckel, RH

2011-01-01

Free fatty acids (FFAs) suppress appetite when injected into the hypothalamus. To examine whether lipoprotein lipase (LPL), a serine hydrolase that releases FFAs from circulating triglyceride (TG)-rich lipoproteins, might contribute to FFA-mediated signaling in the brain, we created neuron-specific LPL-deficient mice. Homozygous mutant (NEXLPL-/-) mice were hyperphagic and became obese by 16 weeks of age. These traits were accompanied by elevations in the hypothalamic orexigenic neuropeptides...

Lipoprotein receptor LRP1 regulates leptin signaling and energy homeostasis in the adult central nervous system.

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Liu, Qiang; Zhang, Juan; Zerbinatti, Celina; Zhan, Yan; Kolber, Benedict J; Herz, Joachim; Muglia, Louis J; Bu, Guojun

2011-01-11

Obesity is a growing epidemic characterized by excess fat storage in adipocytes. Although lipoprotein receptors play important roles in lipid uptake, their role in controlling food intake and obesity is not known. Here we show that the lipoprotein receptor LRP1 regulates leptin signaling and energy homeostasis. Conditional deletion of the Lrp1 gene in the brain resulted in an obese phenotype characterized by increased food intake, decreased energy consumption, and decreased leptin signaling. LRP1 directly binds to leptin and the leptin receptor complex and is required for leptin receptor phosphorylation and Stat3 activation. We further showed that deletion of the Lrp1 gene specifically in the hypothalamus by Cre lentivirus injection is sufficient to trigger accelerated weight gain. Together, our results demonstrate that the lipoprotein receptor LRP1, which is critical in lipid metabolism, also regulates food intake and energy homeostasis in the adult central nervous system.

Targeting low-density lipoprotein receptors with protein-only nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhikun [Universitat Autònoma de Barcelona, Institut de Biotecnologia i de Biomedicina (Spain); Céspedes, María Virtudes [CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN) (Spain); Unzueta, Ugutz [Universitat Autònoma de Barcelona, Institut de Biotecnologia i de Biomedicina (Spain); Álamo, Patricia [CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN) (Spain); Pesarrodona, Mireia [Universitat Autònoma de Barcelona, Institut de Biotecnologia i de Biomedicina (Spain); Mangues, Ramón [CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN) (Spain); Vázquez, Esther; Villaverde, Antonio, E-mail: antoni.villaverde@uab.cat; Ferrer-Miralles, Neus, E-mail: neus.ferrer@uab.cat [Universitat Autònoma de Barcelona, Institut de Biotecnologia i de Biomedicina (Spain)

2015-03-15

Low-density lipoprotein receptors (LDLR) are appealing cell surface targets in drug delivery, as they are expressed in the blood–brain barrier (BBB) endothelium and are able to mediate transcytosis of functionalized drugs for molecular therapies of the central nervous system (CNS). On the other hand, brain-targeted drug delivery is currently limited, among others, by the poor availability of biocompatible vehicles, as most of the nanoparticles under development as drug carriers pose severe toxicity issues. In this context, protein nanoparticles offer functional versatility, easy and cost-effective bioproduction, and full biocompatibility. In this study, we have designed and characterized several chimerical proteins containing different LDLR ligands, regarding their ability to bind and internalize target cells and to self-organize as viral mimetic nanoparticles of about 18 nm in diameter. While the self-assembling of LDLR-binding proteins as nanoparticles positively influences cell penetration in vitro, the nanoparticulate architecture might be not favoring BBB crossing in vivo. These findings are discussed in the context of the use of nanostructured materials as vehicles for the systemic treatment of CNS diseases.

Targeting low-density lipoprotein receptors with protein-only nanoparticles

International Nuclear Information System (INIS)

Xu, Zhikun; Céspedes, María Virtudes; Unzueta, Ugutz; Álamo, Patricia; Pesarrodona, Mireia; Mangues, Ramón; Vázquez, Esther; Villaverde, Antonio; Ferrer-Miralles, Neus

2015-01-01

Low-density lipoprotein receptors (LDLR) are appealing cell surface targets in drug delivery, as they are expressed in the blood–brain barrier (BBB) endothelium and are able to mediate transcytosis of functionalized drugs for molecular therapies of the central nervous system (CNS). On the other hand, brain-targeted drug delivery is currently limited, among others, by the poor availability of biocompatible vehicles, as most of the nanoparticles under development as drug carriers pose severe toxicity issues. In this context, protein nanoparticles offer functional versatility, easy and cost-effective bioproduction, and full biocompatibility. In this study, we have designed and characterized several chimerical proteins containing different LDLR ligands, regarding their ability to bind and internalize target cells and to self-organize as viral mimetic nanoparticles of about 18 nm in diameter. While the self-assembling of LDLR-binding proteins as nanoparticles positively influences cell penetration in vitro, the nanoparticulate architecture might be not favoring BBB crossing in vivo. These findings are discussed in the context of the use of nanostructured materials as vehicles for the systemic treatment of CNS diseases

Onset of lipoprotein-supported steroidogenesis in differentiating granulosa cells of rats: cellular events involved in mediating FSH-enhanced uptake of low-density lipoproteins

International Nuclear Information System (INIS)

Foster, J.D.

1987-01-01

Luteal cells use lipoproteins as the main source of cholesterol in steroidogenesis. However, little is known about the mechanisms underlying hormonal control of lipoprotein uptake. Thus, the authors tested the hypothesis that FSH and androgens regulate low density lipoprotein (LDL)-supported steroidogenesis in maturing granulosa cells by affecting receptor-mediated endocytosis of LDL at a cellular level. For this, immature ovarian granulosa cells were cultured with or without hormones, compactin (de novo synthesis inhibitor), or unlabeled or labeled ( 125 I or gold particles) LDL. Nonhormone-treated cultures produced little progestin; FSH and FSH/androstenedione stimulated steroid secretion. Progestin production by hormone-, but not nonhormone-, treated cultures was decreased by compactin, suggesting that de novo synthesis provided sterol for steroidogenesis. EM quantitation of cells exposed to gold-LDL at 37 0 C revealed that, compared to nonhormone-treated cells, FSH-treated cells (1) bound and internalized more gold-LDL, (2) had a smaller percentage of gold-LDL at their surfaces, (3) displayed a faster apparent rate of LDL internalization and delivery to lysosomes, and (4) contained more gold-labeled lysosomes. Data from biochemical studies in which 125 I-LDL was used supported the morphological findings. In conclusion, this study demonstrates that FSH has important effects at the cellular level on LDL uptake, which seem to underlie the striking increase in progestin production accompanying granulosa cell differentiation

Effect of apolipoprotein M on high density lipoprotein metabolism and atherosclerosis in low density lipoprotein receptor knock-out mice

DEFF Research Database (Denmark)

Christoffersen, Christina; Jauhiainen, Matti; Moser, Markus

2008-01-01

To investigate the role of apoM in high density lipoprotein (HDL) metabolism and atherogenesis, we generated human apoM transgenic (apoM-Tg) and apoM-deficient (apoM(-/-)) mice. Plasma apoM was predominantly associated with 10-12-nm alpha-migrating HDL particles. Human apoM overexpression (11-fol...

Lipoprotein receptor LRP1 regulates leptin signaling and energy homeostasis in the adult central nervous system.

Directory of Open Access Journals (Sweden)

Qiang Liu

2011-01-01

Full Text Available Obesity is a growing epidemic characterized by excess fat storage in adipocytes. Although lipoprotein receptors play important roles in lipid uptake, their role in controlling food intake and obesity is not known. Here we show that the lipoprotein receptor LRP1 regulates leptin signaling and energy homeostasis. Conditional deletion of the Lrp1 gene in the brain resulted in an obese phenotype characterized by increased food intake, decreased energy consumption, and decreased leptin signaling. LRP1 directly binds to leptin and the leptin receptor complex and is required for leptin receptor phosphorylation and Stat3 activation. We further showed that deletion of the Lrp1 gene specifically in the hypothalamus by Cre lentivirus injection is sufficient to trigger accelerated weight gain. Together, our results demonstrate that the lipoprotein receptor LRP1, which is critical in lipid metabolism, also regulates food intake and energy homeostasis in the adult central nervous system.

Comparative microscopic and biochemical study of the uptake of fluorescent and 125I-labeled lipoproteins by skin fibroblasts, smooth muscle cells, and peritoneal macrophages in culture

International Nuclear Information System (INIS)

Reynolds, G.D.; St Clair, R.W.

1985-01-01

Uptake of low density lipoprotein (LDL) and of acetyl LDL was compared in skin fibroblasts, smooth muscle cells, and peritoneal macrophages with the use of lipoproteins labeled with either 125 I or the fluorescent probe 3,3'-dioctadecylindocarbocyanine (DiI). The uptake of DiI-labeled lipoproteins was assessed by quantitative spectrofluorometry and by fluorescence microscopy. The DiI was quantitatively retained by the cells, while the 125 I-LDL was degraded and 125 I-labeled degradation products were excreted from the cells. In smooth muscle cells and fibroblasts the uptake of LDL was virtually the same whether measured with the use of the DiI or 125 I-label. The labeling of acetyl LDL with DiI enhanced its uptake in peritoneal macrophages by an average of 18%. With the DiI label, lipoprotein uptake could be determined after as little as 10 minutes of incubation at 37 C. The pattern of uptake of the DiI-labeled lipoproteins was consistent with binding to specific receptors, because no DiI could be detected in mutant cells without LDL receptors, and uptake was competitively inhibited by addition of excess unlabeled lipoprotein. When the DiI-labeled lipoproteins were removed from the medium, there was a 5-15% loss of DiI from all cell types studied over the first 24 hours

Trafficking of cholesterol from cell bodies to distal axons in Niemann Pick C1-deficient neurons.

Science.gov (United States)

Karten, Barbara; Vance, Dennis E; Campenot, Robert B; Vance, Jean E

2003-02-07

Niemann Pick type C (NPC) disease is a progressive neurodegenerative disorder. In cells lacking functional NPC1 protein, endocytosed cholesterol accumulates in late endosomes/lysosomes. We utilized primary neuronal cultures in which cell bodies and distal axons reside in separate compartments to investigate the requirement of NPC1 protein for transport of cholesterol from cell bodies to distal axons. We have recently observed that in NPC1-deficient neurons compared with wild-type neurons, cholesterol accumulates in cell bodies but is reduced in distal axons (Karten, B., Vance, D. E., Campenot, R. B., and Vance, J. E. (2002) J. Neurochem. 83, 1154-1163). We now show that NPC1 protein is expressed in both cell bodies and distal axons. In NPC1-deficient neurons, cholesterol delivered to cell bodies from low density lipoproteins (LDLs), high density lipoproteins, or cyclodextrin complexes was transported into axons in normal amounts, whereas transport of endogenously synthesized cholesterol was impaired. Inhibition of cholesterol synthesis with pravastatin in wild-type and NPC1-deficient neurons reduced axonal growth. However, LDLs restored a normal rate of growth to wild-type but not NPC1-deficient neurons treated with pravastatin. Thus, although LDL cholesterol is transported into axons of NPC1-deficient neurons, this source of cholesterol does not sustain normal axonal growth. Over the lifespan of NPC1-deficient neurons, these defects in cholesterol transport might be responsible for the observed altered distribution of cholesterol between cell bodies and axons and, consequently, might contribute to the neurological dysfunction in NPC disease.

Low density lipoprotein receptors: preliminary results on 'in vivo' study

International Nuclear Information System (INIS)

Lupattelli, G.; Virgolini, I.; Li, S.R.; Sinzinger, H.

1991-01-01

Plasmatic levels of low density lipoproteins (LDL) are regulated by the receptor pathway and most LDL receptor are located in the liver. A receptor defect due to genetic mutations of the LDL receptor gene is the cause of familial hypercholesterolemia (F.H.), a disease characterized by high cholesterol levels and premature atherosclerosis. Injections of autologous radiolabelled LDL, followed by hepatic scintiscanning, can be used to obtain 'in vivo' quantification of hepatic receptor activity, both in normal and hypercholesterolemic patients. In this study we observe no hepatic increase of radioactivity in patients affected by F.H., confirming the liver receptor defect. Scintigraphy is a non-invasive technique which can be used to diagnose this disease and to monitor the efficiacy of hypolipidemic therapy. (Authors)

Learning from biology: synthetic lipoproteins for drug delivery.

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Huang, Huang; Cruz, William; Chen, Juan; Zheng, Gang

2015-01-01

Synthetic lipoproteins represent a relevant tool for targeted delivery of biological/chemical agents (chemotherapeutics, siRNAs, photosensitizers, and imaging contrast agents) into various cell types. These nanoparticles offer a number of advantages for drugs delivery over their native counterparts while retaining their natural characteristics and biological functions. Their ultra-small size (lipoprotein receptors, i.e., low-density lipoprotein receptor (LDLR) and Scavenger receptor class B member 1 (SRB1) that are found in a number of pathological conditions (e.g., cancer, atherosclerosis), make them superior delivery strategies when compared with other nanoparticle systems. We review the various approaches that have been developed for the generation of synthetic lipoproteins and their respective applications in vitro and in vivo. More specifically, we summarize the approaches employed to address the limitation on use of reconstituted lipoproteins by means of natural or recombinant apolipoproteins, as well as apolipoprotein mimetic molecules. Finally, we provide an overview of the advantages and disadvantages of these approaches and discuss future perspectives for clinical translation of these nanoparticles. © 2014 Wiley Periodicals, Inc.

Deletion of Batf3-dependent antigen-presenting cells does not affect atherosclerotic lesion formation in mice.

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Jesus Gil-Pulido

Full Text Available Atherosclerosis is the main underlying cause for cardiovascular events such as myocardial infarction and stroke and its development might be influenced by immune cells. Dendritic cells (DCs bridge innate and adaptive immune responses by presenting antigens to T cells and releasing a variety of cytokines. Several subsets of DCs can be discriminated that engage specific transcriptional pathways for their development. Basic leucine zipper transcription factor ATF-like 3 (Batf3 is required for the development of classical CD8α+ and CD103+ DCs. By crossing mice deficient in Batf3 with atherosclerosis-prone low density lipoprotein receptor (Ldlr-/--deficient mice we here aimed to further address the contribution of Batf3-dependent CD8α+ and CD103+ antigen-presenting cells to atherosclerosis. We demonstrate that deficiency in Batf3 entailed mild effects on the immune response in the spleen but did not alter atherosclerotic lesion formation in the aorta or aortic root, nor affected plaque phenotype in low density lipoprotein receptor-deficient mice fed a high fat diet. We thus provide evidence that Batf3-dependent antigen-presenting cells do not have a prominent role in atherosclerosis.

The role of lipolysis stimulated lipoprotein receptor in breast cancer and directing breast cancer cell behavior.

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Denise K Reaves

Full Text Available The claudin-low molecular subtype of breast cancer is of particular interest for clinically the majority of these tumors are poor prognosis, triple negative, invasive ductal carcinomas. Claudin-low tumors are characterized by cancer stem cell-like features and low expression of cell junction and adhesion proteins. Herein, we sought to define the role of lipolysis stimulated lipoprotein receptor (LSR in breast cancer and cancer cell behavior as LSR was recently correlated with tumor-initiating features. We show that LSR was expressed in epithelium, endothelium, and stromal cells within the healthy breast tissue, as well as in tumor epithelium. In primary breast tumor bioposies, LSR expression was significantly correlated with invasive ductal carcinomas compared to invasive lobular carcinomas, as well as ERα positive tumors and breast cancer cell lines. LSR levels were significantly reduced in claudin-low breast cancer cell lines and functional studies illustrated that re-introduction of LSR into a claudin-low cell line suppressed the EMT phenotype and reduced individual cell migration. However, our data suggest that LSR may promote collective cell migration. Re-introduction of LSR in claudin-low breast cancer cell lines reestablished tight junction protein expression and correlated with transepithelial electrical resistance, thereby reverting claudin-low lines to other intrinsic molecular subtypes. Moreover, overexpression of LSR altered gene expression of pathways involved in transformation and tumorigenesis as well as enhanced proliferation and survival in anchorage independent conditions, highlighting that reestablishment of LSR signaling promotes aggressive/tumor initiating cell behaviors. Collectively, these data highlight a direct role for LSR in driving aggressive breast cancer behavior.

Lipoprotein Nanoplatform for Targeted Delivery of Diagnostic and Therapeutic Agents

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Jerry D. Glickson

2008-03-01

Full Text Available Low-density lipoprotein (LDL provides a highly versatile natural nanoplatform for delivery of visible or near-infrared fluorescent optical and magnetic resonance imaging (MRI contrast agents and photodynamic therapy and chemotherapeutic agents to normal and neoplastic cells that overexpress low-density lipoprotein receptors (LDLRs. Extension to other lipoproteins ranging in diameter from about 10 nm (high-density lipoprotein [HDL] to over a micron (chylomicrons is feasible. Loading of contrast or therapeutic agents onto or into these particles has been achieved by protein loading (covalent attachment to protein side chains, surface loading (intercalation into the phospholipid monolayer, and core loading (extraction and reconstitution of the triglyceride/cholesterol ester core. Core and surface loading of LDL have been used for delivery of optical imaging agents to tumor cells in vivo and in culture. Surface loading was used for delivery of gadolinium-bis-stearylamide contrast agents for in vivo MRI detection in tumor-bearing mice. Chlorin and phthalocyanine near-infrared photodynamic therapy agents (≤ 400/LDL have been attached by core loading. Protein loading was used to reroute the LDL from its natural receptor (LDLR to folate receptors and could be used to target other receptors. A semisynthetic nanoparticle has been constructed by coating magnetite iron oxide nanoparticles with carboxylated cholesterol and overlaying a monolayer of phospholipid to which apolipoprotein A1 or E was adsorbed for targeting HDL or adsorbing synthetic amphipathic helical peptides ltargeting LDL or folate receptors. These particles can be used for in situ loading of magnetite into cells for MRI-monitored cell tracking or gene expression.

Ultrasound-targeted microbubble destruction improves the low density lipoprotein receptor gene expression in HepG2 cells

International Nuclear Information System (INIS)

Guo Dongping; Li Xiaoyu; Sun, Ping; Tang Yibo; Chen Xiuying; Chen Qi; Fan Leming; Zang Bin; Shao Lizheng; Li Xiaorong

2006-01-01

Ultrasound-targeted microbubble destruction had been employed in gene delivery and promised great potential. Liver has unique features that make it attractive for gene therapy. However, it poses formidable obstacles to hepatocyte-specific gene delivery. This study was designed to test the efficiency of therapeutic gene transfer and expression mediated by ultrasound/microbubble strategy in HepG 2 cell line. Air-filled albumin microbubbles were prepared and mixed with plasmid DNA encoding low density lipoprotein receptor (LDLR) and green fluorescent protein. The mixture of the DNA and microbubbles was administer to cultured HepG 2 cells under variable ultrasound conditions. Transfection rate of the transferred gene and cell viability were assessed by FACS analysis, confocal laser scanning microscopy, Western blot analysis and Trypan blue staining. The result demonstrated that microbubbles with ultrasound irradiation can significantly elevate exogenous LDLR gene expression and the expressed LDLRs were functional and active to uptake their ligands. We conclude that ultrasound-targeted microbubble destruction has the potential to promote safe and efficient LDLR gene transfer into hepatocytes. With further refinement, it may represent an effective nonviral avenue of gene therapy for liver-involved genetic diseases

Toll-like receptor-2 deficiency enhances non-alcoholic steatohepatitis

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Brady Kristen

2010-05-01

Full Text Available Abstract Background Previously we reported that mice deficient in toll-like receptor 4 (TLR-4 signalling were protected from diet-induced non-alcoholic steatohepatitis (NASH. Another member of the toll-like receptor family, TLR-2, has been shown to play a role in lipid trafficking via uptake of diacylated lipoproteins. However, a role for TLR-2 in NASH has not been elucidated. The objectives of the current study were to examine the influence of dietary fat quality and TLR-2 on NASH pathogenesis. Methods Steatohepatitis was induced in male Db, C57BL/6 and TLR-2-/- mice by feeding an L-amino acid-defined diet that was deficient in methionine and choline (MCDD. Mice fed the base diet supplemented with methionine and choline (control diet; CD were used as controls. To determine the role of fat quality, MCDD was enriched with polyunsaturated corn oil (PUFA or coconut oil that is comprised mostly of saturated fat (SAFA; the total amount of each fat was 112.9 g/kg of diet. After 8 weeks of feeding CD or MCDD, hepatic steatosis, inflammation and necrosis were evaluated in histological sections. Total RNA was extracted from frozen liver samples and mRNA expression of TNFα, collagen α1, IL-10, peroxisome proliferator-activated receptor-γ (PPAR-γ, TLR-4, and CD14, was analyzed via real-time PCR. Protein levels of TLR-2 were analyzed by western blot. Results Panlobular macrovessicular steatosis and diffuse leukocyte infiltration were noted in PUFA-fed Db mice. Histological scores demonstrated significantly less steatosis, inflammation and necrosis in SAFA-fed mice of all mouse strains. However, compared to wild type mice, hepatocellular damage was notably more severe in TLR-2-/- mice. Consistent with histological findings, mRNA expression of TNFα was elevated by approximately 3-fold in TLR-2-/- mice; PPAR-γ expression was blunted in this strain compared to wild type. Expression of the matrix protein collagen αI was also significantly higher in TLR-2

Effects of 1,2-cyclohexanedione modification on the metabolism of very low density lipoprotein apolipoprotein B: potential role of receptors in intermediate density lipoprotein catabolism

International Nuclear Information System (INIS)

Packard, C.J.; Boag, D.E.; Clegg, R.; Bedford, D.; Shepherd, J.

1985-01-01

The conversion of very low density (VLDL) to low density lipoproteins (LDL) is a two-step process. The first step is mediated by lipoprotein lipase, but the mechanism responsible for the second is obscure. In this study we examined the possible involvement of receptors at this stage. Apolipoprotein B (apoB)-containing lipoproteins were separated into three fractions, VLDL (Sf 100-400), an intermediate fraction IDL (Sf 12-100), and LDL (Sf 0-12). Autologous 125I-labeled VLDL and 131I-labeled 1,2-cyclohexanedione-modified VLDL were injected into the plasma of four normal subjects and the rate of transfer of apoB radioactivity was followed through IDL to LDL. Modification did not affect VLDL to IDL conversion. Thereafter, however, the catabolism of modified apoB in IDL was retarded and its appearance in LDL was delayed. Hence, functional arginine residues (and by implication, receptors) are required in this process. Confirmation of this was obtained by injecting 125I-labeled IDL and 131I-labeled cyclohexanedione-treated IDL into two additional subjects. Again, IDL metabolism was delayed by approximately 50% as a result of the modification. These data are consistent with the view that receptors are involved in the metabolism of intermediate density lipoprotein

Restoring balance to B cells in ADA deficiency.

Science.gov (United States)

Luning Prak, Eline T

2012-06-01

It is paradoxical that immunodeficiency disorders are associated with autoimmunity. Adenosine deaminase (ADA) deficiency, a cause of X-linked severe combined immunodeficiency (SCID), is a case in point. In this issue of the JCI, Sauer and colleagues investigate the B cell defects in ADA-deficient patients. They demonstrate that ADA patients receiving enzyme replacement therapy had B cell tolerance checkpoint defects. Remarkably, gene therapy with a retrovirus that expresses ADA resulted in the apparent correction of these defects, with normalization of peripheral B cell autoantibody frequencies. In vitro, agents that either block ADA or overexpress adenosine resulted in altered B cell receptor and TLR signaling. Collectively, these data implicate a B cell-intrinsic mechanism for alterations in B cell tolerance in the setting of partial ADA deficiency that is corrected by gene therapy.

Chemokine-like receptor 1 deficiency does not affect the development of insulin resistance and nonalcoholic fatty liver disease in mice.

Directory of Open Access Journals (Sweden)

Nanda Gruben

Full Text Available The adipokine chemerin and its receptor, chemokine-like receptor 1 (Cmklr1, are associated with insulin resistance and nonalcoholic fatty liver disease (NAFLD, which covers a broad spectrum of liver diseases, ranging from simple steatosis to nonalcoholic steatohepatitis (NASH. It is possible that chemerin and/or Cmklr1 exert their effects on these disorders through inflammation, but so far the data have been controversial. To gain further insight into this matter, we studied the effect of whole-body Cmklr1 deficiency on insulin resistance and NAFLD. In view of the primary role of macrophages in hepatic inflammation, we also transplanted bone marrow from Cmklr1 knock-out (Cmklr1-/- mice and wild type (WT mice into low-density lipoprotein receptor knock-out (Ldlr-/- mice, a mouse model for NASH. All mice were fed a high fat, high cholesterol diet containing 21% fat from milk butter and 0.2% cholesterol for 12 weeks. Insulin resistance was assessed by an oral glucose tolerance test, an insulin tolerance test, and by measurement of plasma glucose and insulin levels. Liver pathology was determined by measuring hepatic inflammation, fibrosis, lipid accumulation and the NAFLD activity score (NAS. Whole-body Cmklr1 deficiency did not affect body weight gain or food intake. In addition, we observed no differences between WT and Cmklr1-/- mice for hepatic inflammatory and fibrotic gene expression, immune cell infiltration, lipid accumulation or NAS. In line with this, we detected no differences in insulin resistance. In concordance with whole-body Cmklr1 deficiency, the absence of Cmklr1 in bone marrow-derived cells in Ldlr-/- mice did not affect their insulin resistance or liver pathology. Our results indicate that Cmklr1 is not involved in the pathogenesis of insulin resistance or NAFLD. Thus, we recommend that the associations reported between Cmklr1 and insulin resistance or NAFLD should be interpreted with caution.

Antiatherosclerotic Effects of 1-Methylnicotinamide in Apolipoprotein E/Low-Density Lipoprotein Receptor-Deficient Mice: A Comparison with Nicotinic Acid.

Science.gov (United States)

Mateuszuk, Lukasz; Jasztal, Agnieszka; Maslak, Edyta; Gasior-Glogowska, Marlena; Baranska, Malgorzata; Sitek, Barbara; Kostogrys, Renata; Zakrzewska, Agnieszka; Kij, Agnieszka; Walczak, Maria; Chlopicki, Stefan

2016-02-01

1-Methylnicotinamide (MNA), the major endogenous metabolite of nicotinic acid (NicA), may partially contribute to the vasoprotective properties of NicA. Here we compared the antiatherosclerotic effects of MNA and NicA in apolipoprotein E (ApoE)/low-density lipoprotein receptor (LDLR)-deficient mice. ApoE/LDLR(-/-) mice were treated with MNA or NicA (100 mg/kg). Plaque size, macrophages, and cholesterol content in the brachiocephalic artery, endothelial function in the aorta, systemic inflammation, platelet activation, as well as the concentration of MNA and its metabolites in plasma and urine were measured. MNA and NicA reduced atherosclerotic plaque area, plaque inflammation, and cholesterol content in the brachiocephalic artery. The antiatherosclerotic actions of MNA and NicA were associated with improved endothelial function, as evidenced by a higher concentration of 6-keto-prostaglandin F1 α and nitrite/nitrate in the aortic ring effluent, inhibition of platelets (blunted thromboxane B2 generation), and inhibition of systemic inflammation (lower plasma concentration of serum amyloid P, haptoglobin). NicA treatment resulted in an approximately 2-fold higher concentration of MNA and its metabolites in urine and a 4-fold higher nicotinamide/MNA ratio in plasma, compared with MNA treatment. In summary; MNA displays pronounced antiatherosclerotic action in ApoE/LDLR(-/-) mice, an effect associated with an improvement in prostacyclin- and nitric oxide-dependent endothelial function, inhibition of platelet activation, inhibition of inflammatory burden in plaques, and diminished systemic inflammation. Despite substantially higher MNA availability after NicA treatment, compared with an equivalent dose of MNA, the antiatherosclerotic effect of NicA was not stronger. We suggest that detrimental effects of NicA or its metabolites other than MNA may limit beneficial effects of NicA-derived MNA. Copyright © 2016 by The American Society for Pharmacology and Experimental

Sortilins: new players in lipoprotein metabolism

DEFF Research Database (Denmark)

Willnow, Thomas; Kjølby, Mads Fuglsang; Nykjær, Anders

2011-01-01

PURPOSE OF REVIEW: Sortilins are sorting receptors that direct proteins through secretory and endocytic pathways of the cell. Previously, these receptors have been shown to play important roles in regulating protein transport in neurons and to control neuronal viability and death in many diseases...... on the importance of sorting receptors in control of cellular and systemic lipoprotein metabolism and how altered trafficking pathways may represent a major risk factor for dyslipidemia and atherosclerosis in the human population....

What are lipoproteins doing in the brain?

Science.gov (United States)

Wang, Hong; Eckel, Robert H

2014-01-01

Lipoproteins in plasma transport lipids between tissues, however, only high-density lipoproteins (HDL) appear to traverse the blood-brain barrier (BBB); thus, lipoproteins found in the brain must be produced within the central nervous system. Apolipoproteins E (ApoE) and ApoJ are the most abundant apolipoproteins in the brain, are mostly synthesized by astrocytes, and are found on HDL. In the hippocampus and other brain regions, lipoproteins help to regulate neurobehavioral functions by processes that are lipoprotein receptor-mediated. Moreover, lipoproteins and their receptors also have roles in the regulation of body weight and energy balance, acting through lipoprotein lipase (LPL) and the low-density lipoprotein (LDL) receptor-related protein (LRP). Thus, understanding lipoproteins and their metabolism in the brain provides a new opportunity with potential therapeutic relevance. Copyright © 2013 Elsevier Ltd. All rights reserved.

Neuronal low-density lipoprotein receptor-related protein 1 binds and endocytoses prion fibrils via receptor cluster 4

DEFF Research Database (Denmark)

Jen, Angela; Parkyn, Celia J; Mootoosamy, Roy C

2010-01-01

For infectious prion protein (designated PrP(Sc)) to act as a template to convert normal cellular protein (PrP(C)) to its distinctive pathogenic conformation, the two forms of prion protein (PrP) must interact closely. The neuronal receptor that rapidly endocytoses PrP(C) is the low......-density lipoprotein receptor-related protein 1 (LRP1). We show here that on sensory neurons LRP1 is also the receptor that binds and rapidly endocytoses smaller oligomeric forms of infectious prion fibrils, and recombinant PrP fibrils. Although LRP1 binds two molecules of most ligands independently to its receptor...... both prion and LRP1 biology....

Low-density Lipoprotein Receptor-related Protein-1 (LRP1) Mediates Autophagy and Apoptosis Caused by Helicobacter pylori VacA*

OpenAIRE

Yahiro, Kinnosuke; Satoh, Mamoru; Nakano, Masayuki; Hisatsune, Junzo; Isomoto, Hajime; Sap, Jan; Suzuki, Hidekazu; Nomura, Fumio; Noda, Masatoshi; Moss, Joel; Hirayama, Toshiya

2012-01-01

In Helicobacter pylori infection, vacuolating cytotoxin (VacA)-induced mitochondrial damage leading to apoptosis is believed to be a major cause of cell death. It has also been proposed that VacA-induced autophagy serves as a host mechanism to limit toxin-induced cellular damage. Apoptosis and autophagy are two dynamic and opposing processes that must be balanced to regulate cell death and survival. Here we identify the low-density lipoprotein receptor-related protein-1 (LRP1) as the VacA rec...

The low-density lipoprotein receptor-related protein 1 and amyloid-β clearance in Alzheimer’s disease

Directory of Open Access Journals (Sweden)

Takahisa eKanekiyo

2014-05-01

Full Text Available Accumulation and aggregation of amyloid-β (Aβ peptides in the brain trigger the development of progressive neurodegeneration and dementia associated with Alzheimer’s disease (AD. Perturbation in Aβ clearance, rather than Aβ production, is likely the cause of sporadic, late-onset AD, which accounts for the majority of AD cases. Since cellular uptake and subsequent degradation constitute a major Aβ clearance pathway, the receptor-mediated endocytosis of Aβ has been intensely investigated. Among Aβ receptors, the low-density lipoprotein receptor-related protein 1 (LRP1 is one of the most studied receptors. LRP1 is a large endocytic receptor for more than 40 ligands, including apolipoprotein E (apoE, α2-macroglobulin and Aβ. Emerging in vitro and in vivo evidence demonstrates that LRP1 is critically involved in brain Aβ clearance. LRP1 is highly expressed in a variety of cell types in the brain including neurons, vascular cells and glial cells, where LRP1 functions to maintain brain homeostasis and control Aβ metabolism. LRP1-mediated endocytosis regulates cellular Aβ uptake by binding to Aβ either directly or indirectly through its co-receptors or ligands. Furthermore, LRP1 regulates several signaling pathways, which also likely influences Aβ endocytic pathways. In this review, we discuss how LRP1 regulates the brain Aβ clearance and how this unique endocytic receptor participates in AD pathogenesis. Understanding of the mechanisms underlying LRP1-mediated Aβ clearance should enable the rational design of novel diagnostic and therapeutic strategies for AD.

Activated factor X signaling via protease-activated receptor 2 suppresses pro-inflammatory cytokine production from LPS-stimulated myeloid cells.

LENUS (Irish Health Repository)

Gleeson, Eimear M

2013-07-19

Vitamin K-dependent proteases generated in response to vascular injury and infection enable fibrin clot formation, but also trigger distinct immuno-regulatory signaling pathways on myeloid cells. Factor Xa, a protease crucial for blood coagulation, also induces protease-activated receptor-dependent cell signaling. Factor Xa can bind both monocytes and macrophages, but whether factor Xa-dependent signaling stimulates or suppresses myeloid cell cytokine production in response to Toll-like receptor activation is not known. In this study, exposure to factor Xa significantly impaired pro-inflammatory cytokine production from lipopolysaccharide-treated peripheral blood mononuclear cells, THP-1 monocytic cells and murine macrophages. Furthermore, factor Xa inhibited nuclear factor-kappa B activation in THP-1 reporter cells, requiring phosphatidylinositide 3-kinase activity for its anti-inflammatory effect. Active-site blockade, γ-carboxyglutamic acid domain truncation and a peptide mimic of the factor Xa inter-epidermal growth factor-like region prevented factor Xa inhibition of lipopolysaccharide-induced tumour necrosis factor-α release. In addition, factor Xa anti-inflammatory activity was markedly attenuated by the presence of an antagonist of protease-activated receptor 2, but not protease-activated receptor 1. The key role of protease-activated receptor 2 in eliciting factor Xa-dependent anti-inflammatory signaling on macrophages was further underscored by the inability of factor Xa to mediate inhibition of tumour necrosis factor-α and interleukin-6 release from murine bone marrow-derived protease-activated receptor 2-deficient macrophages. We also show for the first time that, in addition to protease-activated receptor 2, factor Xa requires a receptor-associated protein-sensitive low-density lipoprotein receptor to inhibit lipopolysaccharide-induced cytokine production. Collectively, this study supports a novel function for factor Xa as an endogenous, receptor

Lipoproteins tethered dendrimeric nanoconstructs for effective targeting to cancer cells

Science.gov (United States)

Jain, Anupriya; Jain, Keerti; Mehra, Neelesh Kumar; Jain, N. K.

2013-10-01

In the present investigation, poly (propylene imine) dendrimers up to fifth generation (PPI G5.0) were synthesized using ethylene diamine and acrylonitrile. Lipoproteins (high-density lipoprotein; HDL and low-density lipoprotein; LDL) were isolated from human plasma by discontinuous density gradient ultracentrifugation, characterized and tethered to G5.0 PPI dendrimers to construct LDL- and HDL-conjugated dendrimeric nanoconstructs for tumor-specific delivery of docetaxel. Developed formulations showed sustained release characteristics in in vitro drug release and in vivo pharmacokinetic studies. The cancer targeting potential of lipoprotein coupled dendrimers was investigated by ex vivo cytotoxicity and cell uptake studies using human hepatocellular carcinoma cell lines (HepG2 cells) and biodistribution studies in albino rats of Sprague-Dawley strain. Lipoprotein anchored dendrimeric nanoconstructs showed significant uptake by cancer cells as well as higher biodistribution of docetaxel to liver and spleen. It is concluded that these precisely synthesized engineered dendrimeric nanoconstructs could serve as promising drug carrier for fighting with the fatal disease, i.e., cancer, attributed to their defined targeting and therapeutic potential.

Lipoproteins tethered dendrimeric nanoconstructs for effective targeting to cancer cells

Energy Technology Data Exchange (ETDEWEB)

Jain, Anupriya; Jain, Keerti, E-mail: keertijain02@gmail.com; Mehra, Neelesh Kumar, E-mail: neelesh81mph@gmail.com; Jain, N. K., E-mail: dr.jnarendr@gmail.com [Dr. H. S. Gour University, Pharmaceutics Research Laboratory, Department of Pharmaceutical Sciences (India)

2013-10-15

In the present investigation, poly (propylene imine) dendrimers up to fifth generation (PPI G5.0) were synthesized using ethylene diamine and acrylonitrile. Lipoproteins (high-density lipoprotein; HDL and low-density lipoprotein; LDL) were isolated from human plasma by discontinuous density gradient ultracentrifugation, characterized and tethered to G5.0 PPI dendrimers to construct LDL- and HDL-conjugated dendrimeric nanoconstructs for tumor-specific delivery of docetaxel. Developed formulations showed sustained release characteristics in in vitro drug release and in vivo pharmacokinetic studies. The cancer targeting potential of lipoprotein coupled dendrimers was investigated by ex vivo cytotoxicity and cell uptake studies using human hepatocellular carcinoma cell lines (HepG2 cells) and biodistribution studies in albino rats of Sprague-Dawley strain. Lipoprotein anchored dendrimeric nanoconstructs showed significant uptake by cancer cells as well as higher biodistribution of docetaxel to liver and spleen. It is concluded that these precisely synthesized engineered dendrimeric nanoconstructs could serve as promising drug carrier for fighting with the fatal disease, i.e., cancer, attributed to their defined targeting and therapeutic potential.

Hydrolysis products generated by lipoprotein lipase and endothelial lipase differentially impact THP-1 macrophage cell signalling pathways.

Science.gov (United States)

Essaji, Yasmin; Yang, Yanbo; Albert, Carolyn J; Ford, David A; Brown, Robert J

2013-08-01

Macrophages express lipoprotein lipase (LPL) and endothelial lipase (EL) within atherosclerotic plaques; however, little is known about how lipoprotein hydrolysis products generated by these lipases might affect macrophage cell signalling pathways. We hypothesized that hydrolysis products affect macrophage cell signalling pathways associated with atherosclerosis. To test our hypothesis, we incubated differentiated THP-1 macrophages with products from total lipoprotein hydrolysis by recombinant LPL or EL. Using antibody arrays, we found that the phosphorylation of six receptor tyrosine kinases and three signalling nodes--most associated with atherosclerotic processes--was increased by LPL derived hydrolysis products. EL derived hydrolysis products only increased the phosphorylation of tropomyosin-related kinase A, which is also implicated in playing a role in atherosclerosis. Using electrospray ionization-mass spectrometry, we identified the species of triacylglycerols and phosphatidylcholines that were hydrolyzed by LPL and EL, and we identified the fatty acids liberated by gas chromatography-mass spectrometry. To determine if the total liberated fatty acids influenced signalling pathways, we incubated differentiated THP-1 macrophages with a mixture of the fatty acids that matched the concentrations of liberated fatty acids from total lipoproteins by LPL, and we subjected cell lysates to antibody array analyses. The analyses showed that only the phosphorylation of Akt was significantly increased in response to fatty acid treatment. Overall, our study shows that macrophages display potentially pro-atherogenic signalling responses following acute treatments with LPL and EL lipoprotein hydrolysis products.

Human Lipoproteins at Model Cell Membranes

DEFF Research Database (Denmark)

Browning, K L; Lind, T K; Maric, S

2017-01-01

High and low density lipoproteins (HDL and LDL) are thought to play vital roles in the onset and development of atherosclerosis; the biggest killer in the western world. Key issues of initial lipoprotein (LP) interactions at cellular membranes need to be addressed including LP deposition and lipid...... exchange. Here we present a protocol for monitoring the in situ kinetics of lipoprotein deposition and lipid exchange/removal at model cellular membranes using the non-invasive, surface sensitive methods of neutron reflection and quartz crystal microbalance with dissipation. For neutron reflection, lipid...... support the notion of HDL acting as the 'good' cholesterol, removing lipid material from lipid-loaded cells, whereas LDL acts as the 'bad' cholesterol, depositing lipid material into the vascular wall....

Generation of Novel Traj18-Deficient Mice Lacking Vα14 Natural Killer T Cells with an Undisturbed T Cell Receptor α-Chain Repertoire.

Directory of Open Access Journals (Sweden)

Nyambayar Dashtsoodol

Full Text Available Invariant Vα14 natural killer T (NKT cells, characterized by the expression of a single invariant T cell receptor (TCR α chain encoded by rearranged Trav11 (Vα14-Traj18 (Jα18 gene segments in mice, and TRAV10 (Vα24-TRAJ18 (Jα18 in humans, mediate adjuvant effects to activate various effector cell types in both innate and adaptive immune systems that facilitates the potent antitumor effects. It was recently reported that the Jα18-deficient mouse described by our group in 1997 harbors perturbed TCRα repertoire, which raised concerns regarding the validity of some of the experimental conclusions that have been made using this mouse line. To resolve this concern, we generated a novel Traj18-deficient mouse line by specifically targeting the Traj18 gene segment using Cre-Lox approach. Here we showed the newly generated Traj18-deficient mouse has, apart from the absence of Traj18, an undisturbed TCRα chain repertoire by using next generation sequencing and by detecting normal generation of Vα19Jα33 expressing mucosal associated invariant T cells, whose development was abrogated in the originally described Jα18-KO mice. We also demonstrated here the definitive requirement for NKT cells in the protection against tumors and their potent adjuvant effects on antigen-specific CD8 T cells.

Redefining the essential trafficking pathway for outer membrane lipoproteins

Science.gov (United States)

Grabowicz, Marcin; Silhavy, Thomas J.

2017-01-01

The outer membrane (OM) of Gram-negative bacteria is a permeability barrier and an intrinsic antibiotic resistance factor. Lipoproteins are OM components that function in cell wall synthesis, diverse secretion systems, and antibiotic efflux pumps. Moreover, each of the essential OM machines that assemble the barrier requires one or more lipoproteins. This dependence is thought to explain the essentiality of the periplasmic chaperone LolA and its OM receptor LolB that traffic lipoproteins to the OM. However, we show that in strains lacking substrates that are toxic when mislocalized, both LolA and LolB can be completely bypassed by activating an envelope stress response without compromising trafficking of essential lipoproteins. We identify the Cpx stress response as a monitor of lipoprotein trafficking tasked with protecting the cell from mislocalized lipoproteins. Moreover, our findings reveal that an alternate trafficking pathway exists that can, under certain conditions, bypass the functions of LolA and LolB, implying that these proteins do not perform any truly essential mechanistic steps in lipoprotein trafficking. Instead, these proteins’ key function is to prevent lethal accumulation of mislocalized lipoproteins. PMID:28416660

Redefining the essential trafficking pathway for outer membrane lipoproteins.

Science.gov (United States)

Grabowicz, Marcin; Silhavy, Thomas J

2017-05-02

The outer membrane (OM) of Gram-negative bacteria is a permeability barrier and an intrinsic antibiotic resistance factor. Lipoproteins are OM components that function in cell wall synthesis, diverse secretion systems, and antibiotic efflux pumps. Moreover, each of the essential OM machines that assemble the barrier requires one or more lipoproteins. This dependence is thought to explain the essentiality of the periplasmic chaperone LolA and its OM receptor LolB that traffic lipoproteins to the OM. However, we show that in strains lacking substrates that are toxic when mislocalized, both LolA and LolB can be completely bypassed by activating an envelope stress response without compromising trafficking of essential lipoproteins. We identify the Cpx stress response as a monitor of lipoprotein trafficking tasked with protecting the cell from mislocalized lipoproteins. Moreover, our findings reveal that an alternate trafficking pathway exists that can, under certain conditions, bypass the functions of LolA and LolB, implying that these proteins do not perform any truly essential mechanistic steps in lipoprotein trafficking. Instead, these proteins' key function is to prevent lethal accumulation of mislocalized lipoproteins.

A receptor-based biosensor for lipoprotein docking at the endothelial surface and vascular matrix.

Science.gov (United States)

Siegel, G; Malmsten, M; Klüssendorf, D; Michel, F

2001-12-01

Proteoheparan sulfate can be adsorbed to a methylated silica surface in a monomolecular layer via its transmembrane hydrophobic protein core domain. Due to electrostatic repulsion, its anionic glycosaminoglycan side chains are stretched out into the blood substitute solution, representing a receptor site for specific lipoprotein binding through basic amino acid-rich residues within their apolipoproteins. The binding process was studied by ellipsometric techniques showing that HDL has a high binding affinity to the receptor and a protective effect on interfacial heparan sulfate proteoglycan layers, with respect to LDL and Ca(2+) complexation. LDL was found to deposit strongly at the proteoheparan sulfate, particularly in the presence of Ca(2+), thus creating the complex formation "proteoglycan-low density lipoprotein-calcium". This ternary complex build-up may be interpreted as arteriosclerotic nanoplaque formation on the molecular level responsible for the arteriosclerotic primary lesion. On the other hand, HDL bound to heparan sulfate proteoglycan protected against LDL docking and completely suppressed calcification of the proteoglycan-lipoprotein complex. In addition, HDL and aqueous garlic extract were able to reduce the ternary complex deposition and to disintegrate HS-PG/LDL/Ca(2+) aggregates. Although much remains unclear regarding the mechanism of lipoprotein depositions at proteoglycan-coated surfaces, it seems clear that the use of such systems offers possibilities for investigating lipoprotein deposition at a "nanoscopic" level under close to physiological conditions. In particular, Ca(2+)-promoted LDL deposition and the protective effect of HDL, even at high Ca(2+) and LDL concentrations, agree well with previous clinical observations regarding risk and beneficial factors for early stages of atherosclerosis. Therefore, we believe that the system can be of some use in investigations, e.g. of the interplay between different lipoproteins in arteriosclerotic

Novel primary thymic defect with T lymphocytes expressing gamma delta T cell receptor

DEFF Research Database (Denmark)

Geisler, C; Pallesen, G; Platz, P

1989-01-01

Flow cytometric analysis of the peripheral blood mononuclear cells in a six year old girl with a primary cellular immune deficiency showed a normal fraction of CD3 positive T cells. Most (70%) of the CD3 positive cells, however, expressed the gamma delta and not the alpha beta T cell receptor....... Immunoprecipitation and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that most of the gamma delta T cell receptors existed as disulphide-linked heterodimers. Proliferative responses to mitogens were severely reduced, but specific antibody responses after vaccination could be detected...... deficiency associated with a high proportion of T cells expressing the gamma delta T cell receptor has been described in nude mice, and it is suggested that the immune deficiency of this patient may represent a human analogue....

Hemorheological abnormalities in lipoprotein lipase deficient mice with severe hypertriglyceridemia

International Nuclear Information System (INIS)

Zhao Tieqiang; Guo Jun; Li Hui; Huang Wei; Xian Xunde; Ross, Colin J.D.; Hayden, Michael R.; Wen Zongyao; Liu George

2006-01-01

Severe hypertriglyceridemia (HTG) is a metabolic disturbance often seen in clinical practice. It is known to induce life-threatening acute pancreatitis, but its role in atherogenesis remains elusive. Hemorheological abnormality was thought to play an important role in pathogenesis of both pancreatitis and atherosclerosis. However, hemorheology in severe HTG was not well investigated. Recently, we established a severe HTG mouse model deficient in lipoprotein lipase (LPL) in which severe HTG was observed to cause a significant increase in plasma viscosity. Disturbances of erythrocytes were also documented, including decreased deformability, electrophoresis rate, and membrane fluidity, and increased osmotic fragility. Scanning electron microscopy demonstrated that most erythrocytes of LPL deficient mice deformed with protrusions, irregular appearances or indistinct concaves. Analysis of erythrocyte membrane lipids showed decreased cholesterol (Ch) and phospholipid (PL) contents but unaltered Ch/PL ratio. The changes of membrane lipids may be partially responsible for the hemorheological and morphologic abnormalities of erythrocytes. This study indicated that severe HTG could lead to significant impairment of hemorheology and this model may be useful in delineating the role of severe HTG in the pathogenesis of hyperlipidemic pancreatitis and atherosclerosis

Lipid accumulation in smooth muscle cells under LDL loading is independent of LDL receptor pathway and enhanced by hypoxic conditions.

Science.gov (United States)

Wada, Youichiro; Sugiyama, Akira; Yamamoto, Takashi; Naito, Makoto; Noguchi, Noriko; Yokoyama, Shinji; Tsujita, Maki; Kawabe, Yoshiki; Kobayashi, Mika; Izumi, Akashi; Kohro, Takahide; Tanaka, Toshiya; Taniguchi, Hirokazu; Koyama, Hidenori; Hirano, Ken-ichi; Yamashita, Shizuya; Matsuzawa, Yuji; Niki, Etsuo; Hamakubo, Takao; Kodama, Tatsuhiko

2002-10-01

The effect of a variety of hypoxic conditions on lipid accumulation in smooth muscle cells (SMCs) was studied in an arterial wall coculture and monocultivation model. Low density lipoprotein (LDL) was loaded under various levels of oxygen tension. Oil red O staining of rabbit and human SMCs revealed that lipid accumulation was greater under lower oxygen tension. Cholesterol esters were shown to accumulate in an oxygen tension-dependent manner by high-performance liquid chromatographic analysis. Autoradiograms using radiolabeled LDL indicated that LDL uptake was more pronounced under hypoxia. This result holds in the case of LDL receptor-deficient rabbit SMCs. However, cholesterol biosynthesis and cellular cholesterol release were unaffected by oxygen tension. Hypoxia significantly increases LDL uptake and enhances lipid accumulation in arterial SMCs, exclusive of LDL receptor activity. Although the molecular mechanism is not clear, the model is useful for studying lipid accumulation in arterial wall cells and the difficult-to-elucidate events in the initial stage of atherogenesis.

β1-Adrenergic receptor deficiency in ghrelin-expressing cells causes hypoglycemia in susceptible individuals

Science.gov (United States)

Mani, Bharath K.; Osborne-Lawrence, Sherri; Vijayaraghavan, Prasanna; Hepler, Chelsea; Zigman, Jeffrey M.

2016-01-01

Ghrelin is an orexigenic gastric peptide hormone secreted when caloric intake is limited. Ghrelin also regulates blood glucose, as emphasized by the hypoglycemia that is induced by caloric restriction in mouse models of deficient ghrelin signaling. Here, we hypothesized that activation of β1-adrenergic receptors (β1ARs) localized to ghrelin cells is required for caloric restriction–associated ghrelin release and the ensuing protective glucoregulatory response. In mice lacking the β1AR specifically in ghrelin-expressing cells, ghrelin secretion was markedly blunted, resulting in profound hypoglycemia and prevalent mortality upon severe caloric restriction. Replacement of ghrelin blocked the effects of caloric restriction in β1AR-deficient mice. We also determined that treating calorically restricted juvenile WT mice with beta blockers led to reduced plasma ghrelin and hypoglycemia, the latter of which is similar to the life-threatening, fasting-induced hypoglycemia observed in infants treated with beta blockers. These findings highlight the critical functions of ghrelin in preventing hypoglycemia and promoting survival during severe caloric restriction and the requirement for ghrelin cell–expressed β1ARs in these processes. Moreover, these results indicate a potential role for ghrelin in mediating beta blocker–associated hypoglycemia in susceptible individuals, such as young children. PMID:27548523

ZFAT plays critical roles in peripheral T cell homeostasis and its T cell receptor-mediated response

International Nuclear Information System (INIS)

Doi, Keiko; Fujimoto, Takahiro; Okamura, Tadashi; Ogawa, Masahiro; Tanaka, Yoko; Mototani, Yasumasa; Goto, Motohito; Ota, Takeharu; Matsuzaki, Hiroshi; Kuroki, Masahide; Tsunoda, Toshiyuki; Sasazuki, Takehiko; Shirasawa, Senji

2012-01-01

Highlights: ► We generated Cd4-Cre-mediated T cell-specific Zfat-deficient mice. ► Zfat-deficiency leads to reduction in the number of the peripheral T cells. ► Impaired T cell receptor-mediated response in Zfat-deficient peripheral T cells. ► Decreased expression of IL-7Rα, IL-2Rα and IL-2 in Zfat-deficient peripheral T cells. ► Zfat plays critical roles in peripheral T cell homeostasis. -- Abstract: ZFAT, originally identified as a candidate susceptibility gene for autoimmune thyroid disease, has been reported to be involved in apoptosis, development and primitive hematopoiesis. Zfat is highly expressed in T- and B-cells in the lymphoid tissues, however, its physiological function in the immune system remains totally unknown. Here, we generated the T cell-specific Zfat-deficient mice and demonstrated that Zfat-deficiency leads to a remarkable reduction in the number of the peripheral T cells. Intriguingly, a reduced expression of IL-7Rα and the impaired responsiveness to IL-7 for the survival were observed in the Zfat-deficient T cells. Furthermore, a severe defect in proliferation and increased apoptosis in the Zfat-deficient T cells following T cell receptor (TCR) stimulation was observed with a reduced IL-2Rα expression as well as a reduced IL-2 production. Thus, our findings reveal that Zfat is a critical regulator in peripheral T cell homeostasis and its TCR-mediated response.

The Journey of Lipoproteins Through the Cell: One Birthplace, Multiple Destinations.

Science.gov (United States)

Szewczyk, J; Collet, J-F

2016-01-01

Bacterial lipoproteins are a very diverse group of proteins characterized by the presence of an N-terminal lipid moiety that serves as a membrane anchor. Lipoproteins have a wide variety of crucial functions, ranging from envelope biogenesis to stress response. In Gram-negative bacteria, lipoproteins can be targeted to various destinations in the cell, including the periplasmic side of the cytoplasmic or outer membrane, the cell surface or the external milieu. The sorting mechanisms have been studied in detail in Escherichia coli, but exceptions to the rules established in this model bacterium exist in other bacteria. In this chapter, we will present the current knowledge on lipoprotein sorting in the cell. Our particular focus will be on the surface-exposed lipoproteins that appear to be much more common than previously assumed. We will discuss the different targeting strategies, provide numerous examples of surface-exposed lipoproteins and discuss the techniques used to assess their surface exposure. © 2016 Elsevier Ltd All rights reserved.

Cholesterol efflux from THP-1 macrophages is impaired by the fatty acid component from lipoprotein hydrolysis by lipoprotein lipase

International Nuclear Information System (INIS)

Yang, Yanbo; Thyagarajan, Narmadaa; Coady, Breanne M.; Brown, Robert J.

2014-01-01

Highlights: • Lipoprotein hydrolysis products were produced by lipoprotein lipase. • Hydrolysis products lowers expression of macrophage cholesterol transporters. • Hydrolysis products reduces expression of select nuclear receptors. • Fatty acid products lowers cholesterol transporters and select nuclear receptors. • Fatty acid products reduces cholesterol efflux from macrophages. - Abstract: Lipoprotein lipase (LPL) is an extracellular lipase that primarily hydrolyzes triglycerides within circulating lipoproteins. Macrophage LPL contributes to atherogenesis, but the mechanisms behind it are poorly understood. We hypothesized that the products of lipoprotein hydrolysis generated by LPL promote atherogenesis by inhibiting the cholesterol efflux ability by macrophages. To test this hypothesis, we treated human THP-1 macrophages with total lipoproteins that were hydrolyzed by LPL and we found significantly reduced transcript levels for the cholesterol transporters ATP binding cassette transporter A1 (ABCA1), ABCG1, and scavenger receptor BI. These decreases were likely due to significant reductions for the nuclear receptors liver-X-receptor-α, peroxisome proliferator activated receptor (PPAR)-α, and PPAR-γ. We prepared a mixture of free fatty acids (FFA) that represented the ratios of FFA species within lipoprotein hydrolysis products, and we found that the FFA mixture also significantly reduced cholesterol transporters and nuclear receptors. Finally, we tested the efflux of cholesterol from THP-1 macrophages to apolipoprotein A-I, and we found that the treatment of THP-1 macrophages with the FFA mixture significantly attenuated cholesterol efflux. Overall, these data show that the FFA component of lipoprotein hydrolysis products generated by LPL may promote atherogenesis by inhibiting cholesterol efflux, which partially explains the pro-atherogenic role of macrophage LPL

Cholesterol efflux from THP-1 macrophages is impaired by the fatty acid component from lipoprotein hydrolysis by lipoprotein lipase

Energy Technology Data Exchange (ETDEWEB)

Yang, Yanbo; Thyagarajan, Narmadaa; Coady, Breanne M.; Brown, Robert J., E-mail: rbrown@mun.ca

2014-09-05

Highlights: • Lipoprotein hydrolysis products were produced by lipoprotein lipase. • Hydrolysis products lowers expression of macrophage cholesterol transporters. • Hydrolysis products reduces expression of select nuclear receptors. • Fatty acid products lowers cholesterol transporters and select nuclear receptors. • Fatty acid products reduces cholesterol efflux from macrophages. - Abstract: Lipoprotein lipase (LPL) is an extracellular lipase that primarily hydrolyzes triglycerides within circulating lipoproteins. Macrophage LPL contributes to atherogenesis, but the mechanisms behind it are poorly understood. We hypothesized that the products of lipoprotein hydrolysis generated by LPL promote atherogenesis by inhibiting the cholesterol efflux ability by macrophages. To test this hypothesis, we treated human THP-1 macrophages with total lipoproteins that were hydrolyzed by LPL and we found significantly reduced transcript levels for the cholesterol transporters ATP binding cassette transporter A1 (ABCA1), ABCG1, and scavenger receptor BI. These decreases were likely due to significant reductions for the nuclear receptors liver-X-receptor-α, peroxisome proliferator activated receptor (PPAR)-α, and PPAR-γ. We prepared a mixture of free fatty acids (FFA) that represented the ratios of FFA species within lipoprotein hydrolysis products, and we found that the FFA mixture also significantly reduced cholesterol transporters and nuclear receptors. Finally, we tested the efflux of cholesterol from THP-1 macrophages to apolipoprotein A-I, and we found that the treatment of THP-1 macrophages with the FFA mixture significantly attenuated cholesterol efflux. Overall, these data show that the FFA component of lipoprotein hydrolysis products generated by LPL may promote atherogenesis by inhibiting cholesterol efflux, which partially explains the pro-atherogenic role of macrophage LPL.

Abnormalities in osteoclastogenesis and decreased tumorigenesis in mice deficient for ovarian cancer G protein-coupled receptor 1.

Directory of Open Access Journals (Sweden)

Hui Li

2009-05-01

Full Text Available Ovarian cancer G protein-coupled receptor 1 (OGR1 has been shown to be a proton sensing receptor in vitro. We have shown that OGR1 functions as a tumor metastasis suppressor gene when it is over-expressed in human prostate cancer cells in vivo. To examine the physiological functions of OGR1, we generated conditional OGR1 deficient mice by homologous recombination. OGR1 deficient mice were viable and upon gross-inspection appeared normal. Consistent with in vitro studies showing that OGR1 is involved in osteoclastogenesis, reduced osteoclasts were detected in OGR1 deficient mice. A pH-dependent osteoclasts survival effect was also observed. However, overall abnormality in the bones of these animals was not observed. In addition, melanoma cell tumorigenesis was significantly inhibited in OGR1 deficient mice. OGR1 deficient mice in the mixed background produced significantly less peritoneal macrophages when stimulated with thioglycolate. These macrophages also showed altered extracellular signal-regulated kinases (ERK activation and nitric oxide (NO production in response to lipopolysaccharide. OGR1-dependent pH responses assessed by cAMP production and cell survival in macrophages or brown fat cells were not observed, presumably due to the presence of other proton sensing receptors in these cells. Our results indicate that OGR1's role in osteoclastogenesis is not strong enough to affect overall bone development and its role in tumorigenesis warrants further investigation. The mice generated can be potentially used for several disease models, including cancers or osteoclast-related diseases.

Distinct functional domains contribute to degradation of the low density lipoprotein receptor (LDLR) by the E3 ubiquitin ligase inducible Degrader of the LDLR (IDOL)

NARCIS (Netherlands)

Sorrentino, Vincenzo; Scheer, Lilith; Santos, Ana; Reits, Eric; Bleijlevens, Boris; Zelcer, Noam

2011-01-01

We recently identified the liver X receptor-regulated E3 ubiquitin ligase inducible degrader of the LDL receptor (IDOL) as a modulator of lipoprotein metabolism. Acting as an E3 ubiquitin ligase, IDOL triggers ubiquitination and subsequent degradation of the low density lipoprotein receptor (LDLR).

Lectin-like oxidized low-density lipoprotein receptor-1 promotes endothelial dysfunction in LDL receptor knockout background.

Science.gov (United States)

Hofmann, Anja; Brunssen, Coy; Poitz, David M; Langbein, Heike; Strasser, Ruth H; Henle, Thomas; Ravens, Ursula; Morawietz, Henning

2017-11-01

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the major receptor for oxidized LDL in endothelial cells. LOX-1 is highly expressed in atherosclerotic plaques. The impact of LOX-1 on development of endothelial dysfunction in large vessels in absence or presence of atherosclerosis-prone conditions has not been studied to date. Mice with endothelial cell-specific LOX-1 overexpression (bLOX-1tg) were analyzed. Wild-type (WT) mice served as controls. In addition, bLOX-1tg mice were crossed with LDL receptor knockout (Ldlr -/- ) mice. All mice were fed a western-type diet (WD) or control diet (CD) for 20 weeks. Afterwards, endothelial function was analyzed ex vivo in thoracic aortas using a Mulvany myograph. WD induced hypertriglyceridemia (bLOX-1tg: 1.6-fold; WT: 1.4-fold) and hypercholesterolemia (P LDL-cholesterol (∼9-fold) compared to WT and bLOX-1tg mice on WD. Endothelial function in response to WD was impaired in bLOX-1tg/Ldlr -/- mice (Eff max : 56.7 ± 23.0%) compared to WT (Eff max : 88.2 ± 15.8%, P < 0.001), bLOX-1tg (Eff max : 76.7 ± 12.9%, P < 0.05) and Ldlr -/- mice (Eff max : 70.1 ± 13.1%, P < 0.05). No differences between WT, bLOX-1tg and Ldlr -/- mice were detectable when comparing all genotypes. Endothelial LOX-1 overexpression in an atherosclerosis-prone background impairs endothelial function, proving its importance in the development of atherosclerosis. Copyright © 2017 Elsevier B.V. All rights reserved.

Androgen and FSH synergistically stimulate lipoprotein degradation and utilization by ovary granulosa cells

International Nuclear Information System (INIS)

Schreiber, J.R.; Nakamura, K.; Schmit, V.; Weinstein, D.B.

1984-01-01

Androgen can directly modulate the induction of steroidogenic enzymes by FSH (follicle stimulating hormone) in ovary granulosa cells. In studies of its mechanism of action, the authors examined the androgen effect on granulosa cell interaction with lipoproteins, the physiologic source of cholesterol. After granulosa cells were cultured for 48 hours with and without androgen and/or FSH, the cells were incubated for 24 hours with 125 I-lipoproteins [human high density lipoprotein (HDL), rat HDL, or human low density lipoprotein (LDL)]. The media were then analyzed for lipoprotein protein coat degradation products (mainly 125 I-monoiodotyrosine) and progestin [mainly 20 alpha-dihydroprogesterone (20 alpha-DHP)]. In the absence of FSH and androgen, 2 X 10(5) granulosa cells degraded basal levels of all three lipoproteins, but produced no measurable 20 alpha-DHP. The addition of 10(-7) M androstenedione (A), testosterone (T), or 5 alpha-dihydrotestosterone (DHT) had no effect on lipoprotein protein degradation or 20 alpha-DHP production. FSH alone stimulated lipoprotein protein degradation by 50 to 300% while the addition of androgen synergistically augmented the FSH-stimulated 20 alpha-DHP production as well as protein coat degradation of all three lipoproteins. DHT and T were both effective, indicating that androgens themselves, and not estrogen products, were responsible for the effect on lipoprotein protein degradation and 20 alpha-DHP production

Degradation of high density lipoprotein in cultured rat luteal cells

International Nuclear Information System (INIS)

Rajan, V.P.; Menon, K.M.J.

1986-01-01

In rat ovary luteal cells, degradation of high density lipoprotein (HDL) to tricholoracetic acid (TCA)-soluble products accounts for only a fraction of the HDL-derived cholesterol used for steroidogenesis. In this study the authors have investigated the fate of 125 I]HDL bound to cultured luteal cells using pulse-chase technique. Luteal cell cultures were pulse labeled with [ 125 I]HDL 3 and reincubated in the absence of HDL. By 24 h about 50% of the initallay bound radioactivity was released into the medium, of which 60-65% could be precipitated with 10% TCA. Gel filtration of the chase incubation medium on 10% agarose showed that the amount of TCA-soluble radioactivity was nearly completely accounted for by a sharp peak in the low molecular weight region which was identified as 96% monoiodotyrosine by paper chromatography. The TCA-precipitable radioactivity was nearly completely accounted for by a sharp peak in the low molecular weight region which was identified as 96% monoiodotyrosine by paper chromatography. The TCA-precipitable radioactivity eluted over a wide range of molecular weights (15,000-80,000), and there was very little intact HDL present. Electrophoresis of the chase medium showed that component of the TCA-precipitable portion had mobility similar to apo AI. Lysosomal inhibitors of receptor-mediated endocytosis had no effect on the composition or quantity of radioactivity released during chase incubation. The results show that HDL 3 binding to luteal cells is followed by complete degradation of the lipoprotein, although the TCA-soluble part does not reflect the extent of degradation

Receptor-mediated uptake of low density lipoprotein stimulates bile acid synthesis by cultured rat hepatocytes

International Nuclear Information System (INIS)

Junker, L.H.; Davis, R.A.

1989-01-01

The cellular mechanisms responsible for the lipoprotein-mediated stimulation of bile acid synthesis in cultured rat hepatocytes were investigated. Adding 280 micrograms/ml of cholesterol in the form of human or rat low density lipoprotein (LDL) to the culture medium increased bile acid synthesis by 1.8- and 1.6-fold, respectively. As a result of the uptake of LDL, the synthesis of [14C]cholesterol from [2-14C]acetate was decreased and cellular cholesteryl ester mass was increased. Further studies demonstrated that rat apoE-free LDL and apoE-rich high density lipoprotein (HDL) both stimulated bile acid synthesis 1.5-fold, as well as inhibited the formation of [14C]cholesterol from [2-14C]acetate. Reductive methylation of LDL blocked the inhibition of cholesterol synthesis, as well as the stimulation of bile acid synthesis, suggesting that these processes require receptor-mediated uptake. To identify the receptors responsible, competitive binding studies using 125I-labeled apoE-free LDL and 125I-labeled apoE-rich HDL were performed. Both apoE-free LDL and apoE-rich HDL displayed an equal ability to compete for binding of the other, suggesting that a receptor or a group of receptors that recognizes both apolipoproteins is involved. Additional studies show that hepatocytes from cholestyramine-treated rats displayed 2.2- and 3.4-fold increases in the binding of apoE-free LDL and apoE-rich HDL, respectively. These data show for the first time that receptor-mediated uptake of LDL by the liver is intimately linked to processes activating bile acid synthesis

Choline Deficiency Causes Colonic Type II Natural Killer T (NKT) Cell Loss and Alleviates Murine Colitis under Type I NKT Cell Deficiency.

Science.gov (United States)

Sagami, Shintaro; Ueno, Yoshitaka; Tanaka, Shinji; Fujita, Akira; Niitsu, Hiroaki; Hayashi, Ryohei; Hyogo, Hideyuki; Hinoi, Takao; Kitadai, Yasuhiko; Chayama, Kazuaki

2017-01-01

Serum levels of choline and its derivatives are lower in patients with inflammatory bowel disease (IBD) than in healthy individuals. However, the effect of choline deficiency on the severity of colitis has not been investigated. In the present study, we investigated the role of choline deficiency in dextran sulfate sodium (DSS)-induced colitis in mice. Methionine-choline-deficient (MCD) diet lowered the levels of type II natural killer T (NKT) cells in the colonic lamina propria, peritoneal cavity, and mesenteric lymph nodes, and increased the levels of type II NKT cells in the livers of wild-type B6 mice compared with that in mice fed a control (CTR) diet. The gene expression pattern of the chemokine receptor CXCR6, which promotes NKT cell accumulation, varied between colon and liver in a manner dependent on the changes in the type II NKT cell levels. To examine the role of type II NKT cells in colitis under choline-deficient conditions, we assessed the severity of DSS-induced colitis in type I NKT cell-deficient (Jα18-/-) or type I and type II NKT cell-deficient (CD1d-/-) mice fed the MCD or CTR diets. The MCD diet led to amelioration of inflammation, decreases in interferon (IFN)-γ and interleukin (IL)-4 secretion, and a decrease in the number of IFN-γ and IL-4-producing NKT cells in Jα18-/- mice but not in CD1d-/- mice. Finally, adaptive transfer of lymphocytes with type II NKT cells exacerbated DSS-induced colitis in Jα18-/- mice with MCD diet. These results suggest that choline deficiency causes proinflammatory type II NKT cell loss and alleviates DSS-induced colitis. Thus, inflammation in DSS-induced colitis under choline deficiency is caused by type II NKT cell-dependent mechanisms, including decreased type II NKT cell and proinflammatory cytokine levels.

ZFAT plays critical roles in peripheral T cell homeostasis and its T cell receptor-mediated response

Energy Technology Data Exchange (ETDEWEB)

Doi, Keiko [Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka (Japan); Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka (Japan); Central Research Institute of Life Sciences for the Next Generation of Women Scientists, Fukuoka University, Fukuoka (Japan); Fujimoto, Takahiro [Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka (Japan); Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka (Japan); Okamura, Tadashi [Division of Animal Models, Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo (Japan); Ogawa, Masahiro [Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka (Japan); Tanaka, Yoko [Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka (Japan); Mototani, Yasumasa; Goto, Motohito [Division of Animal Models, Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo (Japan); Ota, Takeharu; Matsuzaki, Hiroshi [Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka (Japan); Kuroki, Masahide [Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka (Japan); Tsunoda, Toshiyuki [Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka (Japan); Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka (Japan); Sasazuki, Takehiko [Institute for Advanced Study, Kyushu University, Fukuoka (Japan); Shirasawa, Senji, E-mail: sshirasa@fukuoka-u.ac.jp [Department of Cell Biology, Faculty of Medicine, Fukuoka University, Fukuoka (Japan); Central Research Institute for Advanced Molecular Medicine, Fukuoka University, Fukuoka (Japan)

2012-08-17

Highlights: Black-Right-Pointing-Pointer We generated Cd4-Cre-mediated T cell-specific Zfat-deficient mice. Black-Right-Pointing-Pointer Zfat-deficiency leads to reduction in the number of the peripheral T cells. Black-Right-Pointing-Pointer Impaired T cell receptor-mediated response in Zfat-deficient peripheral T cells. Black-Right-Pointing-Pointer Decreased expression of IL-7R{alpha}, IL-2R{alpha} and IL-2 in Zfat-deficient peripheral T cells. Black-Right-Pointing-Pointer Zfat plays critical roles in peripheral T cell homeostasis. -- Abstract: ZFAT, originally identified as a candidate susceptibility gene for autoimmune thyroid disease, has been reported to be involved in apoptosis, development and primitive hematopoiesis. Zfat is highly expressed in T- and B-cells in the lymphoid tissues, however, its physiological function in the immune system remains totally unknown. Here, we generated the T cell-specific Zfat-deficient mice and demonstrated that Zfat-deficiency leads to a remarkable reduction in the number of the peripheral T cells. Intriguingly, a reduced expression of IL-7R{alpha} and the impaired responsiveness to IL-7 for the survival were observed in the Zfat-deficient T cells. Furthermore, a severe defect in proliferation and increased apoptosis in the Zfat-deficient T cells following T cell receptor (TCR) stimulation was observed with a reduced IL-2R{alpha} expression as well as a reduced IL-2 production. Thus, our findings reveal that Zfat is a critical regulator in peripheral T cell homeostasis and its TCR-mediated response.

A novel method to generate T-cell receptor-deficient chimeric antigen receptor T cells.

Science.gov (United States)

Kamiya, Takahiro; Wong, Desmond; Png, Yi Tian; Campana, Dario

2018-03-13

Practical methods are needed to increase the applicability and efficacy of chimeric antigen receptor (CAR) T-cell therapies. Using donor-derived CAR-T cells is attractive, but expression of endogenous T-cell receptors (TCRs) carries the risk for graft-versus-host-disease (GVHD). To remove surface TCRαβ, we combined an antibody-derived single-chain variable fragment specific for CD3ε with 21 different amino acid sequences predicted to retain it intracellularly. After transduction in T cells, several of these protein expression blockers (PEBLs) colocalized intracellularly with CD3ε, blocking surface CD3 and TCRαβ expression. In 25 experiments, median TCRαβ expression in T lymphocytes was reduced from 95.7% to 25.0%; CD3/TCRαβ cell depletion yielded virtually pure TCRαβ-negative T cells. Anti-CD3ε PEBLs abrogated TCRαβ-mediated signaling, without affecting immunophenotype or proliferation. In anti-CD3ε PEBL-T cells, expression of an anti-CD19-41BB-CD3ζ CAR induced cytokine secretion, long-term proliferation, and CD19 + leukemia cell killing, at rates meeting or exceeding those of CAR-T cells with normal CD3/TCRαβ expression. In immunodeficient mice, anti-CD3ε PEBL-T cells had markedly reduced GVHD potential; when transduced with anti-CD19 CAR, these T cells killed engrafted leukemic cells. PEBL blockade of surface CD3/TCRαβ expression is an effective tool to prepare allogeneic CAR-T cells. Combined PEBL and CAR expression can be achieved in a single-step procedure, is easily adaptable to current cell manufacturing protocols, and can be used to target other T-cell molecules to further enhance CAR-T-cell therapies. © 2018 by The American Society of Hematology.

Activated α2 -Macroglobulin Induces Mesenchymal Cellular Migration Of Raw264.7 Cells Through Low-Density Lipoprotein Receptor-Related Protein 1.

Science.gov (United States)

Ferrer, Darío G; Dato, Virginia Actis; Fincati, Javier R Jaldín; Lorenc, Valeria E; Sánchez, María C; Chiabrando, Gustavo A

2017-07-01

Distinct modes of cell migration contribute to diverse types of cell movements. The mesenchymal mode is characterized by a multistep cycle of membrane protrusion, the formation of focal adhesion, and the stabilization at the leading edge associated with the degradation of extracellular matrix (ECM) components and with regulated extracellular proteolysis. Both α 2 -Macroglobulin (α 2 M) and its receptor, low density lipoprotein receptor-related protein 1 (LRP1), play important roles in inflammatory processes, by controlling the extracellular activity of several proteases. The binding of the active form of α 2 M (α 2 M*) to LRP1 can also activate different signaling pathways in macrophages, thus inducing extracellular matrix metalloproteinase-9 (MMP-9) activation and cellular proliferation. In the present study, we investigated whether the α 2 M*/LRP1 interaction induces cellular migration of the macrophage-derived cell line, Raw264.7. By using the wound-scratch migration assay and confocal microscopy, we demonstrate that α 2 M* induces LRP1-mediated mesenchymal cellular migration. This migration exhibits the production of enlarged cellular protrusions, MT1-MMP distribution to these leading edge protrusions, actin polymerization, focal adhesion formation, and increased intracellular LRP1/β1-integrin colocalization. Moreover, the presence of calphostin-C blocked the α 2 M*-stimulated cellular protrusions, suggesting that the PKC activation is involved in the cellular motility of Raw264.7 cells. These findings could constitute a therapeutic target for inflammatory processes with deleterious consequences for human health, such as rheumatoid arthritis, atherosclerosis and cancer. J. Cell. Biochem. 118: 1810-1818, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Selective uptake of a toxic lipophilic anthracycline derivative by the low-density lipoprotein receptor pathway in cultured fibroblasts

International Nuclear Information System (INIS)

Vitols, S.G.; Masquelier, M.; Peterson, C.O.

1985-01-01

N-(N-Retinoyl)-L-leucyldoxorubicin 14-linoleate (r11-DOX), a new lipophilic derivative of doxorubicin, was synthesized and incorporated into low-density lipoprotein (LDL). The drug-LDL complex contained 100- 200 drug molecules/LDL particle. When cultured normal human fibroblasts were incubated with 125 I-LDL-incorporated drug, there was a perfect correlation between the cellular uptake plus degradation of 125 I-LDL and the cellular drug accumulation. The presence of excess native LDL inhibited the cellular uptake and degradation of 125 I-LDL and the drug accumulation to the same extent. In contrast, methylated LDL, which does not bind to the LDL receptor, did not alter the cellular uptake and degradation of 125 I-LDL nor did it alter the drug accumulation. When LDL receptor negative fibroblasts from a patient with the homozygous form of familial hypercholesterolemia were incubated with the drug- 125 I-LDL complex, cellular drug accumulation was very low. The drug-LDL complex inhibited the growth of cultured normal human fibroblasts. The drug incorporated into methylated LDL was much less toxic. These findings suggest that r11-DOX incorporated into LDL is delivered to cells selectively by the LDL receptor pathway. This might be of value in the treatment of leukemia, since it has been previously found that leukemic cells exhibit higher LDL receptor activity than white blood cells and bone marrow cells from healthy subjects

Cholesterol efflux from THP-1 macrophages is impaired by the fatty acid component from lipoprotein hydrolysis by lipoprotein lipase.

Science.gov (United States)

Yang, Yanbo; Thyagarajan, Narmadaa; Coady, Breanne M; Brown, Robert J

2014-09-05

Lipoprotein lipase (LPL) is an extracellular lipase that primarily hydrolyzes triglycerides within circulating lipoproteins. Macrophage LPL contributes to atherogenesis, but the mechanisms behind it are poorly understood. We hypothesized that the products of lipoprotein hydrolysis generated by LPL promote atherogenesis by inhibiting the cholesterol efflux ability by macrophages. To test this hypothesis, we treated human THP-1 macrophages with total lipoproteins that were hydrolyzed by LPL and we found significantly reduced transcript levels for the cholesterol transporters ATP binding cassette transporter A1 (ABCA1), ABCG1, and scavenger receptor BI. These decreases were likely due to significant reductions for the nuclear receptors liver-X-receptor-α, peroxisome proliferator activated receptor (PPAR)-α, and PPAR-γ. We prepared a mixture of free fatty acids (FFA) that represented the ratios of FFA species within lipoprotein hydrolysis products, and we found that the FFA mixture also significantly reduced cholesterol transporters and nuclear receptors. Finally, we tested the efflux of cholesterol from THP-1 macrophages to apolipoprotein A-I, and we found that the treatment of THP-1 macrophages with the FFA mixture significantly attenuated cholesterol efflux. Overall, these data show that the FFA component of lipoprotein hydrolysis products generated by LPL may promote atherogenesis by inhibiting cholesterol efflux, which partially explains the pro-atherogenic role of macrophage LPL. Copyright © 2014 Elsevier Inc. All rights reserved.

Staphylococcus aureus lipoproteins trigger human corneal epithelial innate response through toll-like receptor-2

OpenAIRE

Li, Qiong; Kumar, Ashok; Gui, Jian-Fang; Yu, Fu-Shin X.

2007-01-01

Bacterial lipoproteins (LP) are a family of cell wall components found in a wide variety of bacteria. In this study, we characterized the response of HUCL, a telomerase-immortalized human corneal epithelial cell (HCEC) line, to LP isolated from Staphylococcus (S) aureus. S. aureus LP (saLP) prepared by Triton X-114 extraction stimulated the activation of NF-κB, JNK, and P38 signaling pathways in HUCL cells. The extracts failed to stimulate NF-κB activation in HUCL cells after lipoprotein lipa...

Characterization of a family of gamma-ray-induced CHO mutants demonstrates that the ldlA locus is diploid and encodes the low-density lipoprotein receptor

International Nuclear Information System (INIS)

Sege, R.D.; Kozarsky, K.F.; Krieger, M.

1986-01-01

The ldlA locus is one of four Chinese hamster ovary (CHO) cell loci which are known to be required for the synthesis of functional low-density lipoprotein (LDL) receptors. Previous studies have suggested that the ldlA locus is diploid and encodes the LDL receptor. To confirm this assignment, we have isolated a partial genomic clone of the Chinese hamster LDL receptor gene and used this and other nucleic acid and antibody probes to study a family of ldlA mutants isolated after gamma-irradiation. Our analysis suggests that there are two LDL receptor alleles in wild-type CHO cells. Each of the three mutants isolated after gamma-irradiation had detectable deletions affecting one of the two LDL receptor alleles. One of the mutants also had a disruption of the remaining allele, resulting in the synthesis of an abnormal receptor precursor which was not subject to Golgi-associated posttranslational glycoprotein processing. The correlation of changes in the expression, structure, and function of LDL receptors with deletions in the LDL receptor genes in these mutants directly demonstrated that the ldlA locus in CHO cells is diploid and encodes the LDL receptor. In addition, our analysis suggests that CHO cells in culture may contain a partial LDL receptor pseudogene

Down-regulation of lipoprotein lipase increases glucose uptake in L6 muscle cells

Energy Technology Data Exchange (ETDEWEB)

Lopez, Veronica; Saraff, Kumuda [Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262 (United States); Medh, Jheem D., E-mail: jheem.medh@csun.edu [Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262 (United States)

2009-11-06

Thiazolidinediones (TZDs) are synthetic hypoglycemic agents used to treat type 2 diabetes. TZDs target the peroxisome proliferator activated receptor-gamma (PPAR-{gamma}) and improve systemic insulin sensitivity. The contributions of specific tissues to TZD action, or the downstream effects of PPAR-{gamma} activation, are not very clear. We have used a rat skeletal muscle cell line (L6 cells) to demonstrate that TZDs directly target PPAR-{gamma} in muscle cells. TZD treatment resulted in a significant repression of lipoprotein lipase (LPL) expression in L6 cells. This repression correlated with an increase in glucose uptake. Down-regulation of LPL message and protein levels using siRNA resulted in a similar increase in insulin-dependent glucose uptake. Thus, LPL down-regulation improved insulin sensitivity independent of TZDs. This finding provides a novel method for the management of insulin resistance.

Proteinase-Activated Receptor 1 (PAR1 regulates leukemic stem cell functions.

Directory of Open Access Journals (Sweden)

Nicole Bäumer

Full Text Available External signals that are mediated by specific receptors determine stem cell fate. The thrombin receptor PAR1 plays an important role in haemostasis, thrombosis and vascular biology, but also in tumor biology and angiogenesis. Its expression and function in hematopoietic stem cells is largely unknown. Here, we analyzed expression and function of PAR1 in primary hematopoietic cells and their leukemic counterparts. AML patients' blast cells expressed much lower levels of PAR1 mRNA and protein than CD34+ progenitor cells. Constitutive Par1-deficiency in adult mice did not affect engraftment or stem cell potential of hematopoietic cells. To model an AML with Par1-deficiency, we retrovirally introduced the oncogene MLL-AF9 in wild type and Par1-/- hematopoietic progenitor cells. Par1-deficiency did not alter initial leukemia development. However, the loss of Par1 enhanced leukemic stem cell function in vitro and in vivo. Re-expression of PAR1 in Par1-/- leukemic stem cells delayed leukemogenesis in vivo. These data indicate that Par1 contributes to leukemic stem cell maintenance.

Proteinase-Activated Receptor 1 (PAR1) regulates leukemic stem cell functions.

Science.gov (United States)

Bäumer, Nicole; Krause, Annika; Köhler, Gabriele; Lettermann, Stephanie; Evers, Georg; Hascher, Antje; Bäumer, Sebastian; Berdel, Wolfgang E; Müller-Tidow, Carsten; Tickenbrock, Lara

2014-01-01

External signals that are mediated by specific receptors determine stem cell fate. The thrombin receptor PAR1 plays an important role in haemostasis, thrombosis and vascular biology, but also in tumor biology and angiogenesis. Its expression and function in hematopoietic stem cells is largely unknown. Here, we analyzed expression and function of PAR1 in primary hematopoietic cells and their leukemic counterparts. AML patients' blast cells expressed much lower levels of PAR1 mRNA and protein than CD34+ progenitor cells. Constitutive Par1-deficiency in adult mice did not affect engraftment or stem cell potential of hematopoietic cells. To model an AML with Par1-deficiency, we retrovirally introduced the oncogene MLL-AF9 in wild type and Par1-/- hematopoietic progenitor cells. Par1-deficiency did not alter initial leukemia development. However, the loss of Par1 enhanced leukemic stem cell function in vitro and in vivo. Re-expression of PAR1 in Par1-/- leukemic stem cells delayed leukemogenesis in vivo. These data indicate that Par1 contributes to leukemic stem cell maintenance.

The role of TLR2 and bacterial lipoprotein in enhancing airway inflammation and immunity

Directory of Open Access Journals (Sweden)

Amit A Lugade

2011-04-01

Full Text Available Non-typeable Haemophilus influenzae (NTHI colonizes the lower respiratory tract of patients with chronic obstructive pulmonary disease (COPD and also causes exacerbations of the disease. The 16-kDa lipoprotein P6 has been widely studied as a potential vaccine antigen due to its highly conserved expression amongst NTHI strains. Although P6 is known to induce potent inflammatory responses, its role in the pathogenesis of NTHI infection in vivo has not been examined. Additionally, the presence of an amino-terminal lipid motif on P6 serves to activate host TLR2 signaling. The role of host Toll-like receptor 2 (TLR2 and NTHI expression of the lipoprotein P6 on the induction of airway inflammation and generation of adaptive immune responses following chronic NTHI stimulation was evaluated with TLR2-deficient mice and a P6-deficient NTHI strain. Absence of either host TLR2 or bacterial P6 resulted in diminished levels of immune cell infiltration within lungs of mice exposed to NTHI. Pro-inflammatory cytokine secretion was also reduced in lungs that did not express TLR2 or were exposed to NTHI devoid of P6. Induction of specific antibodies to P6 was severely limited in TLR2-deficient mice. Although mice exposed to the P6-deficient NTHI strain were capable of generating antibodies to other surface antigens of NTHI, these levels were lower compared to those observed in mice exposed to P6-expressing NTHI. Therefore, cognate interaction between host TLR2 and bacterial P6 serves to enhance lung inflammation and elicit robust adaptive immune responses during NTHI exposure. Strategies to limit NTHI inflammation while simultaneously promoting robust immune responses may benefit from targeting the TLR2:P6 signaling axis.

Interaction of estradiol and high density lipoproteins on proliferation of the human breast cancer cell line MCF-7 adapted to grow in serum free conditions

International Nuclear Information System (INIS)

Jozan, S.; Faye, J.C.; Tournier, J.F.; Tauber, J.P.; David, J.F.; Bayard, F.

1985-01-01

The responsiveness of the human mammary carcinoma cell line MCF-7 to estradiol and tamoxifen treatment has been studied in different culture conditions. Cells from exponentially growing cultures were compared with cells in their initial cycles after replating from confluent cultures (''confluent-log'' cells). It has been observed that estradiol stimulation of tritiated thymidine incorporation decreases with cell density and that ''confluent-log'' cells are estrogen unresponsive for a period of four cell cycles in serum-free medium conditions. On the other hand, growth of cells replated from exponentially growing, as well as from confluent cultures, can be inhibited by tamoxifen or a combined treatment with tamoxifen and the progestin levonorgestrel. This growth inhibitory effect can be rescued by estradiol when cells are replated from exponentially growing cultures. The growth inhibitory effect cannot be rescued by estradiol alone (10(-10) to 10(-8) M) when cells are replated from confluent cultures. In this condition, the addition of steroid depleted serum is necessary to reverse the state of estradiol unresponsiveness. Serum can be replaced by high density lipoproteins but not by low density lipoproteins or lipoprotein deficient serum. The present data show that estradiol and HDL interact in the control of MCF-7 cell proliferation

DMPD: Lipoprotein trafficking in vascular cells. Molecular Trojan horses and cellularsaboteurs. [Dynamic Macrophage Pathway CSML Database

Lifescience Database Archive (English)

Full Text Available 9287290 Lipoprotein trafficking in vascular cells. Molecular Trojan horses and cell...ml) Show Lipoprotein trafficking in vascular cells. Molecular Trojan horses and cellularsaboteurs. PubmedID ...9287290 Title Lipoprotein trafficking in vascular cells. Molecular Trojan horses

Decreased autophosphorylation of EGF receptor in insulin-deficient diabetic rats

International Nuclear Information System (INIS)

Okamoto, M.; Kahn, C.R.; Maron, R.; White, M.F.

1988-01-01

The authors have previously reported that despite an increase in receptor concentration, there is a decrease in autophosphorylation and tyrosine kinase activity of the insulin receptor in insulin-deficient diabetic rats. To determine if other tyrosine kinases might be altered, they have studied the epidermal growth factor (EGF) receptor kinase in wheat germ agglutinin-purified, Triton X-100-solubilized liver membranes from streptozotocin (STZ)-induced diabetic rats and the insulin-deficient BB rat. They find that autophosphorylation of EGF receptor is decreased in proportion to the severity of the diabetic state in STZ rats with a maximal decrease of 67%. A similar decrease in autophosphorylation was observed in diabetic BB rats that was partially normalized by insulin treatment. Separation of tryptic phosphopeptides by reverse-phase high-performance liquid chromatography revealed a decrease in labeling at all sites of autophosphorylation. A parallel decrease in EGF receptor phosphorylation was also found by immunoblotting with an antiphosphotyrosine antibody. EGF receptor concentration, determined by Scatchard analysis of 125 I-labeled EGF binding, was decreased by 39% in the STZ rat and 27% in the diabetic BB rat. Thus autophosphorylation of EGF receptor, like that of the insulin receptor, is decreased in insulin-deficient rat liver. In the case of EGF receptor, this is due in part to a decrease in receptor number and in part to a decrease in the specific activity of the kinase

CRF1 receptor-deficiency increases cocaine reward.

Science.gov (United States)

Contarino, Angelo; Kitchener, Pierre; Vallée, Monique; Papaleo, Francesco; Piazza, Pier-Vincenzo

2017-05-01

Stimulant drugs produce reward but also activate stress-responsive systems. The corticotropin-releasing factor (CRF) and the related hypothalamus-pituitary-adrenal (HPA) axis stress-responsive systems are activated by stimulant drugs. However, their role in stimulant drug-induced reward remains poorly understood. Herein, we report that CRF 1 receptor-deficient (CRF 1 -/-), but not wild-type, mice show conditioned place preference (CPP) responses to a relatively low cocaine dose (5 mg/kg, i.p.). Conversely, wild-type, but not CRF 1 -/-, mice display CPP responses to a relatively high cocaine dose (20 mg/kg, i.p.), indicating that CRF 1 receptor-deficiency alters the rewarding effects of cocaine. Acute pharmacological antagonism of the CRF 1 receptor by antalarmin also eliminates cocaine reward. Nevertheless, CRF 1 -/- mice display higher stereotypy responses to cocaine than wild-type mice. Despite the very low plasma corticosterone concentration, CRF 1 -/- mice show higher nuclear glucocorticoid receptor (GR) levels in the brain region of the hippocampus than wild-type mice. Full rescue of wild-type-like corticosterone and GR circadian rhythm and level in CRF 1 -/- mice by exogenous corticosterone does not affect CRF 1 receptor-dependent cocaine reward but induces stereotypy responses to cocaine. These results indicate a critical role for the CRF 1 receptor in cocaine reward, independently of the closely related HPA axis activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Association of peroxisome proliferator-activated receptor single-nucleotide polymorphisms and gene-gene interactions with the lipoprotein(a)

Institute of Scientific and Technical Information of China (English)

解惠坚

2014-01-01

Objective To examine the associations of 10 singlenucleotide polymorphisms(SNPs)in peroxisome proliferator-activated receptor(PPARs)gene with lipoprotein(a)level,and to investigate if there is gene-gene interaction among the SNPs on lipoprotein(a)level.Methods Totally 644 subjects(234 men and 410 women)were enrolled from Prevention of Multiple Metabolic Disorders and Metabolic Syndrome Study Cohort,which was an urban community survey study conducted in Jiangsu province.Ten SNPs in PPARα(rs135539,rs4253778,

High-density lipoprotein is a potential growth factor for adrenocortical cells

International Nuclear Information System (INIS)

Murao, Koji; Imachi, Hitomi; Cao, Wenming; Yu, Xiao; Li, Junhua; Yoshida, Kazuya; Ahmed, Rania A.M.; Matsumoto, Kensuke; Nishiuchi, Takamasa; Wong, Norman C.W.; Ishida, Toshihiko

2006-01-01

The entry of cholesterol contained within high-density lipoprotein (HDL) into adrenocortical cells is mediated by a human homologue of SR-BI, CD36, and LIMPII Analogous-1 (CLA-1) and thus augmenting their growth. To address the role of CLA-1, we created a mutant mCLA that lacked the C-terminal tail. HDL CE selective uptake by cells carrying the mCLA-1 receptor was fully active and equivalent to those transfected with full-length CLA-1 (fCLA-1). Expression of mCLA inhibited the proliferation of an adrenocortical cell line and the incorporation of [ 3 H]thymidine into the cells. This effect was sensitive to wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K). Our transcriptional studies revealed that the inhibitory action of mCLA required the transcriptional factor AP-1 and the effect of HDL on AP-1 activation was also abrogated by wortmannin. These findings raise the possibility that the inhibitors of the effects of HDL may be of therapeutic value for adrenocortical tumor

Synthetic Nano-Low Density Lipoprotein as Targeted Drug DeliveryVehicle for Glioblastoma Multiforme

Energy Technology Data Exchange (ETDEWEB)

Nikanjam, Mina; Blakely, Eleanor A.; Bjornstad, Kathleen A.; Shu,Xiao; Budinger, Thomas F.; Forte, Trudy M.

2006-06-14

This paper discribes a synthetic low density lipoprotein(LDL) made by complexing a 29 amino acid that consists of a lipid bindingdomain and the LDL receptor binding domain with a lipid microemulsion.The nano-LDL particles were intermdiate in size between LDL and HDL andbound to LDL receptors on GBM brain tumor cells. Synthetic nano-LDLuptake by GBM cells was LDL receptor specific and dependent on cellreceptor number. It is suggested that these synthetic particles can serveas a delivery vehicle for hydophobic anti-tumor drugs by targeting theLDL receptor.

Facial morphometry of Ecuadorian patients with growth hormone receptor deficiency/Laron syndrome.

Science.gov (United States)

Schaefer, G B; Rosenbloom, A L; Guevara-Aguirre, J; Campbell, E A; Ullrich, F; Patil, K; Frias, J L

1994-01-01

Facial morphometry using computerised image analysis was performed on patients with growth hormone receptor deficiency (Laron syndrome) from an inbred population of southern Ecuador. Morphometrics were compared for 49 patients, 70 unaffected relatives, and 14 unrelated persons. Patients with growth hormone receptor deficiency showed significant decreases in measures of vertical facial growth as compared to unaffected relatives and unrelated persons with short stature from other causes. This report validates and quantifies the clinical impression of foreshortened facies in growth hormone receptor deficiency. Images PMID:7815422

Low density lipoproteins mediated nanoplatforms for cancer targeting

International Nuclear Information System (INIS)

Jain, Anupriya; Jain, Keerti; Kesharwani, Prashant; Jain, Narendra K.

2013-01-01

Chemotherapy is a foremost remedial approach for the treatment of localized and metastasized tumors. In order to explore new treatment modalities for cancer, it is important to identify qualitative or quantitative differences in metabolic processes between normal and malignant cells. One such difference may be that of increased receptor-mediated cellular uptake of low density lipoproteins (LDLs) by cancer cells. Lipoproteins in general and specifically LDL are ideal candidates for loading and delivering cancer therapeutic and diagnostic agents due to their biocompatibility. By mimicking the endogenous shape and structure of lipoproteins, the reconstituted lipoproteins can remain in circulation for an extended period of time, while largely evading the reticuloendothelial cells in the body’s defenses. In this account, we review the field of low density inspired nanoparticles in relation to the delivery of cancer imaging and therapeutic agents. LDL has instinctive cancer targeting potential and has been used to incorporate various lipophillic molecules to transport them to tumors. Nature’s method of rerouting LDL provides a strategy to extend the cancer targeting potential of lipoproteins far off its constricted purview. In this review, we have discussed the various aspects of LDL including its role in cancer imaging and chemotherapy in retrospect and prospect and current efforts aimed to further improve the delivery efficacy of LDL–drug complexes with reduced chances of drug resistance leading to optimal drug delivery. This review provides a strong support for the concept of using LDL as a drug carrier

Low density lipoproteins mediated nanoplatforms for cancer targeting

Energy Technology Data Exchange (ETDEWEB)

Jain, Anupriya; Jain, Keerti; Kesharwani, Prashant, E-mail: prashant_pharmacy04@rediffmail.com; Jain, Narendra K., E-mail: jnarendr@yahoo.co.in [Dr. H. S. Gour University, Pharmaceutics Research Laboratory, Department of Pharmaceutical Sciences (India)

2013-09-15

Chemotherapy is a foremost remedial approach for the treatment of localized and metastasized tumors. In order to explore new treatment modalities for cancer, it is important to identify qualitative or quantitative differences in metabolic processes between normal and malignant cells. One such difference may be that of increased receptor-mediated cellular uptake of low density lipoproteins (LDLs) by cancer cells. Lipoproteins in general and specifically LDL are ideal candidates for loading and delivering cancer therapeutic and diagnostic agents due to their biocompatibility. By mimicking the endogenous shape and structure of lipoproteins, the reconstituted lipoproteins can remain in circulation for an extended period of time, while largely evading the reticuloendothelial cells in the body's defenses. In this account, we review the field of low density inspired nanoparticles in relation to the delivery of cancer imaging and therapeutic agents. LDL has instinctive cancer targeting potential and has been used to incorporate various lipophillic molecules to transport them to tumors. Nature's method of rerouting LDL provides a strategy to extend the cancer targeting potential of lipoproteins far off its constricted purview. In this review, we have discussed the various aspects of LDL including its role in cancer imaging and chemotherapy in retrospect and prospect and current efforts aimed to further improve the delivery efficacy of LDL-drug complexes with reduced chances of drug resistance leading to optimal drug delivery. This review provides a strong support for the concept of using LDL as a drug carrier.

Low density lipoproteins mediated nanoplatforms for cancer targeting

Science.gov (United States)

Jain, Anupriya; Jain, Keerti; Kesharwani, Prashant; Jain, Narendra K.

2013-09-01

Chemotherapy is a foremost remedial approach for the treatment of localized and metastasized tumors. In order to explore new treatment modalities for cancer, it is important to identify qualitative or quantitative differences in metabolic processes between normal and malignant cells. One such difference may be that of increased receptor-mediated cellular uptake of low density lipoproteins (LDLs) by cancer cells. Lipoproteins in general and specifically LDL are ideal candidates for loading and delivering cancer therapeutic and diagnostic agents due to their biocompatibility. By mimicking the endogenous shape and structure of lipoproteins, the reconstituted lipoproteins can remain in circulation for an extended period of time, while largely evading the reticuloendothelial cells in the body's defenses. In this account, we review the field of low density inspired nanoparticles in relation to the delivery of cancer imaging and therapeutic agents. LDL has instinctive cancer targeting potential and has been used to incorporate various lipophillic molecules to transport them to tumors. Nature's method of rerouting LDL provides a strategy to extend the cancer targeting potential of lipoproteins far off its constricted purview. In this review, we have discussed the various aspects of LDL including its role in cancer imaging and chemotherapy in retrospect and prospect and current efforts aimed to further improve the delivery efficacy of LDL-drug complexes with reduced chances of drug resistance leading to optimal drug delivery. This review provides a strong support for the concept of using LDL as a drug carrier.

NADPH oxidase 1 deficiency alters caveolin phosphorylation and angiotensin II-receptor localization in vascular smooth muscle.

Science.gov (United States)

Basset, Olivier; Deffert, Christine; Foti, Michelangelo; Bedard, Karen; Jaquet, Vincent; Ogier-Denis, Eric; Krause, Karl-Heinz

2009-10-01

The superoxide-generating NADPH oxidase NOX1 is thought to be involved in signaling by the angiotensin II-receptor AT1R. However, underlying signaling steps are poorly understood. In this study, we investigated the effect of AngII on aortic smooth muscle from wild-type and NOX1-deficient mice. NOX1-deficient cells showed decreased basal ROS generation and did not produce ROS in response to AngII. Unexpectedly, AngII-dependent Ca(2+) signaling was markedly decreased in NOX1-deficient cells. Immunostaining demonstrated that AT1R was localized on the plasma membrane in wild-type, but intracellularly in NOX1-deficient cells. Immunohistochemistry and immunoblotting showed a decreased expression of AT1R in the aorta of NOX1-deficient mice. To investigate the basis of the abnormal AT1R targeting, we studied caveolin expression and phosphorylation. The amounts of total caveolin and of caveolae were not different in NOX1-deficient mice, but a marked decrease occurred in the phosphorylated form of caveolin. Exogenous H(2)O(2) or transfection of a NOX1 plasmid restored AngII responses in NOX1-deficient cells. Based on these findings, we propose that NOX1-derived reactive oxygen species regulate cell-surface expression of AT1R through mechanisms including caveolin phosphorylation. The lack cell-surface AT1R expression in smooth muscle could be involved in the decreased blood pressure in NOX1-deficient mice.

[The Relationship Study between Expressions of P2X5 Receptor and Deficiency-cold Syndrome/Deficiency-heat Syndrome at Various Ambient Temperatures].

Science.gov (United States)

Yang, Li-ping; Yu, Hong-jie; Huang, Rui; Li, Xin-min; Zhan, Xiang-hong; Hou, Jun-lin

2015-05-01

To detect the expression of the peripheral blood P2X5 receptor at various ambient temperatures, and to explore its relationship with deficiency-cold syndrome and deficiency-heat syndrome. Subjects were selected by questionnaire and expert diagnosis, and assigned to the normal control group, the deficiency-cold syndrome group, and the deficiency-heat syndrome group, 20 in each group. 5 mL venous blood was collected at room temperature (25 °C) and cold temperature (-4-5 °C) respectively. Then the expression of P2X5 receptor was relatively quantified by real-time fluorescence quantitative PCR, and compared at room temperature and cold temperature respectively. The expression of P2X5 receptor in deficiency-cold syndrome and deficiency-heat syndrome groups was lower than that in the normal control group at room temperature (P cold temperature in the deficiency-cold syndrome group than in the normal control group (P receptor showed no difference in all groups at two different temperatures (P > 0.05). The expression of P2X5 receptor was different in different syndrome groups at various ambient temperatures. Ambient temperatures had insignificant effect on the expression of P2X5 receptor of the population with the same syndrome.

Peroxisome Proliferator Activated Receptors and Lipoprotein Metabolism

NARCIS (Netherlands)

Kersten, A.H.

2008-01-01

Plasma lipoproteins are responsible for carrying triglycerides and cholesterol in the blood and ensuring their delivery to target organs. Regulation of lipoprotein metabolism takes place at numerous levels including via changes in gene transcription. An important group of transcription factors that

The effect of insulin deficiency on the plasma clearance and exchange of high-density-lipoprotein phosphatidylcholine in rats.

OpenAIRE

Martins, I J; Redgrave, T G

1992-01-01

Triolein/cholesteryl oleate/cholesterol/phosphatidylcholine emulsions designed to model the lipid composition of chylomicrons were injected intravenously into control and streptozotocin-treated insulin-deficient rats. As previously described for lymph chylomicrons, the emulsion triolein was hydrolysed and phosphatidylcholine was transferred to the plasma high-density lipoproteins (HDL). This mechanism was used to introduce a phospholipid label into HDL in vivo. The subsequent clearance of pho...

Interleukin-21 receptor deficiency increases the initial toll-like receptor 2 response but protects against joint pathology by reducing Th1 and Th17 cells during streptococcal cell wall arthritis.

Science.gov (United States)

Marijnissen, Renoud J; Roeleveld, Debbie M; Young, Deborah; Nickerson-Nutter, Cheryl; Abdollahi-Roodsaz, Shahla; Garcia de Aquino, Sabrina; van de Loo, Fons A J; van Spriel, Annemiek B; Boots, Annemieke M H; van den Berg, Wim B; Koenders, Marije I

2014-04-01

The cytokine interleukin-21 (IL-21) can have both proinflammatory and immunosuppressive effects. The purpose of this study was to investigate the potential dual role of IL-21 in experimental arthritis in relation to Th17 cells. Antigen-induced arthritis (AIA) and chronic streptococcal cell wall (SCW) arthritis were induced in IL-21 receptor-deficient (IL-21R(-/-) ) and wild-type mice. Knee joints, synovial tissue, and serum were analyzed for arthritis pathology and inflammatory markers. During AIA and chronic SCW arthritis, IL-21R deficiency protected against severe inflammation and joint destruction. This was accompanied by suppressed serum IgG1 levels and antigen-specific T cell responses. Levels of IL-17 were reduced during AIA, and synovial lymphocytes isolated during SCW arthritis for flow cytometry demonstrated that mainly IL-17+ interferon-γ (IFNγ)-positive T cells were reduced in IL-21R(-/-) mice. However, during the acute phases of SCW arthritis, significantly higher joint swelling scores were observed, consistent with enhanced tumor necrosis factor and IL-6 expression. Interestingly, IL-21R(-/-) mice were significantly less capable of up-regulating suppressor of cytokine signaling 1 (SOCS-1) and SOCS-3 messenger RNA. IL-21 stimulation also affected the Toll-like receptor 2 (TLR-2)/caspase recruitment domain 15 response to SCW fragments in vitro, indicating that impaired SOCS regulation in the absence of IL-21 signaling might contribute to the increased local activation during SCW arthritis. In contrast to the proinflammatory role of IL-21 in adaptive immunity, which drives IL-17+IFN+ cells and joint pathology during chronic experimental arthritis, IL-21 also has an important immunosuppressive role, presumably by inhibiting TLR signaling via SOCS-1 and SOCS-3. If this dual role of IL-21 in various immune processes is present in human disease, it could make IL-21 a difficult therapeutic target in rheumatoid arthritis. Copyright © 2014 by the American

Silenced B-Cell Receptor Response To Autoantigen In A Poor-Prognostic Subset Of Chronic Lymphocytic Leukemia

DEFF Research Database (Denmark)

Bergh, Ann-Charlotte; Evaldsson, Chamilly; Pedersen, Lone Bredo

2014-01-01

Chronic lymphocytic leukemia B cells express auto/xeno antigen-reactive antibodies that bind to self-epitopes and resemble natural IgM antibodies in their repertoire. One of the antigenic structures recognized is oxidation-induced malonedialdehyde that is present on low-density lipoprotein......-cell receptor unresponsiveness to cognate self-antigen on its own in poor-prognostic subset #1 chronic lymphocytic leukemia, indicating that these cells proliferate by other mechanisms that may override B-cell receptor silencing brought about in a context of self-tolerance/anergy. These novel findings have...

Caenorhabditis elegans reveals a FxNPxY-independent low-density lipoprotein receptor internalization mechanism mediated by epsin1

Science.gov (United States)

Kang, Yuan-Lin; Yochem, John; Bell, Leslie; Sorensen, Erika B.; Chen, Lihsia; Conner, Sean D.

2013-01-01

Low-density lipoprotein receptor (LDLR) internalization clears cholesterol-laden LDL particles from circulation in humans. Defects in clathrin-dependent LDLR endocytosis promote elevated serum cholesterol levels and can lead to atherosclerosis. However, our understanding of the mechanisms that control LDLR uptake remains incomplete. To identify factors critical to LDLR uptake, we pursued a genome-wide RNA interference screen using Caenorhabditis elegans LRP-1/megalin as a model for LDLR transport. In doing so, we discovered an unanticipated requirement for the clathrin-binding endocytic adaptor epsin1 in LDLR endocytosis. Epsin1 depletion reduced LDLR internalization rates in mammalian cells, similar to the reduction observed following clathrin depletion. Genetic and biochemical analyses of epsin in C. elegans and mammalian cells uncovered a requirement for the ubiquitin-interaction motif (UIM) as critical for receptor transport. As the epsin UIM promotes the internalization of some ubiquitinated receptors, we predicted LDLR ubiquitination as necessary for endocytosis. However, engineered ubiquitination-impaired LDLR mutants showed modest internalization defects that were further enhanced with epsin1 depletion, demonstrating epsin1-mediated LDLR endocytosis is independent of receptor ubiquitination. Finally, we provide evidence that epsin1-mediated LDLR uptake occurs independently of either of the two documented internalization motifs (FxNPxY or HIC) encoded within the LDLR cytoplasmic tail, indicating an additional internalization mechanism for LDLR. PMID:23242996

Citrullus lanatus 'sentinel' (watermelon) extract reduces atherosclerosis in LDL receptor-deficient mice.

Science.gov (United States)

Poduri, Aruna; Rateri, Debra L; Saha, Shubin K; Saha, Sibu; Daugherty, Alan

2013-05-01

Watermelon (Citrullus lanatus or C. lanatus) has many potentially bioactive compounds including citrulline, which may influence atherosclerosis. In this study, we determined the effects of C. lanatus, provided as an extract of the cultivar 'sentinel,' on hypercholesterolemia-induced atherosclerosis in mice. Male low-density lipoprotein receptor-deficient mice at 8 weeks old were given either C. lanatus 'sentinel' extract (2% vol/vol; n=10) or a mixture of matching carbohydrates (2% vol/vol; n=8) as the control in drinking water while being fed a saturated fat-enriched diet for 12 weeks ad libitum. Mice consuming C. lanatus 'sentinel' extract had significantly increased plasma citrulline concentrations. Systolic blood pressure was comparable between the two groups. Consumption of C. lanatus 'sentinel' extract led to lower body weight and fat mass without influencing lean mass. There were no differences in food and water intake and in urine output between the two groups. C. lanatus 'sentinel' extract administration decreased plasma cholesterol concentrations that were attributed to reductions of intermediate-/low-density lipoprotein cholesterol. Plasma concentrations of monocyte chemoattractant protein-1 and interferon-gamma were decreased and those of interleukin-10 were increased in mice consuming C. lanatus 'sentinel' extract. Intake of C. lanatus 'sentinel' extract resulted in reductions of atherosclerosis in both aortic arch and thoracic regions. In conclusion, consumption of C. lanatus 'sentinel' extract led to reduced body weight gain, decreased plasma cholesterol concentrations, improved homeostasis of pro- and anti-inflammatory cytokines, and attenuated development of atherosclerosis without affecting systolic blood pressure in hypercholesterolemic mice. Copyright © 2013 Elsevier Inc. All rights reserved.

Hypercholesterolemia Induces Differentiation of Regulatory T Cells in the Liver.

Science.gov (United States)

Mailer, Reiner K W; Gisterå, Anton; Polyzos, Konstantinos A; Ketelhuth, Daniel F J; Hansson, Göran K

2017-05-26

The liver is the central organ that responds to dietary cholesterol intake and facilitates the release and clearance of lipoprotein particles. Persistent hypercholesterolemia leads to immune responses against lipoprotein particles that drive atherosclerosis. However, the effect of hypercholesterolemia on hepatic T-cell differentiation remains unknown. To investigate hepatic T-cell subsets upon hypercholesterolemia. We observed that hypercholesterolemia elevated the intrahepatic regulatory T (Treg) cell population and increased the expression of transforming growth factor-β1 in the liver. Adoptive transfer experiments revealed that intrahepatically differentiated Treg cells relocated to the inflamed aorta in atherosclerosis-prone low-density lipoprotein receptor deficient ( Ldlr -/- ) mice. Moreover, hypercholesterolemia induced the differentiation of intrahepatic, but not intrasplenic, Th17 cells in wild-type mice, whereas the disrupted liver homeostasis in hypercholesterolemic Ldlr -/- mice led to intrahepatic Th1 cell differentiation and CD11b + CD11c + leukocyte accumulation. Our results elucidate a new mechanism that controls intrahepatic T-cell differentiation during atherosclerosis development and indicates that intrahepatically differentiated T cells contribute to the CD4 + T-cell pool in the atherosclerotic aorta. © 2017 American Heart Association, Inc.

Chylomicronemia with a mutant GPIHBP1 (Q115P) that cannot bind lipoprotein lipase

NARCIS (Netherlands)

Beigneux, Anne P; Franssen, Remco; Bensadoun, André; Gin, Peter; Melford, Kristan; Peter, Jorge; Walzem, Rosemary L; Weinstein, Michael M; Davies, Brandon S J; Kuivenhoven, Jan A; Kastelein, John J P; Fong, Loren G; Dallinga-Thie, Geesje M; Young, Stephen G

OBJECTIVE: GPIHBP1 is an endothelial cell protein that binds lipoprotein lipase (LPL) and chylomicrons. Because GPIHBP1 deficiency causes chylomicronemia in mice, we sought to determine whether some cases of chylomicronemia in humans could be attributable to defective GPIHBP1 proteins. METHODS AND

Peroxisomal abnormalities in the immortalized human hepatocyte (IHH) cell line.

Science.gov (United States)

Klouwer, Femke C C; Koster, Janet; Ferdinandusse, Sacha; Waterham, Hans R

2017-04-01

The immortalized human hepatocyte (IHH) cell line is increasingly used for studies related to liver metabolism, including hepatic glucose, lipid, lipoprotein and triglyceride metabolism, and the effect of therapeutic interventions. To determine whether the IHH cell line is a good model to investigate hepatic peroxisomal metabolism, we measured several peroxisomal parameters in IHH cells and, for comparison, HepG2 cells and primary skin fibroblasts. This revealed a marked plasmalogen deficiency and a deficient fatty acid α-oxidation in the IHH cells, due to a defect of PEX7, a cytosolic receptor protein required for peroxisomal import of a subset of peroxisomal proteins. These abnormalities have consequences for the lipid homeostasis of these cells and thus should be taken into account for the interpretation of data previously generated by using this cell line and when considering using this cell line for future research.

Metabolism of lipoproteins by human fetal hepatocytes

International Nuclear Information System (INIS)

Carr, B.R.

1987-01-01

The rate of clearance of lipoproteins from plasma appears to play a role in the development of atherogenesis. The liver may account for as much as two thirds of the removal of low-density lipoprotein and one third of the clearance of high-density lipoprotein in certain animal species and humans, mainly by receptor-mediated pathways. The purpose of the present investigation was to determine if human fetal hepatocytes maintained in vitro take up and degrade lipoproteins. We first determined that the maximal binding capacity of iodine 125-iodo-LDL was approximately 300 ng of low-density lipoprotein protein/mg of membrane protein and an apparent dissociation constant of approximately 60 micrograms low-density lipoprotein protein/ml in membranes prepared from human fetal liver. We found that the maximal uptake of [ 125 I]iodo-LDL and [ 125 I]iodo-HDL by fetal hepatocytes occurred after 12 hours of incubation. Low-density lipoprotein uptake preceded the appearance of degradation products by 4 hours, and thereafter the degradation of low-density lipoprotein increased linearly for at least 24 hours. In contrast, high-density lipoprotein was not degraded to any extent by fetal hepatocytes. [ 125 I]Iodo-LDL uptake and degradation were inhibited more than 75% by preincubation with low-density lipoprotein but not significantly by high-density lipoprotein, whereas [ 125 I]iodo-HDL uptake was inhibited 70% by preincubation with high-density lipoprotein but not by low-density lipoprotein. In summary, human fetal hepatocytes take up and degrade low-density lipoprotein by a receptor-mediated process similar to that described for human extrahepatic tissues

Pneumococcal lipoproteins involved in bacterial fitness, virulence, and immune evasion.

Science.gov (United States)

Kohler, Sylvia; Voß, Franziska; Gómez Mejia, Alejandro; Brown, Jeremy S; Hammerschmidt, Sven

2016-11-01

Streptococcus pneumoniae (pneumococcus) has evolved sophisticated strategies to survive in several niches within the human body either as a harmless commensal or as a serious pathogen causing a variety of diseases. The dynamic interaction between pneumococci and resident host cells during colonization of the upper respiratory tract and at the site of infection is critical for bacterial survival and the development of disease. Pneumococcal lipoproteins are peripherally anchored membrane proteins and have pivotal roles in bacterial fitness including envelope stability, cell division, nutrient acquisition, signal transduction, transport (as substrate-binding proteins of ABC transporter systems), resistance to oxidative stress and antibiotics, and protein folding. In addition, lipoproteins are directly involved in virulence-associated processes such as adhesion, colonization, and persistence through immune evasion. Conversely, lipoproteins are also targets for the host response both as ligands for toll-like receptors and as targets for acquired antibodies. This review summarizes the multifaceted roles of selected pneumococcal lipoproteins and how this knowledge can be exploited to combat pneumococcal infections. © 2016 Federation of European Biochemical Societies.

Lipoprotein profiles in human heterozygote carriers of a functional mutation P297S in scavenger receptor class B1

NARCIS (Netherlands)

Ljunggren, Stefan A.; Levels, Johannes H. M.; Hovingh, Kees; Holleboom, Adriaan G.; Vergeer, Menno; Argyri, Letta; Gkolfinopoulou, Christina; Chroni, Angeliki; Sierts, Jeroen A.; Kastelein, John J.; Kuivenhoven, Jan Albert; Lindahl, Mats; Karlsson, Helen

2015-01-01

The scavenger receptor class B type 1 (SR-B1) is an important HDL receptor involved in cholesterol uptake and efflux, but its physiological role in human lipoprotein metabolism is not fully understood. Heterozygous carriers of the SR-B1(P297S) mutation are characterized by increased HDL cholesterol

NF-κB Protects NKT Cells from Tumor Necrosis Factor Receptor 1-induced Death.

Science.gov (United States)

Kumar, Amrendra; Gordy, Laura E; Bezbradica, Jelena S; Stanic, Aleksandar K; Hill, Timothy M; Boothby, Mark R; Van Kaer, Luc; Joyce, Sebastian

2017-11-15

Semi-invariant natural killer T (NKT) cells are innate-like lymphocytes with immunoregulatory properties. NKT cell survival during development requires signal processing by activated RelA/NF-κB. Nonetheless, the upstream signal(s) integrated by NF-κB in developing NKT cells remains incompletely defined. We show that the introgression of Bcl-x L -coding Bcl2l1 transgene into NF-κB signalling-deficient IκBΔN transgenic mouse rescues NKT cell development and differentiation in this mouse model. We reasoned that NF-κB activation was protecting developing NKT cells from death signals emanating either from high affinity agonist recognition by the T cell receptor (TCR) or from a death receptor, such as tumor necrosis factor receptor 1 (TNFR1) or Fas. Surprisingly, the single and combined deficiency in PKC-θ or CARMA-1-the two signal transducers at the NKT TCR proximal signalling node-only partially recapitulated the NKT cell deficiency observed in IκBΔN tg mouse. Accordingly, introgression of the Bcl2l1 transgene into PKC-θ null mouse failed to rescue NKT cell development. Instead, TNFR1-deficiency, but not the Fas-deficiency, rescued NKT cell development in IκBΔN tg mice. Consistent with this finding, treatment of thymocytes with an antagonist of the inhibitor of κB kinase -which blocks downstream NF-κB activation- sensitized NKT cells to TNF-α-induced cell death in vitro. Hence, we conclude that signal integration by NF-κB protects developing NKT cells from death signals emanating from TNFR1, but not from the NKT TCR or Fas.

Low plasma lecithin : cholesterol acyltransferase and lipid transfer protein activities in growth hormone deficient and acromegalic men: role in altered high density lipoproteins

NARCIS (Netherlands)

Beentjes, JAM; van Tol, A; Sluiter, WJ; Dullaart, RPF

2000-01-01

Growth hormone (GH) deficiency and acromegaly may be associated with increased cardiovascular risk. Little is known about alterations in high density lipoproteins (HDL) in these conditions. Lecithin:cholesterol acyl transferase (LCAT) has the ability to esterify free cholesterol (FC) in HDL.

Low-Density Lipoprotein Receptor-Related Protein 6 (LRP6 Is a Novel Nutritional Therapeutic Target for Hyperlipidemia, Non-Alcoholic Fatty Liver Disease, and Atherosclerosis

Directory of Open Access Journals (Sweden)

Gwang-woong Go

2015-06-01

Full Text Available Low-density lipoprotein receptor-related protein 6 (LRP6 is a member of the low-density lipoprotein receptor family and has a unique structure, which facilitates its multiple functions as a co-receptor for Wnt/β-catenin signaling and as a ligand receptor for endocytosis. The role LRP6 plays in metabolic regulation, specifically in the nutrient-sensing pathway, has recently garnered considerable interest. Patients carrying an LRP6 mutation exhibit elevated levels of LDL cholesterol, triglycerides, and fasting glucose, which cooperatively constitute the risk factors of metabolic syndrome and atherosclerosis. Since the discovery of this mutation, the general role of LRP6 in lipid homeostasis, glucose metabolism, and atherosclerosis has been thoroughly researched. These studies have demonstrated that LRP6 plays a role in LDL receptor-mediated LDL uptake. In addition, when the LRP6 mutant impaired Wnt-LRP6 signaling, hyperlipidemia, non-alcoholic fatty liver disease, and atherosclerosis developed. LRP6 regulates lipid homeostasis and body fat mass via the nutrient-sensing mechanistic target of the rapamycin (mTOR pathway. Furthermore, the mutant LRP6 triggers atherosclerosis by activating platelet-derived growth factor (PDGF-dependent vascular smooth muscle cell differentiation. This review highlights the exceptional opportunities to study the pathophysiologic contributions of LRP6 to metabolic syndrome and cardiovascular diseases, which implicate LRP6 as a latent regulator of lipid metabolism and a novel therapeutic target for nutritional intervention.

SEC24A deficiency lowers plasma cholesterol through reduced PCSK9 secretion

Science.gov (United States)

Chen, Xiao-Wei; Wang, He; Bajaj, Kanika; Zhang, Pengcheng; Meng, Zhuo-Xian; Ma, Danjun; Bai, Yongsheng; Liu, Hui-Hui; Adams, Elizabeth; Baines, Andrea; Yu, Genggeng; Sartor, Maureen A; Zhang, Bin; Yi, Zhengping; Lin, Jiandie; Young, Stephen G; Schekman, Randy; Ginsburg, David

2013-01-01

The secretory pathway of eukaryotic cells packages cargo proteins into COPII-coated vesicles for transport from the endoplasmic reticulum (ER) to the Golgi. We now report that complete genetic deficiency for the COPII component SEC24A is compatible with normal survival and development in the mouse, despite the fundamental role of SEC24 in COPII vesicle formation and cargo recruitment. However, these animals exhibit markedly reduced plasma cholesterol, with mutations in Apoe and Ldlr epistatic to Sec24a, suggesting a receptor-mediated lipoprotein clearance mechanism. Consistent with these data, hepatic LDLR levels are up-regulated in SEC24A-deficient cells as a consequence of specific dependence of PCSK9, a negative regulator of LDLR, on SEC24A for efficient exit from the ER. Our findings also identify partial overlap in cargo selectivity between SEC24A and SEC24B, suggesting a previously unappreciated heterogeneity in the recruitment of secretory proteins to the COPII vesicles that extends to soluble as well as trans-membrane cargoes. DOI: http://dx.doi.org/10.7554/eLife.00444.001 PMID:23580231

Deficiency of the NR4A Orphan Nuclear Receptor NOR1 attenuates Neointima Formation Following Vascular Injury

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Nomiyama, Takashi; Zhao, Yue; Gizard, Florence; Findeisen, Hannes M.; Heywood, Elizabeth B.; Jones, Karrie L.; Conneely, Orla M.; Bruemmer, Dennis

2009-01-01

Background The neuron-derived orphan receptor-1 (NOR1) belongs to the evolutionary highly conserved and most ancient NR4A subfamily of the nuclear hormone receptor superfamily. Members of this subfamily function as early response genes regulating key cellular processes including proliferation, differentiation, and survival. Although NOR1 has previously been demonstrated to be required for smooth muscle cell (SMC) proliferation in vitro, the role of this nuclear receptor for the proliferative response underlying neointima formation and target genes trans-activated by NOR1 remain to be defined. Methods and Results Using a model of guide wire-induced arterial injury, we demonstrate decreased neointima formation in NOR1-/- mice compared to wildtype mice. In vitro, NOR1-deficient SMC exhibit decreased proliferation due to a G1→S phase arrest of the cell cycle and increased apoptosis in response to serum deprivation. NOR1-deficiency alters phosphorylation of the retinoblastoma protein by preventing mitogen-induced cyclin D1 and D2 expression. Conversely, overexpression of NOR1 induces cyclin D1 expression and the transcriptional activity of the cyclin D1 promoter in transient reporter assays. Gel shift and chromatin immunoprecipitation assays identified a putative response element for NR4A receptors in the cyclin D1 promoter, to which NOR1 is recruited in response to mitogenic stimulation. Finally, we provide evidence that these observations are applicable in vivo by demonstrating decreased cyclin D1 expression during neointima formation in NOR1-deficient mice. Conclusions These experiments characterize cyclin D1 as a NOR1-regulated target gene in SMC and demonstrate that NOR1 deficiency decreases neointima formation in response to vascular injury. PMID:19153266

Up-regulated Ectonucleotidases in Fas-Associated Death Domain Protein- and Receptor-Interacting Protein Kinase 1-Deficient Jurkat Leukemia Cells Counteract Extracellular ATP/AMP Accumulation via Pannexin-1 Channels during Chemotherapeutic Drug-Induced Apoptosis.

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Boyd-Tressler, Andrea M; Lane, Graham S; Dubyak, George R

2017-07-01

Pannexin-1 (Panx1) channels mediate the efflux of ATP and AMP from cancer cells in response to induction of extrinsic apoptosis by death receptors or intrinsic apoptosis by chemotherapeutic agents. We previously described the accumulation of extracellular ATP /AMP during chemotherapy-induced apoptosis in Jurkat human leukemia cells. In this study, we compared how different signaling pathways determine extracellular nucleotide pools in control Jurkat cells versus Jurkat lines that lack the Fas-associated death domain (FADD) or receptor-interacting protein kinase 1 (RIP1) cell death regulatory proteins. Tumor necrosis factor- α induced extrinsic apoptosis in control Jurkat cells and necroptosis in FADD-deficient cells; treatment of both lines with chemotherapeutic drugs elicited similar intrinsic apoptosis. Robust extracellular ATP/AMP accumulation was observed in the FADD-deficient cells during necroptosis, but not during apoptotic activation of Panx1 channels. Accumulation of extracellular ATP/AMP was similarly absent in RIP1-deficient Jurkat cells during apoptotic responses to chemotherapeutic agents. Apoptotic activation triggered equivalent proteolytic gating of Panx1 channels in all three Jurkat cell lines. The differences in extracellular ATP/AMP accumulation correlated with cell-line-specific expression of ectonucleotidases that metabolized the released ATP/AMP. CD73 mRNA, and α β -methylene-ADP-inhibitable ecto-AMPase activity were elevated in the FADD-deficient cells. In contrast, the RIP1-deficient cells were defined by increased expression of tartrate-sensitive prostatic acid phosphatase as a broadly acting ectonucleotidase. Thus, extracellular nucleotide accumulation during regulated tumor cell death involves interplay between ATP/AMP efflux pathways and different cell-autonomous ectonucleotidases. Differential expression of particular ectonucleotidases in tumor cell variants will determine whether chemotherapy-induced activation of Panx1 channels

4PS/insulin receptor substrate (IRS)-2 is the alternative substrate of the insulin receptor in IRS-1-deficient mice.

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Patti, M E; Sun, X J; Bruening, J C; Araki, E; Lipes, M A; White, M F; Kahn, C R

1995-10-20

Insulin receptor substrate-1 (IRS-1) is the major cytoplasmic substrate of the insulin and insulin-like growth factor (IGF)-1 receptors. Transgenic mice lacking IRS-1 are resistant to insulin and IGF-1, but exhibit significant residual insulin action which corresponds to the presence of an alternative high molecular weight substrate in liver and muscle. Recently, Sun et al. (Sun, X.-J., Wang, L.-M., Zhang, Y., Yenush, L. P., Myers, M. G., Jr., Glasheen, E., Lane, W.S., Pierce, J. H., and White, M. F. (1995) Nature 377, 173-177) purified and cloned 4PS, the major substrate of the IL-4 receptor-associated tyrosine kinase in myeloid cells, which has significant structural similarity to IRS-1. To determine if 4PS is the alternative substrate of the insulin receptor in IRS-1-deficient mice, we performed immunoprecipitation, immunoblotting, and phosphatidylinositol (PI) 3-kinase assays using specific antibodies to 4PS. Following insulin stimulation, 4PS is rapidly phosphorylated in liver and muscle, binds to the p85 subunit of PI 3-kinase, and activates the enzyme. Insulin stimulation also results in the association of 4PS with Grb 2 in both liver and muscle. In IRS-1-deficient mice, both the phosphorylation of 4PS and associated PI 3-kinase activity are enhanced, without an increase in protein expression. Immunodepletion of 4PS from liver and muscle homogenates removes most of the phosphotyrosine-associated PI 3-kinase activity in IRS-1-deficient mice. Thus, 4PS is the primary alternative substrate, i.e. IRS-2, which plays a major role in physiologic insulin signal transduction via both PI 3-kinase activation and Grb 2/Sos association. In IRS-1-deficient mice, 4PS/IRS-2 provides signal transduction to these two major pathways of insulin signaling.

Staphylococcus aureus lipoproteins trigger human corneal epithelial innate response through toll-like receptor-2.

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Li, Qiong; Kumar, Ashok; Gui, Jian-Fang; Yu, Fu-Shin X

2008-05-01

Bacterial lipoproteins (LP) are a family of cell wall components found in a wide variety of bacteria. In this study, we characterized the response of HUCL, a telomerase-immortalized human corneal epithelial cell (HCEC) line, to LP isolated from Staphylococcus (S) aureus. S. aureus LP (saLP) prepared by Triton X-114 extraction stimulated the activation of NF-kappaB, JNK, and P38 signaling pathways in HUCL cells. The extracts failed to stimulate NF-kappaB activation in HUCL cells after lipoprotein lipase treatment and in cell lines expressing TLR4 or TLR9, but not TLR2, indicating lipoprotein nature of the extracts. saLP induced the up-regulation of a variety of inflammatory cytokines and chemokines (IL-6, IL-8, ICAM-1), antimicrobial molecules (hBD-2, LL-37, and iNOS), and homeostasis genes (Mn-SOD) at both the mRNA level and protein level. Similar inflammatory response to saLP was also observed in primarily cultured HCECs using the production of IL-6 as readout. Moreover, TLR2 neutralizing antibody blocked the saLP-induced secretion of IL-6, IL-8 and hBD2 in HUCL cells. Our findings suggest that saLP activates TLR2 and triggers innate immune response in the cornea to S. aureus infection via production of proinflammatory cytokines and defense molecules.

Ikaros limits follicular B cell activation by regulating B cell receptor signaling pathways

International Nuclear Information System (INIS)

Heizmann, Beate; Sellars, MacLean; Macias-Garcia, Alejandra; Chan, Susan; Kastner, Philippe

2016-01-01

The Ikaros transcription factor is essential for early B cell development, but its effect on mature B cells is debated. We show that Ikaros is required to limit the response of naive splenic B cells to B cell receptor signals. Ikaros deficient follicular B cells grow larger and enter cell cycle faster after anti-IgM stimulation. Unstimulated mutant B cells show deregulation of positive and negative regulators of signal transduction at the mRNA level, and constitutive phosphorylation of ERK, p38, SYK, BTK, AKT and LYN. Stimulation results in enhanced and prolonged ERK and p38 phosphorylation, followed by hyper-proliferation. Pharmacological inhibition of ERK and p38 abrogates the increased proliferative response of Ikaros deficient cells. These results suggest that Ikaros functions as a negative regulator of follicular B cell activation.

Ikaros limits follicular B cell activation by regulating B cell receptor signaling pathways

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Heizmann, Beate [Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Université de Strasbourg, 67404 Illkirch (France); Sellars, MacLean [Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Université de Strasbourg, 67404 Illkirch (France); David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Macias-Garcia, Alejandra [Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Université de Strasbourg, 67404 Illkirch (France); Institute for Medical Engineering and Science at MIT, Cambridge, MA 02139 (United States); Chan, Susan, E-mail: scpk@igbmc.fr [Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Université de Strasbourg, 67404 Illkirch (France); Kastner, Philippe, E-mail: scpk@igbmc.fr [Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), INSERM U964, CNRS UMR 7104, Université de Strasbourg, 67404 Illkirch (France); Faculté de Médecine, Université de Strasbourg, Strasbourg (France)

2016-02-12

The Ikaros transcription factor is essential for early B cell development, but its effect on mature B cells is debated. We show that Ikaros is required to limit the response of naive splenic B cells to B cell receptor signals. Ikaros deficient follicular B cells grow larger and enter cell cycle faster after anti-IgM stimulation. Unstimulated mutant B cells show deregulation of positive and negative regulators of signal transduction at the mRNA level, and constitutive phosphorylation of ERK, p38, SYK, BTK, AKT and LYN. Stimulation results in enhanced and prolonged ERK and p38 phosphorylation, followed by hyper-proliferation. Pharmacological inhibition of ERK and p38 abrogates the increased proliferative response of Ikaros deficient cells. These results suggest that Ikaros functions as a negative regulator of follicular B cell activation.

An unusual case of iron deficiency anemia is associated with extremely low level of transferrin receptor.

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Hao, Shuangying; Li, Huihui; Sun, Xiaoyan; Li, Juan; Li, Kuanyu

2015-01-01

A case study of a female patient, diagnosed with iron deficiency anemia, was unresponsive to oral iron treatment and only partially responsive to parenteral iron therapy, a clinical profile resembling the iron-refractory iron deficiency anemia (IRIDA) disorder. However, the patient failed to exhibit microcytic phenotype, one of the IRIDA hallmarks. Biochemical assays revealed that serum iron, hepcidin, interluekin 6, and transferrin saturation were within the normal range of references or were comparable to her non-anemic offspring. Iron contents in serum and red blood cells and hemoglobin levels were measured, which confirmed the partial improvement of anemia after parenteral iron therapy. Strikingly, serum transferrin receptor in patient was almost undetectable, reflecting the very low activity of bone-marrow erythropoiesis. Our data demonstrate that this is not a case of systemic iron deficiency, but rather cellular iron deficit due to the low level of transferrin receptor, particularly in erythroid tissue.

Deletion in the first cysteine-rich repeat of low density lipoprotein receptor impairs its transport but not lipoprotein binding in fibroblasts from a subject with familial hypercholesterolemia

International Nuclear Information System (INIS)

Leitersdorf, E.; Hobbs, H.H.; Fourie, A.M.; Jacobs, M.; Van Der Westhuyzen, D.R.; Coetzee, G.A.

1988-01-01

The ligand-binding domain of the low density lipoprotein (LDL) receptor is composed of seven cysteine-rich repeats, each ∼ 40 amino acids long. Previous studies showed that if the first repeat of the ligand-binding domain (encoded by exon 2) is deleted, the receptor fails to bind an anti-LDL receptor monoclonal antibody (IgG-C7) but continues to bind LDL with high affinity. Cultured fibroblasts from a Black South African Xhosa patient (TT) with the clinical syndrome of homozygous familial hypercholesterolemia demonstrated high-affinity cell-surface binding of 125 I-labeled LDL but not 125 I-labeled IgG-C7. previous haplotype analysis, using 10 restriction fragment length polymorphic sites, suggested that the patient inherited two identical LDL receptor alleles. The polymerase chain reaction technique was used to selectively amplify exon 2 of the LDL receptor gene from this patient. Sequence analysis of the amplified fragment disclosed a deletion of six base pairs that removes two amino acids, aspartic acid and glycine, from the first cysteine-rich ligand binding repeat. The mutation creates a new Pst I restriction site that can be used to detect the deletion. The existence of this mutant allele confirms that the epitope of IgG-C7 is located in the first cysteine-rich repeat and that this repeat is not necessary for LDL binding. The mutant gene produced a normally sized 120-kilodalton LDL receptor precursor protein that matured to the 160-kilodalton form at less than one-fourth the normal rate

Toll-like receptor 2 or toll-like receptor 4 deficiency does not modify lupus in MRLlpr mice.

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Simon J Freeley

Full Text Available Systemic lupus erythematosus is an autoimmune disease with a high morbidity and nephritis is a common manifestation. Previous studies in murine lupus models have suggest a role for Toll-like receptor 2 and 4. We examined the role of these molecules in MRL lpr mice which is one of the most established and robust murine models. We compared disease parameters in Toll-like receptor 2 or Toll-like receptor 4 deficient mice with their littermate controls. We found no difference in the severity of glomerulonephritis as assessed by histology, serum creatinine and albuminuria when Toll-like receptor 2 or Toll-like receptor 4 deficient MRLlpr mice were compared with Toll-like receptor sufficient controls. We also found similar levels of anti-dsDNA and anti-ssDNA antibodies. These results show that Toll-like receptor 2 and Toll-like receptor 4 do not play a significant role in MRLlpr mice, and therefore they may not be important in human lupus.

Comparative studies of vertebrate scavenger receptor class B type 1: a high-density lipoprotein binding protein

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Holmes RS

2012-06-01

Full Text Available Roger S Holmes,1,2 Laura A Cox11Department of Genetics and Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA; 2School of Biomolecular and Physical Sciences, Griffith University, Nathan, Queensland, AustraliaAbstract: Scavenger receptor class B type 1 protein (SCARB1 plays an essential role in cholesterol homeostasis and functions in binding high density lipoprotein cholesterol (HDL in liver and other tissues of the body. SCARB1 also functions in lymphocyte homeostasis and in the uptake of hepatitis C virus (HCV by the liver. A genetic deficiency of this protein results in autoimmune disorders and significant changes in blood cholesterol phenotype. Comparative SCARB1 amino acid sequences and structures and SCARB1 gene locations were examined using data from several vertebrate genome projects. Vertebrate SCARB1 sequences shared 50%–99% identity as compared with 28%–31% sequence identities with other CD36-like superfamily members, ie, SCARB2 and SCARB3 (also called CD36. At least eight N-glycosylation sites were conserved among most of the vertebrate SCARB1 proteins examined. Sequence alignments, key amino acid residues, and conserved predicted secondary structures were also studied, including: cytoplasmic, transmembrane, and exoplasmic sequences; conserved N-terminal and C-terminal transmembrane glycines which participate in oligomer formation; conserved cystine disulfides and a free SH residue which participates in lipid transport; carboxyl terminal PDZ-binding domain sequences (Ala507-Arg/Lys508-Leu509; and 30 conserved proline and 18 conserved glycine residues, which may contribute to short loop formation within the exoplasmic HDL-binding sequence. Vertebrate SCARB1 genes usually contained 12 coding exons. The human SCARB1 gene contained CpG islands, micro RNA binding sites, and several transcription factor binding sites (including PPARG which may contribute to the high level (13.7 times

Melanocortin 1 Receptor Deficiency Promotes Atherosclerosis in Apolipoprotein E-/- Mice.

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Rinne, Petteri; Kadiri, James J; Velasco-Delgado, Mauricio; Nuutinen, Salla; Viitala, Miro; Hollmén, Maija; Rami, Martina; Savontaus, Eriika; Steffens, Sabine

2018-02-01

The MC1-R (melanocortin 1 receptor) is expressed by monocytes and macrophages where it mediates anti-inflammatory actions. MC1-R also protects against macrophage foam cell formation primarily by promoting cholesterol efflux through the ABCA1 (ATP-binding cassette transporter subfamily A member 1) and ABCG1 (ATP-binding cassette transporter subfamily G member 1). In this study, we aimed to investigate whether global deficiency in MC1-R signaling affects the development of atherosclerosis. Apoe -/- (apolipoprotein E deficient) mice were crossed with recessive yellow (Mc1r e/e ) mice carrying dysfunctional MC1-R and fed a high-fat diet to induce atherosclerosis. Apoe -/- Mc1r e/e mice developed significantly larger atherosclerotic lesions in the aortic sinus and in the whole aorta compared with Apoe -/- controls. In terms of plaque composition, MC1-R deficiency was associated with less collagen and smooth muscle cells and increased necrotic core, indicative of more vulnerable lesions. These changes were accompanied by reduced Abca1 and Abcg1 expression in the aorta. Furthermore, Apoe -/- Mc1r e/e mice showed a defect in bile acid metabolism that aggravated high-fat diet-induced hypercholesterolemia and hepatic lipid accumulation. Flow cytometric analysis of leukocyte profile revealed that dysfunctional MC1-R enhanced arterial accumulation of classical Ly6C high monocytes and macrophages, effects that were evident in mice fed a normal chow diet but not under high-fat diet conditions. In support of enhanced arterial recruitment of Ly6C high monocytes, these cells had increased expression of L-selectin and P-selectin glycoprotein ligand 1. The present study highlights the importance of MC1-R in the development of atherosclerosis. Deficiency in MC1-R signaling exacerbates atherosclerosis by disturbing cholesterol handling and by increasing arterial monocyte accumulation. © 2017 The Authors.

Loss of Acetylcholine Signaling Reduces Cell Clearance Deficiencies in Caenorhabditis elegans.

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Sérgio M Pinto

Full Text Available The ability to eliminate undesired cells by apoptosis is a key mechanism to maintain organismal health and homeostasis. Failure to clear apoptotic cells efficiently can cause autoimmune diseases in mammals. Genetic studies in Caenorhabditis elegans have greatly helped to decipher the regulation of apoptotic cell clearance. In this study, we show that the loss of levamisole-sensitive acetylcholine receptor, but not of a typical neuronal acetylcholine receptor causes a reduction in the number of persistent cell corpses in worms suffering from an engulfment deficiency. This reduction is not caused by impaired or delayed cell death but rather by a partial restoration of the cell clearance capacity. Mutants in acetylcholine turn-over elicit a similar phenotype, implying that acetylcholine signaling is the process responsible for these observations. Surprisingly, tissue specific RNAi suggests that UNC-38, a major component of the levamisole-sensitive receptor, functions in the dying germ cell to influence engulfment efficiency. Animals with loss of acetylcholine receptor exhibit a higher fraction of cell corpses positive for the "eat-me" signal phosphatidylserine. Our results suggest that modulation by ion channels of ion flow across plasma membrane in dying cells can influence the dynamics of phosphatidylserine exposure and thus clearance efficiency.

Stimulation of LDL receptor activity in Hep-G2 cells by a serum factor(s)

International Nuclear Information System (INIS)

Ellsworth, J.L.; Brown, C.; Cooper, A.D.

1988-01-01

The regulation of low-density lipoprotein (LDL) receptor activity in the human hepatoma cell line Hep-G2 by serum components was examined. Incubation of dense monolayers of Hep-G2 cells with fresh medium containing 10% fetal calf serum (FM) produced a time-dependent increase in LDL receptor activity. Uptake and degradation of 125I-LDL was stimulated two- to four-fold, as compared with that of Hep-G2 cells cultured in the same media in which they had been grown to confluence (CM); the maximal 125I-LDL uptake plus degradation increased from 0.2 microgram/mg cell protein/4 h to 0.8 microgram/mg cell protein/4 h. In addition, a two-fold increase in cell surface binding of 125I-LDL to Hep-G2 cells was observed when binding was measured at 4 degrees C. There was no change in the apparent Kd. The stimulation of LDL receptor activity was suppressed in a concentration-dependent manner by the addition of cholesterol, as LDL, to the cell medium. In contrast to the stimulation of LDL receptor activity, FM did not affect the uptake or degradation of 125I-asialoorosomucoid. Addition of FM increased the protein content per dish, and DNA synthesis was stimulated approximately five-fold, as measured by [3H]thymidine incorporation into DNA; however, the cell number did not change. Cellular cholesterol biosynthesis was also stimulated by FM; [14C]acetate incorporation into unesterified and esterified cholesterol was increased approximately five-fold. Incubation of Hep-G2 cells with high-density lipoproteins (200 micrograms protein/ml) or albumin (8.0 mg/ml) in the absence of the serum factor did not significantly increase the total processed 125I-LDL. Stimulation of LDL receptor activity was dependent on a heat-stable, nondialyzable serum component that eluted in the inclusion volume of a Sephadex G-75 column

Hematopoietic sphingosine 1-phosphate lyase deficiency decreases atherosclerotic lesion development in LDL-receptor deficient mice.

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Martine Bot

Full Text Available AIMS: Altered sphingosine 1-phosphate (S1P homeostasis and signaling is implicated in various inflammatory diseases including atherosclerosis. As S1P levels are tightly controlled by S1P lyase, we investigated the impact of hematopoietic S1P lyase (Sgpl1(-/- deficiency on leukocyte subsets relevant to atherosclerosis. METHODS AND RESULTS: LDL receptor deficient mice that were transplanted with Sgpl1(-/- bone marrow showed disrupted S1P gradients translating into lymphopenia and abrogated lymphocyte mitogenic and cytokine response as compared to controls. Remarkably however, Sgpl1(-/- chimeras displayed mild monocytosis, due to impeded stromal retention and myelopoiesis, and plasma cytokine and macrophage expression patterns, that were largely compatible with classical macrophage activation. Collectively these two phenotypic features of Sgpl1 deficiency culminated in diminished atherogenic response. CONCLUSIONS: Here we not only firmly establish the critical role of hematopoietic S1P lyase in controlling S1P levels and T cell trafficking in blood and lymphoid tissue, but also identify leukocyte Sgpl1 as critical factor in monocyte macrophage differentiation and function. Its, partly counterbalancing, pro- and anti-inflammatory activity spectrum imply that intervention in S1P lyase function in inflammatory disorders such as atherosclerosis should be considered with caution.

Familial defective apolipoprotein B-100: low density lipoproteins with abnormal receptor binding

International Nuclear Information System (INIS)

Innerarity, T.L.; Weisgraber, K.H.; Arnold, K.S.; Mahley, R.W.; Krauss, R.M.; Vega, G.L.; Grundy, S.M.

1987-01-01

Previous in vivo turnover studies suggested that retarded clearance of low density lipoproteins (LDL) from the plasma of some hypercholesterolemic patients is due to LDL with defective receptor binding. The present study examined this postulate directly by receptor binding experiments. The LDL from a hypercholesterolemic patient (G.R.) displayed a reduced ability to bind to the LDL receptors on normal human fibroblasts. The G.R. LDL possessed 32% of normal receptor binding activity. Likewise, the G.R. LDL were much less effective than normal LDL in competing with 125 I-labeled normal LDL for cellular uptake and degradation and in stimulating intracellular cholesteryl ester synthesis. The defect in LDL binding appears to be due to a genetic abnormality of apolipoprotein B-100: two brothers of the proband possess LDL defective in receptor binding, whereas a third brother and the proband's son have normally binding LDL. Further, the defect in receptor binding does not appear to be associated wit an abnormal lipid composition or structure of the LDL. Normal and abnormal LDL subpopulations were partially separated from plasma of two subjects by density-gradient ultracentrifugation, a finding consistent with the presence of a normal and a mutant allele. The affected family members appear to be heterozygous for this disorder, which has been designated familial defective apolipoprotein B-100. These studies indicate that the defective receptor binding results in inefficient clearance of LDL and the hypercholesterolemia observed in these patients

The majority of lipoprotein lipase in plasma is bound to remnant lipoproteins: A new definition of remnant lipoproteins.

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Sato, Koichi; Okajima, Fumikazu; Miyashita, Kazuya; Imamura, Shigeyuki; Kobayashi, Junji; Stanhope, Kimber L; Havel, Peter J; Machida, Tetsuo; Sumino, Hiroyuki; Murakami, Masami; Schaefer, Ernst; Nakajima, Katsuyuki

2016-10-01

Lipoprotein lipase (LPL) is a multifunctional protein and a key enzyme involved in the regulation of lipoprotein metabolism. We determined the lipoproteins to which LPL is bound in the pre-heparin and post-heparin plasma. Tetrahydrolipstatin (THL), a potent inhibitor of serine lipases, was used to block the lipolytic activity of LPL, thereby preventing changes in the plasma lipoproteins due to ex vivo lipolysis. Gel filtration was performed to obtain the LPL elution profiles in plasma and the isolated remnant lipoproteins (RLP). When ex vivo lipolytic activity was inhibited by THL in the post-heparin plasma, majority of the LPL was found in the VLDL elution range, specifically in the RLP as inactive dimers. However, in the absence of THL, most of the LPL was found in the HDL elution range as active dimers. Furthermore, majority of the LPL in the pre-heparin plasma was found in the RLP as inactive form, with broadly diffused lipoprotein profiles in the presence and absence of THL. It is suggested that during lipolysis in vivo, the endothelial bound LPL dimers generates RLP, forming circulating RLP-LPL complexes in an inactive form that subsequently binds and initiates receptor-mediated catabolism. Copyright © 2016 Elsevier B.V. All rights reserved.

The role of the class A scavenger receptors, SR-A and MARCO, in the immune system. Part 1. The structure of receptors, their ligand binding repertoires and ability to initiate intracellular signaling

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Szczepan Józefowski

2012-02-01

Full Text Available  Recognition of pathogens by innate immune cells is mediated by pattern recognition receptors (PRR, which include scavenger receptors (SR. The class A SR, SR-A/CD204 and MARCO, are characterized by the presence of collagenous and SR cysteine-rich domains in their extracellular portions. Both receptors are expressed mainly on macrophages and dendritic cells. Thanks to their ability to bind to a wide range of polyanionic ligands, the class A SR may participate in numerous functions of these cells, such as endocytosis, and adhesion to extracellular matrix and to other cells. Among SR-A ligands are oxidized lipoproteins and β-amyloid fibrils, which link SR-A to the pathogenesis of arteriosclerosis and Alzheimer’s disease. Despite the demonstration of class A SR involvement in so many processes, the lack of selective ligands precluded reaching definite conclusions concerning their signaling abilities. Using specific receptor ligation with antibodies, we showed that SR-A and MARCO trigger intracellular signaling, modulating pro-inflammatory and microbicidal activities of macrophages. Surprisingly, despite similarities in structure and ligand binding repertoires, SR-A and MARCO exert opposite effects on interleukin-12 (IL-12 production in macrophages. SR-A ligation also stimulated H2O2 and IL-10 production, but had no effect on the release of several other cytokines. These limited effects of specific SR-A ligation contrast with generalized enhancement of immune responses observed in SR-A-deficient mice. Recent studies have revealed that many of these effects of SR-A deficiency may be caused by compensatory changes in the expression of other receptors and/or disinhibition of signal transduction from receptors belonging to the Toll/IL-1R family, rather than by the loss of the receptor function of SR-A.

Kupffer cell complement receptor clearance function and host defense.

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Loegering, D J

1986-01-01

Kupffer cells are well known to be important for normal host defense function. The development of methods to evaluate the in vivo function of specific receptors on Kupffer cells has made it possible to assess the role of these receptors in host defense. The rationale for studying complement receptors is based on the proposed important role of these receptors in host defense and on the observation that the hereditary deficiency of a complement receptor is associated with recurrent severe bacterial infections. The studies reviewed here demonstrate that forms of injury that are associated with depressed host defense including thermal injury, hemorrhagic shock, trauma, and surgery also cause a decrease in complement receptor clearance function. This decrease in Kupffer cell receptor clearance function was shown not to be the result of depressed hepatic blood flow or depletion of complement components. Complement receptor function was also depressed following the phagocytosis of particulates that are known to depress Kupffer cell host defense function. Endotoxemia and bacteremia also were associated with a depression of complement receptor function. Complement receptor function was experimentally depressed in uninjured animals by the phagocytosis of IgG-coated erythrocytes. There was a close association between the depression of complement receptor clearance function and increased susceptibility to the lethal effects of endotoxin and bacterial infection. These studies support the hypotheses that complement receptors on Kupffer cells are important for normal host defense and that depression of the function of these receptors impairs host defense.

Differential regulation by agonist and phorbol ester of cloned m1 and m2 muscarinic acetylcholine receptors in mouse Y1 adrenal cells and in Y1 cells deficient in cAMP-dependent protein kinase

International Nuclear Information System (INIS)

Scherer, N.M.; Nathanson, N.M.

1990-01-01

Cloned muscarinic acetylcholine m1 and m2 receptors were expressed in stably transfected mouse Y1 adrenal cells and in a variant Y1 line, Kin-8, which is deficient in cAMP-dependent protein kinase activity (PKA - ). m1 and m2 receptors were rapidly internalized following exposure of transfected PKA + or PKA - cells to the muscarinic agonist carbachol. Thus, agonist-dependent internalization of m1 and m2 did not require PKA activity. A differential effect of PKA on regulation by agonist of the m2 receptor, but not the m1 receptor, was unmasked in PKA - cells. These data indicate that the basal activity of PKA may modulate the agonist-dependent internalization of the m2 receptor, but not the m1 receptor. The internalization of the m1 and m2 receptors in both PKA + and PKA - cells was accompanied by desensitization of functional responses. Exposure of PKA + cells to 10 -7 M phorbol 12-myristate 13-acetate (PMA), an activator of protein kinase C, resulted in a 30 ± 9% decrease in the number of m1 receptors on the cell surface. The m2 receptor was not internalized following treatment of either PKA + or PKA - cells with PMA. Thus, the m1 and m2 receptors show differential sensitivity to internalization by PMA. Agonist-dependent internalization of the m1 receptor appeared to be independent of activation of PKC because (1) agonist-dependent internalization of m1 was not attenuated in PKA - cells, (2) the rate and extent of internalization of m1 in cells exposed to PMA were less than those in cells exposed to agonist, and (3) treatment of cells with concanavalin A selectivity blocked internalization of m1 in cells exposed to PMA, but not to agonist. The effects of agonist and PMA on receptor internalization were not additive. Exposure of PKA + or PKA - cells to PMA reduced the magnitude of pilocarpine-stimulated PI hydrolysis by about 25%

Effect of human scavenger receptor class A overexpression in bone marrow-derived cells on cholesterol levels and atherosclerosis in ApoE-deficient mice

NARCIS (Netherlands)

van Eck, M.; de Winther, M. P.; Herijgers, N.; Havekes, L. M.; Hofker, M. H.; Groot, P. H.; van Berkel, T. J.

2000-01-01

In the arterial wall, scavenger receptor class A (SRA) is implicated in pathological lipid deposition. In contrast, in the liver, SRA is suggested to remove modified lipoproteins from the circulation, thereby protecting the body from their pathological action. The role of SRA on bone marrow-derived

Effect of human scavenger receptor class A overexpression in bone marrow-derived cells on cholesterol levels and atherosclerosis in apoE-deficient mice

NARCIS (Netherlands)

Eck, M. van; Winther, M.P.J. de; Herijgers, N.; Havekes, L.M.; Hofker, M.H.; Groot, P.H.E.; Berkel, T.J.C. van

2000-01-01

In the arterial wall, scavenger receptor class A (SRA) is implicated in pathological lipid deposition. In contrast, in the liver, SRA is suggested to remove modified lipoproteins from the circulation, thereby protecting the body from their pathological action. The role of SRA on bone marrow-derived

Estrogen deficiency heterogeneously affects tissue specific stem cells in mice

Science.gov (United States)

Kitajima, Yuriko; Doi, Hanako; Ono, Yusuke; Urata, Yoshishige; Goto, Shinji; Kitajima, Michio; Miura, Kiyonori; Li, Tao-Sheng; Masuzaki, Hideaki

2015-01-01

Postmenopausal disorders are frequently observed in various organs, but their relationship with estrogen deficiency and mechanisms remain unclear. As tissue-specific stem cells have been found to express estrogen receptors, we examined the hypothesis that estrogen deficiency impairs stem cells, which consequently contributes to postmenopausal disorders. Six-week-old C57BL/6 female mice were ovariectomized, following which they received 17β-estradiol replacement or vehicle (control). Sham-operated mice were used as healthy controls. All mice were killed for evaluation 2 months after treatments. Compared with the healthy control, ovariectomy significantly decreased uterine weight, which was partially recovered by 17β-estradiol replacement. Ovariectomy significantly increased the numbers of c-kit-positive hematopoietic stem/progenitor cells in bone marrow, but impaired their capacity to grow mixed cell-type colonies in vitro. Estrogen replacement further increased the numbers of c-kit-positive hematopoietic stem/progenitor cells in bone marrow, without significantly affecting colony growth in vitro. The number of CD105-positive mesenchymal stem cells in bone marrow also significantly decreased after ovariectomy, but completely recovered following estrogen replacement. Otherwise, neither ovariectomy nor estrogen replacement changed the number of Pax7-positive satellite cells, which are a skeletal muscle-type stem cell. Estrogen deficiency heterogeneously affected tissue-specific stem cells, suggesting a likely and direct relationship with postmenopausal disorders. PMID:26245252

Cholesterol Accumulation in Dendritic Cells Links the Inflammasome to Acquired Immunity.

Science.gov (United States)

Westerterp, Marit; Gautier, Emmanuel L; Ganda, Anjali; Molusky, Matthew M; Wang, Wei; Fotakis, Panagiotis; Wang, Nan; Randolph, Gwendalyn J; D'Agati, Vivette D; Yvan-Charvet, Laurent; Tall, Alan R

2017-06-06

Autoimmune diseases such as systemic lupus erythematosus (SLE) are associated with increased cardiovascular disease and reduced plasma high-density lipoprotein (HDL) levels. HDL mediates cholesterol efflux from immune cells via the ATP binding cassette transporters A1 and G1 (ABCA1/G1). The significance of impaired cholesterol efflux pathways in autoimmunity is unknown. We observed that Abca1/g1-deficient mice develop enlarged lymph nodes (LNs) and glomerulonephritis suggestive of SLE. This lupus-like phenotype was recapitulated in mice with knockouts of Abca1/g1 in dendritic cells (DCs), but not in macrophages or T cells. DC-Abca1/g1 deficiency increased LN and splenic CD11b + DCs, which displayed cholesterol accumulation and inflammasome activation, increased cell surface levels of the granulocyte macrophage-colony stimulating factor receptor, and enhanced inflammatory cytokine secretion. Consequently, DC-Abca1/g1 deficiency enhanced T cell activation and T h 1 and T h 17 cell polarization. Nlrp3 inflammasome deficiency diminished the enlarged LNs and enhanced T h 1 cell polarization. These findings identify an essential role of DC cholesterol efflux pathways in maintaining immune tolerance. Copyright © 2017 Elsevier Inc. All rights reserved.

Oxidized low-density lipoproteins upregulate proline oxidase to initiate ROS-dependent autophagy

OpenAIRE

Zabirnyk, Olga; Liu, Wei; Khalil, Shadi; Sharma, Anit; Phang, James M.

2009-01-01

Epidemiological studies showed that high levels of oxidized low-density lipoproteins (oxLDLs) are associated with increased cancer risk. We examined the direct effect of physiologic concentrations oxLDL on cancer cells. OxLDLs were cytotoxic and activate both apoptosis and autophagy. OxLDLs have ligands for peroxisome proliferator-activated receptor gamma and upregulated proline oxidase (POX) through this nuclear receptor. We identified 7-ketocholesterol (7KC) as a main component responsible ...

Kaempferol stimulates gene expression of low-density lipoprotein receptor through activation of Sp1 in cultured hepatocytes

Science.gov (United States)

Ochiai, Ayasa; Miyata, Shingo; Iwase, Masamori; Shimizu, Makoto; Inoue, Jun; Sato, Ryuichiro

2016-01-01

A high level of plasma low-density lipoprotein (LDL) cholesterol is considered a risk factor for atherosclerosis. Because the hepatic LDL receptor (LDLR) is essential for clearing plasma LDL cholesterol, activation of LDLR is a promising therapeutic target for patients with atherosclerotic disease. Here we demonstrated how the flavonoid kaempferol stimulated the gene expression and activity of LDLR in HepG2 cells. The kaempferol-mediated stimulation of LDLR gene expression was completely inhibited by knockdown of Sp1 gene expression. Treatment of HepG2 cells with kaempferol stimulated the recruitment of Sp1 to the promoter region of the LDLR gene, as well as the phosphorylation of Sp1 on Thr-453 and Thr-739. Moreover, these kaempferol-mediated processes were inhibited in the presence of U0126, an ERK pathway inhibitor. These results suggest that kaempferol may increase the activity of Sp1 through stimulation of Sp1 phosphorylation by ERK1/2 and subsequent induction of LDLR expression and activity. PMID:27109240

Interaction of Mycoplasma hominis PG21 with Human Dendritic Cells: Interleukin-23-Inducing Mycoplasmal Lipoproteins and Inflammasome Activation of the Cell.

Science.gov (United States)

Goret, J; Béven, L; Faustin, B; Contin-Bordes, C; Le Roy, C; Claverol, S; Renaudin, H; Bébéar, C; Pereyre, S

2017-08-01

Mycoplasma hominis lacks a cell wall, and lipoproteins anchored to the extracellular side of the plasma membrane are in direct contact with the host components. A Triton X-114 extract of M. hominis enriched with lipoproteins was shown to stimulate the production of interleukin-23 (IL-23) by human dendritic cells (hDCs). The inflammasome activation of the host cell has never been reported upon M. hominis infection. We studied here the interaction between M. hominis PG21 and hDCs by analyzing both the inflammation-inducing mycoplasmal lipoproteins and the inflammasome activation of the host cell. IL-23-inducing lipoproteins were determined using a sequential extraction strategy with two nondenaturing detergents, Sarkosyl and Triton X-114, followed by SDS-PAGE separation and mass spectrometry identification. The activation of the hDC inflammasome was assessed using PCR array and enzyme-linked immunosorbent assay (ELISA). We defined a list of 24 lipoproteins that could induce the secretion of IL-23 by hDCs, 5 with a molecular mass between 20 and 35 kDa and 19 with a molecular mass between 40 and 100 kDa. Among them, lipoprotein MHO_4720 was identified as potentially bioactive, and a synthetic lipopeptide corresponding to the N-terminal part of the lipoprotein was subsequently shown to induce IL-23 release by hDCs. Regarding the hDC innate immune response, inflammasome activation with caspase-dependent production of IL-1β was observed. After 24 h of coincubation of hDCs with M. homini s, downregulation of the NLRP3-encoding gene and of the adaptor PYCARD-encoding gene was noticed. Overall, this study provides insight into both protagonists of the interaction of M. hominis and hDCs. IMPORTANCE Mycoplasma hominis is a human urogenital pathogen involved in gynecologic and opportunistic infections. M. hominis lacks a cell wall, and its membrane contains many lipoproteins that are anchored to the extracellular side of the plasma membrane. In the present study, we focused on

Detection of early stage atherosclerotic plaques using PET and CT fusion imaging targeting P-selectin in low density lipoprotein receptor-deficient mice

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Ikuko, E-mail: nakamuri@riken.jp [RIKEN Center for Molecular Imaging Science, Kobe (Japan); Department of Cardiovascular Medicine, Saga University, Saga (Japan); Hasegawa, Koki [RIKEN Center for Molecular Imaging Science, Kobe (Japan); Department of Pathology and Experimental Medicine, Kumamoto University, Kumamoto (Japan); Wada, Yasuhiro [RIKEN Center for Molecular Imaging Science, Kobe (Japan); Hirase, Tetsuaki; Node, Koichi [Department of Cardiovascular Medicine, Saga University, Saga (Japan); Watanabe, Yasuyoshi, E-mail: yywata@riken.jp [RIKEN Center for Molecular Imaging Science, Kobe (Japan)

2013-03-29

Highlights: ► P-selectin regulates leukocyte recruitment as an early stage event of atherogenesis. ► We developed an antibody-based molecular imaging probe targeting P-selectin for PET. ► This is the first report on successful PET imaging for delineation of P-selectin. ► P-selectin is a candidate target for atherosclerotic plaque imaging by clinical PET. -- Abstract: Background: Sensitive detection and qualitative analysis of atherosclerotic plaques are in high demand in cardiovascular clinical settings. The leukocyte–endothelial interaction mediated by an adhesion molecule P-selectin participates in arterial wall inflammation and atherosclerosis. Methods and results: A {sup 64}Cu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid conjugated anti-P-selectin monoclonal antibody ({sup 64}Cu-DOTA-anti-P-selectin mAb) probe was prepared by conjugating an anti-P-selectin monoclonal antibody with DOTA followed by {sup 64}Cu labeling. Thirty-six hours prior to PET and CT fusion imaging, 3 MBq of {sup 64}Cu-DOTA-anti-P-selectin mAb was intravenously injected into low density lipoprotein receptor-deficient Ldlr-/- mice. After a 180 min PET scan, autoradiography and biodistribution of {sup 64}Cu-DOTA-anti-P-selectin monoclonal antibody was examined using excised aortas. In Ldlr-/- mice fed with a high cholesterol diet for promotion of atherosclerotic plaque development, PET and CT fusion imaging revealed selective and prominent accumulation of the probe in the aortic root. Autoradiography of aortas that demonstrated probe uptake into atherosclerotic plaques was confirmed by Oil red O staining for lipid droplets. In Ldlr-/- mice fed with a chow diet to develop mild atherosclerotic plaques, probe accumulation was barely detectable in the aortic root on PET and CT fusion imaging. Probe biodistribution in aortas was 6.6-fold higher in Ldlr-/- mice fed with a high cholesterol diet than in those fed with a normal chow diet. {sup 64}Cu-DOTA-anti-P-selectin m

Megalin is a receptor for apolipoprotein M, and kidney-specific megalin-deficiency confers urinary excretion of apolipoprotein M

DEFF Research Database (Denmark)

Faber, Kirsten; Hvidberg, Vibeke; Moestrup, Søren K

2006-01-01

. In addition, apoM is expressed at high levels in the kidney tubule cells. In this study, we show that the multiligand receptor megalin, which is expressed in kidney proximal tubule cells, is a receptor for apoM and mediates its uptake in the kidney. To examine apoM binding to megalin, a recombinant apo....... To examine the importance of apoM binding by megalin in vivo, we analyzed mice with a tissue-specific deficiency of megalin in the kidney. Megalin deficiency was associated with pronounced urinary excretion of apoM, whereas apoM was not detected in normal mouse, human, or rat urine. Gel filtration analysis...... showed that the urinary apoM-containing particles were small and devoid of apoA-I. The results suggest that apoM binds to megalin and that megalin-mediated endocytosis in kidney proximal tubules prevents apoM excretion in the urine....

The effects of dietary fatty acids on the postprandial triglyceride-rich lipoprotein/apoB48 receptor axis in human monocyte/macrophage cells.

Science.gov (United States)

Varela, Lourdes M; Ortega-Gomez, Almudena; Lopez, Sergio; Abia, Rocio; Muriana, Francisco J G; Bermudez, Beatriz

2013-12-01

Intestinally produced triglyceride-rich lipoproteins (TRL) play an important role in the progression of atherosclerosis. In this study, we investigated the relevance of monounsaturated fatty acid (MUFA) and saturated fatty acid (SFA) in postprandial TRL in affecting the transcriptional activity of the apolipoprotein-B48 receptor (ApoB48R) and its functionality in human monocyte/macrophage cells. Healthy male volunteers were administered four standardized high-fat meals containing butter, high-palmitic sunflower oil, olive oil (ROO) or a mixture of vegetable and fish oils (50 g/m(2) body surface area) to obtain a panel of postprandial TRL with gradual MUFA oleic acid-to-SFA palmitic acid ratios. The increase in this ratio was linearly associated with a decrease of ApoB48R up-regulation and lipid accumulation in THP-1 and primary monocytes. ApoB48R mRNA levels and intracellular triglycerides were also lower in the monocytes from volunteers after the ingestion of the ROO meal when compared to the ingestion of the butter meal. In THP-1 macrophages, the increase in the MUFA oleic acid-to-SFA palmitic acid ratio in the postprandial TRL was linearly correlated with an increase in ApoB48R down-regulation and a decrease in lipid accumulation. We also revealed that the nuclear receptor transcription factors PPARα, PPARβ/δ, and PPARγ and the PPAR-RXR transcriptional complex were involved in sensing the proportion of MUFA oleic acid and SFA palmitic acid, and these were also involved in adjusting the transcriptional activity of ApoB48R. The results of this study support the notion that MUFA-rich dietary fats may prevent excessive lipid accumulation in monocyte/macrophage cells by targeting the postprandial TRL/ApoB48R axis. © 2013.

Peroxisomal proliferator activated receptor-γ deficiency in a Canadian kindred with familial partial lipodystrophy type 3 (FPLD3

Directory of Open Access Journals (Sweden)

Cao Henian

2006-01-01

Full Text Available Abstract Background Familial partial lipodystrophy (Dunnigan type 3 (FPLD3, Mendelian Inheritance in Man [MIM] 604367 results from heterozygous mutations in PPARG encoding peroxisomal proliferator-activated receptor-γ. Both dominant-negative and haploinsufficiency mechanisms have been suggested for this condition. Methods We present a Canadian FPLD3 kindred with an affected mother who had loss of fat on arms and legs, but no increase in facial, neck, suprascapular or abdominal fat. She had profound insulin resistance, diabetes, severe hypertriglyceridemia and relapsing pancreatitis, while her pre-pubescent daughter had normal fat distribution but elevated plasma triglycerides and C-peptide and depressed high-density lipoprotein cholesterol. Results The mother and daughter were each heterozygous for PPARG nonsense mutation Y355X, whose protein product in vitro was transcriptionally inactive with no dominant-negative activity against the wild-type receptor. In addition the mutant protein appeared to be markedly unstable. Conclusion Taken together with previous studies of human PPARG mutations, these findings suggest that PPAR-γ deficiency due either to haploinsufficiency or to substantial activity loss due to dominant negative interference of the normal allele product's function can each contribute to the FPLD3 phenotype.

Towards the generation of B-cell receptor retrogenic mice.

Directory of Open Access Journals (Sweden)

Jenny Freitag

Full Text Available Transgenic expression of B- and T-cell receptors (BCRs and TCRs, respectively has been a standard tool to study lymphocyte development and function in vivo. The generation of transgenic mice is time-consuming and, therefore, a faster method to study the biology of defined lymphocyte receptors in vivo would be highly welcome. Using 2A peptide-linked multicistronic retroviral vectors to transduce stem cells, TCRs can be expressed rapidly in mice of any background. We aimed at adopting this retrogenic technology to the in vivo expression of BCRs. Using a well characterised BCR specific for hen egg lysozyme (HEL, we achieved surface expression of the retrogenically encoded BCR in a Rag-deficient pro B-cell line in vitro. In vivo, retrogenic BCRs were detectable only intracellularly but not on the surface of B cells from wild type or Rag2-deficient mice. This data, together with the fact that no BCR retrogenic mouse model has been published in the 7 years since the method was originally published for TCRs, strongly suggests that achieving BCR-expression in vivo with retrogenic technology is highly challenging if not impossible.

Flow-cytometric determination of high-density-lipoprotein binding sites on human leukocytes

International Nuclear Information System (INIS)

Schmitz, G.; Wulf, G.; Bruening, T.A.; Assmann, G.

1987-01-01

In this method, leukocytes were isolated from 6 mL of EDTA-blood by density-gradient centrifugation and subsequently incubated with rhodamine isothiocyanate (RITC)-conjugated high-density lipoproteins (HDL). The receptor-bound conjugate particles were determined by fluorescent flow cytometry and compared with 125 I-labeled HDL binding data for the same cells. Human granulocytes express the highest number of HDL binding sites (9.4 x 10(4)/cell), followed by monocytes (7.3 x 10(4)/cell) and lymphocytes (4.0 x 10(4)/cell). Compared with conventional analysis of binding of 125 I-labeled HDL in tissue-culture dishes, the present determination revealed significantly lower values for nonspecific binding. In competition studies, the conjugate competes for the same binding sites as 125 I-labeled HDL. With the use of tetranitromethane-treated HDL3, which fails to compete for the HDL receptor sites while nonspecific binding is not affected, we could clearly distinguish between 37 degrees C surface binding and specific 37 degrees C uptake of RITC-HDL3, confirming that the HDL receptor leads bound HDL particles into an intracellular pathway rather than acting as a docking type of receptor. Patients with familial dysbetalipoproteinemia showed a significantly higher number of HDL binding sites in the granulocyte population but normal in lymphocytes and monocytes, indicating increased uptake of cholesterol-containing lipoproteins. In patients with familial hypercholesterolemia, HDL binding was increased in all three cell types, indicating increased cholesterol uptake and increased cholesterol synthesis. The present method allows rapid determination of HDL binding sites in leukocytes from patients with various forms of hyper- and dyslipoproteinemias

Drosophila lipophorin receptors mediate the uptake of neutral lipids in oocytes and imaginal disc cells by an endocytosis-independent mechanism.

Directory of Open Access Journals (Sweden)

Esmeralda Parra-Peralbo

2011-02-01

Full Text Available Lipids are constantly shuttled through the body to redistribute energy and metabolites between sites of absorption, storage, and catabolism in a complex homeostatic equilibrium. In Drosophila, lipids are transported through the hemolymph in the form of lipoprotein particles, known as lipophorins. The mechanisms by which cells interact with circulating lipophorins and acquire their lipidic cargo are poorly understood. We have found that lipophorin receptor 1 and 2 (lpr1 and lpr2, two partially redundant genes belonging to the Low Density Lipoprotein Receptor (LDLR family, are essential for the efficient uptake and accumulation of neutral lipids by oocytes and cells of the imaginal discs. Females lacking the lpr2 gene lay eggs with low lipid content and have reduced fertility, revealing a central role for lpr2 in mediating Drosophila vitellogenesis. lpr1 and lpr2 are transcribed into multiple isoforms. Interestingly, only a subset of these isoforms containing a particular LDLR type A module mediate neutral lipid uptake. Expression of these isoforms induces the extracellular stabilization of lipophorins. Furthermore, our data indicate that endocytosis of the lipophorin receptors is not required to mediate the uptake of neutral lipids. These findings suggest a model where lipophorin receptors promote the extracellular lipolysis of lipophorins. This model is reminiscent of the lipolytic processing of triglyceride-rich lipoproteins that occurs at the mammalian capillary endothelium, suggesting an ancient role for LDLR-like proteins in this process.

Role of IGF-1R in ameliorating apoptosis of GNE deficient cells.

Science.gov (United States)

Singh, Reema; Chaudhary, Priyanka; Arya, Ranjana

2018-05-09

Sialic acids (SAs) are nine carbon acidic amino sugars, found at the outermost termini of glycoconjugates performing various physiological and pathological functions. SA synthesis is regulated by UDP-GlcNAc 2-epimerase/ManNAc kinase (GNE) that catalyzes rate limiting steps. Mutations in GNE result in rare genetic disorders, GNE myopathy and Sialuria. Recent studies indicate an alternate role of GNE in cell apoptosis and adhesion, besides SA biosynthesis. In the present study, using a HEK cell-based model for GNE myopathy, the role of Insulin-like Growth Factor Receptor (IGF-1R) as cell survival receptor protein was studied to counter the apoptotic effect of non-functional GNE. In the absence of functional GNE, IGF-1R was hyposialylated and transduced a downstream signal upon IGF-1 (IGF-1R ligand) treatment. IGF-1 induced activation of IGF-1R led to AKT (Protein Kinase B) phosphorylation that may phosphorylate BAD (BCL2 Associated Death Promoter) and its dissociation from BCL2 to prevent apoptosis. However, reduced ERK (Extracellular signal-regulated kinases) phosphorylation in GNE deficient cells after IGF-1 treatment suggests downregulation of the ERK pathway. A balance between the ERK and AKT pathways may determine the cell fate towards survival or apoptosis. Our study suggests that IGF-1R activation may rescue apoptotic cell death of GNE deficient cell lines and has potential as therapeutic target.

Development of occlusive neointimal lesions in distal pulmonary arteries of endothelin B receptor-deficient rats: a new model of severe pulmonary arterial hypertension.

Science.gov (United States)

Ivy, D Dunbar; McMurtry, Ivan F; Colvin, Kelley; Imamura, Masatoshi; Oka, Masahiko; Lee, Dong-Seok; Gebb, Sarah; Jones, Peter Lloyd

2005-06-07

Human pulmonary arterial hypertension (PAH) is characterized by proliferation of vascular smooth muscle and, in its more severe form, by the development of occlusive neointimal lesions. However, few animal models of pulmonary neointimal proliferation exist, thereby limiting a complete understanding of the pathobiology of PAH. Recent studies of the endothelin (ET) system demonstrate that deficiency of the ET(B) receptor predisposes adult rats to acute and chronic hypoxic PAH, yet these animals fail to develop neointimal lesions. Herein, we determined and thereafter showed that exposure of ET(B) receptor-deficient rats to the endothelial toxin monocrotaline (MCT) leads to the development of neointimal lesions that share hallmarks of human PAH. The pulmonary hemodynamic and morphometric effects of 60 mg/kg MCT in control (MCT(+/+)) and ET(B) receptor-deficient (MCT(sl/sl)) rats at 6 weeks of age were assessed. MCT(sl/sl) rats developed more severe PAH, characterized by elevated pulmonary artery pressure, diminished cardiac output, and right ventricular hypertrophy. In MCT(sl/sl) rats, morphometric evaluation revealed the presence of neointimal lesions within small distal pulmonary arteries, increased medial wall thickness, and decreased arterial-to-alveolar ratio. In keeping with this, barium angiography revealed diminished distal pulmonary vasculature of MCT(sl/sl) rat lungs. Cells within neointimal lesions expressed smooth muscle and endothelial cell markers. Moreover, cells within neointimal lesions exhibited increased levels of proliferation and were located in a tissue microenvironment enriched with vascular endothelial growth factor, tenascin-C, and activated matrix metalloproteinase-9, factors already implicated in human PAH. Finally, assessment of steady state mRNA showed that whereas expression of ET(B) receptors was decreased in MCT(sl/sl) rat lungs, ET(A) receptor expression increased. Deficiency of the ET(B) receptor markedly accelerates the progression of

A role for the high-density lipoprotein receptor SR-B1 in synovial inflammation via serum amyloid-A.

LENUS (Irish Health Repository)

Mullan, Ronan Hugh

2012-02-01

Acute phase apoprotein Serum Amyloid A (A-SAA), which is strongly expressed in rheumatoid arthritis synovial membrane (RA SM), induces angiogenesis, adhesion molecule expression, and matrix metalloproteinase production through the G-coupled receptor FPRL-1. Here we report alternative signaling through the high-density lipoprotein receptor scavenger receptor-class B type 1 (SR-B1). Quantitative expression\\/localization of SR-B1 in RA SM, RA fibroblast-like cells (FLCs), and microvascular endothelial cells (ECs) was assessed by Western blotting and immunohistology\\/fluorescence. A-SAA-mediated effects were examined using a specific antibody against SR-B1 or amphipathic alpha-Helical Peptides (the SR-B1 antagonists L-37pA and D-37pA), in RA FLCs and ECs. Adhesion molecule expression and cytokine production were quantified using flow cytometry and ELISA. SR-B1 was strongly expressed in the RA SM lining layer and endothelial\\/perivascular regions compared with osteoarthritis SM or normal control synovium. Differential SR-B1 expression in RA FLC lines (n = 5) and ECs correlated closely with A-SAA, but not tumor necrosis factor alpha-induced intercellular adhesion molecule-1 upregulation. A-SAA-induced interleukin-6 and -8 production was inhibited in the presence of anti-SR-B1 in human microvascular endothelial cells and RA FLCs. Moreover, D-37pA and L-37pA inhibited A-SAA-induced vascular cell adhesion molecule-1 and intercellular adhesion molecule expression from ECs in a dose-dependent manner. As SR-B1 is expressed in RA synovial tissue and mediates A-SAA-induced pro-inflammatory pathways, a better understanding of A-SAA-mediated inflammatory pathways may lead to novel treatment strategies for RA.

Erythroblast transferrin receptors and transferrin kinetics in iron deficiency and various anemias

International Nuclear Information System (INIS)

Muta, K.; Nishimura, J.; Ideguchi, H.; Umemura, T.; Ibayashi, H.

1987-01-01

To clarify the role of transferrin receptors in cases of altered iron metabolism in clinical pathological conditions, we studied: number of binding sites; affinity; and recycling kinetics of transferrin receptors on human erythroblasts. Since transferrin receptors are mainly present on erythroblasts, the number of surface transferrin receptors was determined by assay of binding of 125 I-transferrin and the percentage of erythroblasts in bone marrow mononuclear cells. The number of binding sites on erythroblasts from patients with an iron deficiency anemia was significantly greater than in normal subjects. Among those with an aplastic anemia, hemolytic anemia, myelodysplastic syndrome, and polycythemia vera compared to normal subjects, there were no considerable differences in the numbers of binding sites. The dissociation constants (Kd) were measured using Scatchard analysis. The apparent Kd was unchanged (about 10 nmol/L) in patients and normal subjects. The kinetics of endocytosis and exocytosis of 125 I-transferrin, examined by acid treatment, revealed no variations in recycling kinetics among the patients and normal subjects. These data suggest that iron uptake is regulated by modulation of the number of surface transferrin receptors, thereby reflecting the iron demand of the erythroblast

Enveloped viruses disable innate immune responses in dendritic cells by direct activation of TAM receptors.

Science.gov (United States)

Bhattacharyya, Suchita; Zagórska, Anna; Lew, Erin D; Shrestha, Bimmi; Rothlin, Carla V; Naughton, John; Diamond, Michael S; Lemke, Greg; Young, John A T

2013-08-14

Upon activation by the ligands Gas6 and Protein S, Tyro3/Axl/Mer (TAM) receptor tyrosine kinases promote phagocytic clearance of apoptotic cells and downregulate immune responses initiated by Toll-like receptors and type I interferons (IFNs). Many enveloped viruses display the phospholipid phosphatidylserine on their membranes, through which they bind Gas6 and Protein S and engage TAM receptors. We find that ligand-coated viruses activate TAM receptors on dendritic cells (DCs), dampen type I IFN signaling, and thereby evade host immunity and promote infection. Upon virus challenge, TAM-deficient DCs display type I IFN responses that are elevated in comparison to wild-type cells. As a consequence, TAM-deficient DCs are relatively resistant to infection by flaviviruses and pseudotyped retroviruses, but infection can be restored with neutralizing type I IFN antibodies. Correspondingly, a TAM kinase inhibitor antagonizes the infection of wild-type DCs. Thus, TAM receptors are engaged by viruses in order to attenuate type I IFN signaling and represent potential therapeutic targets. Copyright © 2013 Elsevier Inc. All rights reserved.

Identification of the Oxidized Low-Density Lipoprotein Scavenger Receptor CD36 in Plasma

DEFF Research Database (Denmark)

Handberg, Aase; Levin, Klaus; Højlund, Kurt

2006-01-01

BACKGROUND: Macrophage CD36 scavenges oxidized low-density lipoprotein, leading to foam cell formation, and appears to be a key proatherogenic molecule. Increased expression of CD36 has been attributed to hyperglycemia and to defective macrophage insulin signaling in insulin resistance. Premature...

The low-density lipoprotein receptor-related protein 10 is a negative regulator of the canonical Wnt/β-catenin signaling pathway

International Nuclear Information System (INIS)

Jeong, Young-Hee; Sekiya, Manami; Hirata, Michiko; Ye, Mingjuan; Yamagishi, Azumi; Lee, Sang-Mi; Kang, Man-Jong; Hosoda, Akemi; Fukumura, Tomoe; Kim, Dong-Ho; Saeki, Shigeru

2010-01-01

Wnt signaling pathways play fundamental roles in the differentiation, proliferation and functions of many cells as well as developmental, growth, and homeostatic processes in animals. Low-density lipoprotein receptor (LDLR)-related protein (LRP) 5 and LRP6 serve as coreceptors of Wnt proteins together with Frizzled receptors, triggering activation of canonical Wnt/β-catenin signaling. Here, we found that LRP10, a new member of the LDLR gene family, inhibits the canonical Wnt/β-catenin signaling pathway. The β-catenin/T cell factor (TCF) transcriptional activity in HEK293 cells was activated by transfection with Wnt3a or LRP6, which was then inhibited by co-transfection with LRP10. Deletion of the extracellular domain of LRP10 negated its inhibitory effect. The inhibitory effect of LRP10 was consistently conserved in HEK293 cells even when GSK3β phosphorylation was inhibited by incubation with lithium chloride and co-transfection with constitutively active S33Y-mutated β-catenin. Nuclear β-catenin accumulation was unaffected by LRP10. The present studies suggest that LRP10 may interfere with the formation of the β-catenin/TCF complex and/or its binding to target DNA in the nucleus, and that the extracellular domain of LRP10 is critical for inhibition of the canonical Wnt/β-catenin signaling pathway.

Opposing effects of CXCR3 and CCR5 deficiency on CD8+ T cell-mediated inflammation in the central nervous system of virus-infected mice

DEFF Research Database (Denmark)

de Lemos, Carina; Christensen, Jeanette Erbo; Nansen, Anneline

2005-01-01

and therefore protect mice against the otherwise fatal CD8+ T cell-mediated immune attack. Contrary to expectations, the accumulation of mononuclear cells in cerebrospinal fluid was only slightly delayed compared with mice with normal expression of both receptors. Even more surprising, CXCR3/CCR5 double-deficient......T cells play a key role in the control of viral infection in the CNS but may also contribute to immune-mediated cell damage. To study the redundancy of the chemokine receptors CXCR3 and CCR5 in regulating virus-induced CD8+ T cell-mediated inflammation in the brain, CXCR3/CCR5 double-deficient mice...... mice were more susceptible to intracerebral infection than CXCR3-deficient mice. Analysis of effector T cell generation revealed an accelerated antiviral CD8+ T cell response in CXCR3/CCR5 double-deficient mice. Furthermore, while the accumulation of CD8+ T cells in the neural parenchyma...

Effect of I125 on oxidation behavior of lipoprotein subpopulations

International Nuclear Information System (INIS)

Majtenyi, S.

2002-07-01

Lipoproteins play a central role in lipid metabolism. They serve as a transport vehicle for cholesterol and triglycerides keeping them in plasma in solution. Lipoproteins are characterized by the content of specific apoproteins and differences in the hydrated density ranges. Moreover, they are distinguished by electrophoretic mobility and other characteristics as high and low-density lipoproteins, respectively lipoprotein (a). More specifically, HDL is classified into HDL 2 and HDL 3 . In atherogenesis, lipoproteins are considered to play a key-role. Oxidatively modified LDL is selectively taken up via scavenger receptors of the macrophage-monocyte system. These cells are transformed into foam cells promoting atherogenesis in vessels in the subendothelial space. Oxidized HDL essentially appears to loose its protective effects on LDL and its beneficial function in reverse cholesterol transport. Thus, it turns proatherogenic. The effects various species of free radicals exert on lipoproteins are the reason for this oxidative modification. Thyroid function also influences lipoproteins in a complex manner. Based on their hydrated density ranges, lipoprotein subpopulations were fractionated and isolated via isopycnic density gradient ultracentrifugation. After investigation of the general oxidation behavior, initiated by addition of CuSO 4 to the isolated samples of HDL 3 , HDL 2 , LDL and Lp(a), the influence of different activities of radioiodine-125 on the kinetics of the formation of conjugated dienes was assessed. This was achieved by coincubation of plasma with I 125 . The spectrophotometrical measurement of the concentration of conjugated dienes in the course of CuSO 4 -induced lipid peroxidation leads to measurable changes in absorption at 234 nm. These changes in absorption over time result in a characteristically shaped curve graphically plotted. The shape of these curves mirrors different indicators of lipid peroxidation. Therefrom lag time, maximal

Early incorporation of cell-derived cholesterol into pre-beta-migrating high-density lipoprotein

International Nuclear Information System (INIS)

Castro, G.R.; Fielding, C.J.

1988-01-01

Cultures of human skin fibroblasts were labeled to high cholesterol specific activity with [ 3 H]cholesterol and incubated briefly (1-3 min) with normal human plasma. The plasma was fractionated by two-dimensional agarose-polyacrylamide gel electrophoresis and the early appearance of cholesterol label among plasma lipoproteins determined. A major part of the label at 1-min incubation was in a pre-beta-migrating apo A-I lipoprotein fraction with a molecular weight of ca. 70,000. Label was enriched about 30-fold in this fraction relative to its content of apo A-I (1-2% of total apo A-I). The proportion of label in this lipoprotein was strongly correlated with its concentration in plasma. Further incubation (2 min) in the presence of unlabeled cells demonstrated transfer of label from this fraction to a higher molecular weight pre-beta apo A-I species, to low-density lipoprotein, and to the alpha-migrating apo A-I that made up the bulk (96%) of total apo A-I in plasma. The data suggest that a significant part of cell-derived cholesterol is transferred specifically to a pre-beta-migrating lipoprotein A-I species as part of a cholesterol transport transfer sequence in plasma

Secretin receptor involvement in prion-infected cells and animals.

Science.gov (United States)

Kimura, Tomohiro; Nishizawa, Keiko; Oguma, Ayumi; Nishimura, Yuki; Sakasegawa, Yuji; Teruya, Kenta; Nishijima, Ichiko; Doh-ura, Katsumi

2015-07-08

The cellular mechanisms behind prion biosynthesis and metabolism remain unclear. Here we show that secretin signaling via the secretin receptor regulates abnormal prion protein formation in prion-infected cells. Animal studies demonstrate that secretin receptor deficiency slightly, but significantly, prolongs incubation time in female but not male mice. This gender-specificity is consistent with our finding that prion-infected cells are derived from females. Therefore, our results provide initial insights into the reasons why age of disease onset in certain prion diseases is reported to occur slightly earlier in females than males. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Mechanism of action of gemfibrozil on lipoprotein metabolism.

OpenAIRE

Saku, K; Gartside, P S; Hynd, B A; Kashyap, M L

1985-01-01

Gemfibrozil is a potent lipid regulating drug whose major effects are to increase plasma high density lipoproteins (HDL) and to decrease plasma triglycerides (TG) in a wide variety of primary and secondary dyslipoproteinemias. Its mechanism of action is not clear. Six patients with primary familial endogenous hypertriglyceridemia with fasting chylomicronemia (type V lipoprotein phenotype) with concurrent subnormal HDL cholesterol levels (HDL deficiency) were treated initially by diet and once...

Chlordecone, a mixed pregnane X receptor (PXR) and estrogen receptor alpha (ERα) agonist, alters cholesterol homeostasis and lipoprotein metabolism in C57BL/6 mice

International Nuclear Information System (INIS)

Lee, Junga; Scheri, Richard C.; Zhang Yuan; Curtis, Lawrence R.

2008-01-01

Chlordecone (CD) is one of many banned organochlorine (OC) insecticides that are widespread persistent organic pollutants. OC insecticides alter lipid homeostasis in rodents at doses that are not neurotoxic or carcinogenic. Pretreatment of mice or rats with CD altered tissue distribution of a subsequent dose of [ 14 C]CD or [ 14 C]cholesterol (CH). Nuclear receptors regulate expression of genes important in the homeostasis of CH and other lipids. In this study, we report that CD suppresses in vitro reporter systems for human liver X receptors (LXRs) and activates those for human farnesoid X receptor (FXR), pregnane X receptor (PXR) and estrogen receptor α (ERα) in a concentration-dependent manner (0-50 μM). Consistent with human PXR activation in vitro, three days after a single dose of CD (15 mg/kg) hepatic microsomal CYP3A11 protein increases in C57BL/6 mice. CD decreases hepatic CH ester content without altering total CH concentration. Apolipoprotein A-I (apoA-I) contents of hepatic lipoprotein-rich and microsomal fractions of CD-treated mice are higher than controls. There is a significant reduction in non-high density lipoprotein CH but not apolipoprotein B-48/100 (apoB-48/100) in plasma from CD-treated mice after a 4 h fast. At 14 days after 15 mg CD/kg apoA-I and apoB-100 proteins but not CYP3A11 protein in hepatic microsomes are similar to controls. This work indicates that altered CH homeostasis is a mode of OC insecticide action of relevance after a single dose. This at least partially explains altered CH tissue distribution in CD-pretreated mice

Aggravated restenosis and atherogenesis in ApoCIII transgenic mice but lack of protection in ApoCIII knockouts: the effect of authentic triglyceride-rich lipoproteins with and without ApoCIII.

Science.gov (United States)

Li, Haibo; Han, Yingchun; Qi, Rong; Wang, Yuhui; Zhang, Xiaohong; Yu, Maomao; Tang, Yin; Wang, Mengyu; Shu, Ya-Nan; Huang, Wei; Liu, Xinfeng; Rodrigues, Brian; Han, Mei; Liu, George

2015-09-01

Previously, our group and others have demonstrated a causative relationship between severe hypertriglyceridaemia and atherogenesis in mice. Furthermore, clinical investigations have shown high levels of plasma Apolipoprotein C-III (ApoCIII) associated with hypertriglyceridaemia and even cardiovascular disease. However, it remains unclear whether ApoCIII affects restenosis in vivo, and whether such an effect is mediated by ApoCIII alone, or in combination with hypertriglyceridaemia. We sought to investigate ApoCIII in restenosis and clarify how smooth muscle cells (SMCs) respond to authentic triglyceride-rich lipoproteins (TRLs) with or without ApoCIII (TRLs ± ApoCIII). ApoCIII transgenic (ApoCIIItg) and knockout (ApoCIII-/-) mice underwent endothelial denudation to model restenosis. Here, ApoCIIItg mice displayed severe hypertriglyceridaemia and increased neointimal formation compared with wild-type (WT) or ApoCIII-/- mice. Furthermore, increased proliferating cell nuclear antigen (PCNA)-positive cells, Mac-3, and vascular cell adhesion protein-1 (VCAM-1) expression, and 4-hydroxynonenal (4HNE) production were found in lesion sites. ApoCIIItg and ApoCIII-/- mice were then crossed to low-density lipoprotein receptor-deficient (Ldlr-/-) mice and fed an atherogenic diet. ApoCIIItg/Ldlr-/- mice had significantly increased atherosclerotic lesions. However, there was no statistical difference in restenosis between ApoCIII-/- and WT mice, and in atherosclerosis between ApoCIII/Ldlr double knockout and Ldlr-/- mice. SMCs were then incubated in vitro with authentic TRLs ± ApoCIII isolated from extreme hypertriglyceridaemia glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1-deficient (GPIHBP1-/-) mice crossed with ApoCIIItg or ApoCIII-/- mice. It was shown that TRLs + ApoCIII promoted SMC proliferation, VCAM-1 expression, and reactive oxygen species (ROS) production, and activated the Akt pathway. Scavenging ROS significantly reduced SMC

Hypercholesterolemia Tunes Hematopoietic Stem/Progenitor Cells for Inflammation and Atherosclerosis.

Science.gov (United States)

Ma, Xiaojuan; Feng, Yingmei

2016-07-19

As the pathological basis of cardiovascular disease (CVD), atherosclerosis is featured as a chronic inflammation. Hypercholesterolemia is an independent risk factor for CVD. Accumulated studies have shown that hypercholesterolemia is associated with myeloid cell expansion, which stimulates innate and adaptive immune responses, strengthens inflammation, and accelerates atherosclerosis progression. Hematopoietic stem/progenitor cells (HSPC) in bone marrow (BM) expresses a panel of lipoprotein receptors to control cholesterol homeostasis. Deficiency of these receptors abrogates cellular cholesterol efflux, resulting in HSPC proliferation and differentiation in hypercholesterolemic mice. Reduction of the cholesterol level in the lipid rafts by infusion of reconstituted high-density lipoprotein (HDL) or its major apolipoprotein, apoA-I, reverses hypercholesterolemia-induced HSPC expansion. Apart from impaired cholesterol metabolism, inhibition of reactive oxygen species production suppresses HSPC activation and leukocytosis. These data indicate that the mechanisms underlying the effects of hypercholesterolemia on HSPC proliferation and differentiation could be multifaceted. Furthermore, dyslipidemia also regulates HSPC-neighboring cells, resulting in HSPC mobilization. In the article, we review how hypercholesterolemia evokes HSPC activation and mobilization directly or via its modification of BM microenvironment. We hope this review will bring light to finding key molecules to control HSPC expansion, inflammation, and atherosclerosis for the treatment of CVD.

Normal mast cell numbers in the tissues of AhR-deficient mice.

Science.gov (United States)

Pilz, Caroline; Feyerabend, Thorsten; Sonner, Jana; Redaelli, Chiara; Peter, Katharina; Kunze, Anja; Haas, Katharina; Esser, Charlotte; Schäkel, Knut; Wick, Wolfgang; Rodewald, Hans-Reimer; Lanz, Tobias V; Platten, Michael

2016-01-01

The transcription factor aryl hydrocarbon receptor (AhR) acts as an immunomodulatory molecule in several immune cell lineages. Recently, it has been implicated in development and maintenance of immune cells in barrier tissues such as skin and mucosa. To investigate its role on mast cell development and maintenance in skin, peritoneal exudate cells (PECs) and lymph nodes, we studied in depth their phenotype in AhR-deficient mice. Our findings do not provide any evidence for a suspected role of the AhR in mast cell homeostasis. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Possible contribution of taurine to distorted glucagon secretion in intra-islet insulin deficiency: a metabolome analysis using a novel α-cell model of insulin-deficient diabetes.

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Megumi Bessho

Full Text Available Glycemic instability is a serious problem in patients with insulin-deficient diabetes, and it may be due in part to abnormal endogenous glucagon secretion. However, the intracellular metabolic mechanism(s involved in the aberrant glucagon response under the condition of insulin deficiency has not yet been elucidated. To investigate the metabolic traits that underlie the distortion of glucagon secretion under insulin deficient conditions, we generated an αTC1-6 cell line with stable knockdown of the insulin receptor (IRKD, i.e., an in vitro α-cell model for insulin-deficient diabetes, which exhibits an abnormal glucagon response to glucose. A comprehensive metabolomic analysis of the IRKD αTC1-6 cells (IRKD cells revealed some candidate metabolites whose levels differed markedly compared to those in control αTC1-6 cells, but also which could affect the glucagon release in IRKD cells. Of these candidates, taurine was remarkably increased in the IRKD cells and was identified as a stimulator of glucagon in αTC1-6 cells. Taurine also paradoxically exaggerated the glucagon secretion at a high glucose concentration in IRKD cells and islets with IRKD. These results indicate that the metabolic alterations induced by IRKD in α-cells, especially the increase of taurine, may lead to the distorted glucagon response in IRKD cells, suggesting the importance of taurine in the paradoxical glucagon response and the resultant glucose instability in insulin-deficient diabetes.

The LDL Receptor-Related Protein 1: At the Crossroads of Lipoprotein Metabolism and Insulin Signaling

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Dianaly T. Au

2017-01-01

Full Text Available The metabolic syndrome is an escalating worldwide public health concern. Defined by a combination of physiological, metabolic, and biochemical factors, the metabolic syndrome is used as a clinical guideline to identify individuals with a higher risk for type 2 diabetes and cardiovascular disease. Although risk factors for type 2 diabetes and cardiovascular disease have been known for decades, the molecular mechanisms involved in the pathophysiology of these diseases and their interrelationship remain unclear. The LDL receptor-related protein 1 (LRP1 is a large endocytic and signaling receptor that is widely expressed in several tissues. As a member of the LDL receptor family, LRP1 is involved in the clearance of chylomicron remnants from the circulation and has been demonstrated to be atheroprotective. Recently, studies have shown that LRP1 is involved in insulin receptor trafficking and regulation and glucose metabolism. This review summarizes the role of tissue-specific LRP1 in insulin signaling and its potential role as a link between lipoprotein and glucose metabolism in diabetes.

Choline or methionine reverses impaired secretion of VLDL by hepatocytes from choline-deficient rats

International Nuclear Information System (INIS)

Yao, Z.; Vance, D.E.

1987-01-01

Male rats fed a choline-deficient (CD) diet for three days accumulated triacylglycerol (TG) in the liver. Hepatocytes from these rats were cultured and maintained in a medium + choline. The rate of secretion of TG was reduced by 50% in the CD cells. Correspondingly, [ 3 H]oleate and [ 3 H]glycerol were incorporated at a 2-fold higher rate into TG secreted by choline-supplemented cells compared to CD cells. Isolation of lipoprotein fractions by ultracentrifugation showed that the reduced secretion of TG by CD hepatocytes was mainly due to an impaired secretion of very low density lipoprotein (VLDL). Incorporation of [ 3 H]leucine into secreted apoB/sub H/, apoB/sub L/ and apoE was markedly reduced in CD cells compared to choline-supplemented cells. Secretion of high density lipoprotein was not reduced in the CD hepatocytes. Normal secretion of VLDL was resumed upon addition of methionine to the CD cells

Impaired endothelial barrier function in apolipoprotein M-deficient mice is dependent on sphingosine-1-phosphate receptor 1

DEFF Research Database (Denmark)

Christensen, Pernille M; Liu, Catherine H; Swendeman, Steven L

2016-01-01

Apolipoprotein M (ApoM) transports sphingosine-1-phosphate (S1P) in plasma, and ApoM-deficient mice (Apom(-/-)) have ∼50% reduced plasma S1P levels. There are 5 known S1P receptors, and S1P induces adherens junction formation between endothelial cells through the S1P1 receptor, which in turn...... suppresses vascular leak. Increased vascular permeability is a hallmark of inflammation. The purpose of this study was to explore the relationships between vascular leakage in ApoM deficiency and S1P1 function in normal physiology and in inflammation. Vascular permeability in the lungs was assessed...... by accumulation of dextran molecules (70 kDa) and was increased ∼40% in Apom(-/-) mice compared to WT (C57Bl6/j) mice. Reconstitution of plasma ApoM/S1P or treatment with an S1P1 receptor agonist (SEW2871) rapidly reversed the vascular leakage to a level similar to that in WT mice, suggesting that it is caused...

Stimulation of dopamine receptor D5 expressed on dendritic cells potentiates Th17-mediated immunity.

Science.gov (United States)

Prado, Carolina; Contreras, Francisco; González, Hugo; Díaz, Pablo; Elgueta, Daniela; Barrientos, Magaly; Herrada, Andrés A; Lladser, Álvaro; Bernales, Sebastián; Pacheco, Rodrigo

2012-04-01

Dendritic cells (DCs) are responsible for priming T cells and for promoting their differentiation from naive T cells into appropriate effector cells. Emerging evidence suggests that neurotransmitters can modulate T cell-mediated immunity. However, the involvement of specific neurotransmitters or receptors remains poorly understood. In this study, we analyzed the role of dopamine in the regulation of DC function. We found that DCs express dopamine receptors as well as the machinery necessary to synthesize, store, and degrade dopamine. Notably, the expression of D5R decreased upon LPS-induced DC maturation. Deficiency of D5R on the surface of DCs impaired LPS-induced IL-23 and IL-12 production and consequently attenuated the activation and proliferation of Ag-specific CD4(+) T cells. To determine the relevance of D5R expressed on DCs in vivo, we studied the role of this receptor in the modulation of a CD4(+) T cell-driven autoimmunity model. Importantly, D5R-deficient DCs prophylactically transferred into wild-type recipients were able to reduce the severity of experimental autoimmune encephalomyelitis. Furthermore, mice transferred with D5R-deficient DCs displayed a significant reduction in the percentage of Th17 cells infiltrating the CNS without differences in the percentage of Th1 cells compared with animals transferred with wild-type DCs. Our findings demonstrate that by contributing to CD4(+) T cell activation and differentiation to Th17 phenotype, D5R expressed on DCs is able to modulate the development of an autoimmune response in vivo.

Secretion of hepatitis C virus envelope glycoproteins depends on assembly of apolipoprotein B positive lipoproteins.

Directory of Open Access Journals (Sweden)

Vinca Icard

Full Text Available The density of circulating hepatitis C virus (HCV particles in the blood of chronically infected patients is very heterogeneous. The very low density of some particles has been attributed to an association of the virus with apolipoprotein B (apoB positive and triglyceride rich lipoproteins (TRL likely resulting in hybrid lipoproteins known as lipo-viro-particles (LVP containing the viral envelope glycoproteins E1 and E2, capsid and viral RNA. The specific infectivity of these particles has been shown to be higher than the infectivity of particles of higher density. The nature of the association of HCV particles with lipoproteins remains elusive and the role of apolipoproteins in the synthesis and assembly of the viral particles is unknown. The human intestinal Caco-2 cell line differentiates in vitro into polarized and apoB secreting cells during asymmetric culture on porous filters. By using this cell culture system, cells stably expressing E1 and E2 secreted the glycoproteins into the basal culture medium after one week of differentiation concomitantly with TRL secretion. Secreted glycoproteins were only detected in apoB containing density fractions. The E1-E2 and apoB containing particles were unique complexes bearing the envelope glycoproteins at their surface since apoB could be co-immunoprecipitated with E2-specific antibodies. Envelope protein secretion was reduced by inhibiting the lipidation of apoB with an inhibitor of the microsomal triglyceride transfer protein. HCV glycoproteins were similarly secreted in association with TRL from the human liver cell line HepG2 but not by Huh-7 and Huh-7.5 hepatoma cells that proved deficient for lipoprotein assembly. These data indicate that HCV envelope glycoproteins have the intrinsic capacity to utilize apoB synthesis and lipoprotein assembly machinery even in the absence of the other HCV proteins. A model for LVP assembly is proposed.

Cell surface receptors for signal transduction and ligand transport: a design principles study.

Directory of Open Access Journals (Sweden)

Harish Shankaran

2007-06-01

Full Text Available Receptors constitute the interface of cells to their external environment. These molecules bind specific ligands involved in multiple processes, such as signal transduction and nutrient transport. Although a variety of cell surface receptors undergo endocytosis, the systems-level design principles that govern the evolution of receptor trafficking dynamics are far from fully understood. We have constructed a generalized mathematical model of receptor-ligand binding and internalization to understand how receptor internalization dynamics encodes receptor function and regulation. A given signaling or transport receptor system represents a particular implementation of this module with a specific set of kinetic parameters. Parametric analysis of the response of receptor systems to ligand inputs reveals that receptor systems can be characterized as being: i avidity-controlled where the response control depends primarily on the extracellular ligand capture efficiency, ii consumption-controlled where the ability to internalize surface-bound ligand is the primary control parameter, and iii dual-sensitivity where both the avidity and consumption parameters are important. We show that the transferrin and low-density lipoprotein receptors are avidity-controlled, the vitellogenin receptor is consumption-controlled, and the epidermal growth factor receptor is a dual-sensitivity receptor. Significantly, we show that ligand-induced endocytosis is a mechanism to enhance the accuracy of signaling receptors rather than merely serving to attenuate signaling. Our analysis reveals that the location of a receptor system in the avidity-consumption parameter space can be used to understand both its function and its regulation.

The role of registries in rare genetic lipid disorders: Review and introduction of the first global registry in lipoprotein lipase deficiency.

Science.gov (United States)

Steinhagen-Thiessen, Elisabeth; Stroes, Erik; Soran, Handrean; Johnson, Colin; Moulin, Philippe; Iotti, Giorgio; Zibellini, Marco; Ossenkoppele, Bas; Dippel, Michaela; Averna, Maurizio R

2017-07-01

A good understanding of the natural history of rare genetic lipid disorders is a pre-requisite for successful patient management. Disease registries have been helpful in this regard. Lipoprotein Lipase Deficiency (LPLD) is a rare, autosomal-recessive lipid disorder characterized by severe hypertriglyceridemia and a very high risk for recurrent acute pancreatitis, however, only limited data are available on its natural course. Alipogene tiparvovec (Glybera ® ) is the first gene therapy to receive Marketing Authorization in the European Union; GENIALL (GENetherapy In the MAnagement of Lipoprotein Lipase Deficiency), a 15-year registry focusing on LPLD was launched in 2014 as part of its Risk Management Plan. The aim of this publication is to introduce the GENIALL Registry within a structured literature review of registries in rare genetic lipid disorders. A total of 11 relevant initiatives/registries were identified (homozygous Familial Hypercholesterolemia (hoFH) [n = 5]; LPLD [n = 1]; Lysosomal Acid Lipase Deficiency [LALD, n = 1], detection of mutations in genetic lipid disorders [n = 4]). Besides one product registry in hoFH and the LALD registry, all other initiatives are local or country-specific. GENIALL is the first global prospective registry in LPLD that will collect physician and patient generated data on the natural course of LPLD, as well as long-term outcomes of gene therapy. There is a limited number of international initiatives focusing on the natural course of specific rare genetic lipid disorders. The GENIALL LPLD Registry could be the first step towards a future broader global initiative that collects data related to familial chylomicronemia syndrome and their underlying genetic causes. Copyright © 2016. Published by Elsevier B.V.

Activation of Adiponectin Receptor Regulates Proprotein Convertase Subtilisin/Kexin Type 9 Expression and Inhibits Lesions in ApoE-Deficient Mice.

Science.gov (United States)

Sun, Lei; Yang, Xiaoxiao; Li, Qi; Zeng, Peng; Liu, Ying; Liu, Lipei; Chen, Yuanli; Yu, Miao; Ma, Chuanrui; Li, Xiaoju; Li, Yan; Zhang, Rongxin; Zhu, Yan; Miao, Qing Robert; Han, Jihong; Duan, Yajun

2017-07-01

The reduced adiponectin levels are associated with atherosclerosis. Adiponectin exerts its functions by activating adiponectin receptor (AdipoR). Proprotein convertase subtilisin kexin type 9 (PCSK9) degrades LDLR protein (low-density lipoprotein receptor) to increase serum LDL-cholesterol levels. PCSK9 expression can be regulated by PPARγ (peroxisome proliferator-activated receptor γ) or SREBP2 (sterol regulatory element-binding protein 2). The effects of AdipoR agonists on PCSK9 and LDLR expression, serum lipid profiles, and atherosclerosis remain unknown. At cellular levels, AdipoR agonists (ADP355 and AdipoRon) induced PCSK9 transcription/expression that solely depended on activation of PPAR-responsive element in the PCSK9 promoter. AdipoR agonists induced PPARγ expression; thus, the AdipoR agonist-activated PCSK9 expression/production was impaired in PPARγ deficient hepatocytes. Meanwhile, AdipoR agonists transcriptionally activated LDLR expression by activating SRE in the LDLR promoter. Moreover, AMP-activated protein kinase α (AMPKα) was involved in AdipoR agonist-activated PCSK9 expression. In wild-type mice, ADP355 increased PCSK9 and LDLR expression and serum PCSK9 levels, which was associated with activation of PPARγ, AMPKα and SREBP2 and reduction of LDL-cholesterol levels. In contrast, ADP355 reduced PCSK9 expression/secretion in apoE-deficient (apoE -/- ) mice, but it still activated hepatic LDLR, PPARγ, AMPKα, and SREBP2. More importantly, ADP355 inhibited lesions in en face aortas and sinus lesions in aortic root in apoE -/- mice with amelioration of lipid profiles. Our study demonstrates that AdipoR activation by agonists regulated PCSK9 expression differently in wild-type and apoE -/- mice. However, ADP355 activated hepatic LDLR expression and ameliorated lipid metabolism in both types of mice and inhibited atherosclerosis in apoE -/- mice. © 2017 American Heart Association, Inc.

The Use of an IL-1 Receptor Antagonist Peptide to Control Inflammation in the Treatment of Corneal Limbal Epithelial Stem Cell Deficiency

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E. Fok

2015-01-01

Full Text Available Corneal limbal stem cell deficiency (LSCD may be treated using ex vivo limbal epithelial stem cells (LESCs derived from cadaveric donor tissue. However, continuing challenges exist around tissue availability, inflammation, and transplant rejection. Lipopolysaccharide (LPS or recombinant human IL-1β stimulated primary human keratocyte and LESC models were used to investigate the anti-inflammatory properties of a short chain, IL-1 receptor antagonist peptide for use in LESC sheet growth to control inflammation. The peptide was characterized using mass spectroscopy and high performance liquid chromatography. Peptide cytotoxicity, patterns of cell cytokine expression in response to LPS or IL-1β stimulation, and peptide suppression of this response were investigated by MTS/LDH assays, ELISA, and q-PCR. Cell differences in LPS stimulated toll-like receptor 4 expression were investigated using immunocytochemistry. A significant reduction in rIL-1β stimulated inflammatory cytokine production occurred following LESC and keratocyte incubation with anti-inflammatory peptide and in LPS stimulated IL-6 and IL-8 production following keratocyte incubation with peptide (1 mg/mL P<0.05. LESCs produced no cytokine response to LPS stimulation and showed no TLR4 expression. The peptide supported LESC growth when adhered to a silicone hydrogel contact lens indicating potential use in improved LESC grafting through suppression of inflammation.

Growth hormone receptor deficiency (Laron syndrome) in black ...

African Journals Online (AJOL)

Non-Caucasians with growth honnone receptor (GHR) deficiency/Lamn syndrome among the .... 4,3 cm (-2,4 SOS for bone age 8,5 years at age 12); the girl's height at age 7 years was 77,5 cm (-8,0 SOS, height ... of serum incubated with '25I-labelled human growth hormone and expressed as relative specific binding ...

Severe Hypertriglyceridemia due to a novel p.Q240H mutation in the Lipoprotein Lipase gene.

Science.gov (United States)

Soto, Angela Ganan; McIntyre, Adam; Agrawal, Sungeeta; Bialo, Shara R; Hegele, Robert A; Boney, Charlotte M

2015-09-04

Lipoprotein Lipase (LPL) deficiency is a rare autosomal recessive disorder with a heterogeneous clinical presentation. Several mutations in the LPL gene have been identified to cause decreased activity of the enzyme. An 11-week-old, exclusively breastfed male presented with coffee-ground emesis, melena, xanthomas, lipemia retinalis and chylomicronemia. Genomic DNA analysis identified lipoprotein lipase deficiency due to compound heterozygosity including a novel p.Q240H mutation in exon 5 of the lipoprotein lipase (LPL) gene. His severe hypertriglyceridemia, including xanthomas, resolved with dietary long-chain fat restriction. We describe a novel mutation of the LPL gene causing severe hypertriglyceridemia and report the response to treatment. A review of the current literature regarding LPL deficiency syndrome reveals a few potential new therapies under investigation.

In vitro biological efficacy of boronated low density lipoproteins for NCT

International Nuclear Information System (INIS)

Kahl, S.B.; Pate, D.; Laster, B.H.; Popenoe, E.A.; Fairchild, R.G.

1992-01-01

Low Density Lipoproteins (LDLs) are known to be internalized within the cell by receptor-mediated mechanisms. There is evidence that LDLs may be taken up avidly by tumor cells to provide cholesterol for the synthesis of cell membrane. Thus, the possibility exists that LDLs may provide an ideal vehicle for the transport of boron to tumor cells for Neutron Capture Therapy (NCT). A boronated analog of LDL has recently been synthesized for possible application in NCT. The analog was tested in cell culture for uptake and biological efficacy in the thermal neutron beam at the Brookhaven Medical Research Reactor (BMRR). It was found that boron concentrations ten times higher than that required for NCT were easily obtained, and that uptake data were constant with a receptor mediated binding mechanism. The measured intracellular concentration of ∼240 μg 10 B/g cells is significantly higher than that obtained with any other boron compound previously evaluated for possible clinical application

Cell type-specific deficiency of c-kit gene expression in mutant mice of mi/mi genotype.

Science.gov (United States)

Isozaki, K.; Tsujimura, T.; Nomura, S.; Morii, E.; Koshimizu, U.; Nishimune, Y.; Kitamura, Y.

1994-01-01

The mi locus of mice encodes a novel member of the basic-helix-loop-helix-leucine zipper protein family of transcription factors (hereafter called mi factor). In addition to microphthalmus, osteopetrosis, and lack of melanocytes, mice of mi/mi genotype are deficient in mast cells. Since the c-kit receptor tyrosine kinase plays an important role in the development of mast cells, and since the c-kit expression by cultured mast cells from mi/mi mice is deficient in both mRNA and protein levels, the mast cell deficiency of mi/mi mice has been attributed at least in part to the deficient expression of c-kit. However, it remained to be examined whether the c-kit expression was also deficient in tissues of mi/mi mice. In the present study, we examined the c-kit expression by mi/mi skin mast cells using in situ hybridization and immunohistochemistry. Moreover, we examined the c-kit expression by various cells other than mast cells in tissues of mi/mi mice. We found that the c-kit expression was deficient in mast cells but not in erythroid precursors, testicular germ cells, and neurons of mi/mi mice. This suggested that the regulation of the c-kit transcription by the mi factor was dependent on cell types. Mice of mi/mi genotype appeared to be a useful model to analyze the function of transcription factors in the whole-animal level. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:7524330

Inhibitory Effects of North American Wild Rice on Monocyte Adhesion and Inflammatory Modulators in Low-Density Lipoprotein Receptor-Knockout Mice.

Science.gov (United States)

Moghadasian, Mohammed H; Zhao, Ruozhi; Ghazawwi, Nora; Le, Khuong; Apea-Bah, Franklin B; Beta, Trust; Shen, Garry X

2017-10-18

The present study examined the effects of wild rice on monocyte adhesion, inflammatory and fibrinolytic mediators in low-density lipoprotein receptor-knockout (LDLr-KO) mice. Male LDLr-KO mice received a cholesterol (0.06%, w/w)-supplemented diet with or without white or wild rice (60%, w/w) for 20 weeks. White rice significantly increased monocyte adhesion and abundances of monocyte chemoattractant protein-1, tissue necrosis factor-α, intracellular cell adhesion molecule-1, plasminogen activator inhibitor-1, urokinase plasminogen activator (uPA), and uPA receptor in aortae and hearts of LDLr-KO mice compared to the control diet. Wild rice inhibited monocyte adhesion to the aorta, atherosclerosis, and abundances of the inflammatory and fibrinolytic regulators in the cardiovascular tissue of LDLr-KO mice compared to white rice. White or wild rice did not significantly alter the levels of cholesterol, triglycerides, or antioxidant enzymes in plasma. The anti-atherosclerotic effect of wild rice may result from its inhibition on monocyte adhesion and inflammatory modulators in LDLr-KO mice.

Amelioration of hypertriglyceridemia with hypo-alpha-cholesterolemia in LPL deficient mice by hematopoietic cell-derived LPL.

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Yinyuan Ding

Full Text Available BACKGROUND: Macrophage-derived lipoprotein lipase (LPL has been shown uniformly to promote atherosclerotic lesion formation while the extent to which it affects plasma lipid and lipoprotein levels varies in wild-type and hypercholesterolemic mice. It is known that high levels of LPL in the bulk of adipose tissue and skeletal muscle would certainly mask the contribution of macrophage LPL to metabolism of plasma lipoprotein. Therefore, we chose LPL deficient (LPL⁻/⁻ mice with severe hypertriglyceridemia as an alternative model to assess the role of macrophage LPL in plasma lipoprotein metabolism via bone marrow transplant, through which LPL will be produced mainly by hematopoietic cell-derived macrophages. METHODS AND RESULTS: Hypertriglyceridemic LPL⁻/⁻ mice were lethally irradiated, then transplanted with bone marrow from wild-type (LPL⁺/⁺ or LPL⁻/⁻ mice, respectively. Sixteen weeks later, LPL⁺/⁺ →LPL⁻/⁻ mice displayed significant reduction in plasma levels of triglyceride and cholesterol (408±44.9 vs. 2.7±0.5×10³ and 82.9±7.1 vs. 229.1±30.6 mg/dl, p<0.05, respectively, while a 2.7-fold increase in plasma high density lipoprotein- cholesterol (p<0.01 was observed, compared with LPL⁻/⁻→LPL⁻/⁻ control mice. The clearance rate for the oral fat load test in LPL⁺/⁺ →LPL⁻/⁻ mice was faster than that in LPL⁻/⁻→LPL⁻/⁻ mice, but slower than that in wild-type mice. Liver triglyceride content in LPL⁺/⁺→LPL⁻/⁻ mice was also significantly increased, compared with LPL⁻/⁻→LPL⁻/⁻ mice (6.8±0.7 vs. 4.6±0.5 mg/g wet tissue, p<0.05, n = 6. However, no significant change was observed in the expression levels of genes involved in hepatic lipid metabolism between the two groups. CONCLUSIONS: Hematopoietic cell-derived LPL could efficiently ameliorate severe hypertriglyceridemia and hypo-alpha-cholesterolemia at the compensation of increased triglyceride content of liver in LPL�

Cholesterol synthesis by human fetal hepatocytes: effect of lipoproteins

International Nuclear Information System (INIS)

Carr, B.R.; Simpson, E.R.

1984-01-01

The purpose of the present investigation was to determine the effect of various lipoproteins on the rate of cholesterol synthesis of human fetal liver cells maintained in culture. This was accomplished by measuring the rate of incorporation of tritium from tritiated water or carbon 14-labeled acetate into cholesterol in human fetal liver cells. Optimal conditions for each assay were determined. When human fetal liver cells were maintained in the presence of low-density lipoprotein, cholesterol synthesis was inhibited in a concentration-dependent fashion. Intermediate--density lipoprotein and very-low-density lipoprotein also suppressed cholesterol synthesis in human fetal liver cells. In contrast, high-density lipoprotein stimulated cholesterol synthesis in human fetal liver cells. The results of the present as well as our previous investigations suggest that multiple interrelationships exist between fetal liver cholesterol synthesis and lipoprotein-cholesterol utilization by the human fetal adrenal gland and that these processes serve to regulate the lipoprotein-cholesterol levels in fetal plasma

Accumulation of native and methylated low density lipoproteins by healing rabbit arterial wall

International Nuclear Information System (INIS)

Fischman, A.J.; Lees, A.M.; Lees, R.S.; Barlai-Kovach, M.; Strauss, H.W.

1987-01-01

To determine whether healing arterial wall accumulation of low density lipoproteins (LDL) is mediated by the high affinity LDL receptor, normocholesterolemic rabbits were injected with 125 I-LDL, /sup 99m/Tc-LDL, or the reductively methylated analogs of these compounds ( 125 I-MeLDL, /sup 99m/Tc-MeLDL), 1 month after balloon catheter deendothelialization of the abdominal aorta. If the mechanism of accumulation requires interaction with the LDL receptor, reductively methylated lipoproteins which do not bind to the receptor should not accumulate in healing arterial wall. Twenty-four hours after injection of labelled lipoproteins, each animal was injected with Evans blue dye, in order to distinguish reendothelialized from deendothelialized aorta. One hour after dye injection, the aorta was fixed, removed, divided into abdominal (ballooned) and thoracic (unballooned) regions and counted. For all lipoprotein preparations, there were three to four times as many counts in the abdominal as in the thoracic aorta. En face autoradiographs were made of the aortas that had been exposed to 125 I-labelled lipoproteins. In the autoradiographs, the areas of the lowest activity corresponded to the centers of healing endothelial islands. The most intense radioactivity for both lipoproteins occurred in the region of the leading edge of the endothelial islands where active endothelial regeneration was in progress. The overall distribution of native and MeLDL accumulation was the same. The results suggest that low density lipoproteins are accumulated in areas of active endothelial regeneration by a mechanism that does not involve the high affinity LDL receptor

Induction of bacterial lipoprotein tolerance is associated with suppression of toll-like receptor 2 expression.

LENUS (Irish Health Repository)

Wang, Jiang Huai

2012-02-03

Tolerance to bacterial cell wall components including lipopolysaccharide (LPS) may represent an essential regulatory mechanism during bacterial infection. Two members of the Toll-like receptor (TLR) family, TLR2 and TLR4, recognize the specific pattern of bacterial cell wall components. TLR4 has been found to be responsible for LPS tolerance. However, the role of TLR2 in bacterial lipoprotein (BLP) tolerance and LPS tolerance is unclear. Pretreatment of human THP-1 monocytic cells with a synthetic bacterial lipopeptide induced tolerance to a second BLP challenge with diminished tumor necrosis factor-alpha and interleukin-6 production, termed BLP tolerance. Furthermore, BLP-tolerized THP-1 cells no longer responded to LPS stimulation, indicating a cross-tolerance to LPS. Induction of BLP tolerance was CD14-independent, as THP-1 cells that lack membrane-bound CD14 developed tolerance both in serum-free conditions and in the presence of a specific CD14 blocking monoclonal antibody (MEM-18). Pre-exposure of THP-1 cells to BLP suppressed mitogen-activated protein kinase phosphorylation and nuclear factor-kappaB activation in response to subsequent BLP and LPS stimulation, which is comparable with that found in LPS-tolerized cells, indicating that BLP tolerance and LPS tolerance may share similar intracellular pathways. However, BLP strongly enhanced TLR2 expression in non-tolerized THP-1 cells, whereas LPS stimulation had no effect. Furthermore, a specific TLR2 blocking monoclonal antibody (2392) attenuated BLP-induced, but not LPS-induced, tumor necrosis factor-alpha and interleukin-6 production, indicating BLP rather than LPS as a ligand for TLR2 engagement and activation. More importantly, pretreatment of THP-1 cells with BLP strongly inhibited TLR2 activation in response to subsequent BLP stimulation. In contrast, LPS tolerance did not prevent BLP-induced TLR2 overexpression. These results demonstrate that BLP tolerance develops through down-regulation of TLR2

Triglyceride-rich lipoprotein regulates APOB48 receptor gene expression in human THP-1 monocytes and macrophages.

Science.gov (United States)

Bermudez, Beatriz; Lopez, Sergio; Varela, Lourdes M; Ortega, Almudena; Pacheco, Yolanda M; Moreda, Wenceslao; Moreno-Luna, Rafael; Abia, Rocio; Muriana, Francisco J G

2012-02-01

The postprandial metabolism of dietary fats implies that the production of TG-rich lipoproteins (TRL) contributes to the progression of plaque development. TRL and their remnants cause rapid receptor-mediated monocyte/macrophage lipid engorgement via the cell surface apoB48 receptor (apoB48R). However, the mechanistic basis for apoB48 receptor (APOB48R) regulation by postprandial TRL in monocytes and macrophages is not well established. In this study, we investigated the effects of postprandial TRL from healthy volunteers on the expression of APOB48R mRNA and lipid uptake in human THP-1 monocytes and THP-1-derived macrophages. The expression of APOB48R mRNA was upregulated in THP-1 monocytes, but downregulated in THP-1-derived macrophages when treated with postprandial TRL (P < 0.05), in a dose- and time-dependent manner. TG and free cholesterol were dramatically increased in THP-1-derived macrophages (140 and 50%, respectively; P < 0.05) and in THP-1 monocytes (160 and 95%, respectively; P < 0.05). This lipid accumulation was severely decreased (~50%; P < 0.05) in THP-1-derived macrophages by small interfering RNA (siRNA) targeting of APOB48R. Using PPAR and retinoid X receptor (RXR) agonists, antagonists, and siRNA, our data indicate that PPARα, PPARγ, and RXRα are involved in postprandial TRL-induced APOB48R transcriptional regulation. Co-incubation with acyl-CoA synthetase or acyl-CoA:cholesterol acyltransferase inhibitors potentiated the effects of postprandial TRL on the expression of APOB48R mRNA in THP-1 monocytes and THP-1-derived macrophages. Our findings collectively suggest that APOB48R represents a molecular target of postprandial TRL via PPAR-dependent pathways in human THP-1 monocytes and macrophages and advance a potentially important link between postprandial metabolism of dietary fats and atherogenesis.

Impaired clearance of influenza A virus in obese, leptin receptor deficient mice is independent of leptin signaling in the lung epithelium and macrophages.

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Kathryn A Radigan

Full Text Available During the recent H1N1 outbreak, obese patients had worsened lung injury and increased mortality. We used a murine model of influenza A pneumonia to test the hypothesis that leptin receptor deficiency might explain the enhanced mortality in obese patients.We infected wild-type, obese mice globally deficient in the leptin receptor (db/db and non-obese mice with tissue specific deletion of the leptin receptor in the lung epithelium (SPC-Cre/LepR fl/fl or macrophages and alveolar type II cells (LysM-Cre/Lepr fl/fl with influenza A virus (A/WSN/33 [H1N1] (500 and 1500 pfu/mouse and measured mortality, viral clearance and several markers of lung injury severity.The clearance of influenza A virus from the lungs of mice was impaired in obese mice globally deficient in the leptin receptor (db/db compared to normal weight wild-type mice. In contrast, non-obese, SP-C-Cre+/+/LepR fl/fl and LysM-Cre+/+/LepR fl/fl had improved viral clearance after influenza A infection. In obese mice, mortality was increased compared with wild-type mice, while the SP-C-Cre+/+/LepR fl/fl and LysM-Cre+/+/LepR fl/fl mice exhibited improved survival.Global loss of the leptin receptor results in reduced viral clearance and worse outcomes following influenza A infection. These findings are not the result of the loss of leptin signaling in lung epithelial cells or macrophages. Our results suggest that factors associated with obesity or with leptin signaling in non-myeloid populations such as natural killer and T cells may be associated with worsened outcomes following influenza A infection.

Cholesterol is essential for mitosis progression and its deficiency induces polyploid cell formation

International Nuclear Information System (INIS)

Fernandez, Carlos; Lobo, Maria del Val T.; Gomez-Coronado, Diego; Lasuncion, Miguel A.

2004-01-01

As an essential component of mammalian cell membranes, cells require cholesterol for proliferation, which is either obtained from plasma lipoproteins or synthesized intracellularly from acetyl-CoA. In addition to cholesterol, other non-sterol mevalonate derivatives are necessary for DNA synthesis, such as the phosphorylated forms of isopentane, farnesol, geranylgeraniol, and dolichol. The aim of the present study was to elucidate the role of cholesterol in mitosis. For this, human leukemia cells (HL-60) were incubated in a cholesterol-free medium and treated with SKF 104976, which inhibits cholesterol biosynthesis by blocking sterol 14α-demethylase, and the expression of relevant cyclins in the different phases of the cell cycle was analyzed by flow cytometry. Prolonged cholesterol starvation induced the inhibition of cytokinesis and the formation of polyploid cells, which were multinucleated and had mitotic aberrations. Supplementing the medium with cholesterol completely abolished these effects, demonstrating they were specifically due to cholesterol deficiency. This is the first evidence that cholesterol is essential for mitosis completion and that, in the absence of cholesterol, the cells fail to undergo cytokinesis, entered G1 phase at higher DNA ploidy (tetraploidy), and then progressed through S (rereplication) into G2, generating polyploid cells

Low-Density Lipoprotein Modified by Myeloperoxidase in Inflammatory Pathways and Clinical Studies

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Cédric Delporte

2013-01-01

Full Text Available Oxidation of low-density lipoprotein (LDL has a key role in atherogenesis. Among the different models of oxidation that have been studied, the one using myeloperoxidase (MPO is thought to be more physiopathologically relevant. Apolipoprotein B-100 is the unique protein of LDL and is the major target of MPO. Furthermore, MPO rapidly adsorbs at the surface of LDL, promoting oxidation of amino acid residues and formation of oxidized lipoproteins that are commonly named Mox-LDL. The latter is not recognized by the LDL receptor and is accumulated by macrophages. In the context of atherogenesis, Mox-LDL accumulates in macrophages leading to foam cell formation. Furthermore, Mox-LDL seems to have specific effects and triggers inflammation. Indeed, those oxidized lipoproteins activate endothelial cells and monocytes/macrophages and induce proinflammatory molecules such as TNFα and IL-8. Mox-LDL may also inhibit fibrinolysis mediated via endothelial cells and consecutively increase the risk of thrombus formation. Finally, Mox-LDL has been involved in the physiopathology of several diseases linked to atherosclerosis such as kidney failure and consequent hemodialysis therapy, erectile dysfunction, and sleep restriction. All these issues show that the investigations of MPO-dependent LDL oxidation are of importance to better understand the inflammatory context of atherosclerosis.

Depressed immune surveillance against cancer: role of deficient T cell: extracellular matrix interactions.

Science.gov (United States)

Górski, A; Castronovo, V; Stepień-Sopniewska, B; Grieb, P; Ryba, M; Mrowiec, T; Korczak-Kowalska, G; Wierzbicki, P; Matysiak, W; Dybowska, B

1994-07-01

Although T cells infiltrate malignant tumors, the local immune response is usually inefficient and tumors escape destruction. While extracellular matrix proteins strongly costimulate T cell responses in normal individuals, our studies indicate that peripheral blood T cells from cancer patients and tumor infiltrating cells respond poorly or are resistant to stimulative signals mediated by collagen I and IV and fibronectin. Moreover, the adhesive properties of cancer T cells are markedly depressed. Those functional deficiencies are paralleled by variable deficits in integrin and non-integrin T cell receptors for extracellular matrix. Immunotherapy with BCG causes a dramatic but transient increase in T cell: ECM interactions.

Purification of a sarcoplasmic reticulum protein that binds Ca2+ and plasma lipoproteins

International Nuclear Information System (INIS)

Hofmann, S.L.; Brown, M.S.; Lee, E.; Pathak, R.K.; Anderson, R.G.; Goldstein, J.L.

1989-01-01

A protein in the sarcoplasmic reticulum of rabbit skeletal and cardiac muscle was identified because of its ability to bind 125I-labeled low density lipoprotein (LDL) with high affinity after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein, referred to as the 165-kDa protein, is restricted to striated muscle. It was not detected in 14 other tissues, including several that contain smooth muscle, but it appears in rat L6 myoblasts when they differentiate into myocytes. Immunofluorescence and immunoelectron microscopic studies revealed that the protein is present throughout the sarcoplasmic reticulum and the terminal cisternae. It binds 45Ca2+ on nitrocellulose blots and stains metachromatically with Stains-all, a cationic dye that stains Ca2+-binding proteins. It does not appear to be a glycoprotein, and it appears slightly larger than the 160-kDa glycoprotein previously described in sarcoplasmic reticulum. The 165-kDa protein binds LDL, beta-migrating very low density lipoprotein, and a cholesterol-induced high density lipoprotein particle that contains apoprotein E as its sole apoprotein with much higher affinity than it binds high density lipoprotein. The protein is stable to boiling and to treatment with sodium dodecyl sulfate, but it becomes sensitive to these treatments when its cystine residues are reduced and alkylated. The protein was purified 1300-fold to apparent homogeneity from rabbit skeletal muscle membranes. It differs from the cell surface LDL receptor in that (1) its apparent molecular weight is not changed by reduction and alkylation; (2) it is present in Watanabe-heritable hyperlipidemic rabbits, which lack functional LDL receptors; (3) binding of lipoproteins is not inhibited by EDTA; and (4) it is located within the lumen of the sarcoplasmic reticulum where it has no access to plasma lipoproteins

PCSK9 and triglyceride-rich lipoprotein metabolism.

Science.gov (United States)

Druce, I; Abujrad, H; Ooi, T C

2015-07-20

Pro-protein convertase subtilisin-kexin 9 (PCSK9) is known to affect low-density lipoprotein (LDL) metabolism, but there are indications from several lines of research that it may also influence the metabolism of other lipoproteins, especially triglyceride-rich lipoproteins (TRL). This review summarizes the current data on this possible role of PCSK9. A link between PCSK9 and TRL has been suggested through the demonstration of (1) a correlation between plasma PCSK9 and triglyceride (TG) levels in health and disease, (2) a correlation between plasma PCSK9 and markers of carbohydrate metabolism, which is closely related to TG metabolism, (3) an effect of TG-lowering fibrate therapy on plasma PCSK9 levels, (4) an effect of PCSK9 on postprandial lipemia, (5) an effect of PCSK9 on adipose tissue biology, (6) an effect of PCSK9 on apolipoprotein B production from the liver and intestines, (7) an effect of PCSK9 on receptors other than low density lipoprotein receptor (LDLR) that are involved in TRL metabolism, and (8) an effect of anti-PCSK9 therapy on serum TG levels. The underlying mechanisms are unclear but starting to emerge. © 2015 the Journal of Biomedical Research. All rights reserved.

Rational Targeting of Cellular Cholesterol in Diffuse Large B-Cell Lymphoma (DLBCL) Enabled by Functional Lipoprotein Nanoparticles: A Therapeutic Strategy Dependent on Cell of Origin.

Science.gov (United States)

Rink, Jonathan S; Yang, Shuo; Cen, Osman; Taxter, Tim; McMahon, Kaylin M; Misener, Sol; Behdad, Amir; Longnecker, Richard; Gordon, Leo I; Thaxton, C Shad

2017-11-06

Cancer cells have altered metabolism and, in some cases, an increased demand for cholesterol. It is important to identify novel, rational treatments based on biology, and cellular cholesterol metabolism as a potential target for cancer is an innovative approach. Toward this end, we focused on diffuse large B-cell lymphoma (DLBCL) as a model because there is differential cholesterol biosynthesis driven by B-cell receptor (BCR) signaling in germinal center (GC) versus activated B-cell (ABC) DLBCL. To specifically target cellular cholesterol homeostasis, we employed high-density lipoprotein-like nanoparticles (HDL NP) that can generally reduce cellular cholesterol by targeting and blocking cholesterol uptake through the high-affinity HDL receptor, scavenger receptor type B-1 (SCARB1). As we previously reported, GC DLBCL are exquisitely sensitive to HDL NP as monotherapy, while ABC DLBCL are less sensitive. Herein, we report that enhanced BCR signaling and resultant de novo cholesterol synthesis in ABC DLBCL drastically reduces the ability of HDL NPs to reduce cellular cholesterol and induce cell death. Therefore, we combined HDL NP with the BCR signaling inhibitor ibrutinib and the SYK inhibitor R406. By targeting both cellular cholesterol uptake and BCR-associated de novo cholesterol synthesis, we achieved cellular cholesterol reduction and induced apoptosis in otherwise resistant ABC DLBCL cell lines. These results in lymphoma demonstrate that reduction of cellular cholesterol is a powerful mechanism to induce apoptosis. Cells rich in cholesterol require HDL NP therapy to reduce uptake and molecularly targeted agents that inhibit upstream pathways that stimulate de novo cholesterol synthesis, thus, providing a new paradigm for rationally targeting cholesterol metabolism as therapy for cancer.

In HepG2 cells, coexisting carnitine deficiency masks important indicators of marginal biotin deficiency.

Science.gov (United States)

Bogusiewicz, Anna; Boysen, Gunnar; Mock, Donald M

2015-01-01

A large number of birth defects are related to nutrient deficiencies; concern that biotin deficiency is teratogenic in humans is reasonable. Surprisingly, studies indicate that increased urinary 3-hydroxyisovalerylcarnitine (3HIAc), a previously validated marker of biotin deficiency, is not a valid biomarker in pregnancy. In this study we hypothesized that coexisting carnitine deficiency can prevent the increase in 3HIAc due to biotin deficiency. We used a 2-factor nutrient depletion design to induce isolated and combined biotin and carnitine deficiency in HepG2 cells and then repleted cells with carnitine. To elucidate the metabolic pathogenesis, we quantitated intracellular and extracellular free carnitine, acylcarnitines, and acylcarnitine ratios using liquid chromatography-tandem mass spectrometry. Relative to biotin-sufficient, carnitine-sufficient cells, intracellular acetylcarnitine increased by 90%, propionylcarnitine more than doubled, and 3HIAc increased by >10-fold in biotin-deficient, carnitine-sufficient (BDCS) cells, consistent with a defensive mechanism in which biotin-deficient cells transesterify the acyl-coenzyme A (acyl-CoA) substrates of the biotin-dependent carboxylases to the related acylcarnitines. Likewise, in BDCS cells, the ratio of acetylcarnitine to malonylcarnitine and the ratio of propionylcarnitine to methylmalonylcarnitine both more than tripled, and the ratio of 3HIAc to 3-methylglutarylcarnitine (MGc) increased by >10-fold. In biotin-deficient, carnitine-deficient (BDCD) cells, the 3 substrate-derived acylcarnitines changed little, but the substrate:product ratios were masked to a lesser extent. Moreover, carnitine repletion unmasked biotin deficiency in BDCD cells as shown by increases in acetylcarnitine, propionylcarnitine, and 3HIAc (each increased by >50-fold). Likewise, ratios of acetylcarnitine:malonylcarnitine, propionylcarnitine:methylmalonylcarnitine, and 3HIAc:MGc all increased by >8-fold. Our findings provide strong

Plasma lipoprotein(a) levels in patients with homozygous autosomal dominant hypercholesterolemia

NARCIS (Netherlands)

Sjouke, B.; Yahya, R.; Tanck, M.W.T.; Defesche, J.C.; Graaf, J. de; Wiegman, A.; Kastelein, J.J.; Mulder, M.T.; Hovingh, G.K.; Roeters van Lennep, J.E.

2017-01-01

BACKGROUND: Patients with autosomal dominant hypercholesterolemia (ADH), caused by mutations in either low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin-kexin type 9 (PCSK9) are characterized by high low-density lipoprotein cholesterol levels and

Endothelium in brain: Receptors, mitogenesis, and biosynthesis in glial cells

International Nuclear Information System (INIS)

MacCumber, M.W.; Ross, C.A.; Snyder, S.H.

1990-01-01

The authors have explored the cellular loci of endothelin (ET) actions and formation in the brain, using cerebellar mutant mice was well as primary and continuous cell cultures. A glial role is favored by several observations: (1) mutant mice lacking neuronal Purkinje cells display normal ET receptor binding and enhanced stimulation by ET of inositolphospholipid turnover; (ii) in weaver mice lacking neuronal granule cells, ET stimulation of inositolphospholipid turnover is not significantly diminished; (iii) C 6 glioma cells and primary cultures of cerebellar astroglia exhibit substantial ET receptor binding and ET-induced stimulation of inositolphospholipid turnover; (iv) ET promotes mitogenesis of C 6 glioma cells and primary cerebellar astroglia; and (v) primary cultures of cerebellar astroglia contain ET mRNA. ET also appears to have a neuronal role, since it stimulates inositolphospholipid turnover in primary cultures of cerebellar granule cells, and ET binding declines in granule cell-deficient mice. Thus, ET can be produced by glia and act upon both glia and neurons in a paracrine fashion

T cells exacerbate Lyme borreliosis in TLR2-deficient mice

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Carrie E. Lasky

2016-11-01

Full Text Available Infection of humans with the spirochete, Borrelia burgdorferi, causes Lyme borreliosis and can lead to clinical manifestations such as, arthritis, carditis and neurological conditions. Experimental infection of mice recapitulates many of these symptoms and serves as a model system for the investigation of disease pathogenesis and immunity. Innate immunity is known to drive the development of Lyme arthritis and carditis, but the mechanisms driving this response remain unclear. Innate immune cells recognize B. burgdorferi surface lipoproteins primarily via Toll-like receptor (TLR2; however, previous work has demonstrated TLR2-/- mice had exacerbated disease and increased bacterial burden. We demonstrate increased CD4 and CD8 T cell infiltrates in B. burgdorferi-infected joints and hearts of C3H TLR2-/- mice. In vivo depletion of either CD4 or CD8 T cells reduced Borrelia-induced joint swelling and lowered tissue spirochete burden, while depletion of CD8 T cells alone reduced disease severity scores. Exacerbation of Lyme arthritis correlated with increased production of CXCL9 by synoviocytes and this was reduced with CD8 T cell depletion. These results demonstrate T cells can exacerbate Lyme disease pathogenesis and prolong disease resolution possibly through dysregulation of inflammatory responses and inhibition of bacterial clearance.

Uptake by J774 macrophages of very-low-density lipoproteins isolated from apoE-deficient mice is mediated by a distinct receptor and stimulated by lipoprotein lipase

NARCIS (Netherlands)

Hendriks, W.L.; Sman van der - Beer, F. de; Vlijmen, B.J.M. van; Vark, L.C. van; Hofker, M.H.; Havekes, L.M.

1997-01-01

Apolipoprotein (apo) E-deficient mice display marked accumulation in the plasma of VLDL deficient in both apoE and apoBl00 but containing apoB48, apoA-1, apoCs, and apoA-IV. Since apoE-deficient mice develop severe atherosclerotic lesions with lipid-laden macrophages, we reasoned that the uptake of

Resistance to diet-induced adiposity in cannabinoid receptor-1 deficient mice is not due to impaired adipocyte function

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Oosterveer Maaike H

2011-12-01

Full Text Available Abstract Background Overactivity and/or dysregulation of the endocannabinoid system (ECS contribute to development of obesity. In vitro studies indicate a regulatory role for the cannabinoid receptor 1 (CB1 in adipocyte function and CB1-receptor deficient (CB1-/- mice are resistant to high fat diet-induced obesity. Whether this phenotype of CB1-/- mice is related to altered fat metabolism in adipose tissue is unknown. Methods We evaluated adipose tissue differentiation/proliferation markers and quantified lipogenic and lipolytic activities in fat tissues of CB1-/- and CB1+/+ mice fed a high-fat (HF or a high-fat/fish oil (HF/FO diet as compared to animals receiving a low-fat chow diet. Comparison between HF diet and HF/FO diet allowed to investigate the influence of dietary fat quality on adipose tissue biology in relation to CB1 functioning. Results The adiposity-resistant phenotype of the CB1-/- mice was characterized by reduced fat mass and adipocyte size in HF and HF/FO-fed CB1-/- mice in parallel to a significant increase in energy expenditure as compared to CB1+/+ mice. The expression levels of adipocyte differentiation and proliferation markers were however maintained in these animals. Consistent with unaltered lipogenic gene expression, the fatty acid synthesis rates in adipose tissues from CB1-/- and CB1+/+ mice were unchanged. Whole-body and adipose-specific lipoprotein lipase (LPL activities were also not altered in CB1-/- mice. Conclusions These findings indicate that protection against diet-induced adiposity in CB1-deficient mice is not related to changes in adipocyte function per se, but rather results from increased energy dissipation by oxidative and non-oxidative pathways.

Plasma lipoprotein(a) levels in patients with homozygous autosomal dominant hypercholesterolemia

NARCIS (Netherlands)

Sjouke, Barbara; Yahya, Reyhana; Tanck, Michael W. T.; Defesche, Joep C.; de Graaf, Jacqueline; Wiegman, Albert; Kastelein, John J. P.; Mulder, Monique T.; Hovingh, G. Kees; Roeters van Lennep, Jeanine E.

2017-01-01

Patients with autosomal dominant hypercholesterolemia (ADH), caused by mutations in either low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), or proprotein convertase subtilisin-kexin type 9 (PCSK9) are characterized by high low-density lipoprotein cholesterol levels and in some

Loci of catabolism of beta-very low density lipoprotein in vivo delineated with a residualizing label, 125I-dilactitol tyramine

International Nuclear Information System (INIS)

Daugherty, A.; Thorpe, S.R.; Lange, L.G.; Sobel, B.E.; Schonfeld, G.

1985-01-01

beta-Very low density lipoprotein (beta-VLDL) may be a major atherogenic lipoprotein, and knowledge of the sites of its catabolism should facilitate elucidation of mechanisms important in the regulation of its plasma concentrations. In this study, catabolic sites of beta-VLDL have been delineated in normolipidemic rabbits with a novel, radioiodinated, residualizing label, 125 I-dilactitol tyramine ( 125 I-DLT). Comparative studies of beta-VLDL and low density lipoprotein catabolism were performed with 125 I-DLT conjugated to each lipoprotein and with lipoproteins iodine-labeled conventionally. Conjugation did not alter size distributions or charge characteristics of lipoprotein particles. The overall processing (binding and degradation) of lipoproteins by cultured rabbit skin fibroblasts was not influenced by 125 I-DLT derivatization, suggesting that attachment of the label did not influence cell receptor-lipoprotein interactions. Furthermore, although degradation products of 125 I-lipoproteins leaked out of the cells and into the medium, the degradation products of 125 I-DLT lipoproteins were retained by the cells. The principal catabolic site of beta-VLDL in normolipidemic rabbits was found to be the liver with 54 +/- 4% of injected 125 I retained in this organ 24 h after injection of 125 I-DLT-beta-VLDL. When catabolism was normalized to tissue weight, the liver and adrenals were found to be approximately equally active in the metabolism of beta-VLDL. In agreement with results of other studies with residualizing labels, the principal organ of catabolism of 125 I-DLT-LDL in vivo was the liver. The adrenals were the most highly catabolizing organ when results were normalized for tissue weight

Plasma levels of 27-hydroxycholesterol in humans and mice with monogenic disturbances of high density lipoprotein metabolism

DEFF Research Database (Denmark)

Karuna, Ratna; Holleboom, Adriaan G; Motazacker, Mohammad M

2011-01-01

Secretion of 27-hydroxycholesterol (27OHC) from macrophages is considered as an alternative to HDL-mediated reverse transport of excess cholesterol. We investigated 27OHC-concentrations in plasma of humans and mice with monogenic disorders of HDL metabolism. As compared to family controls mutations...... activities of LCAT and CETP, respectively, than the formation and transfer of cholesterylesters. 27OHC plasma levels were also decreased in apoA-I-, ABCA1- or LCAT-knockout mice but increased in SR-BI-knockout mice. Transplantation of ABCA1- and/or ABCG1-deficient bone marrow into LDL receptor deficient mice...... decreased plasma levels of 27OHC. In conclusion, mutations or absence of HDL genes lead to distinct alterations in the quantity, esterification or lipoprotein distribution of 27OHC. These findings argue against the earlier suggestion that 27OHC-metabolism in plasma occurs independently of HDL....

Dysregulation of Aldosterone Secretion in Mast Cell-Deficient Mice.

Science.gov (United States)

Boyer, Hadrien-Gaël; Wils, Julien; Renouf, Sylvie; Arabo, Arnaud; Duparc, Céline; Boutelet, Isabelle; Lefebvre, Hervé; Louiset, Estelle

2017-12-01

Resident adrenal mast cells have been shown to activate aldosterone secretion in rat and man. Especially, mast cell proliferation has been observed in adrenal tissues from patients with aldosterone-producing adrenocortical adenoma. In the present study, we show that the activity of adrenal mast cells is stimulated by low-sodium diet and correlates with aldosterone synthesis in C57BL/6 and BALB/c mice. We have also investigated the regulation of aldosterone secretion in mast cell-deficient C57BL/6 Kit W-sh/W-sh mice in comparison with wild-type C57BL/6 mice. Kit W-sh/W-sh mice submitted to normal sodium diet had basal plasma aldosterone levels similar to those observed in wild-type animals. Conversely, low-sodium diet unexpectedly induced an exaggerated aldosterone response, which seemed to result from an increase in adrenal renin and angiotensin type 1 receptor expression. Severe hyperaldosteronism was associated with an increase in systolic blood pressure and marked hypokalemia, which favored polyuria. Adrenal renin and angiotensin type 1 receptor overexpression may represent a compensatory mechanism aimed at activating aldosterone production in the absence of mast cells. Finally, C57BL/6 Kit W-sh/W-sh mice represent an unexpected animal model of primary aldosteronism, which has the particularity to be triggered by sodium restriction. © 2017 American Heart Association, Inc.

TLR-mediated inflammatory responses to Streptococcus pneumoniae are highly dependent on surface expression of bacterial lipoproteins.

Science.gov (United States)

Tomlinson, Gillian; Chimalapati, Suneeta; Pollard, Tracey; Lapp, Thabo; Cohen, Jonathan; Camberlein, Emilie; Stafford, Sian; Periselneris, Jimstan; Aldridge, Christine; Vollmer, Waldemar; Picard, Capucine; Casanova, Jean-Laurent; Noursadeghi, Mahdad; Brown, Jeremy

2014-10-01

Streptococcus pneumoniae infections induce inflammatory responses that contribute toward both disease pathogenesis and immunity, but the host-pathogen interactions that mediate these effects are poorly defined. We used the surface lipoprotein-deficient ∆lgt pneumococcal mutant strain to test the hypothesis that lipoproteins are key determinants of TLR-mediated immune responses to S. pneumoniae. We show using reporter assays that TLR2 signaling is dependent on pneumococcal lipoproteins, and that macrophage NF-κB activation and TNF-α release were reduced in response to the ∆lgt strain. Differences in TNF-α responses between Δlgt and wild-type bacteria were abrogated for macrophages from TLR2- but not TLR4-deficient mice. Transcriptional profiling of human macrophages revealed attenuated TLR2-associated responses to ∆lgt S. pneumoniae, comprising many NF-κB-regulated proinflammatory cytokine and chemokine genes. Importantly, non-TLR2-associated responses were preserved. Experiments using leukocytes from IL-1R-associated kinase-4-deficient patients and a mouse pneumonia model confirmed that proinflammatory responses were lipoprotein dependent. Our data suggest that leukocyte responses to bacterial lipoproteins are required for TLR2- and IL-1R-associated kinase-4-mediated inflammatory responses to S. pneumoniae. Copyright © 2014 The Authors.

Stimulation of cholesteryl ester synthesis in mouse peritoneal macrophages by cholesterol-rich very low density lipoproteins from the Watanabe heritable hyperlipidemic rabbit, an animal model of familial hypercholesterolemia

International Nuclear Information System (INIS)

Kita, T.; Yokode, M.; Watanabe, Y.; Narumiya, S.; Kawai, C.

1986-01-01

Cholesterol-rich very low density lipoproteins (VLDL) from the homozygous Watanabe heritable hyperlipidemic (WHHL) rabbit induced marked cholesteryl ester accumulation in mouse peritoneal macrophages. This WHHL rabbit, an animal model of human familial hypercholesterolemia, has severe hypercholesterolemia, cutaneous xanthomas, and fulminant atherosclerosis due to the deficiency of the low density lipoprotein (LDL) receptor. When incubated with mouse peritoneal macrophages, the VLDL from WHHL rabbit (WHHL-VLDL) stimulated cholesteryl [ 14 C]oleate synthesis 124-fold more than did VLDL from the normal Japanese White rabbit (control-VLDL). The enhancement in cholesteryl ester synthesis and accumulation of WHHL-VLDL was due to the presence of a high affinity binding receptor site on the macrophage cell surface that mediated the uptake and lysosomal degradation of WHHL-VLDL. Competition studies showed that the uptake and degradation of 125 I-WHHL-VLDL was inhibited by unlabeled excess WHHL-VLDL and beta-migrating VLDL (beta-VLDL), but not LDL. Furthermore, the degradation of WHHL-VLDL was not blocked by either fucoidin, polyinosinic acid, or polyguanylic acid, potent inhibitors of the acetylated (acetyl)-LDL binding site, or by acetyl-LDL. These results suggest that macrophages possess a high affinity receptor that recognizes the cholesterol-rich VLDL present in the plasma of the WHHL rabbit and that the receptor which mediates ingestion of WHHL-VLDL seems to be the same as that for beta-VLDL and leads to cholesteryl ester deposition within macrophages. Thus, the uptake of the cholesterol-rich VLDL from the WHHL rabbit by macrophages in vivo may play a significant role in the pathogenesis of atherosclerosis in the WHHL rabbit

Lipoprotein Lipase Maintains Microglial Innate Immunity in Obesity

NARCIS (Netherlands)

Gao, Yuanqing; Vidal-Itriago, Andrés; Kalsbeek, Martin J; Layritz, Clarita; García-Cáceres, Cristina; Tom, Robby Zachariah; Eichmann, Thomas O; Vaz, Frédéric M; Houtkooper, Riekelt H; van der Wel, Nicole; Verhoeven, Arthur J; Yan, Jie; Kalsbeek, A.; Eckel, Robert H; Hofmann, Susanna M; Yi, Chun-Xia

2017-01-01

Consumption of a hypercaloric diet upregulates microglial innate immune reactivity along with a higher expression of lipoprotein lipase (Lpl) within the reactive microglia in the mouse brain. Here, we show that knockdown of the Lpl gene specifically in microglia resulted in deficient microglial

Lipoprotein internalisation induced by oncogenic AMPK activation is essential to maintain glioblastoma cell growth.

Science.gov (United States)

Ríos, M; Foretz, M; Viollet, B; Prieto, A; Fraga, M; García-Caballero, T; Costoya, J A; Señarís, R

2014-12-01

Metabolic adaptations are essential during tumour growth to maintain the high proliferation levels exhibited by cancer cells. In this study, we examined the transformations that occurred in the lipid metabolism in astrocytic tumours, and the possible role of the fuel-sensing enzyme AMPK. Metabolic targets might help design new and effective drugs for cancer. To accomplish this objective, we studied both mice and human astrocytic tumours. We first used a mouse model of astrocytoma driven by oncogenic H-RasV12 and/or with PTEN deletion based on the common constitutive activation of the Raf/MEK/ERK and PI3K/AKT cascades in human astrocytomas. We then confirmed the results in human glioblastoma cell lines and in glioblastoma tissue samples from patients. We show that the high levels of activated AMPK, observed in astrocytic tumours, increase extracellular lipid internalisation and reduce energy expenditure by inhibiting 'de novo' fatty acid (FA) synthesis, which allows tumour cells to obtain building blocks and energy to be able to create new organelles and new cells. Our findings demonstrate that AMPK plays a crucial role in glioblastoma cell growth and suggest that blocking lipoprotein receptors could potentially be used as a plausible therapeutic approach for these and other type of tumours with high levels of AMPK. Copyright © 2014 Elsevier Ltd. All rights reserved.

Citrullus lanatus `Sentinel' (Watermelon) Extract Reduces Atherosclerosis in LDL Receptor Deficient Mice

Science.gov (United States)

Poduri, Aruna; Rateri, Debra L.; Saha, Shubin K.; Saha, Sibu; Daugherty, Alan

2012-01-01

Watermelon (Citrullus lanatus or C. lanatus) has many potentially bioactive compounds including citrulline, which may influence atherosclerosis. In this study, we determined the effects of C. lanatus, provided as an extract of the cultivar `sentinel', on hypercholesterolemia-induced atherosclerosis in mice. Male LDL receptor deficient mice at 8 weeks old were given either C. lanatus `sentinel' extract (2% vol/vol; n=10) or a mixture of matching carbohydrates (2% vol/vol; n=8) as the control in drinking water, while fed a saturated fat-enriched diet for 12 weeks ad libitum. Mice consuming C. lanatus `sentinel' extract had significantly increased plasma citrulline concentrations. Systolic blood pressure was comparable between the two groups. Consumption of C. lanatus `sentinel' extract led to lower body weight and fat mass without influencing lean mass. There were no differences in food and water intake, and urine output between the two groups. C. lanatus `sentinel' extract administration decreased plasma cholesterol concentrations that were attributed to reductions of intermediate/low density lipoprotein cholesterol. Plasma concentrations of MCP-1 and IFN-γ were decreased and IL-10 increased in mice consuming C. lanatus `sentinel' extract. Intake of C. lanatus `sentinel' extract resulted in reductions of atherosclerosis in both aortic arch and thoracic regions. In conclusion, consumption of C. lanatus `sentinel' extract led to reduced body weight gain, decreased plasma cholesterol concentrations, improved homeostasis of pro- and anti-inflammatory cytokines, and attenuated development of atherosclerosis without affecting systolic blood pressure in hypercholesterolemic mice. PMID:22902326

ST2 negatively regulates TLR2 signaling, but is not required for bacterial lipoprotein-induced tolerance.

LENUS (Irish Health Repository)

Liu, Jinghua

2010-05-15

Activation of TLR signaling is critical for host innate immunity against bacterial infection. Previous studies reported that the ST2 receptor, a member of the Toll\\/IL-1 receptor superfamily, functions as a negative regulator of TLR4 signaling and maintains LPS tolerance. However, it is undetermined whether ST2 negatively regulates TLR2 signaling and furthermore, whether a TLR2 agonist, bacterial lipoprotein (BLP)-induced tolerance is dependent on ST2. In this study, we show that BLP stimulation-induced production of proinflammatory cytokines and immunocomplex formation of TLR2-MyD88 and MyD88-IL-1R-associated kinase (IRAK) were significantly enhanced in ST2-deficient macrophages compared with those in wild-type controls. Furthermore, overexpression of ST2 dose-dependently attenuated BLP-induced NF-kappaB activation, suggesting a negative regulatory role of ST2 in TLR2 signaling. A moderate but significantly attenuated production of TNF-alpha and IL-6 on a second BLP stimulation was observed in BLP-pretreated, ST2-deficient macrophages, which is associated with substantially reduced IRAK-1 protein expression and downregulated TLR2-MyD88 and MyD88-IRAK immunocomplex formation. ST2-deficient mice, when pretreated with a nonlethal dose of BLP, benefitted from an improved survival against a subsequent lethal BLP challenge, indicating BLP tolerance develops in the absence of the ST2 receptor. Taken together, our results demonstrate that ST2 acts as a negative regulator of TLR2 signaling, but is not required for BLP-induced tolerance.

Large-scale preparation of the homogeneous LolA–lipoprotein complex and efficient in vitro transfer of lipoproteins to the outer membrane in a LolB-dependent manner

OpenAIRE

Watanabe, Shoji; Oguchi, Yuki; Yokota, Naoko; Tokuda, Hajime

2007-01-01

An ATP-binding cassette transporter LolCDE complex of Escherichia coli releases lipoproteins destined to the outer membrane from the inner membrane as a complex with a periplasmic chaperone, LolA. Interaction of the LolA–lipoprotein complex with an outer membrane receptor, LolB, then causes localization of lipoproteins to the outer membrane. As far as examined, formation of the LolA–lipoprotein complex strictly depends on ATP hydrolysis by the LolCDE complex in the presence of LolA. It has be...

Ectodomains of the LDL receptor-related proteins LRP1b and LRP4 have anchorage independent functions in vivo.

Directory of Open Access Journals (Sweden)

Martin F Dietrich

2010-04-01

Full Text Available The low-density lipoprotein (LDL receptor gene family is a highly conserved group of membrane receptors with diverse functions in developmental processes, lipoprotein trafficking, and cell signaling. The low-density lipoprotein (LDL receptor-related protein 1b (LRP1B was reported to be deleted in several types of human malignancies, including non-small cell lung cancer. Our group has previously reported that a distal extracellular truncation of murine Lrp1b that is predicted to secrete the entire intact extracellular domain (ECD is fully viable with no apparent phenotype.Here, we have used a gene targeting approach to create two mouse lines carrying internally rearranged exons of Lrp1b that are predicted to truncate the protein closer to the N-terminus and to prevent normal trafficking through the secretary pathway. Both mutations result in early embryonic lethality, but, as expected from the restricted expression pattern of LRP1b in vivo, loss of Lrp1b does not cause cellular lethality as homozygous Lrp1b-deficient blastocysts can be propagated normally in culture. This is similar to findings for another LDL receptor family member, Lrp4. We provide in vitro evidence that Lrp4 undergoes regulated intramembraneous processing through metalloproteases and gamma-secretase cleavage. We further demonstrate negative regulation of the Wnt signaling pathway by the soluble extracellular domain.Our results underline a crucial role for Lrp1b in development. The expression in mice of truncated alleles of Lrp1b and Lrp4 with deletions of the transmembrane and intracellular domains leads to release of the extracellular domain into the extracellular space, which is sufficient to confer viability. In contrast, null mutations are embryonically (Lrp1b or perinatally (Lrp4 lethal. These findings suggest that the extracellular domains of both proteins may function as a scavenger for signaling ligands or signal modulators in the extracellular space, thereby

Soluble transferrin receptor: a differentiating marker between iron deficiency anaemia and anaemia of chronic disorders

International Nuclear Information System (INIS)

Saboor, M.; Moinuddin, A.; Naureen, A.

2012-01-01

Background: Iron deficiency anaemia and anaemia of chronic disorders are the two major causes of microcytic and hypochromic anaemia. Many times the diagnosis of these conditions becomes difficult through conventional laboratory tests. Determination of soluble transferrin receptors is a helpful laboratory test for the differential diagnosis of these conditions. The study was conducted to evaluate the role of soluble transferrin receptors in the differential diagnosis between iron deficiency anaemia and anaemia of chronic disorders. Methods: A total of 80 blood samples were evaluated, i.e., 20 samples from normal adult male, 20 samples from normal adult female, 20 samples from iron deficiency anaemia group and 20 samples from patients with anaemia of chronic disorders. Soluble transferrin receptors were determined by ELISA technique using Quantikine IVD kit (R and D Systems). Results: There was significant difference in the levels of sTfR in iron deficiency anaemia and anaemia of chronic disorders. Statistically non-significant difference was observed between the levels of sTfR in patients with anaemia of chronic disorders as compared to normal control group. Conclusion: The sTfR determination can be used as a reliable differentiating marker in the diagnosis of iron deficiency anaemia and anaemia of chronic disorders. (author)

Simvastatin reduces neointimal thickening in low-density lipoprotein receptor-deficient mice after experimental angioplasty without changing plasma lipids.

Science.gov (United States)

Chen, Zhiping; Fukutomi, Tatsuya; Zago, Alexandre C; Ehlers, Raila; Detmers, Patricia A; Wright, Samuel D; Rogers, Campbell; Simon, Daniel I

2002-07-02

Statins exert antiinflammatory and antiproliferative actions independent of cholesterol lowering. To determine whether these actions might affect neointimal formation, we investigated the effect of simvastatin on the response to experimental angioplasty in LDL receptor-deficient (LDLR-/-) mice, a model of hypercholesterolemia in which changes in plasma lipids are not observed in response to simvastatin. Carotid artery dilation (2.5 atm) and complete endothelial denudation were performed in male C57BL/6J LDLR-/- mice treated with low-dose (2 mg/kg) or high-dose (20 mg/kg) simvastatin or vehicle subcutaneously 72 hours before and then daily after injury. After 7 and 28 days, intimal and medial sizes were measured and the intima to media area ratio (I:M) was calculated. Total plasma cholesterol and triglyceride levels were similar in simvastatin- and vehicle-treated mice. Intimal thickening and I:M were reduced significantly by low- and high-dose simvastatin compared with vehicle alone. Simvastatin treatment was associated with reduced cellular proliferation (BrdU), leukocyte accumulation (CD45), and platelet-derived growth factor-induced phosphorylation of the survival factor Akt and increased apoptosis after injury. Simvastatin modulates vascular repair after injury in the absence of lipid-lowering effects. Although the mechanisms are not yet established, additional research may lead to new understanding of the actions of statins and novel therapeutic interventions for preventing restenosis.

Activation of aryl hydrocarbon receptor reduces carbendazim-induced cell death

International Nuclear Information System (INIS)

Wei, Kuo-Liang; Chen, Fei-Yun; Lin, Chih-Yi; Gao, Guan-Lun; Kao, Wen-Ya; Yeh, Chi-Hui; Chen, Chang-Rong; Huang, Hao-Chun; Tsai, Wei-Ren; Jong, Koa-Jen; Li, Wan-Jung; Su, Jyan-Gwo Joseph

2016-01-01

Carbendazim inhibits microtubule assembly, thus blocking mitosis and inhibiting cancer cell proliferation. Accordingly, carbendazim is being explored as an anticancer drug. Data show that carbendazim increased mRNA and protein expressions and promoter activity of CYP1A1. In addition, carbendazim activated transcriptional activity of the aryl hydrocarbon response element, and induced nuclear translocation of the aryl hydrocarbon receptor (AhR), a sign the AhR is activated. Carbendazim-induced CYP1A1 expression was blocked by AhR antagonists, and was abolished in AhR signal-deficient cells. Results demonstrated that carbendazim activated the AhR, thereby stimulating CYP1A1 expression. In order to understand whether AhR-induced metabolic enzymes turn carbendazim into less-toxic metabolites, Hoechst 33342 staining to reveal carbendazim-induced nuclear changes and flow cytometry to reveal the subG 0 /G 1 population were applied to monitor carbendazim-induced cell apoptosis. Carbendazim induced less apoptosis in Hepa-1c1c7 cells than in AhR signal-deficient Hepa-1c1c7 mutant cells. Pretreatment with β-NF, an AhR agonist that highly induces CYP1A1 expression, decreased carbendazim-induced cell death. In addition, the lower the level of AhR was, the lower the vitality present in carbendazim-treated cells, including hepatoma cells and their derivatives with AhR RNA interference, also embryonic kidney cells, bladder carcinoma cells, and AhR signal-deficient Hepa-1c1c7 cells. In summary, carbendazim is an AhR agonist. The toxicity of carbendazim was lower in cells with the AhR signal. This report provides clues indicating that carbendazim is more potent at inducing cell death in tissues without than in those with the AhR signal, an important reference for applying carbendazim in cancer chemotherapy. - Highlights: • Carbendazim induced transcriptional activity of the aryl hydrocarbon response element. • Carbendazim induced nuclear translocation of the aryl hydrocarbon

Activation of aryl hydrocarbon receptor reduces carbendazim-induced cell death

Energy Technology Data Exchange (ETDEWEB)

Wei, Kuo-Liang [Division of Gastroenterology and Hepatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan, ROC (China); College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan, ROC (China); Chen, Fei-Yun; Lin, Chih-Yi [Department of Biochemical Science and Technology, National Chiayi University, Chiayi 60004, Taiwan, ROC (China); Gao, Guan-Lun [Department of Biochemical Science and Technology, National Chiayi University, Chiayi 60004, Taiwan, ROC (China); Department of Biological Resources, National Chiayi University, Chiayi, 60004, Taiwan, ROC (China); Kao, Wen-Ya [Department of Biochemical Science and Technology, National Chiayi University, Chiayi 60004, Taiwan, ROC (China); Yeh, Chi-Hui [Department of Environmental Engineering, College of Engineering, Da-Yeh University, Dacun, Changhua 51591, Taiwan, ROC (China); Chen, Chang-Rong [Department of Biochemical Science and Technology, National Chiayi University, Chiayi 60004, Taiwan, ROC (China); Huang, Hao-Chun [Division of Gastroenterology and Hepatology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan, ROC (China); Tsai, Wei-Ren [Division of Applied Toxicology, Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Council of Agriculture, Executive Yuan, Taichung 41358, Taiwan, ROC (China); Jong, Koa-Jen [Department of Biological Resources, National Chiayi University, Chiayi, 60004, Taiwan, ROC (China); Li, Wan-Jung [Department of Biochemical Science and Technology, National Chiayi University, Chiayi 60004, Taiwan, ROC (China); Su, Jyan-Gwo Joseph, E-mail: jgjsu@mail.ncyu.edu.tw [Department of Biochemical Science and Technology, National Chiayi University, Chiayi 60004, Taiwan, ROC (China)

2016-09-01

Carbendazim inhibits microtubule assembly, thus blocking mitosis and inhibiting cancer cell proliferation. Accordingly, carbendazim is being explored as an anticancer drug. Data show that carbendazim increased mRNA and protein expressions and promoter activity of CYP1A1. In addition, carbendazim activated transcriptional activity of the aryl hydrocarbon response element, and induced nuclear translocation of the aryl hydrocarbon receptor (AhR), a sign the AhR is activated. Carbendazim-induced CYP1A1 expression was blocked by AhR antagonists, and was abolished in AhR signal-deficient cells. Results demonstrated that carbendazim activated the AhR, thereby stimulating CYP1A1 expression. In order to understand whether AhR-induced metabolic enzymes turn carbendazim into less-toxic metabolites, Hoechst 33342 staining to reveal carbendazim-induced nuclear changes and flow cytometry to reveal the subG{sub 0}/G{sub 1} population were applied to monitor carbendazim-induced cell apoptosis. Carbendazim induced less apoptosis in Hepa-1c1c7 cells than in AhR signal-deficient Hepa-1c1c7 mutant cells. Pretreatment with β-NF, an AhR agonist that highly induces CYP1A1 expression, decreased carbendazim-induced cell death. In addition, the lower the level of AhR was, the lower the vitality present in carbendazim-treated cells, including hepatoma cells and their derivatives with AhR RNA interference, also embryonic kidney cells, bladder carcinoma cells, and AhR signal-deficient Hepa-1c1c7 cells. In summary, carbendazim is an AhR agonist. The toxicity of carbendazim was lower in cells with the AhR signal. This report provides clues indicating that carbendazim is more potent at inducing cell death in tissues without than in those with the AhR signal, an important reference for applying carbendazim in cancer chemotherapy. - Highlights: • Carbendazim induced transcriptional activity of the aryl hydrocarbon response element. • Carbendazim induced nuclear translocation of the aryl

Specific deletion of LDL receptor-related protein on macrophages has skewed in vivo effects on cytokine production by invariant natural killer T cells.

Directory of Open Access Journals (Sweden)

Roman Covarrubias

Full Text Available Expression of molecules involved in lipid homeostasis such as the low density lipoprotein receptor (LDLr on antigen presenting cells (APCs has been shown to enhance invariant natural killer T (iNKT cell function. However, the contribution to iNKT cell activation by other lipoprotein receptors with shared structural and ligand binding properties to the LDLr has not been described. In this study, we investigated whether a structurally related receptor to the LDLr, known as LDL receptor-related protein (LRP, plays a role in iNKT cell activation. We found that, unlike the LDLr which is highly expressed on all immune cells, the LRP was preferentially expressed at high levels on F4/80+ macrophages (MΦ. We also show that CD169+ MΦs, known to present antigen to iNKT cells, exhibited increased expression of LRP compared to CD169- MΦs. To test the contribution of MΦ LRP to iNKT cell activation we used a mouse model of MΦ LRP conditional knockout (LRP-cKO. LRP-cKO MΦs pulsed with glycolipid alpha-galactosylceramide (αGC elicited normal IL-2 secretion by iNKT hybridoma and in vivo challenge of LRP-cKO mice led to normal IFN-γ, but blunted IL-4 response in both serum and intracellular expression by iNKT cells. Flow cytometric analyses show similar levels of MHC class-I like molecule CD1d on LRP-cKO MΦs and normal glycolipid uptake. Survey of the iNKT cell compartment in LRP-cKO mice revealed intact numbers and percentages and no homeostatic disruption as evidenced by the absence of programmed death-1 and Ly-49 surface receptors. Mixed bone marrow chimeras showed that the inability iNKT cells to make IL-4 is cell extrinsic and can be rescued in the presence of wild type APCs. Collectively, these data demonstrate that, although MΦ LRP may not be necessary for IFN-γ responses, it can contribute to iNKT cell activation by enhancing early IL-4 secretion.

In HepG2 Cells, Coexisting Carnitine Deficiency Masks Important Indicators of Marginal Biotin Deficiency123

Science.gov (United States)

Bogusiewicz, Anna; Boysen, Gunnar; Mock, Donald M

2015-01-01

Background: A large number of birth defects are related to nutrient deficiencies; concern that biotin deficiency is teratogenic in humans is reasonable. Surprisingly, studies indicate that increased urinary 3-hydroxyisovalerylcarnitine (3HIAc), a previously validated marker of biotin deficiency, is not a valid biomarker in pregnancy. Objective: In this study we hypothesized that coexisting carnitine deficiency can prevent the increase in 3HIAc due to biotin deficiency. Methods: We used a 2-factor nutrient depletion design to induce isolated and combined biotin and carnitine deficiency in HepG2 cells and then repleted cells with carnitine. To elucidate the metabolic pathogenesis, we quantitated intracellular and extracellular free carnitine, acylcarnitines, and acylcarnitine ratios using liquid chromatography–tandem mass spectrometry. Results: Relative to biotin-sufficient, carnitine-sufficient cells, intracellular acetylcarnitine increased by 90%, propionylcarnitine more than doubled, and 3HIAc increased by >10-fold in biotin-deficient, carnitine-sufficient (BDCS) cells, consistent with a defensive mechanism in which biotin-deficient cells transesterify the acyl-coenzyme A (acyl-CoA) substrates of the biotin-dependent carboxylases to the related acylcarnitines. Likewise, in BDCS cells, the ratio of acetylcarnitine to malonylcarnitine and the ratio of propionylcarnitine to methylmalonylcarnitine both more than tripled, and the ratio of 3HIAc to 3-methylglutarylcarnitine (MGc) increased by >10-fold. In biotin-deficient, carnitine-deficient (BDCD) cells, the 3 substrate-derived acylcarnitines changed little, but the substrate:product ratios were masked to a lesser extent. Moreover, carnitine repletion unmasked biotin deficiency in BDCD cells as shown by increases in acetylcarnitine, propionylcarnitine, and 3HIAc (each increased by >50-fold). Likewise, ratios of acetylcarnitine:malonylcarnitine, propionylcarnitine:methylmalonylcarnitine, and 3HIAc:MGc all increased

Interleukin-33 Receptor (ST2 Deficiency Improves the Outcome of Staphylococcus aureus-Induced Septic Arthritis

Directory of Open Access Journals (Sweden)

Larissa Staurengo-Ferrari

2018-05-01

Full Text Available The ST2 receptor is a member of the Toll/IL-1R superfamily and interleukin-33 (IL-33 is its agonist. Recently, it has been demonstrated that IL-33/ST2 axis plays key roles in inflammation and immune mediated diseases. Here, we investigated the effect of ST2 deficiency in Staphylococcus aureus-induced septic arthritis physiopathology. Synovial fluid samples from septic arthritis and osteoarthritis individuals were assessed regarding IL-33 and soluble (s ST2 levels. The IL-33 levels in samples from synovial fluid were significantly increased, whereas no sST2 levels were detected in patients with septic arthritis when compared with osteoarthritis individuals. The intra-articular injection of 1 × 107 colony-forming unity/10 μl of S. aureus American Type Culture Collection 6538 in wild-type (WT mice induced IL-33 and sST2 production with a profile resembling the observation in the synovial fluid of septic arthritis patients. Data using WT, and ST2 deficient (−/− and interferon-γ (IFN-γ−/− mice showed that ST2 deficiency shifts the immune balance toward a type 1 immune response that contributes to eliminating the infection due to enhanced microbicide effect via NO production by neutrophils and macrophages. In fact, the treatment of ST2−/− bone marrow-derived macrophage cells with anti-IFN-γ abrogates the beneficial phenotype in the absence of ST2, which confirms that ST2 deficiency leads to IFN-γ expression and boosts the bacterial killing activity of macrophages against S. aureus. In agreement, WT cells achieved similar immune response to ST2 deficiency by IFN-γ treatment. The present results unveil a previously unrecognized beneficial effect of ST2 deficiency in S. aureus-induced septic arthritis.

Normalization of TAM post-receptor signaling reveals a cell invasive signature for Axl tyrosine kinase.

Science.gov (United States)

Kimani, Stanley G; Kumar, Sushil; Davra, Viralkumar; Chang, Yun-Juan; Kasikara, Canan; Geng, Ke; Tsou, Wen-I; Wang, Shenyan; Hoque, Mainul; Boháč, Andrej; Lewis-Antes, Anita; De Lorenzo, Mariana S; Kotenko, Sergei V; Birge, Raymond B

2016-09-06

Tyro3, Axl, and Mertk (TAMs) are a family of three conserved receptor tyrosine kinases that have pleiotropic roles in innate immunity and homeostasis and when overexpressed in cancer cells can drive tumorigenesis. In the present study, we engineered EGFR/TAM chimeric receptors (EGFR/Tyro3, EGFR/Axl, and EGF/Mertk) with the goals to interrogate post-receptor functions of TAMs, and query whether TAMs have unique or overlapping post-receptor activation profiles. Stable expression of EGFR/TAMs in EGFR-deficient CHO cells afforded robust EGF inducible TAM receptor phosphorylation and activation of downstream signaling. Using a series of unbiased screening approaches, that include kinome-view analysis, phosphor-arrays, RNAseq/GSEA analysis, as well as cell biological and in vivo readouts, we provide evidence that each TAM has unique post-receptor signaling platforms and identify an intrinsic role for Axl that impinges on cell motility and invasion compared to Tyro3 and Mertk. These studies demonstrate that TAM show unique post-receptor signatures that impinge on distinct gene expression profiles and tumorigenic outcomes.

Methamphetamine Increases Locomotion and Dopamine Transporter Activity in Dopamine D5 Receptor-Deficient Mice

OpenAIRE

Hayashizaki, Seiji; Hirai, Shinobu; Ito, Yumi; Honda, Yoshiko; Arime, Yosefu; Sora, Ichiro; Okado, Haruo; Kodama, Tohru; Takada, Masahiko

2013-01-01

Dopamine regulates the psychomotor stimulant activities of amphetamine-like substances in the brain. The effects of dopamine are mediated through five known dopamine receptor subtypes in mammals. The functional relevance of D5 dopamine receptors in the central nervous system is not well understood. To determine the functional relevance of D5 dopamine receptors, we created D5 dopamine receptor-deficient mice and then used these mice to assess the roles of D5 dopamine receptors in the behaviora...

Cell-Type-Specific Regulation of the Retinoic Acid Receptor Mediated by the Orphan Nuclear Receptor TLX†

Science.gov (United States)

Kobayashi, Mime; Yu, Ruth T.; Yasuda, Kunio; Umesono, Kazuhiko

2000-01-01

Malformations in the eye can be caused by either an excess or deficiency of retinoids. An early target gene of the retinoid metabolite, retinoic acid (RA), is that encoding one of its own receptors, the retinoic acid receptor β (RARβ). To better understand the mechanisms underlying this autologous regulation, we characterized the chick RARβ2 promoter. The region surrounding the transcription start site of the avian RARβ2 promoter is over 90% conserved with the corresponding region in mammals and confers strong RA-dependent transactivation in primary cultured embryonic retina cells. This response is selective for RAR but not retinoid X receptor-specific agonists, demonstrating a principal role for RAR(s) in retina cells. Retina cells exhibit a far higher sensitivity to RA than do fibroblasts or osteoblasts, a property we found likely due to expression of the orphan nuclear receptor TLX. Ectopic expression of TLX in fibroblasts resulted in increased sensitivity to RA induction, an effect that is conserved between chick and mammals. We have identified a cis element, the silencing element relieved by TLX (SET), within the RARβ2 promoter region which confers TLX- and RA-dependent transactivation. These results indicate an important role for TLX in autologous regulation of the RARβ gene in the eye. PMID:11073974

Cell-type-specific regulation of the retinoic acid receptor mediated by the orphan nuclear receptor TLX.

Science.gov (United States)

Kobayashi, M; Yu, R T; Yasuda, K; Umesono, K

2000-12-01

Malformations in the eye can be caused by either an excess or deficiency of retinoids. An early target gene of the retinoid metabolite, retinoic acid (RA), is that encoding one of its own receptors, the retinoic acid receptor beta (RARbeta). To better understand the mechanisms underlying this autologous regulation, we characterized the chick RARbeta2 promoter. The region surrounding the transcription start site of the avian RARbeta2 promoter is over 90% conserved with the corresponding region in mammals and confers strong RA-dependent transactivation in primary cultured embryonic retina cells. This response is selective for RAR but not retinoid X receptor-specific agonists, demonstrating a principal role for RAR(s) in retina cells. Retina cells exhibit a far higher sensitivity to RA than do fibroblasts or osteoblasts, a property we found likely due to expression of the orphan nuclear receptor TLX. Ectopic expression of TLX in fibroblasts resulted in increased sensitivity to RA induction, an effect that is conserved between chick and mammals. We have identified a cis element, the silencing element relieved by TLX (SET), within the RARbeta2 promoter region which confers TLX- and RA-dependent transactivation. These results indicate an important role for TLX in autologous regulation of the RARbeta gene in the eye.

Repletion of zinc in zinc-deficient cells strongly up-regulates IL-1β-induced IL-2 production in T-cells.

Science.gov (United States)

Daaboul, Doha; Rosenkranz, Eva; Uciechowski, Peter; Rink, Lothar

2012-10-01

Mild zinc deficiency in humans negatively affects IL-2 production resulting in declined percentages of cytolytic T cells and decreased NK cell lytic activity, which enhances the susceptibility to infections and malignancies. T-cell activation is critically regulated by zinc and the normal physiological zinc level in T-cells slightly lies below the optimal concentration for T-cell functions. A further reduction in zinc level leads to T-cell dysfunction and autoreactivity, whereas high zinc concentrations (100 μM) were shown to inhibit interleukin-1 (IL-1)-induced IL-1 receptor kinase (IRAK) activation. In this study, we investigated the molecular mechanism by which zinc regulates the IL-1β-induced IL-2 expression in T-cells. Zinc supplementation to zinc-deficient T-cells increased intracellular zinc levels by altering the expression of zinc transporters, particularly Zip10 and Zip12. A zinc signal was observed in the murine T-cell line EL-4 6.1 after 1 h of stimulation with IL-1β, measured by specific zinc sensors FluoZin-3 and ZinPyr-1. This signal is required for the phosphorylation of MAPK p38 and NF-κB subunit p65, which triggers the transcription of IL-2 and strongly increases its production. These results indicate that short-term zinc supplementation to zinc-deficient T-cells leads to a fast rise in zinc levels which subsequently enhance cytokine production. In conclusion, low and excessive zinc levels might be equally problematic for zinc-deficient subjects, and stabilized zinc levels seem to be essential to avoid negative concentration-dependent zinc effects on T-cell activation.

Lipoprotein metabolism in familial hypercholesterolemia: Serial assessment using a one-step ultracentrifugation method

Directory of Open Access Journals (Sweden)

Hayato Tada

2015-04-01

Full Text Available Objectives: It is well known that familial hypercholesterolemia (FH is a common inherited disorder that can markedly elevate the level of plasma LDL cholesterol. However, little data exists regarding the clinical impact of the plasma triglyceride (TG-rich lipoprotein fraction, including VLDL and IDL, in FH. Thus, we assessed the hypothesis that the mutations in the LDL receptor modulate lipoprotein metabolism other than the LDL fraction. Design and methods: We investigated plasma lipoprotein with a one-step ultracentrifugation method for 146 controls (mean age=61.4±17.1 yr, mean LDL cholesterol=92.7±61.2 mg/dl, 213 heterozygous mutation-determined FH subjects (mean age=46.0±18.0 yr, mean LDL cholesterol=225.1±61.2 mg/dl, and 16 homozygous/compound heterozygous mutation-determined FH subjects (mean age=26.9±17.1 yr, mean LDL cholesterol=428.6±86.1 mg/dl. In addition, we evaluated cholesterol/TG ratio in each lipoprotein fraction separated by ultracentrifugation. Results: In addition to total cholesterol and LDL cholesterol levels, VLDL cholesterol (19.5±10.4, 25.2±19.3, 29.5±21.4 mg/dl, respectively and IDL cholesterol (8.3±3.7, 16.8±11.5, 40.0±37.3 mg/dl, respectively exhibited a tri-model distribution according to their status in LDL receptor mutation(s. Moreover, the ratios of cholesterol/TG of each lipoprotein fraction increased significantly in heterozygous FH and homozygous/compound heterozygous FH groups, compared with that of controls, suggesting that the abnormality in LDL receptor modulates the quality as well as the quantity of each lipoprotein fraction. Conclusions: Our results indicate that cholesterol in TG-rich lipoproteins, including VLDL and IDL, are significantly higher in FH subjects, revealing a tri-modal distribution according to the number of LDL receptor mutations. Keywords: LDL cholesterol, Familial hypercholesterolemia, Ultracentrifugation, Lipoprotein

Expression and function of β-adrenergic receptors in human hematopoietic cell lines

International Nuclear Information System (INIS)

Maeki, T.; Andersson, L.C.; Kontula, K.K.

1992-01-01

We investigated the expression and functional characteristics of β-adrenoceptors in a panel of 10 phenotypically different human hematopoietic cell lines. A binding assay with [ 125 I]iodocyanopindolol as the ligand revealed that cell lines of myelomonocytic or histiocytic derivation (HL-60, ML-2, RC-2A, U-937) expressed high numbers of β-adrenoceptors. An intermediate density of receptors was found in a non-T, non-B cell leukemia line (Nall-1), whereas T-cell (JM, CCRF-CEM), B-cell (Raji) or erythroleukemic cell lines (K-562, HEL) displayed minimala or undetectable binding of the radioligand. Isoprenaline-stimulated cAMP production by the cells correlated to their extent of β-adrenoceptor expression. Southern blot hybridization analysis of genomic DNA from the cell lines with a 32 P-labelled β 2 -adrenoceptor cDNA probe revealed no evidence for major rearrangement or amplification of the receptor gene. Incubation with isoprenaline in vitro suppressed the proliferation of the receptor-rich RC-2A cells but did not affect the growth rate of the receptor-deficient K-562 cells. Treatment with propranolol slightly enhanced the proliferation of the RC-2A cells but did not markedly alter the growth rate of two other cell lines, regardless of their β-adrenoceptor status. These findings indicate a regulatory influence by the sympathoadrenergic system on selected cells of the myelomonocytic lineage. (au)

Pervasive and stochastic changes in the TCR repertoire of regulatory T-cell-deficient mice.

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Zheng, Lingjie; Sharma, Rahul; Kung, John T; Deshmukh, Umesh S; Jarjour, Wael N; Fu, Shu Man; Ju, Shyr-Te

2008-04-01

We hypothesize that regulatory T-cell (Treg)-deficient strains have an altered TCR repertoire in part due to the expansion of autoimmune repertoire by self-antigen. We compared the Vbeta family expression profile between B6 and Treg-lacking B6.Cg-Foxp3(sf)(/Y) (B6.sf) mice using fluorescent anti-Vbeta mAbs and observed no changes. However, while the spectratypes of 20 Vbeta families among B6 mice were highly similar, the Vbeta family spectratypes of B6.sf mice were remarkably different from B6 mice and from each other. Significant spectratype changes in many Vbeta families were also observed in Treg-deficient IL-2 knockout (KO) and IL-2Ralpha KO mice. Such changes were not observed with anti-CD3 mAb-treated B6 mice or B6 CD4+CD25- T cells. TCR transgenic (OT-II.sf) mice displayed dramatic reduction of clonotypic TCR with concomitant increase in T cells bearing non-transgenic Vbeta and Valpha families, including T cells with dual receptors expressing reduced levels of transgenic Valpha and endogenous Valpha. Collectively, the data demonstrate that Treg deficiency allows polyclonal expansion of T cells in a stochastic manner, resulting in widespread changes in the TCR repertoire.

HOIP Deficiency Causes Embryonic Lethality by Aberrant TNFR1-Mediated Endothelial Cell Death

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Nieves Peltzer

2014-10-01

Full Text Available Summary: Linear ubiquitination is crucial for innate and adaptive immunity. The linear ubiquitin chain assembly complex (LUBAC, consisting of HOIL-1, HOIP, and SHARPIN, is the only known ubiquitin ligase that generates linear ubiquitin linkages. HOIP is the catalytically active LUBAC component. Here, we show that both constitutive and Tie2-Cre-driven HOIP deletion lead to aberrant endothelial cell death, resulting in defective vascularization and embryonic lethality at midgestation. Ablation of tumor necrosis factor receptor 1 (TNFR1 prevents cell death, vascularization defects, and death at midgestation. HOIP-deficient cells are more sensitive to death induction by both tumor necrosis factor (TNF and lymphotoxin-α (LT-α, and aberrant complex-II formation is responsible for sensitization to TNFR1-mediated cell death in the absence of HOIP. Finally, we show that HOIP’s catalytic activity is necessary for preventing TNF-induced cell death. Hence, LUBAC and its linear-ubiquitin-forming activity are required for maintaining vascular integrity during embryogenesis by preventing TNFR1-mediated endothelial cell death. : HOIP is the main catalytic subunit of the linear ubiquitin chain assembly complex (LUBAC, a crucial regulator of TNF and other immune signaling pathways. Peltzer et al. find that HOIP deficiency results in embryonic lethality at midgestation due to endothelial cell death mediated by TNFR1. Aberrant formation of a TNF-mediated cell-death-inducing complex in HOIP-deficient (but not -proficient cells underlies the phenotype, with the catalytic activity of HOIP required for the control of cell death in response to TNF.

Challenging the roles of CD44 and lipolysis stimulated lipoprotein receptor in conveying Clostridium perfringens iota toxin cytotoxicity in breast cancer.

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Fagan-Solis, Katerina D; Reaves, Denise K; Rangel, M Cristina; Popoff, Michel R; Stiles, Bradley G; Fleming, Jodie M

2014-07-02

Translational exploration of bacterial toxins has come to the forefront of research given their potential as a chemotherapeutic tool. Studies in select tissues have demonstrated that Clostridium perfringens iota toxin binds to CD44 and lipolysis stimulated lipoprotein receptor (LSR) cell-surface proteins. We recently demonstrated that LSR expression correlates with estrogen receptor positive breast cancers and that LSR signaling directs aggressive, tumor-initiating cell behaviors. Herein, we identify the mechanisms of iota toxin cytotoxicity in a tissue-specific, breast cancer model with the ultimate goal of laying the foundation for using iota toxin as a targeted breast cancer therapy. In vitro model systems were used to determine the cytotoxic effect of iota toxin on breast cancer intrinsic subtypes. The use of overexpression and knockdown technologies confirmed the roles of LSR and CD44 in regulating iota toxin endocytosis and induction of cell death. Lastly, cytotoxicity assays were used to demonstrate the effect of iota toxin on a validated set of tamoxifen resistant breast cancer cell lines. Treatment of 14 breast cancer cell lines revealed that LSR+/CD44- lines were highly sensitive, LSR+/CD44+ lines were slightly sensitive, and LSR-/CD44+ lines were resistant to iota cytotoxicity. Reduction in LSR expression resulted in a significant decrease in toxin sensitivity; however, overexpression of CD44 conveyed toxin resistance. CD44 overexpression was correlated with decreased toxin-stimulated lysosome formation and decreased cytosolic levels of iota toxin. These findings indicated that expression of CD44 drives iota toxin resistance through inhibition of endocytosis in breast cancer cells, a role not previously defined for CD44. Moreover, tamoxifen-resistant breast cancer cells exhibited robust expression of LSR and were highly sensitive to iota-induced cytotoxicity. Collectively, these data are the first to show that iota toxin has the potential to be an

Recombinant Lipoproteins as Novel Vaccines with Intrinsic Adjuvant.

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Chong, Pele; Huang, Jui-Hsin; Leng, Chih-Hsiang; Liu, Shih-Jen; Chen, Hsin-Wei

2015-01-01

A core platform technology for high production of recombinant lipoproteins with built-in immunostimulator for novel subunit vaccine development has been established. This platform technology has the following advantages: (1) easily convert antigen into lipidated recombinant protein using a fusion sequence containing lipobox and express high level (50-150mg/L) in Escherichia coli; (2) a robust high-yield up- and downstream bioprocess for lipoprotein production is successfully developed to devoid endotoxin contamination; (3) the lipid moiety of recombinant lipoproteins, which is identical to that of bacterial lipoproteins is recognized as danger signals by the immune system (Toll-like receptor 2 agonist), so both innate and adaptive immune responses can be induced by lipoproteins; and (4) successfully demonstrate the feasibility and safety of this core platform technology in meningococcal group B subunit vaccine, dengue subunit vaccine, novel subunit vaccine against Clostridium difficile-associated diseases, and HPV-based immunotherapeutic vaccines in animal model studies. © 2015 Elsevier Inc. All rights reserved.

Characterization of Ebola virus entry by using pseudotyped viruses: identification of receptor-deficient cell lines.

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Wool-Lewis, R J; Bates, P

1998-04-01

Studies analyzing Ebola virus replication have been severely hampered by the extreme pathogenicity of this virus. To permit analysis of the host range and function of the Ebola virus glycoprotein (Ebo-GP), we have developed a system for pseudotyping these glycoproteins into murine leukemia virus (MLV). This pseudotyped virus, MLV(Ebola), can be readily concentrated to titers which exceed 5 x 10(6) infectious units/ml and is effectively neutralized by antibodies specific for Ebo-GP. Analysis of MLV(Ebola) infection revealed that the host range conferred by Ebo-GP is very broad, extending to cells of a variety of species. Notably, all lymphoid cell lines tested were completely resistant to infection; we speculate that this is due to the absence of a cellular receptor for Ebo-GP on B and T cells. The generation of high-titer MLV(Ebola) pseudotypes will be useful for the analysis of immune responses to Ebola virus infection, development of neutralizing antibodies, analysis of glycoprotein function, and isolation of the cellular receptor(s) for the Ebola virus.

Germinated Brown Rice Attenuates Atherosclerosis and Vascular Inflammation in Low-Density Lipoprotein Receptor-Knockout Mice.

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Zhao, Ruozhi; Ghazzawi, Nora; Wu, Jiansu; Le, Khuong; Li, Chunyang; Moghadasian, Mohammed H; Siow, Yaw L; Apea-Bah, Franklin B; Beta, Trust; Yin, Zhengfeng; Shen, Garry X

2018-05-02

The present study investigates the impact of germinated brown rice (GBR) on atherosclerosis and the underlying mechanism in low-density lipoprotein receptor-knockout (LDLr-KO) mice. The intensity of atherosclerosis in aortas of LDLr-KO mice receiving diet supplemented with 60% GBR (weight/weight) was significantly less than that in mice fed with 60% white rice (WR) or control diet ( p mice fed with WR diet was significantly more than that from mice receiving the control diet ( p mice in comparison to the WR diet ( p mice compared to WR. The anti-atherosclerotic effect of GBR in LDLr-KO mice at least in part results from its anti-inflammatory activity.

The dynamin chemical inhibitor dynasore impairs cholesterol trafficking and sterol-sensitive genes transcription in human HeLa cells and macrophages.

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Emmanuelle Girard

Full Text Available Intracellular transport of cholesterol contributes to the regulation of cellular cholesterol homeostasis by mechanisms that are yet poorly defined. In this study, we characterized the impact of dynasore, a recently described drug that specifically inhibits the enzymatic activity of dynamin, a GTPase regulating receptor endocytosis and cholesterol trafficking. Dynasore strongly inhibited the uptake of low-density lipoprotein (LDL in HeLa cells, and to a lower extent in human macrophages. In both cell types, dynasore treatment led to the abnormal accumulation of LDL and free cholesterol (FC within the endolysosomal network. The measure of cholesterol esters (CE further showed that the delivery of regulatory cholesterol to the endoplasmic reticulum (ER was deficient. This resulted in the inhibition of the transcriptional control of the three major sterol-sensitive genes, sterol-regulatory element binding protein 2 (SREBP-2, 3-hydroxy-3-methyl-coenzymeA reductase (HMGCoAR, and low-density lipoprotein receptor (LDLR. The sequestration of cholesterol in the endolysosomal compartment impaired both the active and passive cholesterol efflux in HMDM. Our data further illustrate the importance of membrane trafficking in cholesterol homeostasis and validate dynasore as a new pharmacological tool to study the intracellular transport of cholesterol.

Identifying activated T cells in reconstituted RAG deficient mice using retrovirally transduced Pax5 deficient pro-B cells.

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Nadesan Gajendran

Full Text Available Various methods have been used to identify activated T cells such as binding of MHC tetramers and expression of cell surface markers in addition to cytokine-based assays. In contrast to these published methods, we here describe a strategy to identify T cells that respond to any antigen and track the fate of these activated T cells. We constructed a retroviral double-reporter construct with enhanced green fluorescence protein (EGFP and a far-red fluorescent protein from Heteractis crispa (HcRed. LTR-driven EGFP expression was used to enrich and identify transduced cells, while HcRed expression is driven by the CD40Ligand (CD40L promoter, which is inducible and enables the identification and cell fate tracing of T cells that have responded to infection/inflammation. Pax5 deficient pro-B cells that can give rise to different hematopoietic cells like T cells, were retrovirally transduced with this double-reporter cassette and were used to reconstitute the T cell pool in RAG1 deficient mice that lack T and B cells. By using flow cytometry and histology, we identified activated T cells that had developed from Pax5 deficient pro-B cells and responded to infection with the bacterial pathogen Listeria monocytogenes. Microscopic examination of organ sections allowed visual identification of HcRed-expressing cells. To further characterize the immune response to a given stimuli, this strategy can be easily adapted to identify other cells of the hematopoietic system that respond to infection/inflammation. This can be achieved by using an inducible reporter, choosing the appropriate promoter, and reconstituting mice lacking cells of interest by injecting gene-modified Pax5 deficient pro-B cells.

Hepatic S1P deficiency lowers plasma cholesterol levels in apoB-containing lipoproteins when LDLR function is compromised.

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Basu, Debapriya; Huq, Afroza; Iqbal, Jahangir; Hussain, M Mahmood; Jiang, Xian-Cheng; Jin, Weijun

2015-01-01

Site-1 protease (S1P) is the key enzyme required for activation of the sterol regulatory element binding proteins (SREBPs) that govern lipid synthesis. While S1P has been speculated to influence plasma apoB-containing lipoprotein (Blp) metabolism, there has been little investigative work. LDL receptor (LDLR) is the major receptor for clearing plasma LDL cholesterol (LDL-c). Proprotein convertase subtilisin kexin type 9 (PCSK9) modulates LDL-c through post-translational degradation of the LDLR. A hepatic-specific knockdown (KD) of S1P was achieved using floxed S1P mouse models (S1P(f/f) and LDLR(-/-)S1P(f/f)) and hepatic expression of Cre recombinase. Lipids were measured in total plasma and size fractionated plasma using colorimetric assays. Realtime polymerase chain reaction, western blotting and ELISA were used to determine hepatic expression of key genes/protein. Plasmid mediated overexpression and siRNA mediated knockdown of genes were performed in mouse primary hepatocytes to determine the mechanistic basis of PCSK9 gene regulation. A hepatic-specific KD of S1P resulted in a 45 % and 38 % reduction in plasma total cholesterol and triglyceride levels, respectively. Hepatic S1P KD had a minimal effect on plasma Blp cholesterol (Blp-c) in S1P(f/f) mice, despite significantly reducing VLDL secretion. Notably, hepatic S1P KD decreased the LDL receptor (LDLR) mRNA expression by 50 %. However, the reduction in LDLR protein levels was less than that of mRNA expression, especially under fed conditions. Further assessment of hepatic S1P deficiency revealed that it increased LDLR protein stability in vivo. Mechanistically, hepatic S1P KD was shown to decrease the liver and plasma levels of the protein proprotein convertase subtilisin/kexin type 9 (PCSK9), which degrades LDLR protein. This effect was more prominent in the fed condition and sufficient to account for the discordance in LDLR mRNA and protein levels. Furthermore, hepatic S1P was shown to regulate PCSK9

L-Cysteine-induced up-regulation of the low-density lipoprotein receptor is mediated via a transforming growth factor-alpha signalling pathway.

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Tanaka, Yuma; Shimada, Masaya; Nagaoka, Satoshi

2014-02-14

Sulphur-containing amino acids regulate plasma cholesterol levels in animals and humans. However, their mechanism of action remains unclear. Low-density lipoprotein receptor (LDLR) plays an important role in cholesterol metabolism. We therefore investigated the effects of sulphur-containing amino acids on the expression of LDLR in hepatocytes. HepG2 cells were cultured in Dulbecco's Modified Eagle's Medium with or without sulphur-containing amino acids and cysteine-containing compounds. We found that L-cysteine increased LDLR mRNA and enhanced LDLR gene promoter activity through the extracellular-signal-related kinase and p38 mitogen-activated protein kinase signalling pathways in HepG2 cells. Moreover, we observed that L-cysteine stimulated the release of transforming growth factor-alpha (TGF-α) and that TGF-α increased the LDLR mRNA levels. This study provides a report of the L-cysteine mediated up-regulation of the LDLR expression via TGF-α signalling pathway. Our findings provide insights into cholesterol homeostasis and amino acid signalling. Copyright © 2014 Elsevier Inc. All rights reserved.

Ponatinib promotes a G1 cell-cycle arrest of merlin/NF2-deficient human schwann cells.

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Petrilli, Alejandra M; Garcia, Jeanine; Bott, Marga; Klingeman Plati, Stephani; Dinh, Christine T; Bracho, Olena R; Yan, Denise; Zou, Bing; Mittal, Rahul; Telischi, Fred F; Liu, Xue-Zhong; Chang, Long-Sheng; Welling, D Bradley; Copik, Alicja J; Fernández-Valle, Cristina

2017-05-09

Neurofibromatosis type 2 (NF2) is a genetic syndrome that predisposes individuals to multiple benign tumors of the central and peripheral nervous systems, including vestibular schwannomas. Currently, there are no FDA approved drug therapies for NF2. Loss of function of merlin encoded by the NF2 tumor suppressor gene leads to activation of multiple mitogenic signaling cascades, including platelet-derived growth factor receptor (PDGFR) and SRC in Schwann cells. The goal of this study was to determine whether ponatinib, an FDA-approved ABL/SRC inhibitor, reduced proliferation and/or survival of merlin-deficient human Schwann cells (HSC). Merlin-deficient HSC had higher levels of phosphorylated PDGFRα/β, and SRC than merlin-expressing HSC. A similar phosphorylation pattern was observed in phospho-protein arrays of human vestibular schwannoma samples compared to normal HSC. Ponatinib reduced merlin-deficient HSC viability in a dose-dependent manner by decreasing phosphorylation of PDGFRα/β, AKT, p70S6K, MEK1/2, ERK1/2 and STAT3. These changes were associated with decreased cyclin D1 and increased p27Kip1levels, leading to a G1 cell-cycle arrest as assessed by Western blotting and flow cytometry. Ponatinib did not modulate ABL, SRC, focal adhesion kinase (FAK), or paxillin phosphorylation levels. These results suggest that ponatinib is a potential therapeutic agent for NF2-associated schwannomas and warrants further in vivo investigation.

Oral administration of a Spirulina extract enriched for Braun-type lipoproteins protects mice against influenza A(H1N1) virus infection

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Previous studies indicate that Immulina, a commercial extract of Arthrospira (Spirulina) platensis, is a potent activator of innate immune cells and that Braun-type lipoproteins (a principal toll-like receptor (TLR) 2 ligand) are the main active components within this product. In the present study, ...

Mycobacterium tuberculosis lipoproteins in virulence and immunity - fighting with a double-edged sword.

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Becker, Katja; Sander, Peter

2016-11-01

Bacterial lipoproteins are secreted membrane-anchored proteins characterized by a lipobox motif. This lipobox motif directs post-translational modifications at the conserved cysteine through the consecutive action of three enzymes: Lgt, LspA and Lnt, which results in di- or triacylated forms. Lipoproteins are abundant in all bacteria including Mycobacterium tuberculosis and often involved in virulence and immunoregulatory processes. On the one hand, disruption of the biosynthesis pathway of lipoproteins leads to attenuation of M. tuberculosis in vivo, and mycobacteria deficient for certain lipoproteins have been assessed as attenuated live vaccine candidates. On the other hand, several mycobacterial lipoproteins form immunodominant antigens which promote an immune response. Some of these have been explored in DNA or subunit vaccination approaches against tuberculosis. The immune recognition of specific lipoproteins, however, might also benefit long-term survival of M. tuberculosis through immune modulation, while others induce protective responses. Exploiting lipoproteins as vaccines is thus a complex matter which requires deliberative investigation. The dual role of lipoproteins in the immunity to and pathogenicity of mycobacteria is discussed here. © 2016 Federation of European Biochemical Societies.

Lipoprotein biosynthesis as a target for anti-Wolbachia treatment of filarial nematodes

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Slatko Barton E

2010-10-01

Full Text Available Abstract Background Lymphatic filariasis and onchocerciasis are debilitating diseases caused by filarial nematodes. Disease pathogenesis is induced by inflammatory responses following the death of the parasite. Wolbachia endosymbionts of filariae are potent inducers of innate and adaptive inflammation and bacterial lipoproteins have been identified as the ligands that bind toll-like receptors (TLR 2 and TLR6. Lipoproteins are important structural and functional components of bacteria and therefore enzymes involved in Wolbachia lipoprotein biosynthesis are potential chemotherapeutic targets. Results Globomycin, a signal peptidase II (LspA inhibitor, has activity against Gram-negative bacteria and a putative lspA gene has been identified from the Wolbachia genome of Brugia malayi (wBm. The amino acids required for function are strictly conserved and functionality was verified by complementation tests in a temperature-sensitive Escherichia coli lspA mutant. Also, transformation of wild type E. coli with Wolbachia lspA conferred significant globomycin resistance. A cell-based screen has been developed utilizing a Wolbachia-containing Aedes albopictus cell line to assay novel compounds active against Wolbachia. Globomycin was screened using this assay, which resulted in a dose-dependent reduction in Wolbachia load. Furthermore, globomycin was also effective in reducing the motility and viability of adult B. malayi in vitro. Conclusions These studies validate lipoprotein biosynthesis as a target in an organism for which no genetic tools are available. Further studies to evaluate drugs targeting this pathway are underway as part of the A-WOL drug discovery and development program.

Smac Mimetic Bypasses Apoptosis Resistance in FADD- or Caspase-8-Deficient Cells by Priming for Tumor Necrosis Factor α-Induced Necroptosis

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Bram Laukens

2011-10-01

Full Text Available Searching for new strategies to bypass apoptosis resistance, we investigated the potential of the Smac mimetic BV6 in Jurkat leukemia cells deficient in key molecules of the death receptor pathway. Here, we demonstrate for the first time that Smac mimetic primes apoptosis-resistant, FADD- or caspase-8-deficient leukemia cells for TNFα-induced necroptosis in a synergistic manner. In contrast to TNFα, Smac mimetic significantly enhances CD95-induced apoptosis in wild-type but not in FADD-deficient cells. Interestingly, Smac mimetic- and TNFα-mediated cell death occurs without characteristic features of apoptosis (i.e., caspase activation, DNA fragmentation in FADD-deficient cells. By comparison, Smac mimetic and TNFα trigger activation of caspase-8, -9, and -3 and DNA fragmentation in wild-type cells. Consistently, the caspase inhibitor zVAD.fmk fails to block Smac mimetic- and TNFα-triggered cell death in FADD- or caspase-8-deficient cells, while it confers protection in wild-type cells. By comparison, necrostatin-1, an RIP1 kinase inhibitor, abolishes Smac mimetic- and TNFα-induced cell death in FADD- or caspase-8-deficient. Thus, Smac mimetic enhances TNFα-induced cell death in leukemia cells via two distinct pathways in a context-dependent manner: it primes apoptosis-resistant cells lacking FADD or caspase-8 to TNFα-induced, RIP1-dependent and caspase-independent necroptosis, whereas it sensitizes apoptosis-proficient cells to TNFα-mediated, caspase-dependent apoptosis. These findings have important implications for the therapeutic exploitation of necroptosis as an alternative cell death program to overcome apoptosis resistance.

Biogenesis and Membrane Targeting of Lipoproteins.

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Narita, Shin-Ichiro; Tokuda, Hajime

2010-09-01

Bacterial lipoproteins represent a unique class of membrane proteins, which are anchored to membranes through triacyl chains attached to the amino-terminal cysteine. They are involved in various functions localized in cell envelope. Escherichia coli possesses more than 90 species of lipoproteins, most of which are localized in the outer membrane, with others being in the inner membrane. All lipoproteins are synthesized in the cytoplasm with an N-terminal signal peptide, translocated across the inner membrane by the Sec translocon to the periplasmic surface of the inner membrane, and converted to mature lipoproteins through sequential reactions catalyzed by three lipoprotein-processing enzymes: Lgt, LspA, and Lnt. The sorting of lipoproteins to the outer membrane requires a system comprising five Lol proteins. An ATP-binding cassette transporter, LolCDE, initiates the sorting by mediating the detachment of lipoproteins from the inner membrane. Formation of the LolA-lipoprotein complex is coupled to this LolCDE-dependent release reaction. LolA accommodates the amino-terminal acyl chain of lipoproteins in its hydrophobic cavity, thereby generating a hydrophilic complex that can traverse the periplasmic space by diffusion. Lipoproteins are then transferred to LolB on the outer membrane and anchored to the inner leaflet of the outer membrane by the action of LolB. In contrast, since LolCDE does not recognize lipoproteins possessing Asp at position +2, these lipoproteins remain anchored to the inner membrane. Genes for Lol proteins are widely conserved among gram-negative bacteria, and Lol-mediated outer membrane targeting of lipoproteins is considered to be the general lipoprotein localization mechanism.

Lipoprotein distribution and serum concentrations of 7α-hydroxy-4-cholesten-3-one and bile acids: effects of monogenic disturbances in high-density lipoprotein metabolism

DEFF Research Database (Denmark)

Steiner, Carine; Holleboom, Adriaan G; Karuna, Ratna

2012-01-01

BA (bile acid) formation is considered an important final step in RCT (reverse cholesterol transport). HDL (high-density lipoprotein) has been reported to transport BAs. We therefore investigated the effects of monogenic disturbances in human HDL metabolism on serum concentrations and lipoprotein...... concentrations of conjugated and secondary BAs differed between heterozygous carriers of SCARB1 (scavenger receptor class B1) mutations and unaffected individuals (P...

Impact of glutathione peroxidase-1 deficiency on macrophage foam cell formation and proliferation: implications for atherogenesis.

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Fei Cheng

Full Text Available Clinical and experimental evidence suggests a protective role for the antioxidant enzyme glutathione peroxidase-1 (GPx-1 in the atherogenic process. GPx-1 deficiency accelerates atherosclerosis and increases lesion cellularity in ApoE(-/- mice. However, the distribution of GPx-1 within the atherosclerotic lesion as well as the mechanisms leading to increased macrophage numbers in lesions is still unknown. Accordingly, the aims of the present study were (1 to analyze which cells express GPx-1 within atherosclerotic lesions and (2 to determine whether a lack of GPx-1 affects macrophage foam cell formation and cellular proliferation. Both in situ-hybridization and immunohistochemistry of lesions of the aortic sinus of ApoE(-/- mice after 12 weeks on a Western type diet revealed that both macrophages and - even though to a less extent - smooth muscle cells contribute to GPx-1 expression within atherosclerotic lesions. In isolated mouse peritoneal macrophages differentiated for 3 days with macrophage-colony-stimulating factor (MCSF, GPx-1 deficiency increased oxidized low density-lipoprotein (oxLDL induced foam cell formation and led to increased proliferative activity of peritoneal macrophages. The MCSF- and oxLDL-induced proliferation of peritoneal macrophages from GPx-1(-/-ApoE(-/- mice was mediated by the p44/42 MAPK (p44/42 mitogen-activated protein kinase, namely ERK1/2 (extracellular-signal regulated kinase 1/2, signaling pathway as demonstrated by ERK1/2 signaling pathways inhibitors, Western blots on cell lysates with primary antibodies against total and phosphorylated ERK1/2, MEK1/2 (mitogen-activated protein kinase kinase 1/2, p90RSK (p90 ribosomal s6 kinase, p38 MAPK and SAPK/JNK (stress-activated protein kinase/c-Jun N-terminal kinase, and immunohistochemistry of mice atherosclerotic lesions with antibodies against phosphorylated ERK1/2, MEK1/2 and p90RSK. Representative effects of GPx-1 deficiency on both macrophage proliferation and

Identification of the receptor scavenging hemopexin-heme complexes

DEFF Research Database (Denmark)

Hvidberg, Vibeke; Maniecki, Maciej B; Jacobsen, Christian

2005-01-01

and is suggested to facilitate cellular heme metabolism. Using a ligand-affinity approach, we purified the human hemopexin-heme receptor and identified it as the low-density lipoprotein receptor-related protein (LRP)/CD91, a receptor expressed in several cell types including macrophages, hepatocytes, neurons......, and syncytiotrophoblasts. Binding experiments, including Biacore analysis, showed that hemopexin-heme complex formation elicits the high receptor affinity. Uptake studies of radio-labeled hemopexin-heme complex in LRP/CD91-expressing COS cells and confocal microscopy of the cellular processing of fluorescent hemopexin......-heme complexes are removed by a receptor-mediated pathway showing striking similarities to the CD163-mediated haptoglobin-hemoglobin clearance in macrophages. Furthermore, the data indicate a hitherto unknown role of LRP/CD91 in inflammation....

Characterization of LDL-receptors of freshly isolated mononuclear cells of healthy subjects and of FH-patients

International Nuclear Information System (INIS)

Banyai, M.

1991-05-01

The central role of the LDL (=low density lipoproteins) receptor in artherosclerosis was first appreciated when it was shown that its absence was responsible for FH (familial hypercholesterolemia). To determine the high affinity cell surface binding activity in circulating human mononuclear cells (MNCs), these cells were incubated with low concentrations (1-50 μg protein/ml) of 123 I-LDL or 111 In-LDL either in the presence or absence of an excess of unlabeled LDL at 4 deg C for 45 minutes. MNCs of healthy subjects and of heterozygous FH-patients were found to possess high affinity LDL receptors immediately after they were isolated from the blood stream. The results indicate that the FH-patients enclosed in this study possess a reduced number of the same high affinity binding sites as healthy subjects confirming the diagnosis of heterozygous FH. In this study 123 I-LDL binding and 111 In-LDL binding to MNCs has been shown to saturable, reversible and displaceable and time-dependent. 123 I-LDL and 111 In-LDL as well can be recommended for the in-vitro determination of LDL-receptor binding activity as both binding processes show approximately the same characteristics. (author)

Characterization of lipoproteins in human and canine cerebrospinal fluid (CSF)

International Nuclear Information System (INIS)

Pitas, R.E.; Weisgraber, K.H.; Boyles, J.K.; Lee, S.; Mahley, R.W.

1986-01-01

Previously the authors demonstrated that rat brain astrocytes in vitro synthesize and secrete apo-E and possess apo-B,E(LDL) receptors. The apo-E secreted by astrocytes and apo-E in rat brain extracts differed from serum apo-E in two respects. Brain apo-E had a higher apparent molecular weight and a higher percentage of more acidic isoforms. To characterize further the apo-E within the central nervous system, apo-E in human and canine CSF was investigated. Compared to plasma apo-E, CSF apo-E had a higher apparent M/sub r/ and a higher percentage of acidic isoforms which were sialylated, as shown by neuraminidase digestion. The apo-E in human CSF was approx.5-10% of the plasma level. In CSF 60-80% of the apo-E was in lipoproteins with d = 1.09-1.15. The remainder of the apo-E was in the d > 1.21 fraction. Human CSF lipoproteins were primarily spherical (110-190 A) while canine CSF lipoproteins were a mixture of discs (205 x 65 A) while canine CSF lipoproteins were a mixture of discs (205 x 65 A) and spheres (100-150 A). The CSF also contained apo-AI in the d = 1.09-1.15 g/ml fraction. Human CSF lipoproteins containing both apo-E and apo-AI were isolated on an anti-apo-E affinity column, suggesting that apo-E and AI occurred in the same particles. The CSF apo-E-containing lipoproteins competed for binding of 125 I-LDL to the apo-B,E(LDL) receptor. There was no detectable apo-B in CSF. These data suggest that CSF lipoproteins might transport lipid and regulate lipid homeostasis within the brain

DNA binding properties of dioxin receptors in wild-type and mutant mouse hepatoma cells

International Nuclear Information System (INIS)

Cuthill, S.; Poellinger, L.

1988-01-01

The current model of action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) entails stimulation of target gene transcription via the formation of dioxin-receptor complexes and subsequent accumulation of the complexes within the cell nucleus. Here, the authors have analyzed the DNA binding properties of the dioxin receptor in wild-type mouse hepatoma (Hepa 1c1c7) cells and a class of nonresponsive mutant cells which fail to accumulate dioxin-receptor complexes within the nucleus in vivo. In vitro, both the wild-type and mutant [ 3 H]dioxin-receptor complexes exhibited low affinity for DNA-cellulose (5-8% and around 4% retention, respectively) in the absence of prior biochemical manipulations. However, following chromatography on heparin-Sepharose, the wild-type but not the mutant dioxin receptor was transformed to a species with an increased affinity for DNA (40-50% retention on DNA-cellulose). The gross molecular structure of the mutant, non DNA binding dioxin receptor did not appear to be altered as compared to that of the wild-type receptor. These results imply that the primary deficiency in the mutant dioxin receptor form may reside at the DNA binding level and that, in analogy to steroid hormone receptors, DNA binding of the receptor may be an essential step in the regulation of target gene transcription by dioxin

Residues in the 5th module of the low-density lipoprotein receptor that bind apoE and apoB-100

International Nuclear Information System (INIS)

Kroon, P.A.; Zhang, H.-Y.; Smith, R.

2000-01-01

Full text: The low-density lipoprotein receptor (LDLR) binds and removes cholesterol-rich lipoproteins from the circulation. Its ligand-binding (LB) domain consists of seven cysteine-rich LB modules that bind apoB-100 and apoE. These modules fold into well-defined structures with three disulfide bonds, in the presence of Ca 2+ . The 5th module (LB5) is unique in that it is required to bind both apoB-100 and apoE. The aim of the current study was to map residues in human LB5 that are required for ligand binding. This was done by alanine mutagenesis of a series of residues that are conserved in human, mouse, rat and rabbit LB5 (E9, S14, E16, H19, S21, K31, and K33), but not in the other six modules. E37 (R37 in the rabbit) was included, since it has been previously hypothesized to play a role in binding. The variant LB5 modules were first produced as recombinant peptides, and subjected to oxidative folding to determine whether the mutations interfered with Ca 2+ '-dependent folding. Only the S14A and E16A mutations interfered significantly with folding, suggesting that S14 and E16 are required for the structural framework of LB5 and that their substitution in the LDLR may interfere with its folding. The native LDLR and E9A, H19A, S21A, K31A, K33A and E37A LDLRs were expressed in LDLR negative IdlA-7 CHO cells. Labeling with 125 I-lgG-C7 showed that all receptors were expressed on the cell surface. Binding of Dil-labeled LDL (Dil-LDL) and Dil-labeled DMPC, complexed with the N-terminal receptor-binding domain of apoE3 (Dil-E3), at 4 deg C, was used to assess receptor binding. Binding of Dil-E3 (0.1 μ/ml) to the H19A, S21A, K31A, K33A and E37A LDLRs was 65-92% of binding to the native LDLR. In contrast, the E9A LDLR only bound 3% of that of the native LDLR. The binding of Dil-LDL (0.5 Ag/ml) to the E9A LDLR was 23% of that of the native LDLR, while binding to the remaining variant LDLRs ranged from 44-70% of what of the native LDLR. We conclude that (i) E9 of LB5

Transport of lipoprotein lipase across endothelial cells

International Nuclear Information System (INIS)

Saxena, U.; Klein, M.G.; Goldberg, I.J.

1991-01-01

Lipoprotein lipase (LPL), synthesized in muscle and fat, hydrolyzes plasma triglycerides primarily while bound to luminal endothelial cell surfaces. To obtain information about the movement of LPL from the basal to the luminal endothelial cell surface, the authors studied the transport of purified bovine milk LPL across bovine aortic endothelial cell monolayers. 125 I-labeled LPL ( 125 I-LPL) added to the basal surface of the monolayers was detected on the apical side of the cells in two compartments: (1) in the medium of the upper chamber, and (2) bound to the apical cell surface. The amount of 125 I-LPL on the cell surface, but not in the medium, reached saturation with time and LPL dose. Catalytically active LPL was transported to the apical surface but very little LPL activity appeared in the medium. Heparinase treatment of the basal cell surface and addition of dextran sulfate to the lower chamber decreased the amount of 125 I-LPL appearing on the apical surface. Similarly, the presence of increasing molar ratios of oleic acid/bovine serum albumin at the basal surface decreased the transport of active LPL across the monolayer. Thus, a saturable transport system, which requires haparan sulfate proteoglycans and is inhibited by high concentrations of free fatty acids on the basal side of the cells, appears to exist for passage of enzymatically active LPL across endothelial cells. They postulate that regulation of LPL transport to the endothelial luminal surface modulates the physiologically active pool of LPL in vivo

Lipophorin Receptor: The Insect Lipoprotein Receptor

Indian Academy of Sciences (India)

IAS Admin

Director of ... function of the Lp is to deliver lipids throughout the insect body for metabolism ... Lipid is used as a major energy source for development as well as other metabolic .... LpR4 receptor variant was expressed exclusively in the brain and.

Chimeric RXFP1 and RXFP2 receptors highlight the similar mechanism of activation utilizing their N-terminal low density lipoprotein class A modules

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Shoni eBruell

2013-11-01

Full Text Available Relaxin family peptide (RXFP receptors 1 and 2 are unique G-protein coupled receptors in that they contain an N-terminal low density lipoprotein type A (LDLa module which is necessary for receptor activation. The current hypothesis suggests that upon ligand binding the LDLa module interacts with the transmembrane (TM domain of a homodimer partner receptor to induce the active receptor conformations. We recently demonstrated that three residues in the N-terminus of the RXFP1 LDLa module are potentially involved in hydrophobic interactions with the receptor to drive activation. RXFP2 shares two out of three of the residues implicated, suggesting that the two LDLa modules could be interchanged without adversely affecting activity. However, in 2007 it was shown that a chimera consisting of the RXFP1 receptor with its LDLa swapped for that of RXFP2 did not signal. We noticed this construct also contained the RXFP2 region linking the LDLa to the leucine-rich repeats. We therefore constructed chimeric RXFP1 and RXFP2 receptors with their LDLa modules swapped immediately C-terminally to the final cysteine residue of the module, retaining the native linker. In addition, we exchanged the TM domains of the chimeras to explore if matching the LDLa module with the TM domain of its native receptor altered activity. All of the chimeras were expressed at the surface of HEK293T cells with ligand binding profiles similar to the wild-type receptors. Importantly, as predicted, ligand binding was able to induce cAMP based signalling. Chimeras of RXFP1 with the LDLa of RXFP2 demonstrated reduced H2 relaxin potency with the pairing of the RXFP2 TM with the RXFP2 LDLa necessary for full ligand efficacy. In contrast the ligand mediated potencies and efficacies on the RXFP2 chimeras were similar suggesting the RXFP1 LDLa module has similar efficacy on the RXFP2 TM domain. Our studies demonstrate the LDLa modules of RXFP1 and RXFP2 modulate receptor activation via a

Analysis of the binding of pro-urokinase and urokinase-plasminogen activator inhibitor-1 complex to the low density lipoprotein receptor-related protein using a Fab fragment selected from a phage-displayed Fab library

NARCIS (Netherlands)

Horn, I. R.; Moestrup, S. K.; van den Berg, B. M.; Pannekoek, H.; Nielsen, M. S.; van Zonneveld, A. J.

1995-01-01

The low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) mediates endocytosis of a number of structurally unrelated ligands, including complexes of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) or urokinase plasminogen

Reducing inflammation and rescuing FTD-related behavioral deficits in progranulin-deficient mice with α7 nicotinic acetylcholine receptor agonists.

Science.gov (United States)

Minami, S Sakura; Shen, Vivian; Le, David; Krabbe, Grietje; Asgarov, Rustam; Perez-Celajes, Liberty; Lee, Chih-Hung; Li, Jinhe; Donnelly-Roberts, Diana; Gan, Li

2015-10-15

Mutations in the progranulin gene cause frontotemporal dementia (FTD), a debilitating neurodegenerative disease that involves atrophy of the frontal and temporal lobes and affects personality, behavior, and language. Progranulin-deficient mouse models of FTD exhibit deficits in compulsive and social behaviors reminiscent of patients with FTD, and develop excessive microgliosis and increased release of inflammatory cytokines. Activation of nicotinic acetylcholine receptors (nAChRs) by nicotine or specific α7 nAChR agonists reduces neuroinflammation. Here, we investigated whether activation of nAChRs by nicotine or α7 agonists improved the excessive inflammatory and behavioral phenotypes of a progranulin-deficient FTD mouse model. We found that treatment with selective α7 agonists, PHA-568487 or ABT-107, strongly suppressed the activation of NF-κB in progranulin-deficient cells. Treatment with ABT-107 also reduced microgliosis, decreased TNFα levels, and reduced compulsive behavior in progranulin-deficient mice. Collectively, these data suggest that targeting activation of the α7 nAChR pathway may be beneficial in decreasing neuroinflammation and reversing some of the behavioral deficits observed in progranulin-deficient FTD. Copyright © 2015. Published by Elsevier Inc.

Essential oil of Pinus koraiensis leaves exerts antihyperlipidemic effects via up-regulation of low-density lipoprotein receptor and inhibition of acyl-coenzyme A: cholesterol acyltransferase.

Science.gov (United States)

Kim, Ji-Hyun; Lee, Hyo-Jung; Jeong, Soo-Jin; Lee, Min-Ho; Kim, Sung-Hoon

2012-09-01

Hyperlipidemia is an important factor to induce metabolic syndrome such as obesity, diabetes and cardiovascular diseases. Recently, some antihyperlipidemic agents from herbal medicines have been in the spotlight in the medical science field. Thus, the present study evaluated the antihyperlipidemic activities of the essential oil from the leaves of Pinus koraiensis SIEB (EOPK) that has been used as a folk remedy for heart disease. The reverse transcription polymerase chain reaction (RT-PCR) revealed that EOPK up-regulated low density lipoprotein receptor (LDLR) at the mRNA level as well as negatively suppressed the expression of sterol regulatory element-binding protein (SREBP)-1c, SREBP-2, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), fatty acid synthase (FAS) and glycerol-3-phosphate acyltransferase (GPAT) involved in lipid metabolism in HepG2 cells. Also, western blotting showed that EOPK activated LDLR and attenuated the expression of FAS at the protein level in the cells. Consistently, EOPK significantly inhibited the level of human acylcoenzyme A: cholesterol acyltransferase (hACAT)1 and 2 and reduced the low-density lipoprotein (LDL) oxidation activity. Furthermore, chromatography-mass spectrometry (GC-MS) analysis showed that EOPK, an essential oil mixture, contained camphene (21.11%), d-limonene (21.01%), α-pinene (16.74%) and borneol (11.52%). Overall, the findings suggest that EOPK can be a potent pharmaceutical agent for the prevention and treatment of hyperlipidemia. Copyright © 2012 John Wiley & Sons, Ltd.

Replication fork stability confers chemoresistance in BRCA-deficient cells

DEFF Research Database (Denmark)

Chaudhuri, Arnab Ray; Callen, Elsa; Ding, Xia

2016-01-01

/4 complex protein, PTIP, protects Brca1/2-deficient cells from DNA damage and rescues the lethality of Brca2-deficient embryonic stem cells. However, PTIP deficiency does not restore homologous recombination activity at double-strand breaks. Instead, its absence inhibits the recruitment of the MRE11......Cells deficient in the Brca1 and Brca2 genes have reduced capacity to repair DNA double-strand breaks by homologous recombination and consequently are hypersensitive to DNA-damaging agents, including cisplatin and poly(ADP-ribose) polymerase (PARP) inhibitors. Here we show that loss of the MLL3...... nuclease to stalled replication forks, which in turn protects nascent DNA strands from extensive degradation. More generally, acquisition of PARP inhibitors and cisplatin resistance is associated with replication fork protection in Brca2-deficient tumour cells that do not develop Brca2 reversion mutations...

Early childhood BMI trajectories in monogenic obesity due to leptin, leptin receptor, and melanocortin 4 receptor deficiency.

Science.gov (United States)

Kohlsdorf, Katja; Nunziata, Adriana; Funcke, Jan-Bernd; Brandt, Stephanie; von Schnurbein, Julia; Vollbach, Heike; Lennerz, Belinda; Fritsch, Maria; Greber-Platzer, Susanne; Fröhlich-Reiterer, Elke; Luedeke, Manuel; Borck, Guntram; Debatin, Klaus-Michael; Fischer-Posovszky, Pamela; Wabitsch, Martin

2018-02-27

To evaluate whether early childhood body mass index (BMI) is an appropriate indicator for monogenic obesity. A cohort of n = 21 children living in Germany or Austria with monogenic obesity due to congenital leptin deficiency (group LEP, n = 6), leptin receptor deficiency (group LEPR, n = 6) and primarily heterozygous MC4 receptor deficiency (group MC4R, n = 9) was analyzed. A control group (CTRL) was defined that consisted of n = 22 obese adolescents with no mutation in the above mentioned genes. Early childhood (0-5 years) BMI trajectories were compared between the groups at selected time points. The LEP and LEPR group showed a tremendous increase in BMI during the first 2 years of life with all patients displaying a BMI >27 kg/m 2 (27.2-38.4 kg/m 2 ) and %BMI P95 (percentage of the 95th percentile BMI for age and sex) >140% (144.8-198.6%) at the age of 2 years and a BMI > 33 kg/m 2 (33.3-45.9 kg/m 2 ) and %BMI P95  > 184% (184.1-212.6%) at the age of 5 years. The MC4R and CTRL groups had a later onset of obesity with significantly lower BMI values at both time points (p BMI trajectories in this pediatric cohort with monogenic obesity we suggest that BMI values >27.0 kg/m 2 or %BMI P95  > 140% at the age of 2 years and BMI values >33.0 kg/m 2 or %BMI P95  > 184% at the age of 5 years may be useful cut points to identify children who should undergo genetic screening for monogenic obesity due to functionally relevant mutations in the leptin gene or leptin receptor gene.

A monomeric G protein-coupled receptor isolated in a high-density lipoprotein particle efficiently activates its G protein

DEFF Research Database (Denmark)

Whorton, Matthew R; Bokoch, Michael P; Rasmussen, Søren Gøgsig Faarup

2007-01-01

G protein-coupled receptors (GPCRs) respond to a diverse array of ligands, mediating cellular responses to hormones and neurotransmitters, as well as the senses of smell and taste. The structures of the GPCR rhodopsin and several G proteins have been determined by x-ray crystallography, yet...... the organization of the signaling complex between GPCRs and G proteins is poorly understood. The observations that some GPCRs are obligate heterodimers, and that many GPCRs form both homo- and heterodimers, has led to speculation that GPCR dimers may be required for efficient activation of G proteins. However......, technical limitations have precluded a definitive analysis of G protein coupling to monomeric GPCRs in a biochemically defined and membrane-bound system. Here we demonstrate that a prototypical GPCR, the beta2-adrenergic receptor (beta2AR), can be incorporated into a reconstituted high-density lipoprotein...

Deficiency of ATP-binding cassette transporters A1 and G1 in macrophages increases inflammation and accelerates atherosclerosis in mice.

Science.gov (United States)

Westerterp, Marit; Murphy, Andrew J; Wang, Mi; Pagler, Tamara A; Vengrenyuk, Yuliya; Kappus, Mojdeh S; Gorman, Darren J; Nagareddy, Prabhakara R; Zhu, Xuewei; Abramowicz, Sandra; Parks, John S; Welch, Carrie; Fisher, Edward A; Wang, Nan; Yvan-Charvet, Laurent; Tall, Alan R

2013-05-24

Plasma high-density lipoprotein levels are inversely correlated with atherosclerosis. Although it is widely assumed that this is attributable to the ability of high-density lipoprotein to promote cholesterol efflux from macrophage foam cells, direct experimental support for this hypothesis is lacking. To assess the role of macrophage cholesterol efflux pathways in atherogenesis. We developed mice with efficient deletion of the ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1) in macrophages (MAC-ABC(DKO) mice) but not in hematopoietic stem or progenitor populations. MAC-ABC(DKO) bone marrow (BM) was transplanted into Ldlr(-/-) recipients. On the chow diet, these mice had similar plasma cholesterol and blood monocyte levels but increased atherosclerosis compared with controls. On the Western-type diet, MAC-ABC(DKO) BM-transplanted Ldlr(-/-) mice had disproportionate atherosclerosis, considering they also had lower very low-density lipoprotein/low-density lipoprotein cholesterol levels than controls. ABCA1/G1-deficient macrophages in lesions showed increased inflammatory gene expression. Unexpectedly, Western-type diet-fed MAC-ABC(DKO) BM-transplanted Ldlr(-/-) mice displayed monocytosis and neutrophilia in the absence of hematopoietic stem and multipotential progenitor cells proliferation. Mechanistic studies revealed increased expressions of machrophage colony stimulating factor and granulocyte colony stimulating factor in splenic macrophage foam cells, driving BM monocyte and neutrophil production. These studies show that macrophage deficiency of ABCA1/G1 is proatherogenic likely by promoting plaque inflammation and uncover a novel positive feedback loop in which cholesterol-laden splenic macrophages signal BM progenitors to produce monocytes, with suppression by macrophage cholesterol efflux pathways.

Context-Dependent Role of Oxidized Lipids and Lipoproteins in Inflammation.

Science.gov (United States)

Miller, Yury I; Shyy, John Y-J

2017-02-01

Oxidized low-density lipoprotein (OxLDL), which contains hundreds of different oxidized lipid molecules, is a hallmark of hyperlipidemia and atherosclerosis. The same oxidized lipids found in OxLDL are also formed in apoptotic cells, and are present in tissues as well as in the circulation under pathological conditions. In many disease contexts, oxidized lipids constitute damage signals, or patterns, that activate pattern-recognition receptors (PRRs) and significantly contribute to inflammation. Here, we review recent discoveries and emerging trends in the field of oxidized lipids and the regulation of inflammation, focusing on oxidation products of polyunsaturated fatty acids esterified into cholesteryl esters (CEs) and phospholipids (PLs). We also highlight context-dependent activation and biased agonism of Toll-like receptor-4 (TLR4) and the NLRP3 inflammasome, among other signaling pathways activated by oxidized lipids. Copyright © 2016 Elsevier Ltd. All rights reserved.

β1-adrenergic receptor stimulation by agonist Compound 49b restores insulin receptor signal transduction in vivo

Science.gov (United States)

Jiang, Youde; Zhang, Qiuhua; Ye, Eun-Ah

2014-01-01

Purpose Determine whether Compound 49b treatment ameliorates retinal changes due to the lack of β2-adrenergic receptor signaling. Methods Using retinas from 3-month-old β2-adrenergic receptor-deficient mice, we treated mice with our novel β1-/β2-adrenergic receptor agonist, Compound 49b, to assess the effects of adrenergic agonists acting only on β1-adrenergic receptors due to the absence of β2-adrenergic receptors. Western blotting or enzyme-linked immunosorbent assay (ELISA) analyses were performed for β1- and β2-adrenergic receptors, as well as key insulin resistance proteins, including TNF-α, SOCS3, IRS-1Ser307, and IRTyr960. Analyses were also performed on key anti- and proapoptotic proteins: Akt, Bcl-xL, Bax, and caspase 3. Electroretinogram analyses were conducted to assess functional changes, while histological assessment was conducted for changes in retinal thickness. Results A 2-month treatment of β2-adrenergic receptor-deficient mice with daily eye drops of 1 mM Compound 49b, a novel β1- and β2-adrenergic receptor agonist, reversed the changes in insulin resistance markers (TNF-α and SOCS3) observed in untreated β2-adrenergic receptor-deficient mice, and concomitantly increased morphological integrity (retinal thickness) and functional responses (electroretinogram amplitude). These results suggest that stimulating β1-adrenergic receptors on retinal endothelial cells or Müller cells can compensate for the loss of β2-adrenergic receptor signaling on Müller cells, restore insulin signal transduction, reduce retinal apoptosis, and enhance retinal function. Conclusions Since our previous studies with β1-adrenergic receptor knockout mice confirmed that the reverse also occurs (β2-adrenergic receptor stimulation can compensate for the loss of β1-adrenergic receptor activity), it appears that increased activity in either of these pathways alone is sufficient to block insulin resistance–based retinal cell apoptosis. PMID:24966659

Vitamin C Deficiency Reduces Muscarinic Receptor Coronary Artery Vasoconstriction and Plasma Tetrahydrobiopterin Concentration in Guinea Pigs

Directory of Open Access Journals (Sweden)

Gry Freja Skovsted

2017-07-01

Full Text Available Vitamin C (vitC deficiency is associated with increased cardiovascular disease risk, but its specific interplay with arteriolar function is unclear. This study investigates the effect of vitC deficiency in guinea pigs on plasma biopterin status and the vasomotor responses in coronary arteries exposed to vasoconstrictor/-dilator agents. Dunkin Hartley female guinea pigs (n = 32 were randomized to high (1500 mg/kg diet or low (0 to 50 mg/kg diet vitC for 10–12 weeks. At euthanasia, coronary artery segments were dissected and mounted in a wire-myograph. Vasomotor responses to potassium, carbachol, sodium nitroprusside (SNP, U46619, sarafotoxin 6c (S6c and endothelin-1 (ET-1 were recorded. Plasma vitC and tetrahydrobiopterin were measured by HPLC. Plasma vitC status reflected the diets with deficient animals displaying reduced tetrahydrobiopterin. Vasoconstrictor responses to carbachol were significantly decreased in vitC deficient coronary arteries independent of their general vasoconstrictor/vasodilator capacity (p < 0.001. Moreover, in vitC deficient animals, carbachol-induced vasodilator responses correlated with coronary artery diameter (p < 0.001. Inhibition of cyclooxygenases with indomethacin increased carbachol-induced vasoconstriction, suggesting an augmented carbachol-induced release of vasodilator prostanoids. Atropine abolished carbachol-induced vasomotion, supporting a specific muscarinic receptor effect. Arterial responses to SNP, potassium, S6c, U46619 and ET-1 were unaffected by vitC status. The study shows that vitC deficiency decreases tetrahydrobiopterin concentrations and muscarinic receptor mediated contraction in coronary arteries. This attenuated vasoconstrictor response may be linked to altered production of vasoactive arachidonic acid metabolites and reduced muscarinic receptor expression/signaling.

Homozygous Familial Hypercholesterolemia Patients With Identical Mutations Variably Express the LDLR (Low-Density Lipoprotein Receptor): Implications for the Efficacy of Evolocumab.

Science.gov (United States)

Thedrez, Aurélie; Blom, Dirk J; Ramin-Mangata, Stéphane; Blanchard, Valentin; Croyal, Mikaël; Chemello, Kévin; Nativel, Brice; Pichelin, Matthieu; Cariou, Bertrand; Bourane, Steeve; Tang, Lihua; Farnier, Michel; Raal, Frederick J; Lambert, Gilles

2018-03-01

Evolocumab, a PCSK9 (proprotein convertase subtilisin kexin type 9)-neutralizing antibody, lowers low-density lipoprotein cholesterol (LDL-C) in homozygous familial hypercholesterolemic (HoFH) patients with reduced LDLR (low-density lipoprotein receptor) function. However, their individual responses are highly variable, even among carriers of identical LDLR genetic defects. We aimed to elucidate why HoFH patients variably respond to PCSK9 inhibition. Lymphocytes were isolated from 22 HoFH patients enrolled in the TAUSSIG trial (Trial Assessing Long Term Use of PCSK9 Inhibition in Subjects With Genetic LDL Disorders). Ten patients were true homozygotes (FH1/FH1) and 5 identical compound heterozygotes (FH1/FH2). Lymphocytes were plated with or without mevastatin, recombinant PCSK9 (rPCSK9), or a PCSK9-neutralizing antibody. Cell surface LDLR expression was analyzed by flow cytometry. All HoFH lymphocytes had reduced cell surface LDLR expression compared with non-FH lymphocytes, for each treatment modality. Lymphocytes from FH1/FH2 patients (LDLR defective/negative) displayed the lowest LDLR expression levels followed by lymphocytes from FH1/FH1 patients (defective/defective). Mevastatin increased, whereas rPCSK9 reduced LDLR expression. The PCSK9-neutralizing antibody restored LDLR expression. Lymphocytes displaying higher LDLR expression levels were those isolated from patients presenting with lowest levels of LDL-C and apolipoprotein B, before and after 24 weeks of evolocumab treatment. These negative correlations remained significant in FH1/FH1 patients and appeared more pronounced when patients with apolipoprotein E3/E3 genotypes were analyzed separately. Significant positive correlations were found between the levels of LDLR expression and the percentage reduction in LDL-C on evolocumab treatment. Residual LDLR expression in HoFH is a major determinant of LDL-C levels and seems to drive their individual response to evolocumab. © 2017 American Heart Association

Blood Lipoproteins under the Action of Exogenous Sex Steroids in the Postresuscitation Period

Directory of Open Access Journals (Sweden)

L. N. Shcherbakova

2011-01-01

dehydroepiandrosterone sulfate activation of the receptor transport of polyunsaturated fatty acids to the cells and that of reverse cholesterol outflow from the cell membranes in the resuscitated animals. Key words: cardiac arrest, reproductive steroids, blood lipoproteins, gynodian, postresuscitation period.

Scratching the surface: Regulation of cell surface receptors in cholesterol metabolism

NARCIS (Netherlands)

Nelson, J.K.

2016-01-01

Elevated plasma levels of low density lipoprotein cholesterol (LDL) are an established risk factor for the development of atherosclerosis and cardiovascular diseases. The LDL-Receptor is a key determinant in regulating LDL levels in plasma, and current lipid-lowering strategies aim to increase its

Effect of iron deficiency on the expression of insulin-like growth factor-II and its receptor in neuronal and glial cells.

Science.gov (United States)

Morales González, E; Contreras, I; Estrada, J A

2014-09-01

Many studies have demonstrated that iron deficiency modifies the normal function of the central nervous system and alters cognitive abilities. When cellular damage occurs in the central nervous system, neuroprotective mechanisms, such as the production of neurotrophic factors, are essential in order for nervous tissue to function correctly. Insulin-like growth factor II (IGF- II) is a neurotrophic factor that was recently shown to be involved in the normal functioning of cognitive processes in animal models. However, the impact of iron deficiency on the expression and function of this molecule has not yet been clarified. Mixed primary cell cultures from the central nervous system were collected to simulate iron deficiency using deferoxamine. The expression of IGF-I, IGF-II, IGF-IR, and IGF-IIR was determined with the western blot test. We observed increased expression of IGF-II, along with a corresponding decrease in the expression of IGF-IIR, in iron-deficient mixed primary cell cultures. We did not observe alterations in the expression of these proteins in isolated microglia or neuronal cultures under the same conditions. We did not detect differences in the expression of IGF-I and IGF-IR in iron-deficient cultures. In vitro iron deficiency increases the expression of IGF-II in mixed glial cell cultures, which may have a beneficial effect on brain tissue homeostasis in a situation in which iron availability is decreased. Copyright © 2013 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

Tandem mass spectrometry, but not T-cell receptor excision circle analysis, identifies newborns with late-onset adenosine deaminase deficiency.

Science.gov (United States)

la Marca, Giancarlo; Canessa, Clementina; Giocaliere, Elisa; Romano, Francesca; Duse, Marzia; Malvagia, Sabrina; Lippi, Francesca; Funghini, Silvia; Bianchi, Leila; Della Bona, Maria Luisa; Valleriani, Claudia; Ombrone, Daniela; Moriondo, Maria; Villanelli, Fabio; Speckmann, Carsten; Adams, Stuart; Gaspar, Bobby H; Hershfield, Michael; Santisteban, Ines; Fairbanks, Lynette; Ragusa, Giovanni; Resti, Massimo; de Martino, Maurizio; Guerrini, Renzo; Azzari, Chiara

2013-06-01

Adenosine deaminase (ADA)-severe combined immunodeficiency (SCID) is caused by genetic variants that disrupt the function of ADA. In its early-onset form, it is rapidly fatal to infants. Delayed or late-onset ADA-SCID is characterized by insidious progressive immunodeficiency that leads to permanent organ damage or death. Quantification of T-cell receptor excision circles (TRECs) or tandem mass spectrometry (tandem-MS) analysis of dried blood spots (DBSs) collected at birth can identify newborns with early-onset ADA-SCID and are used in screening programs. However, it is not clear whether these analyses can identify newborns who will have delayed or late-onset ADA-SCID before symptoms appear. We performed a retrospective study to evaluate whether tandem-MS and quantitative TREC analyses of DBSs could identify newborns who had delayed-onset ADA-SCID later in life. We tested stored DBSs collected at birth from 3 patients with delayed-onset ADA-SCID using tandem-MS (PCT EP2010/070517) to evaluate levels of adenosine and 2'-deoxyadenosine and real-time PCR to quantify TREC levels. We also analyzed DBSs from 3 newborns with early-onset ADA-SCID and 2 healthy newborn carriers of ADA deficiency. The DBSs taken at birth from the 3 patients with delayed-onset ADA-SCID had adenosine levels of 10, 25, and 19 μmol/L (normal value, <1.5 μmol/L) and 2'-deoxyadenosine levels of 0.7, 2.7, and 2.4 μmol/L (normal value, <0.07 μmol/L); the mean levels of adenosine and 2'-deoxyadenosine were respectively 12.0- and 27.6-fold higher than normal values. DBSs taken at birth from all 3 patients with delayed-onset ADA deficiency had normal TREC levels, but TRECs were undetectable in blood samples taken from the same patients at the time of diagnosis. Tandem-MS but not TREC quantification identifies newborns with delayed- or late-onset ADA deficiency. Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Gender-specific effects of endogenous testosterone: female alpha-estrogen receptor-deficient C57Bl/6J mice develop glomerulosclerosis.

Science.gov (United States)

Elliot, S J; Berho, M; Korach, K; Doublier, S; Lupia, E; Striker, G E; Karl, M

2007-08-01

Young female mice on a C57Bl/6J (B6) background are considered glomerulosclerosis (GS)-resistant but aging B6 mice develop mild GS. Estrogen deficiency accelerates while estrogen replacement retards GS in young sclerosis-prone oligosyndactyly mutant mice on an ROP background. To explore the effects of sex hormones on glomerular structure and function in the context of gender and genetic background, we studied mice in which the estrogen-receptor (ER) genes alpha- or -beta were deleted (alpha- or betaER knockout (KO)) and crossed into the B6 background. We also studied ovariectomized (Ovx) B6 mice given testosterone. Male and female betaERKO and male alphaERKO mice had no glomerular dysfunction at 9 months of age; however, alphaERKO female mice displayed albuminuria and GS. Ovx prevented glomerular dysfunction in alphaERKO female mice by eliminating endogenous testosterone production while exogenous testosterone induced GS in Ovx B6 mice. Androgen receptor (AR) expression and function was found in microdissected glomeruli and cultured mesangial cells. Testosterone compared to placebo increased both AR expression and TGF-beta1 mRNA levels in glomeruli isolated from female B6 mice. Estrogen deficiency had no deleterious effects on the glomeruli in B6 mice. Our study shows that genetic traits strongly influence the GS-promoting effects of estrogen deficiency while testosterone induces GS in a gender-specific manner.

Estrogen-related receptor α decreases RHOA stability to induce orientated cell migration.

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Sailland, Juliette; Tribollet, Violaine; Forcet, Christelle; Billon, Cyrielle; Barenton, Bruno; Carnesecchi, Julie; Bachmann, Alice; Gauthier, Karine Cécile; Yu, Shan; Giguère, Vincent; Chan, Franky L; Vanacker, Jean-Marc

2014-10-21

Several physiopathological processes require orientated cellular migration. This phenomenon highly depends on members of the RHO family of GTPases. Both excessive and deficient RHO activity impair directional migration. A tight control is thus exerted on these proteins through the regulation of their activation and of their stability. Here we show that the estrogen-related receptor α (ERRα) directly activates the expression of TNFAIP1, the product of which [BTB/POZ domain-containing adapter for Cullin3-mediated RhoA degradation 2 (BACURD2)] regulates RHOA protein turnover. Inactivation of the receptor leads to enhanced RHOA stability and activation. This results in cell disorientation, increased actin network, and inability to form a lamellipodium at the migration edge. As a consequence, directional migration, but not cell motility per se, is impaired in the absence of the receptor, under pathological as well as physiological conditions. Altogether, our results show that the control exerted by ERRα on RHOA stability is required for directional migration.

Conventional dendritic cells at the crossroads between immunity and cholesterol homeostasis in atherosclerosis.

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Gautier, Emmanuel L; Huby, Thierry; Saint-Charles, Flora; Ouzilleau, Betty; Pirault, John; Deswaerte, Virginie; Ginhoux, Florent; Miller, Elizabeth R; Witztum, Joseph L; Chapman, M John; Lesnik, Philippe

2009-05-05

Immunoinflammatory mechanisms are implicated in the atherogenic process. The polarization of the immune response and the nature of the immune cells involved, however, are major determinants of the net effect, which may be either proatherogenic or antiatherogenic. Dendritic cells (DCs) are central to the regulation of immunity, the polarization of the immune response, and the induction of tolerance to antigens. The potential role of DCs in atherosclerosis, however, remains to be defined. We created a mouse model in which the lifespan and immunogenicity of conventional DCs are enhanced by specific overexpression of the antiapoptotic gene hBcl-2 under the control of the CD11c promoter. When studied in either low-density lipoprotein receptor-deficient or apolipoprotein E-deficient backgrounds, DC-hBcl2 mice exhibited an expanded DC population associated with enhanced T-cell activation, a T-helper 1 and T-helper 17 cytokine expression profile, and elevated production of T-helper 1-driven IgG2c autoantibodies directed against oxidation-specific epitopes. This proatherogenic signature, however, was not associated with acceleration of atherosclerotic plaque progression, because expansion of the DC population was unexpectedly associated with an atheroprotective decrease in plasma cholesterol levels. Conversely, depletion of DCs in hyperlipidemic CD11c-diphtheria toxin receptor/apolipoprotein E-deficient transgenic mice resulted in enhanced cholesterolemia, thereby arguing for a close relationship between the DC population and plasma cholesterol levels. Considered together, the present data reveal that conventional DCs are central to the atherosclerotic process, because they are directly implicated in both cholesterol homeostasis and the immune response.

Macrophage Liver Kinase B1 Inhibits Foam Cell Formation and Atherosclerosis.

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Liu, Zhaoyu; Zhu, Huaiping; Dai, Xiaoyan; Wang, Cheng; Ding, Ye; Song, Ping; Zou, Ming-Hui

2017-10-13

LKB1 (liver kinase B1) is a serine/threonine kinase and tumor suppressor, which regulates the homeostasis of hematopoietic cells and immune responses. Macrophages transform into foam cells upon taking-in lipids. No role for LKB1 in foam cell formation has previously been reported. We sought to establish the role of LKB1 in atherosclerotic foam cell formation. LKB1 expression was examined in human carotid atherosclerotic plaques and in western diet-fed atherosclerosis-prone Ldlr -/- and ApoE -/- mice. LKB1 expression was markedly reduced in human plaques when compared with nonatherosclerotic vessels. Consistently, time-dependent reduction of LKB1 levels occurred in atherosclerotic lesions in western diet-fed Ldlr -/- and ApoE -/- mice. Exposure of macrophages to oxidized low-density lipoprotein downregulated LKB1 in vitro. Furthermore, LKB1 deficiency in macrophages significantly increased the expression of SRA (scavenger receptor A), modified low-density lipoprotein uptake and foam cell formation, all of which were abolished by blocking SRA. Further, we found LKB1 phosphorylates SRA resulting in its lysosome degradation. To further investigate the role of macrophage LKB1 in vivo, ApoE -/- LKB1 fl/fl LysM cre and ApoE -/- LKB1 fl/fl mice were fed with western diet for 16 weeks. Compared with ApoE -/- LKB1 fl/fl wild-type control, ApoE -/- LKB1 fl/fl LysM cre mice developed more atherosclerotic lesions in whole aorta and aortic root area, with markedly increased SRA expression in aortic root lesions. We conclude that macrophage LKB1 reduction caused by oxidized low-density lipoprotein promotes foam cell formation and the progression of atherosclerosis. © 2017 American Heart Association, Inc.

MCP-1/CCR-2-double-deficiency severely impairs the migration of hematogenous inflammatory cells following transient cerebral ischemia in mice.

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Schuette-Nuetgen, Katharina; Strecker, Jan-Kolja; Minnerup, Jens; Ringelstein, E Bernd; Schilling, Matthias

2012-02-01

Monocyte chemoattractant protein-1 (MCP-1) and its receptor CCR-2 are known to play a major role in inflammatory responses after cerebral ischemia. Mice deficient in either MCP-1 or CCR-2 have been reported to develop smaller infarct sizes and show decreased numbers of infiltrating inflammatory cells. In the present study we used green fluorescent protein (GFP) transgenic mice to investigate the effect of MCP-1/CCR-2-double deficiency on the recruitment of inflammatory cells in a model of both, mild and severe cerebral ischemia. We show that MCP-1/CCR-2-double deficiency virtually entirely abrogates the recruitment of hematogenous macrophages and significantly reduces neutrophil migration to the ischemic brain 4 and 7 days following focal cerebral ischemia. This argues for a predominant role of the MCP-1/CCR-2 axis in chemotaxis of monocytes despite a wide redundancy in the chemokine-receptor-system. Chemokine analysis revealed that even candidates known to be involved in monocyte and neutrophil recruitment like MIP-1α, CXCL-1, C5a, G-CSF and GM-CSF showed a reduced and delayed or even a lack of relevant compensatory response in MCP-1(-/-)/CCR-2(-/-)-mice. Solely, chemokine receptor 5 (CCR-5) increased early in both, but rose above wildtype levels at day 7 in MCP-1(-/-)/CCR-2(-/-)-animals, which might explain the higher number of activated microglial cells compared to control mice. Our study was, however, not powered to investigate infarct volumes. Further studies are needed to clarify whether these mechanisms of inflammatory cell recruitment might be essential for early infarct development and final infarct size and to evaluate potential therapeutic implications. Copyright © 2011 Elsevier Inc. All rights reserved.

Genetic spectrum of low density lipoprotein receptor gene variations in South Indian population.

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ArulJothi, K N; Suruthi Abirami, B; Devi, Arikketh

2018-03-01

Low density lipoprotein receptor (LDLR) is a membrane bound receptor maintaining cholesterol homeostasis along with Apolipoprotein B (APOB), Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) and other genes of lipid metabolism. Any pathogenic variation in these genes alters the function of the receptor and leads to Familial Hypercholesterolemia (FH) and other cardiovascular diseases. This study was aimed at screening the LDLR, APOB and PCSK9 genes in Hypercholesterolemic patients to define the genetic spectrum of FH in Indian population. Familial Hypercholesterolemia patients (n=78) of South Indian Tamil population with LDL cholesterol and Total cholesterol levels above 4.9mmol/l and 7.5mmol/l with family history of Myocardial infarction were involved. DNA was isolated by organic extraction method from blood samples and LDLR, APOB and PCSK9 gene exons were amplified using primers that cover exon-intron boundaries. The amplicons were screened using High Resolution Melt (HRM) Analysis and the screened samples were sequenced after purification. This study reports 20 variations in South Indian population for the first time. In this set of variations 9 are novel variations which are reported for the first time, 11 were reported in other studies also. The in silico analysis for all the variations detected in this study were done to predict the probabilistic effect in pathogenicity of FH. This study adds 9 novel variations and 11 recurrent variations to the spectrum of LDLR gene mutations in Indian population. All these variations are reported for the first time in Indian population. This spectrum of variations was different from the variations of previous Indian reports. Copyright © 2017 Elsevier B.V. All rights reserved.

p75 Neurotrophin Receptor Signaling Activates Sterol Regulatory Element-binding Protein-2 in Hepatocyte Cells via p38 Mitogen-activated Protein Kinase and Caspase-3.

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Pham, Dan Duc; Do, Hai Thi; Bruelle, Céline; Kukkonen, Jyrki P; Eriksson, Ove; Mogollón, Isabel; Korhonen, Laura T; Arumäe, Urmas; Lindholm, Dan

2016-05-13

Nerve growth factor (NGF) influences the survival and differentiation of a specific population of neurons during development, but its role in non-neuronal cells has been less studied. We observed here that NGF and its pro-form, pro-NGF, are elevated in fatty livers from leptin-deficient mice compared with controls, concomitant with an increase in low density lipoprotein receptors (LDLRs). Stimulation of mouse primary hepatocytes with NGF or pro-NGF increased LDLR expression through the p75 neurotrophin receptor (p75NTR). Studies using Huh7 human hepatocyte cells showed that the neurotrophins activate the sterol regulatory element-binding protein-2 (SREBP2) that regulates genes involved in lipid metabolism. The mechanisms for this were related to stimulation of p38 mitogen-activated protein kinase (p38 MAPK) and activation of caspase-3 and SREBP2 cleavage following NGF and pro-NGF stimulations. Cell fractionation experiments showed that caspase-3 activity was increased particularly in the membrane fraction that harbors SREBP2 and caspase-2. Experiments showed further that caspase-2 interacts with pro-caspase-3 and that p38 MAPK reduced this interaction and caused caspase-3 activation. Because of the increased caspase-3 activity, the cells did not undergo cell death following p75NTR stimulation, possibly due to concomitant activation of nuclear factor-κB (NF-κB) pathway by the neurotrophins. These results identify a novel signaling pathway triggered by ligand-activated p75NTR that via p38 MAPK and caspase-3 mediate the activation of SREBP2. This pathway may regulate LDLRs and lipid uptake particularly after injury or during tissue inflammation accompanied by an increased production of growth factors, including NGF and pro-NGF. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Lipoprotein(a Induces Human Aortic Valve Interstitial Cell Calcification

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Bin Yu, PhD

2017-08-01

Full Text Available Lipoprotein(a, or Lp(a, significantly increased alkaline phosphatase activity, release of phosphate, calcium deposition, hydroxyapatite, cell apoptosis, matrix vesicle formation, and phosphorylation of signal transduction proteins; increased expression of chondro-osteogenic mediators; and decreased SOX9 and matrix Gla protein (p < 0.001. Inhibition of MAPK38 and GSK3β significantly reduced Lp(a-induced calcification of human aortic valve interstitial cells (p < 0.001. There was abundant presence of Lp(a and E06 immunoreactivity in diseased human aortic valves. The present study demonstrates a causal effect for Lp(a in aortic valve calcification and suggests that interfering with the Lp(apathway could provide a novel therapeutic approach in the management of this debilitating disease.

Macrophage specific overexpression of the human macrophage scavenger receptor in transgenic mice, using a 180-kb yeast artificial chromosome, leads to enhanced foam cell formation of isolated peritoneal macrophages

NARCIS (Netherlands)

de Winther, M. P.; van Dijk, K. W.; van Vlijmen, B. J.; Gijbels, M. J.; Heus, J. J.; Wijers, E. R.; van den Bos, A. C.; Breuer, M.; Frants, R. R.; Havekes, L. M.; Hofker, M. H.

1999-01-01

Macrophage scavenger receptors class A (MSR) are thought to play an important role in atherogenesis by mediating the unrestricted uptake of modified lipoproteins by macrophages in the vessel wall leading to foam cell formation. To investigate the in vivo role of the MSR in this process, a transgenic

BMI-1 Mediates Estrogen-Deficiency-Induced Bone Loss by Inhibiting Reactive Oxygen Species Accumulation and T Cell Activation.

Science.gov (United States)

Li, Jinbo; Wang, Qian; Yang, Renlei; Zhang, Jiaqi; Li, Xing; Zhou, Xichao; Miao, Dengshun

2017-05-01

Previous studies have shown that estrogen regulates bone homeostasis through regulatory effects on oxidative stress. However, it is unclear how estrogen deficiency triggers reactive oxygen species (ROS) accumulation. Recent studies provide evidence that the B lymphoma Mo-MLV insertion region 1 (BMI-1) plays a critical role in protection against oxidative stress and that this gene is directly regulated by estrogen via estrogen receptor (ER) at the transcriptional level. In this study, ovariectomized mice were given drinking water with/without antioxidant N-acetyl-cysteine (NAC, 1 mg/mL) supplementation, and compared with each other and with sham mice. Results showed that ovariectomy resulted in bone loss with increased osteoclast surface, increased ROS levels, T cell activation, and increased TNF and RANKL levels in serum and in CD4 T cells; NAC supplementation largely prevented these alterations. BMI-1 expression levels were dramatically downregulated in CD4 T cells from ovariectomized mice. We supplemented drinking water to BMI-1-deficient mice with/without NAC and compared them with each other and with wild-type (WT) mice. We found that BMI-1 deficiency mimicked alterations observed in ovariectomy whereas NAC supplementation reversed all alterations induced by BMI-1 deficiency. Because T cells are critical in mediating ovariectomy-induced bone loss, we further assessed whether BMI-1 overexpression in lymphocytes can protect against estrogen deficiency-induced osteoclastogenesis and bone loss by inhibiting oxidative stress, T cell activation, and RANKL production. When WT and Eμ-BMI-1 transgenic mice with BMI-1 specifically overexpressed in lymphocytes were ovariectomized and compared with each other and with WT sham mice, we found that BMI-1 overexpression in lymphocytes clearly reversed all alterations induced by ovariectomy. Results from this study indicate that estrogen deficiency downregulates BMI-1 and subsequently increases ROS, T cell activation, and

The role of CCK2 receptors in energy homeostasis: insights from the CCK2 receptor-deficient mouse.

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Weiland, Tracey J; Voudouris, Nicholas J; Kent, Stephen

2004-09-15

The present study explored the contribution of type 2 cholecystokinin (CCK) receptors in energy regulation. A total of 78 CCK2 receptor-deficient mice and 80 wild-type controls were acclimated to a 12:12 light-dark cycle at 30 +/- 1 degrees C. Using a computer-monitored biotelemetry system, circadian patterns of body temperature, food intake, and activity were monitored for 4 days. Body weight and water consumption were manually recorded during this period. Results indicate that CCK2 receptor invalidation produces elevated body temperature during both the photophase and scotophase (by 0.38 and 0.12 degrees C, respectively), increased body weight (29.3 +/- 0.2 vs. 26.8 +/- 0.2 g) and water consumption (4.1 +/- 0.1 vs. 3.2 +/- 0.1 ml), and decreased scotophase locomotor activity (WT: 7.0 +/- 0.2 vs. KO: 6.1 +/- 0.2 counts/min). These findings suggest an important role for CCK2 receptors in processes underlying energy regulation during basal and possibly pathological states.

The Murine Natural Cytotoxic Receptor NKp46/NCR1 Controls TRAIL Protein Expression in NK Cells and ILC1s

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Sam Sheppard

2018-03-01

Full Text Available Summary: TRAIL is an apoptosis-inducing ligand constitutively expressed on liver-resident type 1 innate lymphoid cells (ILC1s and a subset of natural killer (NK cells, where it contributes to NK cell anti-tumor, anti-viral, and immunoregulatory functions. However, the intrinsic pathways involved in TRAIL expression in ILCs remain unclear. Here, we demonstrate that the murine natural cytotoxic receptor mNKp46/NCR1, expressed on ILC1s and NK cells, controls TRAIL protein expression. Using NKp46-deficient mice, we show that ILC1s lack constitutive expression of TRAIL protein and that NK cells activated in vitro and in vivo fail to upregulate cell surface TRAIL in the absence of NKp46. We show that NKp46 regulates TRAIL expression in a dose-dependent manner and that the reintroduction of NKp46 in mature NK cells deficient for NKp46 is sufficient to restore TRAIL surface expression. These studies uncover a link between NKp46 and TRAIL expression in ILCs with potential implications in pathologies involving NKp46-expressing cells. : Sheppard et al. find that mice deficient in the activating receptor NCR1/NKp46 (Ncr1−/− fail to express the apoptosis-inducing ligand TRAIL at the surface of group 1 innate lymphoid cells (ILC1s. Keywords: NK cell, natural killer cell, NKp46, ILC1, TRAIL, IL-15, IL-2

Analysis of a two-domain binding site for the urokinase-type plasminogen activator-plasminogen activator inhibitor-1 complex in low-density-lipoprotein-receptor-related protein.

Science.gov (United States)

Andersen, O M; Petersen, H H; Jacobsen, C; Moestrup, S K; Etzerodt, M; Andreasen, P A; Thøgersen, H C

2001-07-01

The low-density-lipoprotein-receptor (LDLR)-related protein (LRP) is composed of several classes of domains, including complement-type repeats (CR), which occur in clusters that contain binding sites for a multitude of different ligands. Each approximately 40-residue CR domain contains three conserved disulphide linkages and an octahedral Ca(2+) cage. LRP is a scavenging receptor for ligands from extracellular fluids, e.g. alpha(2)-macroglobulin (alpha(2)M)-proteinase complexes, lipoprotein-containing particles and serine proteinase-inhibitor complexes, like the complex between urokinase-type plasminogen activator (uPA) and the plasminogen activator inhibitor-1 (PAI-1). In the present study we analysed the interaction of the uPA-PAI-1 complex with an ensemble of fragments representing a complete overlapping set of two-domain fragments accounting for the ligand-binding cluster II (CR3-CR10) of LRP. By ligand blotting, solid-state competition analysis and surface-plasmon-resonance analysis, we demonstrate binding to multiple CR domains, but show a preferential interaction between the uPA-PAI-1 complex and a two-domain fragment comprising CR domains 5 and 6 of LRP. We demonstrate that surface-exposed aspartic acid and tryptophan residues at identical positions in the two homologous domains, CR5 and CR6 (Asp(958,CR5), Asp(999,CR6), Trp(953,CR5) and Trp(994,CR6)), are critical for the binding of the complex as well as for the binding of the receptor-associated protein (RAP) - the folding chaperone/escort protein required for transport of LRP to the cell surface. Accordingly, the present work provides (1) an identification of a preferred binding site within LRP CR cluster II; (2) evidence that the uPA-PAI-1 binding site involves residues from two adjacent protein domains; and (3) direct evidence identifying specific residues as important for the binding of uPA-PAI-1 as well as for the binding of RAP.

Colistin-Resistant, Lipopolysaccharide-Deficient Acinetobacter baumannii Responds to Lipopolysaccharide Loss through Increased Expression of Genes Involved in the Synthesis and Transport of Lipoproteins, Phospholipids, and Poly-β-1,6-N-Acetylglucosamine

Science.gov (United States)

Henry, Rebekah; Vithanage, Nuwan; Harrison, Paul; Seemann, Torsten; Coutts, Scott; Moffatt, Jennifer H.; Nation, Roger L.; Li, Jian; Harper, Marina; Adler, Ben

2012-01-01

We recently demonstrated that colistin resistance in Acinetobacter baumannii can result from mutational inactivation of genes essential for lipid A biosynthesis (Moffatt JH, et al., Antimicrob. Agents Chemother. 54:4971–4977). Consequently, strains harboring these mutations are unable to produce the major Gram-negative bacterial surface component, lipopolysaccharide (LPS). To understand how A. baumannii compensates for the lack of LPS, we compared the transcriptional profile of the A. baumannii type strain ATCC 19606 to that of an isogenic, LPS-deficient, lpxA mutant strain. The analysis of the expression profiles indicated that the LPS-deficient strain showed increased expression of many genes involved in cell envelope and membrane biogenesis. In particular, upregulated genes included those involved in the Lol lipoprotein transport system and the Mla-retrograde phospholipid transport system. In addition, genes involved in the synthesis and transport of poly-β-1,6-N-acetylglucosamine (PNAG) also were upregulated, and a corresponding increase in PNAG production was observed. The LPS-deficient strain also exhibited the reduced expression of genes predicted to encode the fimbrial subunit FimA and a type VI secretion system (T6SS). The reduced expression of genes involved in T6SS correlated with the detection of the T6SS-effector protein AssC in culture supernatants of the A. baumannii wild-type strain but not in the LPS-deficient strain. Taken together, these data show that, in response to total LPS loss, A. baumannii alters the expression of critical transport and biosynthesis systems associated with modulating the composition and structure of the bacterial surface. PMID:22024825

Colistin-resistant, lipopolysaccharide-deficient Acinetobacter baumannii responds to lipopolysaccharide loss through increased expression of genes involved in the synthesis and transport of lipoproteins, phospholipids, and poly-β-1,6-N-acetylglucosamine.

Science.gov (United States)

Henry, Rebekah; Vithanage, Nuwan; Harrison, Paul; Seemann, Torsten; Coutts, Scott; Moffatt, Jennifer H; Nation, Roger L; Li, Jian; Harper, Marina; Adler, Ben; Boyce, John D

2012-01-01

We recently demonstrated that colistin resistance in Acinetobacter baumannii can result from mutational inactivation of genes essential for lipid A biosynthesis (Moffatt JH, et al., Antimicrob. Agents Chemother. 54:4971-4977). Consequently, strains harboring these mutations are unable to produce the major Gram-negative bacterial surface component, lipopolysaccharide (LPS). To understand how A. baumannii compensates for the lack of LPS, we compared the transcriptional profile of the A. baumannii type strain ATCC 19606 to that of an isogenic, LPS-deficient, lpxA mutant strain. The analysis of the expression profiles indicated that the LPS-deficient strain showed increased expression of many genes involved in cell envelope and membrane biogenesis. In particular, upregulated genes included those involved in the Lol lipoprotein transport system and the Mla-retrograde phospholipid transport system. In addition, genes involved in the synthesis and transport of poly-β-1,6-N-acetylglucosamine (PNAG) also were upregulated, and a corresponding increase in PNAG production was observed. The LPS-deficient strain also exhibited the reduced expression of genes predicted to encode the fimbrial subunit FimA and a type VI secretion system (T6SS). The reduced expression of genes involved in T6SS correlated with the detection of the T6SS-effector protein AssC in culture supernatants of the A. baumannii wild-type strain but not in the LPS-deficient strain. Taken together, these data show that, in response to total LPS loss, A. baumannii alters the expression of critical transport and biosynthesis systems associated with modulating the composition and structure of the bacterial surface.

Pineal germinoma in a child with interferon-γ receptor 1 deficiency. case report and literature review.

Science.gov (United States)

Taramasso, L; Boisson-Dupuis, S; Garrè, M L; Bondi, E; Cama, A; Nozza, P; Morana, G; Casanova, J L; Marazzi, M G

2014-11-01

Interferon-γ receptor 1 (IFN-γR1) deficiency is one of the primary immunodeficiencies conferring Mendelian Susceptibility to Mycobacterial Disease (MSMD). Some cases of neoplasms have been recently reported in patients with MSMD, underlying the already known link between immunodeficiency and carcinogenesis. We report the first case of intracranial tumour, i.e. pineal germinoma, in a 11-year-old patient with complete IFN-γR1 deficiency. The first clinical presentation of the genetic immunodeficiency dates back to when the child was aged 2 y and 10 mo, when he presented a multi-focal osteomyelitis caused by Mycobacterium scrofulaceum. The diagnosis of IFN-γR1 deficiency (523delT/523delT in IFNGR1 gene) was subsequently made. The child responded to antibiotic therapy and remained in stable clinical condition until the age of 11 years, when he started complaining of frontal, chronic headache. MRI revealed a solid pineal region mass lesion measuring 20 × 29 × 36 mm. Histological findings revealed a diagnosis of pineal germinoma. The patient received chemotherapy followed by local whole ventricular irradiation with boost on pineal site, experiencing complete remission, and to date he is tumor-free at four years follow-up. Four other cases of tumors have been reported in patients affected by MSMD in our knowledge: a case of Kaposi sarcoma, a case of B-cell lymphoma, a case of cutaneous squamous cell carcinoma and a case of oesophageal squamous cell carcinoma. In conclusion, in patients with MSMD, not only the surveillance of infectious diseases, but also that of tumors is important.

The Syk protein tyrosine kinase can function independently of CD45 or Lck in T cell antigen receptor signaling

NARCIS (Netherlands)

Chu, D. H.; Spits, H.; Peyron, J. F.; Rowley, R. B.; Bolen, J. B.; Weiss, A.

1996-01-01

The protein tyrosine phosphatase CD45 is a critical component of the T cell antigen receptor (TCR) signaling pathway, acting as a positive regulator of Src family protein tyrosine kinases (PTKs) such as Lck. Most CD45-deficient human and murine T cell lines are unable to signal through their TCRs.

Osbpl8 deficiency in mouse causes an elevation of high-density lipoproteins and gender-specific alterations of lipid metabolism.

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Olivier Béaslas

Full Text Available OSBP-related protein 8 (ORP8 encoded by Osbpl8 is an endoplasmic reticulum sterol sensor implicated in cellular lipid metabolism. We generated an Osbpl8(-/- (KO C57Bl/6 mouse strain. Wild-type and Osbpl8KO animals at the age of 13-weeks were fed for 5 weeks either chow or high-fat diet, and their plasma lipids/lipoproteins and hepatic lipids were analyzed. The chow-fed Osbpl8KO male mice showed a marked elevation of high-density lipoprotein (HDL cholesterol (+79% and phospholipids (+35%, while only minor increase of apolipoprotein A-I (apoA-I was detected. In chow-fed female KO mice a less prominent increase of HDL cholesterol (+27% was observed, while on western diet the HDL increment was prominent in both genders. The HDL increase was accompanied by an elevated level of HDL-associated apolipoprotein E in male, but not female KO animals. No differences between genotypes were observed in lecithin:cholesterol acyltransferase (LCAT or hepatic lipase (HL activity, or in the fractional catabolic rate of fluorescently labeled mouse HDL injected in chow-diet fed animals. The Osbpl8KO mice of both genders displayed reduced phospholipid transfer protein (PLTP activity, but only on chow diet. These findings are consistent with a model in which Osbpl8 deficiency results in altered biosynthesis of HDL. Consistent with this hypothesis, ORP8 depleted mouse hepatocytes secreted an increased amount of nascent HDL into the culture medium. In addition to the HDL phenotype, distinct gender-specific alterations in lipid metabolism were detected: Female KO animals on chow diet showed reduced lipoprotein lipase (LPL activity and increased plasma triglycerides, while the male KO mice displayed elevated plasma cholesterol biosynthetic markers cholestenol, desmosterol, and lathosterol. Moreover, modest gender-specific alterations in the hepatic expression of lipid homeostatic genes were observed. In conclusion, we report the first viable OsbplKO mouse model

Human placenta secretes apolipoprotein B-100-containing lipoproteins

DEFF Research Database (Denmark)

Munk-Madsen, Eva; Lindegaard, Marie Louise Skakkebæk; Andersen, Claus B

2004-01-01

Supply of lipids from the mother is essential for fetal growth and development. In mice, disruption of yolk sac cell secretion of apolipoprotein (apo) B-containing lipoproteins results in embryonic lethality. In humans, the yolk sac is vestigial. Nutritional functions are instead established very...... lipoproteins secreted from placental tissue showed spherical particles with a diameter of 47 +/- 10 nm. These results demonstrate that human placenta expresses both apoB and MTP and consequently synthesize and secrete apoB-100-containing lipoproteins. Placental lipoprotein formation constitutes a novel pathway...

Staphylococcus aureus Lpl Lipoproteins Delay G2/M Phase Transition in HeLa Cells.

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Nguyen, Minh-Thu; Deplanche, Martine; Nega, Mulugeta; Le Loir, Yves; Peisl, Loulou; Götz, Friedrich; Berkova, Nadia

2016-01-01

The cell cycle is an ordered set of events, leading to cell growth and division into two daughter cells. The eukaryotic cell cycle consists of interphase (G 1 , S, and G 2 phases), followed by the mitotic phase and G 0 phase. Many bacterial pathogens secrete cyclomodulins that interfere with the host cell cycle. In Staphylococcus aureus four cyclomodulins have been described so far that all represent toxins and are secreted into the culture supernatant. Here we show that the membrane-anchored lipoprotein-like proteins (Lpl), encoded on a genomic island called νSaα, interact with the cell cycle of HeLa cells. By comparing wild type and lpl deletion mutant it turned out that the lpl cluster is causative for the G2/M phase transition delay and also contributes to increased invasion frequency. The lipoprotein Lpl1, a representative of the lpl cluster, also caused G2/M phase transition delay. Interestingly, the lipid modification, which is essential for TLR2 signaling and activation of the immune system, is not necessary for cyclomodulin activity. Unlike the other staphylococcal cyclomodulins Lpl1 shows no cytotoxicity even at high concentrations. As all Lpl proteins are highly conserved there might be a common function that is accentuated by their multiplicity in a tandem gene cluster. The cell surface localized Lpls' suggests a correlation between G2/M phase transition delay and host cell invasion.

The fibrate drug gemfibrozil disrupts lipoprotein metabolism in rainbow trout

International Nuclear Information System (INIS)

Prindiville, John S.; Mennigen, Jan A.; Zamora, Jake M.; Moon, Thomas W.; Weber, Jean-Michel

2011-01-01

Gemfibrozil (GEM) is a fibrate drug consistently found in effluents from sewage treatment plants. This study characterizes the pharmacological effects of GEM on the plasma lipoproteins of rainbow trout (Oncorhynchus mykiss). Our goals were to quantify the impact of the drug on: 1) lipid constituents of lipoproteins (phospholipids (PL), triacylglycerol (TAG), and cholesterol), 2) lipoprotein classes (high, low and very low density lipoproteins), and 3) fatty acid composition of lipoproteins. Potential mechanisms of GEM action were investigated by measuring lipoprotein lipase activity (LPL) and the hepatic gene expression of LPL and of the peroxisome proliferator-activated receptor (PPAR) α, β, and γ isoforms. GEM treatment resulted in decreased plasma lipoprotein levels (- 29%) and a reduced size of all lipoprotein classes (lower PL:TAG ratios). However, the increase in HDL-cholesterol elicited by GEM in humans failed to be observed in trout. Therefore, HDL-cholesterol cannot be used to assess the impact of the drug on fish. GEM also modified lipoprotein composition by reducing the abundance of long-chain n-3 fatty acids, thereby potentially reducing the nutritional quality of exposed fish. The relative gene expression of LPL was increased, but the activity of the enzyme was not, and we found no evidence for the activation of PPAR pathways. The depressing effects of GEM on fish lipoproteins demonstrated here may be a concern in view of the widespread presence of fibrates in aquatic environments. Work is needed to test whether exposure to environmental concentrations of these drugs jeopardizes the capacity of fish for reproduction, temperature acclimation or migratory behaviors.

Farnesoid X receptor up-regulates expression of Lipid transfer inhibitor protein in liver cells and mice

Energy Technology Data Exchange (ETDEWEB)

Li, Liangpeng [Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Third Military Medical University, Chongqing 400038 (China); Liu, Hong [Department of Hematology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037 (China); Peng, Jiahe; Wang, Yongchao; Zhang, Yan; Dong, Jinyu; Liu, Xiaohua; Guo, Dongmei [Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Third Military Medical University, Chongqing 400038 (China); Jiang, Yu, E-mail: yujiang61@gmail.com [Department of Biochemistry and Molecular Biology, College of Basic Medical Science, Third Military Medical University, Chongqing 400038 (China)

2013-11-29

Highlights: •FXR up-regulates apoF. •It binds to ER1 element. •It activates apoF gene promoter. -- Abstract: Apolipoprotein F is a component protein mainly secreted by liver and resides on several lipoprotein classes. It can inhibit lipids transfer between different lipoproteins. FXR is a member of the nuclear receptor superfamily which is also highly expressed in the liver. It modulates bile acids synthesis and lipids metabolism by transcriptional regulation. We aimed to determine whether apoF can be regulated by FXR. The FXR agonist Chenodeoxycholic acid (CDCA) and GW4064 both can activate the expression of apoF in liver cell lines and in C57/BL6 mouse liver. This is dependent on the binding of FXR to the FXR element ER1 (−2904 to −2892 bp) in the apoF gene promoter. Taken together, we have identified apoF as likely another target gene of FXR.

Sorting of bacterial lipoproteins to the outer membrane by the Lol system.

Science.gov (United States)

Narita, Shin-ichiro; Tokuda, Hajime

2010-01-01

Bacterial lipoproteins comprise a subset of membrane proteins with a lipid-modified cysteine residue at their amino termini through which they are anchored to the membrane. In Gram-negative bacteria, lipoproteins are localized on either the inner or the outer membrane. The Lol system is responsible for the transport of lipoproteins to the outer membrane.The Lol system comprises an inner-membrane ABC transporter LolCDE complex, a periplasmic carrier protein, LolA, and an outer membrane receptor protein, LolB. Lipoproteins are synthesized as precursors in the cytosol and then translocated across the inner membrane by the Sec translocon to the outer leaflet of the inner membrane, where lipoprotein precursors are processed to mature lipoproteins. The LolCDE complex then mediates the release of outer membrane-specific lipoproteins from the inner membrane while the inner membrane-specific lipoproteins possessing Asp at position 2 are not released by LolCDE because it functions as a LolCDE avoidance signal, causing the retention of these lipoproteins in the inner membrane. A water-soluble lipoprotein-LolA complex is formed as a result of the release reaction mediated by LolCDE. This complex traverses the hydrophilic periplasm to reach the outer membrane, where LolB accepts a lipoprotein from LolA and then catalyzes its incorporation into the inner leaflet of the outer membrane.

Mesenchymal Stem Cell-Derived Factors Restore Function to Human Frataxin-Deficient Cells.

Science.gov (United States)

Kemp, Kevin; Dey, Rimi; Cook, Amelia; Scolding, Neil; Wilkins, Alastair

2017-08-01

Friedreich's ataxia is an inherited neurological disorder characterised by mitochondrial dysfunction and increased susceptibility to oxidative stress. At present, no therapy has been shown to reduce disease progression. Strategies being trialled to treat Friedreich's ataxia include drugs that improve mitochondrial function and reduce oxidative injury. In addition, stem cells have been investigated as a potential therapeutic approach. We have used siRNA-induced knockdown of frataxin in SH-SY5Y cells as an in vitro cellular model for Friedreich's ataxia. Knockdown of frataxin protein expression to levels detected in patients with the disorder was achieved, leading to decreased cellular viability, increased susceptibility to hydrogen peroxide-induced oxidative stress, dysregulation of key anti-oxidant molecules and deficiencies in both cell proliferation and differentiation. Bone marrow stem cells are being investigated extensively as potential treatments for a wide range of neurological disorders, including Friedreich's ataxia. The potential neuroprotective effects of bone marrow-derived mesenchymal stem cells were therefore studied using our frataxin-deficient cell model. Soluble factors secreted by mesenchymal stem cells protected against cellular changes induced by frataxin deficiency, leading to restoration in frataxin levels and anti-oxidant defences, improved survival against oxidative stress and stimulated both cell proliferation and differentiation down the Schwann cell lineage. The demonstration that mesenchymal stem cell-derived factors can restore cellular homeostasis and function to frataxin-deficient cells further suggests that they may have potential therapeutic benefits for patients with Friedreich's ataxia.

Adipocyte Glucocorticoid Receptor Deficiency Attenuates Aging- and HFD-Induced Obesity and Impairs the Feeding-Fasting Transition.

Science.gov (United States)

Mueller, Kristina M; Hartmann, Kerstin; Kaltenecker, Doris; Vettorazzi, Sabine; Bauer, Mandy; Mauser, Lea; Amann, Sabine; Jall, Sigrid; Fischer, Katrin; Esterbauer, Harald; Müller, Timo D; Tschöp, Matthias H; Magnes, Christoph; Haybaeck, Johannes; Scherer, Thomas; Bordag, Natalie; Tuckermann, Jan P; Moriggl, Richard

2017-02-01

Glucocorticoids (GCs) are important regulators of systemic energy metabolism, and aberrant GC action is linked to metabolic dysfunctions. Yet, the extent to which normal and pathophysiological energy metabolism depend on the GC receptor (GR) in adipocytes remains unclear. Here, we demonstrate that adipocyte GR deficiency in mice significantly impacts systemic metabolism in different energetic states. Plasma metabolomics and biochemical analyses revealed a marked global effect of GR deficiency on systemic metabolite abundance and, thus, substrate partitioning in fed and fasted states. This correlated with a decreased lipolytic capacity of GR-deficient adipocytes under postabsorptive and fasting conditions, resulting from impaired signal transduction from β-adrenergic receptors to adenylate cyclase. Upon prolonged fasting, the impaired lipolytic response resulted in abnormal substrate utilization and lean mass wasting. Conversely, GR deficiency attenuated aging-/diet-associated obesity, adipocyte hypertrophy, and liver steatosis. Systemic glucose tolerance was improved in obese GR-deficient mice, which was associated with increased insulin signaling in muscle and adipose tissue. We conclude that the GR in adipocytes exerts central but diverging roles in the regulation of metabolic homeostasis depending on the energetic state. The adipocyte GR is indispensable for the feeding-fasting transition but also promotes adiposity and associated metabolic disorders in fat-fed and aged mice. © 2017 by the American Diabetes Association.

The biology of PCSK9 from the endoplasmic reticulum to lysosomes: new and emerging therapeutics to control low-density lipoprotein cholesterol

Directory of Open Access Journals (Sweden)

Poirier S

2013-10-01

Full Text Available Steve Poirier,1,2 Gaétan Mayer1–31Laboratory of Molecular Cell Biology, Montreal Heart Institute, Montréal, QC, Canada; 2Départements de Pharmacologie, 3Médecine, Faculté de Médecine, Université de Montréal, Montréal, QC, CanadaAbstract: Proprotein convertase subtilisin/kexin type 9 (PCSK9 directly binds to the epidermal growth factor-like repeat A domain of low-density lipoprotein receptor and induces its degradation, thereby controlling circulating low-density lipoprotein cholesterol (LDL-C concentration. Heterozygous loss-of-function mutations in PCSK9 can decrease the incidence of coronary heart disease by up to 88%, owing to lifelong reduction of LDL-C. Moreover, two subjects with PCSK9 loss-of-function mutations on both alleles, resulting in a total absence of functional PCSK9, were found to have extremely low circulating LDL-C levels without other apparent abnormalities. Accordingly, PCSK9 could represent a safe and effective pharmacological target to increase clearance of LDL-C and to reduce the risk of coronary heart disease. Recent clinical trials using anti-PCSK9 monoclonal antibodies that block the PCSK9:low-density lipoprotein receptor interaction were shown to considerably reduce LDL-C levels by up to 65% when given alone and by up to 72% in patients already receiving statin therapy. In this review, we will discuss how major scientific breakthroughs in PCSK9 cell biology have led to the development of new and forthcoming LDL-C-lowering pharmacological agents.Keywords: PCSK9, LDLR, LDL-cholesterol, lipoproteins, coronary heart disease, inhibitors, monoclonal antibody therapy

Dual role of Fcγ receptors in host defense and disease in Borrelia burgdorferi-infected mice

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Alexia Anne Belperron

2014-06-01

Full Text Available Arthritis in mice infected with the Lyme disease spirochete, Borrelia burgdorferi, results from the influx of innate immune cells responding to the pathogen in the joint and is influenced in part by mouse genetics. Production of inflammatory cytokines by innate immune cells in vitro is largely mediated by Toll-like receptor (TLR interaction with Borrelia lipoproteins, yet surprisingly mice deficient in TLR2 or the TLR signaling molecule MyD88 still develop arthritis comparable to that seen in wild type mice after B. burgdorferi infection. These findings suggest that other, MyD88-independent inflammatory pathways can contribute to arthritis expression. Clearance of B. burgdorferi is dependent on the production of specific antibody and phagocytosis of the organism. As Fc receptors (FcγR are important for IgG-mediated clearance of immune complexes and opsonized particles by phagocytes, we examined the role that FcγR play in host defense and disease in B. burgdorferi-infected mice. B. burgdorferi-infected mice deficient in the Fc receptor common gamma chain (FcεRγ-/- mice harbored ~10 fold more spirochetes than similarly infected wild type mice, and this was associated with a transient increase in arthritis severity. While the elevated pathogen burdens seen in B. burgdorferi-infected MyD88-/- mice were not affected by concomitant deficiency in FcγR, arthritis was reduced in FcεRγ-/-MyD88-/- mice in comparison to wild type or single knockout mice. Gene expression analysis from infected joints demonstrated that absence of both MyD88 and FcγR lowers mRNA levels of proteins involved in inflammation, including Cxcl1 (KC, Xcr1 (Gpr5, IL-1beta, and C reactive protein. Taken together, our results demonstrate a role for FcγR-mediated immunity in limiting pathogen burden and arthritis in mice during the acute phase of B. burgdorferi infection, and further suggest that this pathway contributes to the arthritis that develops in B. burgdorferi

The Influence of Decreased Levels of High Density Lipoprotein ...

African Journals Online (AJOL)

very low density lipoprotein cholesterol, and triglyceride were assayed. ... Abiodun and Gwarzo: Association of high density lipoprotein cholesterol with haemolysis in sickle cell disease ... analyses were carried out to determine the correlation.

CD86 and beta2-adrenergic receptor signaling pathways, respectively, increase Oct-2 and OCA-B Expression and binding to the 3'-IgH enhancer in B cells.

Science.gov (United States)

Podojil, Joseph R; Kin, Nicholas W; Sanders, Virginia M

2004-05-28

Stimulation of CD86 (formerly known as B7-2) and/or the beta2-adrenergic receptor on a CD40 ligand/interleukin-4-activated B cell increased the rate of mature IgG1 transcription. To identify the mechanism responsible for this effect, we determined whether CD86 and/or beta2-adrenergic receptor stimulation regulated transcription factor expression and binding to the 3'-IgH enhancer in vitro and in vivo. We showed that CD86 stimulation increased the nuclear localization of NF-kappaB1 (p50) and phosphorylated RelA (p65) and increased Oct-2 expression and binding to the 3'-IgH enhancer, in a protein kinase C-dependent manner. These effects were lost when CD86-deficient or NF-kappaB1-deficient B cells were used. CD86 stimulation also increased the level of IkappaB-alpha phosphorylation but in a protein kinase C-independent manner. Beta2-adrenergic receptor stimulation increased CREB phosphorylation, OCA-B expression, and OCA-B binding to the 3'-IgH enhancer in a protein kinase A-dependent manner, an effect lost when beta2-adrenergic receptor-deficient B cells were used. Also, the beta2-adrenergic receptor-induced increase in the level of mature IgG1 transcript was lost when OCA-B-deficient B cells were used. These data are the first to show that CD86 stimulation up-regulates the expression of the transcription factor Oct-2 in a protein kinase C- and NF-kappaB1-dependent manner, and that beta2-adrenergic receptor stimulation up-regulates the expression of the coactivator OCA-B in a protein kinase A-dependent manner to cooperate with Oct-2 binding to the 3'-IgH enhancer.

Abalation of Ghrelin receptor in leptin-deficient mice has paradoxical effects on glucose homeostasis compared to Ghrelin-abalated Leptin-deficient mice

Science.gov (United States)

Ghrelin is produced predominantly in stomach and is known to be the endogenous ligand of the growth hormone secretagogue receptor (GHSR). Ghrelin is a GH stimulator and an orexigenic hormone. In contrast, leptin is an anorexic hormone, and leptin-deficient ob/ob mice are obese and diabetic. To study...

High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

Energy Technology Data Exchange (ETDEWEB)

Wolfe, Adam R. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Atkinson, Rachel L. [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Reddy, Jay P. [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Debeb, Bisrat G.; Larson, Richard; Li, Li [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Masuda, Hiroko; Brewer, Takae [Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Atkinson, Bradley J. [Department of Clinical Pharmacy Services, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Brewster, Abeena [Morgan Welch Inflammatory Breast Cancer Research Program and Clinic, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Ueno, Naoto T. [Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Woodward, Wendy A., E-mail: wwoodward@mdanderson.org [Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas (United States); Department of Clinical Cancer Prevention, University of Texas MD Anderson Cancer Center, Houston, Texas (United States)

2015-04-01

Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

International Nuclear Information System (INIS)

Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

2015-01-01

Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

Scavenger receptors in homeostasis and immunity.

Science.gov (United States)

Canton, Johnathan; Neculai, Dante; Grinstein, Sergio

2013-09-01

Scavenger receptors were originally identified by their ability to recognize and to remove modified lipoproteins; however, it is now appreciated that they carry out a striking range of functions, including pathogen clearance, lipid transport, the transport of cargo within the cell and even functioning as taste receptors. The large repertoire of ligands recognized by scavenger receptors and their broad range of functions are not only due to the wide range of receptors that constitute this family but also to their ability to partner with various co-receptors. The ability of individual scavenger receptors to associate with different co-receptors makes their responsiveness extremely versatile. This Review highlights recent insights into the structural features that determine the function of scavenger receptors and the emerging role that these receptors have in immune responses, notably in macrophage polarization and in the pathogenesis of diseases such as atherosclerosis and Alzheimer's disease.

Cell-specific cre recombinase expression allows selective ablation of glutamate receptors from mouse horizontal cells.

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Sebastian Ströh

Full Text Available In the mouse retina, horizontal cells form an electrically coupled network and provide feedback signals to photoreceptors and feedforward signals to bipolar cells. Thereby, horizontal cells contribute to gain control at the first visual synapse and to the antagonistic organization of bipolar and ganglion cell receptive fields. However, the nature of horizontal cell output remains a matter of debate, just as the exact contribution of horizontal cells to center-surround antagonism. To facilitate studying horizontal cell function, we developed a knockin mouse line which allows ablating genes exclusively in horizontal cells. This knockin line expresses a Cre recombinase under the promoter of connexin57 (Cx57, a gap junction protein only expressed in horizontal cells. Consistently, in Cx57+/Cre mice, Cre recombinase is expressed in almost all horizontal cells (>99% and no other retinal neurons. To test Cre activity, we crossbred Cx57+/Cre mice with a mouse line in which exon 11 of the coding sequence for the ionotropic glutamate receptor subunit GluA4 was flanked by two loxP sites (GluA4fl/fl. In GluA4fl/fl:Cx57+/Cre mice, GluA4 immunoreactivity was significantly reduced (∼ 50% in the outer retina where horizontal cells receive photoreceptor inputs, confirming the functionality of the Cre/loxP system. Whole-cell patch-clamp recordings from isolated horizontal cell somata showed a reduction of glutamate-induced inward currents by ∼ 75%, suggesting that the GluA4 subunit plays a major role in mediating photoreceptor inputs. The persistent current in GluA4-deficient cells is mostly driven by AMPA and to a very small extent by kainate receptors as revealed by application of the AMPA receptor antagonist GYKI52466 and concanavalin A, a potentiator of kainate receptor-mediated currents. In summary, the Cx57+/Cre mouse line provides a versatile tool for studying horizontal cell function. GluA4fl/fl:Cx57+/Cre mice, in which horizontal cells receive less

Cell-Specific Cre Recombinase Expression Allows Selective Ablation of Glutamate Receptors from Mouse Horizontal Cells

Science.gov (United States)

Janssen-Bienhold, Ulrike; Schultz, Konrad; Cimiotti, Kerstin; Weiler, Reto; Willecke, Klaus; Dedek, Karin

2013-01-01

In the mouse retina, horizontal cells form an electrically coupled network and provide feedback signals to photoreceptors and feedforward signals to bipolar cells. Thereby, horizontal cells contribute to gain control at the first visual synapse and to the antagonistic organization of bipolar and ganglion cell receptive fields. However, the nature of horizontal cell output remains a matter of debate, just as the exact contribution of horizontal cells to center-surround antagonism. To facilitate studying horizontal cell function, we developed a knockin mouse line which allows ablating genes exclusively in horizontal cells. This knockin line expresses a Cre recombinase under the promoter of connexin57 (Cx57), a gap junction protein only expressed in horizontal cells. Consistently, in Cx57+/Cre mice, Cre recombinase is expressed in almost all horizontal cells (>99%) and no other retinal neurons. To test Cre activity, we crossbred Cx57+/Cre mice with a mouse line in which exon 11 of the coding sequence for the ionotropic glutamate receptor subunit GluA4 was flanked by two loxP sites (GluA4fl/fl). In GluA4fl/fl:Cx57+/Cre mice, GluA4 immunoreactivity was significantly reduced (∼50%) in the outer retina where horizontal cells receive photoreceptor inputs, confirming the functionality of the Cre/loxP system. Whole-cell patch-clamp recordings from isolated horizontal cell somata showed a reduction of glutamate-induced inward currents by ∼75%, suggesting that the GluA4 subunit plays a major role in mediating photoreceptor inputs. The persistent current in GluA4-deficient cells is mostly driven by AMPA and to a very small extent by kainate receptors as revealed by application of the AMPA receptor antagonist GYKI52466 and concanavalin A, a potentiator of kainate receptor-mediated currents. In summary, the Cx57+/Cre mouse line provides a versatile tool for studying horizontal cell function. GluA4fl/fl:Cx57+/Cre mice, in which horizontal cells receive less excitatory input

Effect of doxazosin on cholesterol synthesis in cell culture

International Nuclear Information System (INIS)

D'Eletto, R.D.; Javitt, N.B.

1989-01-01

The effect of doxazosin on cholesterol synthesis was determined by measuring the content of deuterium-enriched cholesterol in rabbit fibroblasts with and without receptors for low-density lipoproteins (LDL) and in hepatoma (Hep G2 cells). Doxazosin, at concentrations of 5-20 mumol/L, increased LDL binding to hepatic cells in a dose-related manner. Also, in these hepatic cells, doxazosin produced dose-related decreases in both newly synthesized cholesterol and cholesterol ester. In rabbit fibroblasts that were LDL receptor negative, de novo cholesterol synthesis was markedly reduced by increasing concentrations of doxazosin. Taken together, these results suggest that doxazosin may have a direct inhibitory effect on cholesterol synthesis independent of the LDL receptor. The inhibition of cholesterol synthesis by doxazosin may cause cells to compensate by upregulating the LDL receptor, thereby increasing the importation of lipoprotein cholesterol and reducing LDL cholesterol in the medium. This hypothesis supports findings in the clinical setting whereby doxazosin has a beneficial effect on the lipid profile, and suggests a useful additional property for this antihypertensive agent

Signaling by Kit protein-tyrosine kinase--the stem cell factor receptor.

Science.gov (United States)

Roskoski, Robert

2005-11-11

Signaling by stem cell factor and Kit, its receptor, plays important roles in gametogenesis, hematopoiesis, mast cell development and function, and melanogenesis. Moreover, human and mouse embryonic stem cells express Kit transcripts. Stem cell factor exists as both a soluble and a membrane-bound glycoprotein while Kit is a receptor protein-tyrosine kinase. The complete absence of stem cell factor or Kit is lethal. Deficiencies of either produce defects in red and white blood cell production, hypopigmentation, and sterility. Gain-of-function mutations of Kit are associated with several human neoplasms including acute myelogenous leukemia, gastrointestinal stromal tumors, and mastocytomas. Kit consists of an extracellular domain, a transmembrane segment, a juxtamembrane segment, and a protein kinase domain that contains an insert of about 80 amino acid residues. Binding of stem cell factor to Kit results in receptor dimerization and activation of protein kinase activity. The activated receptor becomes autophosphorylated at tyrosine residues that serve as docking sites for signal transduction molecules containing SH2 domains. The adaptor protein APS, Src family kinases, and Shp2 tyrosyl phosphatase bind to phosphotyrosine 568. Shp1 tyrosyl phosphatase and the adaptor protein Shc bind to phosphotyrosine 570. C-terminal Src kinase homologous kinase and the adaptor Shc bind to both phosphotyrosines 568 and 570. These residues occur in the juxtamembrane segment of Kit. Three residues in the kinase insert domain are phosphorylated and attract the adaptor protein Grb2 (Tyr703), phosphatidylinositol 3-kinase (Tyr721), and phospholipase Cgamma (Tyr730). Phosphotyrosine 900 in the distal kinase domain binds phosphatidylinositol 3-kinase which in turn binds the adaptor protein Crk. Phosphotyrosine 936, also in the distal kinase domain, binds the adaptor proteins APS, Grb2, and Grb7. Kit has the potential to participate in multiple signal transduction pathways as a result of

[Learning and Memory Capacity and NMDA Receptor Expression in Shen Deficiency Constitution Rats].

Science.gov (United States)

Sun, Yu-ru; Sun, Yao-guang; Zhang, Qi; Wang, Xiao-di; Wang, Xing; Sun, Li-jun

2016-05-01

To explore material bases and neurobiological mechanisms of "Shen storing will" by observing learning and memory capacities and N-methyl-D-aspartic acid (NMDA) receptor expressions in Shen deficiency constitution (SDC) rats. Totally 40 SD rats were randomly divided into the model group, the Zuogui Pill (ZP) group, the Yougui Pill (YP) group, the blank control group (consisting of normal pregnant rats), 10 in each group. SDC young rat model (inherent deficiency and postnatal malnutrition) was prepared by the classic way of "cat scaring rat". Medication started when they were scared by cat. Rats in the ZP group and the YP group were administered by gastrogavage with ZP suspension 0.1875 g/mL and YP suspension 0.0938 g/mL respectively. Equal volume of normal saline was administered to rats in the blank control group and the model group by gastrogavage. All medication was given once per day, 5 days in a week for 2 consecutive months. Learning and memory capacities were detected by Morris water maze test. Expressions of NMDA receptor subunits NR2A and NR2B in hippocamus were detected by immunohistochemical method. Compared with the blank control group, the latency period, total distance in Morris water maze test were longer in the model group (P learning and memory capacities and lowered NMDA receptor expressions. ZP and YP could up-regulate learning and memory capacities and NMDA receptor expressions, thereby improving deterioration of brain functions in SDC rats.

Recent Advances in Hepatitis C Virus Cell Entry

Directory of Open Access Journals (Sweden)

Jean Dubuisson

2010-03-01

Full Text Available More than 170 million patients worldwide are chronically infected with hepatitis C virus (HCV. Prevalence rates range from 0.5% in Northern European countries to 28% in some areas of Egypt. HCV is hepatotropic, and in many countries chronic hepatitis C is a leading cause of liver disease including fibrosis, cirrhosis and hepatocellular carcinoma. HCV persists in 50–85% of infected patients, and once chronic infection is established, spontaneous clearance is rare. HCV is a member of the Flaviviridae family, in which it forms its own genus. Many lines of evidence suggest that the HCV life cycle displays many differences to that of other Flaviviridae family members. Some of these differences may be due to the close interaction of HCV with its host’s lipid and particular triglyceride metabolism in the liver, which may explain why the virus can be found in association with lipoproteins in serum of infected patients. This review focuses on the molecular events underlying the HCV cell entry process and the respective roles of cellular co-factors that have been implied in these events. These include, among others, the lipoprotein receptors low density lipoprotein receptor and scavenger receptor BI, the tight junction factors occludin and claudin-1 as well as the tetraspanin CD81. We discuss the roles of these cellular factors in HCV cell entry and how association of HCV with lipoproteins may modulate the cell entry process.

Dopamine receptor D5 deficiency results in a selective reduction of hippocampal NMDA receptor subunit NR2B expression and impaired memory.

Science.gov (United States)

Moraga-Amaro, Rodrigo; González, Hugo; Ugalde, Valentina; Donoso-Ramos, Juan Pablo; Quintana-Donoso, Daisy; Lara, Marcelo; Morales, Bernardo; Rojas, Patricio; Pacheco, Rodrigo; Stehberg, Jimmy

2016-04-01

Pharmacological evidence associates type I dopamine receptors, including subtypes D1 and D5, with learning and memory. Analyses using genetic approaches have determined the relative contribution of dopamine receptor D1 (D1R) in cognitive tasks. However, the lack of drugs that can discriminate between D1R and D5R has made the pharmacological distinction between the two receptors difficult. Here, we aimed to determine the role of D5R in learning and memory. In this study we tested D5R knockout mice and wild-type littermates in a battery of behavioral tests, including memory, attention, locomotion, anxiety and motivational evaluations. Our results show that genetic deficiency of D5R significantly impairs performance in the Morris water maze paradigm, object location and object recognition memory, indicating a relevant role for D5R in spatial memory and recognition memory. Moreover, the lack of D5R resulted in decreased exploration and locomotion. In contrast, D5R deficiency had no impact on working memory, anxiety and depressive-like behavior, measured using the spontaneous alternation, open-field, tail suspension test, and forced swimming test. Electrophysiological analyses performed on hippocampal slices showed impairment in long-term-potentiation in mice lacking D5R. Further analyses at the molecular level showed that genetic deficiency of D5R results in a strong and selective reduction in the expression of the NMDA receptor subunit NR2B in the hippocampus. These findings demonstrate the relevant contribution of D5R in memory and suggest a functional interaction of D5R with hippocampal glutamatergic pathways. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glycan-deficient PrP stimulates VEGFR2 signaling via glycosaminoglycan.

Science.gov (United States)

Gao, Zhenxing; Zhang, Huixia; Hu, Fei; Yang, Liheng; Yang, Xiaowen; Zhu, Ying; Sy, Man-Sun; Li, Chaoyang

2016-06-01

Whether the two N-linked glycans are important in prion, PrP, biology is unresolved. In Chinese hamster ovary (CHO) cells, the two glycans are clearly not important in the cell surface expression of transfected human PrP. Compared to fully-glycosylated PrP, glycan-deficient PrP preferentially partitions to lipid raft. In CHO cells glycan-deficient PrP also interacts with glycosaminoglycan (GAG) and vascular endothelial growth factor receptor 2 (VEGFR2), resulting in VEGFR2 activation and enhanced Akt phosphorylation. Accordingly, CHO cells expressing glycan-deficient PrP lacking the GAG binding motif or cells treated with heparinase to remove GAG show diminished Akt signaling. Being in lipid raft is critical, chimeric glycan-deficient PrP with CD4 transmembrane and cytoplasmic domains is absent in lipid raft and does not activate Akt signaling. CHO cells bearing glycan-deficient PrP also exhibit enhanced cellular adhesion and migration. Based on these findings, we propose a model in which glycan-deficient PrP, GAG, and VEGFR2 interact, activating VEGFR2 and resulting in changes in cellular behavior. Copyright © 2016 Elsevier Inc. All rights reserved.

Efficient T-cell surveillance of the CNS requires expression of the CXC chemokine receptor 3

DEFF Research Database (Denmark)

Christensen, Jeanette Erbo; Nansen, Anneline; Moos, Torben

2004-01-01

T-cells play an important role in controlling viral infections inside the CNS. To study the role of the chemokine receptor CXCR3 in the migration and positioning of virus-specific effector T-cells within the brain, CXCR3-deficient mice were infected intracerebrally with lymphocytic choriomeningitis......-cell-mediated immunopathology. Quantitative analysis of the cellular infiltrate in CSF of infected mice revealed modest, if any, decrease in the number of mononuclear cells recruited to the meninges in the absence of CXCR3. However, immunohistological analysis disclosed a striking impairment of CD8+ T-cells from CXCR3...

Expression of an IRF-3 fusion protein and mouse estrogen receptor, inhibits hepatitis C viral replication in RIG-I-deficient Huh 7.5 cells

Directory of Open Access Journals (Sweden)

Liu Chen

2011-09-01

Full Text Available Abstract Interferon Regulatory Factor-3 (IRF-3 plays a central role in the induction of interferon (IFN production and succeeding interferon-stimulated genes (ISG expression en route for restraining hepatitis C virus (HCV infection. Here, we established a stable Huh7.5-IRF3ER cell line expressing a fusion protein of IRF-3 and mouse estrogen receptor (ER to examine IFN production and anti-HCV effects of IRF-3 in retinoic acid inducible-gene-I (RIG-I deficient Huh 7.5 cells. Homodimerization of the IRF-3ER fusion protein was detected by Western blotting after treatment with the estrogen receptor agonist 4-hydrotamoxifen (4-HT in Huh7.5-IRF3ER cells. Expression of IFN-α, IFN-β, and their inhibitory effects on HCV replication were demonstrated by real-time polymerase chain reaction (PCR. Peak expression of IFN-α and IFN-β was achieved 24-hours post 4-HT treatment, coinciding with the appearance of phosphorylated signal transducer and activator of transcription (STAT proteins. Additionally, HCV viral replication declined in time-dependent fashion. In previous studies, a novel IFN-mediated pathway regulating expression of 1-8U and heterogeneous nuclear ribonucleoprotein M (hnRNP M inhibited HCV internal ribosomal entry site (IRES-dependent translation. When expression of ISGs such as 1-8U and hnRNP M were measured in 4-HT-treated Huh7.5-IRF3ER cells, both genes were positively regulated by activation of the IRF-3ER fusion protein. In conclusion, the anti-HCV effects of IRF-3ER homodimerization inhibited HCV RNA replication as well as HCV IRES-dependent translation in Huh7.5-IRF3ER cells. The results of this study indicate that IRF-3ER homodimerization is a key step to restore IFN expression in Huh7.5-IRF3ER cells and in achieving its anti-HCV effects.

Common low-density lipoprotein receptor p.G116S variant has a large effect on plasma low-density lipoprotein cholesterol in circumpolar inuit populations.

Science.gov (United States)

Dubé, Joseph B; Wang, Jian; Cao, Henian; McIntyre, Adam D; Johansen, Christopher T; Hopkins, Scarlett E; Stringer, Randa; Hosseinzadeh, Siyavash; Kennedy, Brooke A; Ban, Matthew R; Young, T Kue; Connelly, Philip W; Dewailly, Eric; Bjerregaard, Peter; Boyer, Bert B; Hegele, Robert A

2015-02-01

Inuit are considered to be vulnerable to cardiovascular disease because their lifestyles are becoming more Westernized. During sequence analysis of Inuit individuals at extremes of lipid traits, we identified 2 nonsynonymous variants in low-density lipoprotein receptor (LDLR), namely p.G116S and p.R730W. Genotyping these variants in 3324 Inuit from Alaska, Canada, and Greenland showed they were common, with allele frequencies 10% to 15%. Only p.G116S was associated with dyslipidemia: the increase in LDL cholesterol was 0.54 mmol/L (20.9 mg/dL) per allele (P=5.6×10(-49)), which was >3× larger than the largest effect sizes seen with other common variants in other populations. Carriers of p.G116S had a 3.02-fold increased risk of hypercholesterolemia (95% confidence interval, 2.34-3.90; P=1.7×10(-17)), but did not have classical familial hypercholesterolemia. In vitro, p.G116S showed 60% reduced ligand-binding activity compared with wild-type receptor. In contrast, p.R730W was associated with neither LDL cholesterol level nor altered in vitro activity. LDLR p.G116S is thus unique: a common dysfunctional variant in Inuit whose large effect on LDL cholesterol may have public health implications. © 2014 American Heart Association, Inc.

Human luteinized granulosa cells secrete apoB100-containing lipoproteins

NARCIS (Netherlands)

Gautier, Thomas; Becker, Steffi; Drouineaud, Veronique; Menetrier, Franck; Sagot, Paul; Nofer, Jerzy-Roch; von Otte, Soeren; Lagrost, Laurent; Masson, David; Tietge, Uwe J. F.

Thus far, liver, intestine, heart, and placenta have been shown to secrete apolipoprotein (apo) B-containing lipoproteins. In the present study, we first investigated lipoproteins in human follicular fluid (FF), surrounding developing oocytes within the ovary, as well as in corresponding plasma

Structure of the LDL receptor extracellular domain at endosomalpH

Energy Technology Data Exchange (ETDEWEB)

Rudenko, Gabby; Henry, Lisa; Henderson, Keith; Ichtchenko,Konstantin; Brown, Michael S.; Goldstein, Joseph L.; Deisenhofer, Johann

2002-09-05

The structure of the low-density lipoprotein receptor extracellular portion has been determined. The document proposes a mechanism for the release of lipoprotein in the endosome. Without this release, the mechanism of receptor recycling cannot function.

Exposure to long wavelength ultraviolet radiation decreases processing of low density lipoprotein by cultured human fibroblasts

International Nuclear Information System (INIS)

Djavaheri-Mergny, M.; Santus, R.; Mora, L.; Maziere, J.C.; Faculte de Medecine Saint-Antoine, 75 -Paris; Maziere, C.; Auclair, M.; Dubertret, L.

1993-01-01

Exposure of MRC5 human fibroblasts to UVA radiation (365 nm) resulted in a dose-dependent decrease in low density lipoprotein (LDL) uptake and degradation by cells. Following a 25 J/cm 2 irradiation dose, about 45% and 70% reduction in 125 I-LDL uptake and degradation were observed, respectively. Under the same conditions, the 14 C-sucrose uptake was also decreased to about the same extent as LDL uptake. Cell pretreatment with the antioxidants vitamin E and vitamin C did not prevent the UVA-induced fall in LDL degradation. These results point to the possible effects of UVA radiation on receptor-mediated and nonspecific uptake of exogenous molecules. With special regard to the alterations in receptor-mediated processing of exogenous ligands, such a phenomenon could be of importance in UVA-induced skin degenerative processes. (Author)

Effects of the antitumor drug OSI-906, a dual inhibitor of IGF-1 receptor and insulin receptor, on the glycemic control, β-cell functions, and β-cell proliferation in male mice.

Science.gov (United States)

Shirakawa, Jun; Okuyama, Tomoko; Yoshida, Eiko; Shimizu, Mari; Horigome, Yuka; Tuno, Takayuki; Hayasaka, Moe; Abe, Shiori; Fuse, Masahiro; Togashi, Yu; Terauchi, Yasuo

2014-06-01

The IGF-1 receptor has become a therapeutic target for the treatment of cancer. The efficacy of OSI-906 (linstinib), a dual inhibitor of IGF-1 receptor and insulin receptor, for solid cancers has been examined in clinical trials. The effects of OSI-906, however, on the blood glucose levels and pancreatic β-cell functions have not yet been reported. We investigated the impact of OSI-906 on glycemic control, insulin secretion, β-cell mass, and β-cell proliferation in male mice. Oral administration of OSI-906 worsened glucose tolerance in a dose-dependent manner in the wild-type mice. OSI-906 at a dose equivalent to the clinical daily dose (7.5 mg/kg) transiently evoked glucose intolerance and hyperinsulinemia. Insulin receptor substrate (IRS)-2-deficient mice and mice with diet-induced obesity, both models of peripheral insulin resistance, exhibited more severe glucose intolerance after OSI-906 administration than glucokinase-haploinsufficient mice, a model of impaired insulin secretion. Phloridzin improved the hyperglycemia induced by OSI-906 in mice. In vitro, OSI-906 showed no effect on insulin secretion from isolated islets. After daily administration of OSI-906 for a week to mice, the β-cell mass and β-cell proliferation rate were significantly increased. The insulin signals in the β-cells were apparently unaffected in those mice. Taken together, the results suggest that OSI-906 could exacerbate diabetes, especially in patients with insulin resistance. On the other hand, the results suggest that the β-cell mass may expand in response to chemotherapy with this drug.

Fps/Fes protein-tyrosine kinase regulates mast cell adhesion and migration downstream of Kit and beta1 integrin receptors.

Science.gov (United States)

Smith, Julie A; Samayawardhena, Lionel A; Craig, Andrew W B

2010-03-01

Activation of Kit receptor protein-tyrosine kinase (PTK) by its ligand Stem Cell Factor (SCF) is required for the development of mast cells, and for the regulation of mast cell proliferation, migration and modulation of inflammatory mediator release. Recent studies have implicated the non-receptor PTK Fps/Fes (hereafter referred to as Fes) in signaling downstream of oncogenic Kit, however, the potential role of Fes in regulating Kit signaling is not well defined. In this study, we show that SCF induces transient tyrosine phosphorylation of wild-type Fes as well as kinase-dead Fes in bone marrow-derived mast cells (BMMCs). The latter finding implicates an upstream kinase acting on Fes, which we identified as Fyn PTK. SCF treatment of BMMCs promoted recruitment of Fes to Kit, potentially via direct interaction of the Fes SH2 domain with phosphorylated Kit. While Fes was not required for SCF-induced signaling to Akt and Erk kinases, Fes-deficient (fes-/-) BMMCs displayed a defect in sustained p38 kinase activation, compared to control cells. SCF-treated Fes-deficient BMMCs also displayed elevated beta1 integrin-mediated cell adhesion and spreading on fibronectin, compared to control cells, and a reduction in cell polarization at later times of SCF treatment. Restoring Fes expression in fes-/- BMMCs by retroviral transduction was sufficient to rescue cell spreading and polarization defects. Interestingly, SCF-induced chemotaxis of BMMCs was also defective in Fes-deficient BMMCs, and restored in Fes-rescue BMMCs. Overall, these results implicate Fes in regulating cross-talk between Kit and beta1 integrins to promote cytoskeletal reorganization and motility of mast cells.

Lipoproteins and lipoprotein mimetics for imaging and drug delivery.

Science.gov (United States)

Thaxton, C Shad; Rink, Jonathan S; Naha, Pratap C; Cormode, David P

2016-11-15

Lipoproteins are a set of natural nanoparticles whose main role is the transport of fats within the body. While much work has been done to develop synthetic nanocarriers to deliver drugs or contrast media, natural nanoparticles such as lipoproteins represent appealing alternatives. Lipoproteins are biocompatible, biodegradable, non-immunogenic and are naturally targeted to some disease sites. Lipoproteins can be modified to act as contrast agents in many ways, such as by insertion of gold cores to provide contrast for computed tomography. They can be loaded with drugs, nucleic acids, photosensitizers or boron to act as therapeutics. Attachment of ligands can re-route lipoproteins to new targets. These attributes render lipoproteins attractive and versatile delivery vehicles. In this review we will provide background on lipoproteins, then survey their roles as contrast agents, in drug and nucleic acid delivery, as well as in photodynamic therapy and boron neutron capture therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Surface-Exposed Lipoproteins: An Emerging Secretion Phenomenon in Gram-Negative Bacteria.

Science.gov (United States)

Wilson, Marlena M; Bernstein, Harris D

2016-03-01

Bacterial lipoproteins are hydrophilic proteins that are anchored to a cell membrane by N-terminally linked fatty acids. It is widely believed that nearly all lipoproteins produced by Gram-negative bacteria are either retained in the inner membrane (IM) or transferred to the inner leaflet of the outer membrane (OM). Lipoproteins that are exposed on the cell surface have also been reported but are generally considered to be rare. Results from a variety of recent studies, however, now suggest that the prevalence of surface-exposed lipoproteins has been underestimated. In this review we describe the evidence that the surface exposure of lipoproteins in Gram-negative bacteria is a widespread phenomenon and discuss possible mechanisms by which these proteins might be transported across the OM. Published by Elsevier Ltd.

Resistance to diet-induced adiposity in cannabinoid receptor-1 deficient mice is not due to impaired adipocyte function

NARCIS (Netherlands)

Oosterveer, Maaike H.; Koolman, Anniek H.; de Boer, Pieter T.; Bos, Trijnie; Bleeker, Aycha; Bloks, Vincent W.; Kuipers, Folkert; Sauer, Pieter J. J.; van Dijk, Gertjan

2011-01-01

Background: Overactivity and/or dysregulation of the endocannabinoid system (ECS) contribute to development of obesity. In vitro studies indicate a regulatory role for the cannabinoid receptor 1 (CB1) in adipocyte function and CB1-receptor deficient (CB1-/-) mice are resistant to high fat