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Sadao Takahashi - One of the best experts on this subject based on the ideXlab platform.
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role of VLDL Receptor in atherogenesis
Current Opinion in Lipidology, 2021Co-Authors: Sadao TakahashiAbstract:Purpose of review My group previously discovered and characterized the rabbit and human VLDL Receptors. For more than 30 years, I have focused on research regarding the functions of VLDL Receptors in the fields of lipoprotein metabolism and atherogenesis. In this review, I introduce the roles of VLDL Receptors in lipoprotein metabolism under physiological conditions and in atherogenesis under nonphysiological conditions. Recent findings I propose that the VLDL Receptor plays key roles in the metabolism of postprandial remnant lipoproteins in concert with lipoprotein lipase (LPL). Furthermore, I propound a new mechanism for macrophage foam cell formation via VLDL Receptors by remnant lipoproteins and lipoprotein(a) [Lp(a)] in addition to scavenger Receptor pathways. Summary The VLDL Receptor is a so-called macrophage β-VLDL Receptor, which is involved in macrophage foam cell formation by remnant lipoproteins. Furthermore, Lp(a) is a VLDL Receptor ligand and is directly taken up through macrophage VLDL Receptors for macrophage foam cell formation. Additionally, the roles of VLDL Receptors in atherogenesis are canvassed. Supplementary video abstract http://links.lww.com/COL/A21.
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the VLDL Receptor plays a key role in the metabolism of postprandial remnant lipoproteins
Clinica Chimica Acta, 2019Co-Authors: Yoshiharu Tokita, Katsuyuki Nakajima, Akira Tanaka, Sadao TakahashiAbstract:Abstract A new concept to account for the process of postprandial remnant lipoprotein metabolism is proposed based on the characteristics of lipoprotein particles and their Receptors. The characteristics of remnant lipoprotein (RLP) were investigated using an immuno-separation method. The majority of the postprandial lipoproteins increased after fat intake was shown to be VLDL remnants, not chylomicron (CM) remnants, based on the significantly high ratio of apoB100/apoB48 in the RLP and the high degree of similarity in the particle size of the apoB48 and apoB100 carrying lipoproteins, which fluctuate in parallel during a 6 h period after fat intake. The VLDL Receptor was discovered as a Receptor for TG-rich lipoprotein metabolism and is located in peripheral tissues such as skeletal muscle, adipose tissue, etc., but not in the liver. Postprandial VLDL particles are strongly bound and internalized into cells expressing the VLDL Receptor. Ligands that bind to VLDL Receptor, such as LPL and Lp(a), present in RLP. The presence of various specific ligands in VLDL remnants may enhance the capacity for binding to the VLDL Receptor, which play the role primarily for energy delivery to the peripheral tissues, but is also a causal factor in atherogenic diseases when excessively and/or continuously remained in plasma.
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triglyceride rich lipoprotein lpl VLDL Receptor and lp a VLDL Receptor pathways for macrophage foam cell formation
Journal of Atherosclerosis and Thrombosis, 2017Co-Authors: Sadao TakahashiAbstract:Very low-density lipoprotein (VLDL) Receptor is a member of the low-density lipoprotein (LDL) Receptor family. It binds triglyceride rich lipoprotein (TGRL) but not LDL, because it recognizes apolipoprotein (apo)E only but not apoB. The VLDL Receptor functions as a peripheral lipoprotein Receptor in concert with lipoprotein lipase (LPL) in heart, muscle, adipose tissue and macrophages. In contrast to the LDL Receptor, VLDL Receptor binds apo E2/2 VLDL and apoE3/3 VLDL particles, and its expression is not down-regulated by intracellular lipoproteins. It has been reported that both LDL-cholesterol (LDL-C) and postprandial triglyceride (chyromicron and VLDL remnants) are risk factors for human atherosclerotic cardiovascular disease (ASCVD). True ligands such as lipoprotein particles of the VLDL Receptor are chyromicron remnant (CMR) and VLDL remnant (postprandial hyperlipidemia). Although the oxidized LDL (oxLDL)-scavenger Receptors pathway is considered to be the main mechanism for macrophage foam cell formation, it seems that the TGRL-LPL-VLDL Receptor pathway is also involved. Since Lp(a) is one of the ligands for the VLDL Receptor, the Lp(a)-VLDL Receptor pathway is another potential alternative. The expression of VLDL Receptor protein in mouse macrophages is modest compared to that in rabbit and human macrophages, both in vitro and in vivo. Therefore, we need to elucidate the mechanism of human ASCVD not by using the mouse model and scavenger Receptors pathway but instead using the rabbit model and VLDL Receptor pathway, respectively.
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comparative reactivity of remnant like lipoprotein particles rlp and low density lipoprotein ldl to ldl Receptor and VLDL Receptor effect of a high dose statin on VLDL Receptor expression
Clinica Chimica Acta, 2012Co-Authors: Michiko Imagawa, Sadao Takahashi, Yasuo Zenimaru, Jinya Suzuki, Isamu Miyamori, Tomoko Kimura, Tadao Iwasaki, Hiroaki Hattori, Tokuo T Yamamoto, Takamitsu NakanoAbstract:Abstract Background Comparison of the reactivity of remnant-like lipoprotein particles (RLP) and LDL particles to LDL Receptor and VLDL Receptor has not been investigated. Methods LDL Receptor- or VLDL Receptor-transfected ldlA-7, HepG2 and L6 cells were used. Human LDL and rabbit β-VLDL were isolated by ultracentrifugation. Human RLP was isolated using an immunoaffinity mixed gel. The effect of statin on lipoprotein Receptors was examined. Results Both LDL Receptor and VLDL Receptor recognized RLP. In LDL Receptor transfectants, RLP, β-VLDL and LDL all bound to LDL Receptor. Cold RLP competed efficiently with DiI-β-VLDL; however, cold LDL competed weakly. In VLDL Receptor transfectants, RLP and β-VLDL bound to VLDL Receptor, but not LDL. RLP bound to VLDL Receptor with higher affinity than β-VLDL because of higher apolipoprotein E in RLP. LDL Receptor expression was induced in HepG2 by the low concentration of statin while VLDL Receptor expression was induced in L6 myoblasts at higher concentration. Conclusions RLP are bound to hepatic LDL Receptor more efficiently than LDL, which may explain the mechanism by which statins prevent cardiovascular risk by primarily reducing plasma RLP rather than by reducing LDL. Additionally, a high-dose of statins also may reduce plasma RLP through muscular VLDL Receptor.
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Species differences of macrophage very low-density-lipoprotein (VLDL) Receptor protein expression
Biochemical and biophysical research communications, 2011Co-Authors: Sadao Takahashi, Takashi Ito, Yasuo Zenimaru, Jinya Suzuki, Isamu Miyamori, Masao Takahashi, Masafumi Takahashi, Takafumi Ishida, Tatsuro Ishida, Ken-ichi HirataAbstract:Triglyceride-rich lipoproteins (TGRLs) and low-density-lipoprotein (LDL) cholesterol are independent risk factors for coronary artery disease. We have previously proposed that the very low-density-lipoprotein (VLDL) Receptor is one of the Receptors required for foam cell formation by TGRLs in human macrophages. However, the VLDL Receptor proteins have not been detected in atherosclerotic lesions of several animal models. Here we showed no VLDL Receptor protein was detected in mouse macrophage cell lines (Raw264.7 and J774.2) or in mouse peritoneal macrophages in vitro. Furthermore, no VLDL Receptor protein was detected in macrophages in atherosclerotic lesions of chow-fed apolipoprotein E-deficient or cholesterol-fed LDL Receptor-deficient mice in vivo. In contrast, macrophage VLDL Receptor protein was clearly detected in human macrophages in vitro and in atherosclerotic lesions in myocardial infarction-prone Watanabe-heritable hyperlipidemic (WHHLMI) rabbits in vivo. There are species differences in the localization of VLDL Receptor protein in vitro and in vivo. Since VLDL Receptor is expressed on macrophages in atheromatous plaques of both rabbit and human but not in mouse models, the mechanisms of atherogenesis and/or growth of atherosclerotic lesions in mouse models may be partly different from those of humans and rabbits.
Nosratola D. Vaziri - One of the best experts on this subject based on the ideXlab platform.
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Effect of Cyclosporine on HMG-CoA Reductase, Cholesterol 7␣-Hydroxylase, LDL Receptor, HDL Receptor, VLDL Receptor, and Lipoprotein Lipase Expressions 1
2020Co-Authors: Nosratola D. Vaziri, Kaihui Liang, Habib AzadAbstract:ABSTRACT Long-term administration of cyclosporine (CsA) has been shown to cause hypercholesteremia, hypertriglyceridemia, and elevations of plasma low-density and very low-density lipoprotein (LDL and VLDL) levels in humans. This study was undertaken to explore the effects of CsA on expressions of the key lipid regulatory enzymes and Receptors. Thus, hepatic expressions of cholesterol 7␣-hydroxylase (the rate-limiting step in cholesterol conversion to bile acids), LDL Receptor, and highdensity lipoprotein (HDL) Receptor proteins, as well as 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity were determined in rats treated with CsA (18 mg/kg/day) or placebo for 3 weeks. In addition, skeletal muscle and adipose tissue expressions of lipoprotein lipase and VLDL Receptor were measured. Western blot analysis was used for all protein measurements using appropriate antibodies against the respective proteins. CsA-treated animals showed mild but significant elevations of plasma cholesterol and triglyceride concentrations. This was associated with a marked down-regulation of cholesterol 7␣-hydroxylase in the liver and a severe reduction of lipoprotein lipase abundance in skeletal muscle and adipose tissue. However, hepatic LDL Receptor and HDL Receptor expressions and HMG-CoA reductase activity were not altered by CsA therapy. Likewise, skeletal muscle and adipose tissue VLDL Receptor protein expressions were unaffected by CsA administration under the given condition. In conclusion, CsA administration for 3 weeks resulted in a significant reduction of hepatic cholesterol 7␣-hydroxylase and marked down-regulation of skeletal muscle and adipose tissue lipoprotein lipase abundance in rats. The former abnormality can contribute to hypercholesterolemia by limiting cholesterol catabolism, whereas the latter may contribute to hypertriglyceridemia and VLDL accumulation by limiting triglyceride-rich lipoprotein clearance in CsA-treated animals
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Protein restriction and AST-120 improve lipoprotein lipase and VLDL Receptor in focal glomerulosclerosis.
Kidney international, 2003Co-Authors: Tadashi Sato, Kaihui Liang, Nosratola D. VaziriAbstract:Protein restriction and AST-120 improve lipoprotein lipase and VLDL Receptor in focal glomerulosclerosis. Background Imai rats exhibit spontaneous focal glomerulosclerosis (FGS) with progressive proteinuria and hyperlipidemia leading to renal insufficiency by age 34 weeks. Recently, we reported marked down-regulations of skeletal muscle and adipose tissue lipoprotein lipase (LPL) and very low-density lipoprotein (VLDL) Receptor in male Imai rats at 32 weeks of age. Dietary protein restriction and oral adsorbent AST-120 (AST) have been shown to slow progression of renal disease and attenuate hyperlipidemia in the Imai rats. This study tested the hypothesis that amelioration of proteinuria by protein restriction or use of oral adsorbent AST-120 beginning at 10 weeks of age may improve renal disease and LPL and VLDL Receptor deficiencies in Imai rats. Methods Ten-week-old male Imai rats were randomly assigned to those fed either a regular diet, low protein diet (LPD), or regular diet containing the adsorbent preparation, AST-120. Ten-week-old male Sprague-Dawley rats served as controls. The animals were observed for 24 weeks. Six rats were included in each group. All diets were prepared in powder form. Results The untreated 34-week-old Imai rats showed severe proteinuria, hypoalbuminemia, 50% reduction in creatinine clearance, hypercholesterolemia, hypertriglyceridemia, and elevated plasma VLDL concentration. This was associated with significant reductions in plasma post-heparin LPL activity, hepatic lipase activity, as well as adipose tissue and skeletal muscle immunodetectable LPL and VLDL Receptor proteins. Protein restriction mitigated the decline in creatinine clearance, ameliorated proteinuria, hypoalbuminemia, hypertension, and hypercholesterolemia, lowered plasma VLDL, and improved plasma postheparin LPL activity, hepatic lipase activity, LPL, and VLDL Receptor proteins in skeletal muscle and adipose tissue. Similar improvements were observed in all parameters with AST administration. Conclusion Moderate protein restriction and use of oral adsorbent can slow progression of renal disease and, thereby, ameliorate LPL, hepatic lipase, and VLDL Receptor deficiencies and the associated hyperlipidemia in rats with spontaneous FGS.
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effect of diet on adipose tissue and skeletal muscle VLDL Receptor and lpl implications for obesity and hyperlipidemia
Atherosclerosis, 2002Co-Authors: Christian K Roberts, Kaihui Liang, James R Barnard, Nosratola D. VaziriAbstract:This study was designed to examine the effect of a high-fat (primarily saturated), refined-carbohydrate (sucrose) diet (HFS), which is known to induce obesity and hyperlipidemia, on adipose tissue and skeletal muscle lipoprotein lipase (LPL) and very-low density lipoprotein Receptor (VLDL-R) protein expressions. Female Fischer rats were placed on either a HFS or a low-fat, complex-carbohydrate (LFCC) diet for 22 months beginning at 2 months of age. After 20 months, a subgroup of the HFS rats were switched to the LFCC diet for 2 months (HFS/LFCC). Body weight, feed efficiency, plasma total cholesterol, VLDL-C, low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) concentrations and LDL-C to high-density lipoprotein cholesterol ratio were all significantly raised by the HFS diet and improved by conversion to the LFCC diet. Adipose tissue heparin-releasable, extractable and total LPL activity expressed per cell were significantly increased in the HFS-fed group. However, LPL protein abundance normalized against total cellular protein was unchanged in the HFS group. This observation is consistent with the presence of adipose tissue hypertrophy. Skeletal muscle LPL protein abundance and heparin-releasable activity were reduced by the HFS diet and improved after switching to the LFCC diet. Both adipose tissue and skeletal muscle VLDL-R protein levels were significantly reduced by the HFS diet and increased after conversion to the LFCC diet. We conclude that an HFS diet induces changes in LPL and VLDL-R in a manner which favors shunting of dietary fat from skeletal muscle to adipose tissue and decreases TG-rich lipoprotein clearance contributing to increased plasma lipids and obesity. Conversion to a LFCC diet can ameliorate the dyslipidemia and tissue changes induced by long-term HFS diet consumption.
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Down-regulation of lipoprotein lipase and VLDL Receptor in rats with focal glomerulosclerosis.
Kidney international, 2002Co-Authors: Tadashi Sato, Kaihui Liang, Nosratola D. VaziriAbstract:Down-regulation of lipoprotein lipase and VLDL Receptor in rats with focal glomerulosclerosis. Background Patients and animals with nephrotic syndrome and those with chronic renal failure (CRF) often exhibit hypertriglyceridemia and impaired very low-density lipoprotein (VLDL) clearance. Imai rats that were originally derived from Sprague-Dawley rats develop spontaneous proteinuria, hyperlipidemia, progressive renal insufficiency and histologic changes of focal glomerulosclerosis (FGS), closely resembling human FGS. This study was undertaken to test the hypothesis that elevation of plasma triglyceride and VLDL concentrations in the Imai rats is associated with deficiency of lipoprotein lipase (LPL) and VLDL Receptor which are the main pathways of triglyceride-rich lipoprotein clearance. Methods Male Imai and Sprague-Dawley control rats were fed regular rat chow and studied at 10 and 34 weeks of age. Tissue LPL and VLDL-r protein abundance (Western analysis) and post-heparin lipolytic activity were determined. Results At 10 weeks of age, Imai rats showed mild proteinuria, moderate hyperlipidemia, normal creatinine clearance and blood pressure. By 34 weeks of age, the study animal exhibited severe proteinuria, marked hyperlipidemia, significant renal insufficiency and hypertension. This was associated with a severe progressive reduction in skeletal muscle and adipose tissue LPL and VLDL-r protein abundance and depressed plasma post heparin, lipolytic activity. Conclusion Progressive hyperlipidemia in the Imai rats with spontaneous FGS is accompanied by severe combined LPL and VLDL-r deficiencies that can, in part, account for the associated hypertriglyceridemia and elevated plasma VLDL concentrations.
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effect of cyclosporine on hmg coa reductase cholesterol 7alpha hydroxylase ldl Receptor hdl Receptor VLDL Receptor and lipoprotein lipase expressions
Journal of Pharmacology and Experimental Therapeutics, 2000Co-Authors: Nosratola D. Vaziri, Kaihui Liang, Habib AzadAbstract:Long-term administration of cyclosporine (CsA) has been shown to cause hypercholesteremia, hypertriglyceridemia, and elevations of plasma low-density and very low-density lipoprotein (LDL and VLDL) levels in humans. This study was undertaken to explore the effects of CsA on expressions of the key lipid regulatory enzymes and Receptors. Thus, hepatic expressions of cholesterol 7alpha-hydroxylase (the rate-limiting step in cholesterol conversion to bile acids), LDL Receptor, and high-density lipoprotein (HDL) Receptor proteins, as well as 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity were determined in rats treated with CsA (18 mg/kg/day) or placebo for 3 weeks. In addition, skeletal muscle and adipose tissue expressions of lipoprotein lipase and VLDL Receptor were measured. Western blot analysis was used for all protein measurements using appropriate antibodies against the respective proteins. CsA-treated animals showed mild but significant elevations of plasma cholesterol and triglyceride concentrations. This was associated with a marked down-regulation of cholesterol 7alpha-hydroxylase in the liver and a severe reduction of lipoprotein lipase abundance in skeletal muscle and adipose tissue. However, hepatic LDL Receptor and HDL Receptor expressions and HMG-CoA reductase activity were not altered by CsA therapy. Likewise, skeletal muscle and adipose tissue VLDL Receptor protein expressions were unaffected by CsA administration under the given condition. In conclusion, CsA administration for 3 weeks resulted in a significant reduction of hepatic cholesterol 7alpha-hydroxylase and marked down-regulation of skeletal muscle and adipose tissue lipoprotein lipase abundance in rats. The former abnormality can contribute to hypercholesterolemia by limiting cholesterol catabolism, whereas the latter may contribute to hypertriglyceridemia and VLDL accumulation by limiting triglyceride-rich lipoprotein clearance in CsA-treated animals.
Tokuo Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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expression of the VLDL Receptor is up regulated by cell differentiation in hl 60 cells
2000Co-Authors: Sadao Takahashi, Jinya Suzuki, Tokuo Yamamoto, Mitsuyuki Kohno, Shotaro Kosaka, Katsuhiko Masamura, Koji Oida, Isamu MiyamoriAbstract:HL-60 cells were induced to differentiate into monocyte-macrophage. The level of VLDL Receptor mRNA and protein increased in a dose-dependent and time dependent manner after 1 α, 25-dihydroxyvitamin D3 administration. Whereas the level of LDL Receptor mRNA was not altered. On the other hand, VLDL Receptor mRNA level was not changed during differentiation of the cells into macrophagic cells with phorbol 12-myristate 13-acetate (PMA). Different levels of VLDL Receptor induction in the differentiation of HL-60 cells could provide significant information to investigate the regulation mechanisms for induction and function of VLDL Receptor.
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very low density lipoprotein Receptor binds apolipoprotein e2 2 as well as apolipoprotein e3 3
FEBS Letters, 1996Co-Authors: Sadao Takahashi, Jinya Suzuki, Tokuo Yamamoto, Mitsuyuki Kohno, Koji Oida, Minoru Ookubo, Toshio Murase, Tsuguhiko NakaiAbstract:Abstract The VLDL Receptor, a newly identified lipoprotein Receptor, recognizes apoE containing lipoproteins. The human VLDL Receptor was overexpressed in ldlA-7, a mutant Chinese hamster ovary cells lacking LDL Receptors. Each VLDL obtained from a normolipidemic subject with two e3 or e2 alleles similarly competed for the binding of radiolabeled rabbit β-VLDL to the VLDL Receptors. The anti-apoE monoclonal antibody 1D7, which inhibited binding of apoE3 to the LDL Receptors, failed to compete for the binding of VLDL (apoE3 or apoE2) to the VLDL Receptors. Results indicate that the binding site of apoE on the VLDL Receptor may differ from its binding site on the LDL Receptor.
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VLDL Receptor in health and disease interview with a Receptor in avian oocytes and mammalian muscle and fat cells
Journal of Atherosclerosis and Thrombosis, 1996Co-Authors: Hideaki Bujo, Tokuo YamamotoAbstract:The VLDL Receptor is made up of five functional domains that resemble the LDL Receptor. In mammals, the Receptor is highly expressed in muscle and fat cells, while in chicken, it is abundant in oocytes. The extremely high degree of amino acid conservation of the VLDL Receptor during the evolution suggests that the Receptor plays an essential role in vertebrates. Recent studies on the chicken VLDL Receptor revealed that the Receptor plays a key role in the uptake of yolk precursors in oocytes and mediates the growth of oocytes. The VLDL Receptor is an essential Receptor in avian species and the Receptor-deficient mutant hens are sterile and exhibit severe hyperlipidemia with aortic atherosclerosis.
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genetic association of the very low density lipoprotein VLDL Receptor gene with sporadic alzheimer s disease
Nature Genetics, 1995Co-Authors: Kaoru Okuizumi, Tokuo Yamamoto, Osamu Onodera, Yoshio Namba, Kazuhiko Ikeda, Koji Seki, Akira Ueki, Shinichiro Nanko, Hajime Tanaka, Hitoshi TakahashiAbstract:A specific isoform of apolipoprotein E has been associated with the accelerated rate of disease expression of sporadic Alzheimer's disease (AD) and late-onset familial AD (FAD)1–12. An earlier age at onset has also been demonstrated in familial AD patients with mutations in the amyloid precursor protein (APR) gene (APP717 and APP670/671)13 carrying the APOEɛ-4 allele compared to those who do not, but not in familial AD patients with APP692 or 693 mutations14, or in chromosome 14-linked familial AD patients15.Hypothesizing that Receptors for apoE-containing lipoprotein16–22 act as a potential risk factor for AD, we performed an association study using a polymorphic triplet (CGG) repeat21,23 in the gene for the VLDL Receptor (VLDL-R), a Receptor for apoE-containing lipoproteins.The frequency of the 5-repeat allele was significantly higher in all of the Japanese sporadic AD patients (P<0.02) than in the Japanese controls. Moreover, the odds ratio was significantly increased in the AD patients homozygous for the 5-repeat allele (OR=2.1,95% Cl=[1.1–4.2]). Multiple logistic regression analysis reveals that the relative risk conferred by the presence of two copies of the 5-repeat allele and at least one copy of the APOEɛ-4 allele is 8.7 (95% Cl=[2.9–25.8]). Our results suggest that the VLDL-R gene is a susceptibility gene for AD.
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normal plasma lipoproteins and fertility in gene targeted mice homozygous for a disruption in the gene encoding very low density lipoprotein Receptor
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Philip K Frykman, Tokuo Yamamoto, Michael S Brown, Joseph L Goldstein, Joachim HerzAbstract:The very low density lipoprotein (VLDL) Receptor is a recently cloned member of the low density lipoprotein (LDL) Receptor family that mediates the binding and uptake of VLDL when overexpressed in animal cells. Its sequence is 94% identical in humans and rabbits and 84% identical in humans and chickens, implying a conserved function. Its high level expression in muscle and adipose tissue suggests a role in VLDL triacylglycerol delivery. Mutations in the chicken homologue cause female sterility, owing to impaired VLDL and vitellogenin uptake during egg yolk formation. We used homologous recombination in mouse embryonic stem cells to produce homozygous knockout mice that lack immunodetectable VLDL Receptors. Homozygous mice of both sexes were viable and normally fertile. Plasma levels of cholesterol, triacylglycerol, and lipoproteins were normal when the mice were fed normal, high-carbohydrate, or high-fat diets. The sole abnormality detected was a modest decrease in body weight, body mass index, and adipose tissue mass as determined by the weights of epididymal fat pads. We conclude that the VLDL Receptor is not required for VLDL clearance from plasma or for ovulation in mice.
Johannes Nimpf - One of the best experts on this subject based on the ideXlab platform.
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Image_3_Differential Action of Reelin on Oligomerization of ApoER2 and VLDL Receptor in HEK293 Cells Assessed by Time-Resolved Anisotropy and Fluorescence Lifetime Imaging Microscopy.TIF
2019Co-Authors: Paula Dlugosz, Roland Tresky, Johannes NimpfAbstract:The canonical Reelin signaling cascade regulates correct neuronal layering during embryonic brain development. Details of this pathway are still not fully understood since the participating components are highly variable and create a complex mixture of interacting molecules. Reelin is proteolytically processed resulting in five different fragments some of which carrying the binding site for two different but highly homologous Receptors, apolipoprotein E Receptor 2 (ApoER2) and very low density lipoprotein Receptor (VLDLR). The Receptors are expressed in different variants in different areas of the developing brain. Binding of Reelin and its central fragment to the Receptors results in phosphorylation of the intracellular adapter disabled-1 (Dab1) in neurons. Here, we studied the changes of the arrangement of the Receptors upon Reelin binding and its central fragment at the molecular level in human embryonic kidney 293 (HEK293) cells by time-resolved anisotropy and fluorescence lifetime imaging microscopy (FLIM). In the off-state of the pathway ApoER2 and VLDLR form homo or hetero-di/oligomers. Upon binding of full length Reelin ApoER2 and VLDLR homo-oligomers are rearranged to higher order Receptor clusters which leads to Dab1 phosphorylation. When the central fragment of Reelin binds to the Receptors the cluster size of homo-oligomers is not affected and Dab1 is not phosphorylated. Hetero-oligomerization, however, can be induced, but does not lead to Dab1 phosphorylation. Cells expressing only ApoER2 or VLDLR change their shape when stimulated with the central fragment. Cells expressing ApoER2 produce filopodia/lamellipodia and cell size increases, whereas VLDLR-expressing cells decrease in size. These findings demonstrate that the primary event in the canonical Reelin pathway is the rearrangement of preformed Receptor homo-oligomers to higher order clusters. In addition the possibility of yet another signaling mechanism which is mediated by the central Reelin fragment independent of Dab1 phosphorylation became apparent.
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Differential Action of Reelin on Oligomerization of ApoER2 and VLDL Receptor in HEK293 Cells Assessed by Time-Resolved Anisotropy and Fluorescence Lifetime Imaging Microscopy
Frontiers Media S.A., 2019Co-Authors: Paula Dlugosz, Roland Tresky, Johannes NimpfAbstract:The canonical Reelin signaling cascade regulates correct neuronal layering during embryonic brain development. Details of this pathway are still not fully understood since the participating components are highly variable and create a complex mixture of interacting molecules. Reelin is proteolytically processed resulting in five different fragments some of which carrying the binding site for two different but highly homologous Receptors, apolipoprotein E Receptor 2 (ApoER2) and very low density lipoprotein Receptor (VLDLR). The Receptors are expressed in different variants in different areas of the developing brain. Binding of Reelin and its central fragment to the Receptors results in phosphorylation of the intracellular adapter disabled-1 (Dab1) in neurons. Here, we studied the changes of the arrangement of the Receptors upon Reelin binding and its central fragment at the molecular level in human embryonic kidney 293 (HEK293) cells by time-resolved anisotropy and fluorescence lifetime imaging microscopy (FLIM). In the off-state of the pathway ApoER2 and VLDLR form homo or hetero-di/oligomers. Upon binding of full length Reelin ApoER2 and VLDLR homo-oligomers are rearranged to higher order Receptor clusters which leads to Dab1 phosphorylation. When the central fragment of Reelin binds to the Receptors the cluster size of homo-oligomers is not affected and Dab1 is not phosphorylated. Hetero-oligomerization, however, can be induced, but does not lead to Dab1 phosphorylation. Cells expressing only ApoER2 or VLDLR change their shape when stimulated with the central fragment. Cells expressing ApoER2 produce filopodia/lamellipodia and cell size increases, whereas VLDLR-expressing cells decrease in size. These findings demonstrate that the primary event in the canonical Reelin pathway is the rearrangement of preformed Receptor homo-oligomers to higher order clusters. In addition the possibility of yet another signaling mechanism which is mediated by the central Reelin fragment independent of Dab1 phosphorylation became apparent
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Table_1_Differential Action of Reelin on Oligomerization of ApoER2 and VLDL Receptor in HEK293 Cells Assessed by Time-Resolved Anisotropy and Fluorescence Lifetime Imaging Microscopy.docx
2019Co-Authors: Paula Dlugosz, Roland Tresky, Johannes NimpfAbstract:The canonical Reelin signaling cascade regulates correct neuronal layering during embryonic brain development. Details of this pathway are still not fully understood since the participating components are highly variable and create a complex mixture of interacting molecules. Reelin is proteolytically processed resulting in five different fragments some of which carrying the binding site for two different but highly homologous Receptors, apolipoprotein E Receptor 2 (ApoER2) and very low density lipoprotein Receptor (VLDLR). The Receptors are expressed in different variants in different areas of the developing brain. Binding of Reelin and its central fragment to the Receptors results in phosphorylation of the intracellular adapter disabled-1 (Dab1) in neurons. Here, we studied the changes of the arrangement of the Receptors upon Reelin binding and its central fragment at the molecular level in human embryonic kidney 293 (HEK293) cells by time-resolved anisotropy and fluorescence lifetime imaging microscopy (FLIM). In the off-state of the pathway ApoER2 and VLDLR form homo or hetero-di/oligomers. Upon binding of full length Reelin ApoER2 and VLDLR homo-oligomers are rearranged to higher order Receptor clusters which leads to Dab1 phosphorylation. When the central fragment of Reelin binds to the Receptors the cluster size of homo-oligomers is not affected and Dab1 is not phosphorylated. Hetero-oligomerization, however, can be induced, but does not lead to Dab1 phosphorylation. Cells expressing only ApoER2 or VLDLR change their shape when stimulated with the central fragment. Cells expressing ApoER2 produce filopodia/lamellipodia and cell size increases, whereas VLDLR-expressing cells decrease in size. These findings demonstrate that the primary event in the canonical Reelin pathway is the rearrangement of preformed Receptor homo-oligomers to higher order clusters. In addition the possibility of yet another signaling mechanism which is mediated by the central Reelin fragment independent of Dab1 phosphorylation became apparent.
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The Reelin Receptors Apolipoprotein E Receptor 2 (ApoER2) and VLDL Receptor
MDPI AG, 2018Co-Authors: Paula Dlugosz, Johannes NimpfAbstract:Apolipoprotein E Receptor 2 (ApoER2) and VLDL Receptor belong to the low density lipoprotein Receptor family and bind apolipoprotein E. These Receptors interact with the clathrin machinery to mediate endocytosis of macromolecules but also interact with other adapter proteins to perform as signal transduction Receptors. The best characterized signaling pathway in which ApoER2 and VLDL Receptor (VLDLR) are involved is the Reelin pathway. This pathway plays a pivotal role in the development of laminated structures of the brain and in synaptic plasticity of the adult brain. Since Reelin and apolipoprotein E, are ligands of ApoER2 and VLDLR, these Receptors are of interest with respect to Alzheimer’s disease. We will focus this review on the complex structure of ApoER2 and VLDLR and a recently characterized ligand, namely clusterin
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differential functions of apoer2 and very low density lipoprotein Receptor in reelin signaling depend on differential sorting of the Receptors
Journal of Biological Chemistry, 2010Co-Authors: Sarah Duit, Sophia M Blake, Wolfgang J Schneider, Harald Mayer, Johannes NimpfAbstract:ApoER2 and very low density lipoprotein (VLDL) Receptor transmit the Reelin signal into target cells of the central nervous system. To a certain extent, both Receptors can compensate for each other, and only the loss of both Receptors results in the reeler phenotype, which is characterized by a gross defect in the architecture of laminated brain structures. Nevertheless, both Receptors also have specific distinct functions, as corroborated by analyses of the subtle phenotypes displayed in mice lacking either ApoER2 or VLDL Receptor. The differences in their function(s), however, have not been defined at the cellular level. Here, using a panel of chimeric Receptors, we demonstrate that endocytosis of Reelin and the fate of the individual Receptors upon stimulation are linked to their specific sorting to raft versus non-raft domains of the plasma membrane. VLDL Receptor residing in the non-raft domain endocytoses and destines Reelin for degradation via the clathrin-coated pit/clathrin-coated vesicle/endosome pathway without being degraded to a significant extent. Binding of Reelin to ApoER2, a resident of rafts, leads to the production of specific Receptor fragments with specific functions of their own and to degradation of ApoER2 via lysosomes. These features contribute to a Receptor-specific fine tuning of the Reelin signal, leading to a novel model that emphasizes negative feedback loops specifically mediated by ApoER2 and VLDL Receptor, respectively.
Leonid Medved - One of the best experts on this subject based on the ideXlab platform.
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fibrin VLDL Receptor dependent pathway promotes leukocyte transmigration by inhibiting src kinase fyn and is a target for fibrin β15 42 peptide
Thrombosis and Haemostasis, 2019Co-Authors: Sergiy Yakovlev, Dudley K. Strickland, Chunzhang Cao, Li Zhang, Rebeca Galisteo, Leonid MedvedAbstract:According to the current view, binding of fibrin degradation product E1 fragment to endothelial VE-cadherin promotes transendothelial migration of leukocytes and thereby inflammation, and fibrin-derived β15-42 peptide reduces leukocyte transmigration by competing with E1 for binding to VE-cadherin and, in addition, by signaling through Src kinase Fyn. However, the very low affinity of β15-42 to VE-cadherin raised a question about its ability to inhibit E1-VE-cadherin interaction. Further, our previous study revealed that fibrin promotes leukocyte transmigration through the very-low-density lipoprotein (VLDL) Receptor (VLDLR)-dependent pathway and suggested a possible link between the inhibitory properties of β15-42 and this pathway. To test such a link and the proposed inhibitory mechanisms for β15-42, we performed in vitro experiments using surface plasmon resonance, enzyme-linked immunosorbent assay, and leukocyte transendothelial migration assay, and in vivo studies with wild-type and VLDLR-deficient mice using mouse model of peritonitis. The experiments revealed that β15-42 cannot inhibit E1-VE-cadherin interaction at the concentrations used in the previous in vivo studies leaving the proposed Fyn-dependent signaling mechanism as a viable explanation for the inhibitory effect of β15-42. While testing this mechanism, we confirmed that Fyn plays a critical role in controlling fibrin-induced transendothelial migration of leukocytes and found that signaling through the VLDLR-dependent pathway results in inhibition of Fyn, thereby increasing leukocyte transmigration. Furthermore, our in vivo experiments revealed that β15-42 inhibits this pathway, thereby preventing inhibition of Fyn and reducing leukocyte transmigration. Thus, this study clarifies the molecular mechanism underlying the VLDLR-dependent pathway of leukocyte transmigration and reveals that this pathway is a target for β15-42.
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nuclear magnetic resonance solution structure of the recombinant fragment containing three fibrin binding cysteine rich domains of the very low density lipoprotein Receptor
Biochemistry, 2018Co-Authors: Koyeli Banerjee, Sergiy Yakovlev, Leonid Medved, James M Gruschus, Nico TjandraAbstract:Our previous studies revealed that interaction of fibrin with the very low density lipoprotein (VLDL) Receptor plays a prominent role in transendothelial migration of leukocytes and thereby inflammation. The major goal of our subsequent studies is to establish the structural basis for this interaction. As the first step toward this goal, we localized the fibrin-binding sites within cysteine-rich (CR) domains 2–4 of the VLDL Receptor. In this study, we have made a next step toward this goal by establishing the nuclear magnetic resonance solution structure of the recombinant VLDLR(2–4) fragment containing all three fibrin-binding CR domains of this Receptor. The structure revealed that all three CR domains have a similar general fold. Each domain contains a calcium-binding loop, and the loop in the CR3 domain has a unique conformation relative to the other two. Domains CR2 and CR3 interact with each other, while CR4 is flexible relative to the other two domains. In addition, analysis of the electrostatic po...
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nuclear magnetic resonance solution structure of the recombinant fragment containing three fibrin binding cysteine rich domains of the very low density lipoprotein Receptor
Biochemistry, 2018Co-Authors: Koyeli Banerjee, Sergiy Yakovlev, Leonid Medved, James M Gruschus, Nico TjandraAbstract:Our previous studies revealed that interaction of fibrin with the very low density lipoprotein (VLDL) Receptor plays a prominent role in transendothelial migration of leukocytes and thereby inflammation. The major goal of our subsequent studies is to establish the structural basis for this interaction. As the first step toward this goal, we localized the fibrin-binding sites within cysteine-rich (CR) domains 2-4 of the VLDL Receptor. In this study, we have made a next step toward this goal by establishing the nuclear magnetic resonance solution structure of the recombinant VLDLR(2-4) fragment containing all three fibrin-binding CR domains of this Receptor. The structure revealed that all three CR domains have a similar general fold. Each domain contains a calcium-binding loop, and the loop in the CR3 domain has a unique conformation relative to the other two. Domains CR2 and CR3 interact with each other, while CR4 is flexible relative to the other two domains. In addition, analysis of the electrostatic potential surface of VLDLR(2-4) revealed extended negatively charged regions in each of its CR domains. The presence of these regions suggests that they may interact with three positively charged clusters of the fibrin βN domain whose involvement in interaction with the VLDL Receptor was demonstrated earlier. Altogether, these findings provide a solid background for our next step toward establishing the structural basis for fibrin-VLDL Receptor interaction.
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interaction of fibrin with the very low density lipoprotein VLDL Receptor further characterization and localization of the VLDL Receptor binding site in fibrin βn domains
Biochemistry, 2017Co-Authors: Sergiy Yakovlev, Leonid MedvedAbstract:Our recent study revealed that fibrin and the very low-density lipoprotein Receptor (VLDLR) interact with each other through a pair of fibrin βN-domains and CR domains of the Receptor and this interaction promotes transendothelial migration of leukocytes and thereby inflammation. The major objectives of this study were to further clarify the molecular mechanism of fibrin–VLDLR interaction and to identify amino acid residues in the βN-domains involved in this interaction. Our binding experiments with the (β15–66)2 fragment, which corresponds to a pair of fibrin βN-domains, and the VLDLR(1–8) fragment, consisting of eight CR domains of VLDLR, revealed that interaction between them strongly depends on ionic strength and chemical modification of all Lys or Arg residues in (β15–66)2 results in abrogation of this interaction. To identify which of these residues are involved in the interaction, we mutated all Lys or Arg residues in each of the three positively charged Lys/Arg clusters of the (β15–66)2 fragment, ...
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anti VLDL Receptor monoclonal antibodies inhibit fibrin VLDL Receptor interaction and reduce fibrin dependent leukocyte transmigration
Thrombosis and Haemostasis, 2016Co-Authors: Sergiy Yakovlev, Dudley K. Strickland, Alexey M Belkin, Ling Chen, Chunzhang Cao, Li Zhang, Leonid MedvedAbstract:Our previous studies revealed that the interaction of fibrin with the very low density lipoprotein Receptor (VLDLR) promotes transendothelial migration of leukocytes and thereby inflammation, and localised the fibrin-binding site to CR-domains 2–4 of this Receptor. In the present study, we tested interaction of three anti-VLDLR monoclonal antibodies, mAb 1H10, 1H5, and 5F3, with recombinant fragments of VLDLR containing various combinations of its CR-domains and found that the epitopes for mAb 1H10 and mAb 1H5 overlap with the fibrin-binding site of VLDLR. Based on these findings, we hypothesised that mAb 1H10 and mAb 1H5 should inhibit fibrin-VLDLR interaction and modulate leukocyte transmigration. To test this hypothesis, we first demonstrated that these monoclonal antibodies both have high affinity to the fibrin-binding fragments of the VLDL Receptor and efficiently inhibit interaction between the VLDLR-binding fragment of fibrin and the fibrin-binding fragments of VLDLR. Next, in the in vitro experiments using leukocyte transendothelial migration assay we found that both monoclonal antibodies efficiently inhibit leukocyte transmigration induced by fibrin mimetic NDSK-II. Finally, in vivo experiments using mouse model of peritonitis revealed that mAb 1H10 and mAb 1H5 both significantly reduce infiltration of leukocytes into the peritoneum. Furthermore, our experiments using mouse model of myocardial ischemia-reperfusion injury revealed that both monoclonal antibodies significantly reduce myocardial injury induced by ischaemia-reperfusion. Thus, the results obtained indicate that monoclonal antibodies 1H10 and 1H5 are novel specific inhibitors of fibrin-VLDLR-dependent leukocyte transmigration pathway. They may represent potential therapeutics for treatment of fibrin-dependent inflammation including myocardial ischaemia-reperfusion injury.
