Cos cells overexpressing the LDL-receptor take up Apo E from fresh cerebrospinal fluid

1994 ◽  
Vol 15 ◽  
pp. S16
Keyword(s):  
Cerebrospinal Fluid ◽  
Ldl Receptor ◽  
Cos Cells ◽  
Apo E

scholarly journals Marked increases in concentrations of apolipoprotein in the cerebrospinal fluid of poliovirus-infected macaques: relations between apolipoprotein concentrations and severity of brain injury

1997 ◽  
Vol 321 (1) ◽  
pp. 145-149 ◽  
Author(s):  
Kuniaki SAITO ◽  
Mitsuru SEISHIMA ◽  
Melvyn P. HEYES ◽  
Hua SONG ◽  
Suwako FUJIGAKI ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Motor Impairment ◽  
Motor Deficits ◽  
Cns Injury ◽  
Functional Roles ◽  
Apolipoprotein A ◽  
Apo E ◽  
Complete Paralysis ◽  
The Central Nervous System ◽  
Vascular Component

Apolipoproteins in cerebrospinal fluid (CSF) might have important functional roles in the pathophysiology of brain and lipid metabolism in the vascular component. The present study examined apolipoprotein A-I (apo-A-I) and apolipoprotein E (apo-E) levels in CSF and serum from poliovirus-infected macaques. Poliovirus-infected macaques developed motor deficits and were classified into three groups: (1) muscle weakness in one or both legs; (2) partial paralysis in one or both legs; (3) complete paralysis in one or both legs. No motor deficits were evident in the control or sham-treated macaques. Apo-A-I concentrations in CSF were markedly elevated in poliovirus-infected macaques with weakness, partial or complete paralysis, in comparison with either control or sham-treated animals, and were proportional to the severity of motor impairment. Apo-E concentrations in CSF were also significantly elevated in poliovirus-infected macaques with complete paralysis. The magnitude of increase in CSF apo-A-I or apo-E concentrations was also closely associated with the degree of histologic neurological damage and inflammation (lesion scores). However, no changes in serum apo-A-I and apo-E concentrations were observed in the poliovirus-infected macaques compared with control macaques. Furthermore there were no significant correlations apo-A-I or apo-E concentrations between serum and CSF. We hypothesize that the elevation of apo-A-I and apo-E concentrations after poliovirus infection is caused by immune stimulation within the central nervous system (CNS). Measures of CSF apo-A-I and apo-E levels might serve as a useful marker for the severity and/or the range of CNS injury.

scholarly journals Phagocytic chimeric receptors require both transmembrane and cytoplasmic domains from the mannose receptor.

1992 ◽  
Vol 176 (6) ◽  
pp. 1673-1680 ◽  
Author(s):  
B A Kruskal ◽  
K Sastry ◽  
A B Warner ◽  
C E Mathieu ◽  
R A Ezekowitz
Keyword(s):  
Pneumocystis Carinii ◽  
Ldl Receptor ◽  
Cytoplasmic Tail ◽  
Mannose Receptor ◽  
Fc Receptor ◽  
Site Directed Mutagenesis ◽  
Cytoplasmic Domains ◽  
Phagocytic Cells ◽  
Chimeric Receptors ◽  
Cos Cells

Phagocytosis has traditionally been viewed as a specialized function of myeloid and monocytic cells. The mannose receptor (MR) is an opsonin-independent phagocytic receptor expressed on tissue macrophages. When human MR cDNA is transfected into Cos cells, these usually non-phagocytic cells express cell surface MR and bind and ingest MR ligands such as zymosan, yeast, and Pneumocystis carinii. Expression of cDNA for Fc gamma RI (CD64), the high-affinity Fc receptor, in Cos cells confers binding but barely detectable phagocytosis of antibody-opsonized erythrocytes (EA). We report here that chimeric receptors containing the ligand-binding ectodomain of the Fc receptor and the transmembrane and cytoplasmic domains of the MR ingest bound EA very efficiently, whereas chimeras with the Fc receptor ecto- and transmembrane domains and the MR tail, or the Fc receptor ecto- and cytoplasmic domains and the MR transmembrane region, are significantly less phagocytic. All of the chimeric receptors bind ligand with equal avidity, but gain of functional phagocytosis is only conferred by the MR transmembrane and cytoplasmic domains. Endocytosis of monomeric immunoglobulin G by chimeric receptors demonstrates a similar pattern, with optimal uptake by the chimera containing both tail and transmembrane regions from the MR. The chimeric receptors with only the transmembrane or the cytoplasmic domain contributed by the MR were less efficient. Site-directed mutagenesis of the single tyrosine residue in the cytoplasmic tail (which is present in a motif homologous to an endocytosis consensus motif in the LDL receptor cytoplasmic tail [Chen, W.-J., J. L. Goldstein, and M. S. Brown. 1990. J. Biol. Chem. 265:3116]) reduces the efficiency of phagocytosis and endocytosis to a similar extent.

scholarly journals Characterization of Apolipoprotein E-containing Lipoproteins in Cerebrospinal Fluid: Effect of Phenotype on the Distribution of Apolipoprotein E

1999 ◽  
Vol 45 (9) ◽  
pp. 1431-1438 ◽  
Author(s):  
Kazuyoshi Yamauchi ◽  
Minoru Tozuka ◽  
Hiroya Hidaka ◽  
Eiko Hidaka ◽  
Yoshiyuki Kondo ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Apolipoprotein E ◽  
Gel Filtration ◽  
Distribution Profile ◽  
Serum Fractions ◽  
Apo E ◽  
The Central Nervous System ◽  
Unique Composition ◽  
Apoe Phenotype

Abstract Background: Apolipoprotein (apo) E, one of the main apolipoproteins in the central nervous system, may play an important role in lipid metabolism; however, the details of its function are poorly understood. In this study, we characterized apoE-containing lipoproteins in cerebrospinal fluid (CSF) and examined the effect of apoE phenotype on the distribution of apoE among the lipoprotein fractions. Methods: CSF lipoproteins were fractionated by gel filtration and ultracentrifugation, and then characterized by electrophoresis, immunoblot, electron microscopy, and analysis of apoE, total cholesterol, and phospholipid concentrations. Results: The ratio of sialylated to nonsialylated apoE was higher in CSF than in serum. However, the fundamental forms containing apoE homodimers or heterodimers [such as apo(E-AII) and apo(AII-E2-AII) complexes] were similar in CSF and serum. apoE-containing lipoproteins were fractionated at densities of <1.006, 1.063–1.125, and 1.125–1.21 kg/L. Neither apoE nor apoAI was detected in the fraction with a density range of 1.006–1.063 kg/L. The diameters of the lipoprotein particles with densities of <1.006, 1.063–1.125, and 1.125–1.21 kg/L were 16.7 ± 3.1, 14.0 ± 3.2, and 11.6 ± 2.8 nm (mean ± SD, n = 200), respectively. All of these lipoproteins exhibited a spherical structure. The distribution profile of apoE-containing lipoproteins was affected by the apoE phenotype. A relatively large amount of apoE-containing lipoproteins was isolated from the fraction with a density >1.125 kg/L obtained from CSF associated with apoE2 or apoE3. This tendency was more obvious in CSF associated with apoE2 than in CSF without apoE2. apoE-containing lipoproteins were predominantly observed in the fraction with a density of <1.006 kg/L obtained from CSF associated with apoE4. Conclusions: The lipoproteins in CSF have a unique composition that is different from that of the lipoproteins in plasma. However, the differences in diameter between the CSF fractions were not as large as for the serum fractions. Our data suggest that the apoE phenotype may affect the distribution profile of apoE-containing lipoproteins in the CSF. This would mean that the metabolism of apoE-containing lipoproteins depends on the apoE isoform present.

scholarly journals The influence of particle size and multiple apoprotein E-receptor interactions on the endocytic targeting of beta-VLDL in mouse peritoneal macrophages.

1991 ◽  
Vol 115 (6) ◽  
pp. 1547-1560 ◽  
Author(s):  
I Tabas ◽  
J N Myers ◽  
T L Innerarity ◽  
X X Xu ◽  
K Arnold ◽  
...  
Keyword(s):  
Low Density Lipoprotein ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Peritoneal Macrophages ◽  
Low Density ◽  
Cholesterol Acyl Transferase ◽  
Ldl Receptors ◽  
Apo E ◽  
Partial Neutralization ◽  
Mouse Peritoneal Macrophages

Low density lipoprotein (LDL) and beta-very low density lipoprotein (beta-VLDL) are internalized by the same receptor in mouse peritoneal macrophages and yet their endocytic patterns differ; beta-VLDL is targeted to both widely distributed and perinuclear vesicles, whereas LDL is targeted almost entirely to perinuclear lysosomes. This endocytic divergence may have important metabolic consequences since beta-VLDL is catabolized slower than LDL and is a more potent stimulator of acyl-CoA/cholesterol acyl transferase (ACAT) than LDL. The goal of this study was to explore the determinants of beta-VLDL responsible for its pattern of endocytic targeting. Fluorescence microscopy experiments revealed that large, intestinally derived, apoprotein (Apo) E-rich beta-VLDL was targeted mostly to widely distributed vesicles, whereas small, hepatically derived beta-VLDL was targeted more centrally (like LDL). Furthermore, the large beta-VLDL had a higher ACAT-stimulatory potential than the smaller beta-VLDL. The basis for these differences was not due to fundamental differences in the means of uptake; both large and small beta-VLDL were internalized by receptor-mediated endocytosis (i.e., not phagocytosis) involving the interaction of Apo E of the beta-VLDL with the macrophage LDL receptor. However, large beta-VLDL was much more resistant to acid-mediated release from LDL receptors than small beta-VLDL. Furthermore, partial neutralization of the multiple Apo Es on these particles by immunotitration resulted in a more perinuclear endocytic pattern, a lower ACAT-stimulatory potential, and an increased sensitivity to acid-mediated receptor release. These data are consistent with the hypothesis that the interaction of the multivalent Apo Es of large beta-VLDL with multiple macrophage LDL receptors leads to a diminished or retarded release of the beta-VLDL from its receptor in the acidic sorting endosome which, in turn, may lead to the widely distributed endocytic pattern of large beta-VLDL. These findings may represent a physiologically relevant example of a previously described laboratory phenomenon whereby receptor cross-linking by multivalent ligands leads to a change in receptor targeting.

Changes in cerebrospinal fluid IgG and apolipoprotein E indices in patients with multiple sclerosis during demyelination and remyelination.

1987 ◽  
Vol 33 (7) ◽  
pp. 1155-1157 ◽  
Author(s):  
N Rifai ◽  
R H Christenson ◽  
B B Gelman ◽  
L M Silverman
Keyword(s):  
Multiple Sclerosis ◽  
Cerebrospinal Fluid ◽  
Apolipoprotein E ◽  
Clinical Remission ◽  
Laboratory Evaluation ◽  
Apo E ◽  
Igg Index ◽  
Oligoclonal Banding ◽  
Reliable Marker

Abstract Approximately 85% of patients with multiple sclerosis (MS) can be diagnosed by using magnetic resonance imaging and laboratory tests such as determination of the cerebrospinal fluid (CSF) IgG Index and electrophoresis to detect oligoclonal banding. However, these tests results are abnormal in MS patients whether they are in clinical remission or acute exacerbation. Because apolipoprotein E (apo E) is synthesized in the central and peripheral nervous system, particularly during remyelination, we propose that apo E might be a reliable marker of the remyelination that accompanies clinical remission in MS patients. We studied 33 patients with MS, 22 in remission and 11 in exacerbation, and 26 controls of comparable ages. The apo E Index, calculated from the concentrations of apo E and albumin in CSF and serum, allowed us to discriminate between MS patients in remission and MS patients in exacerbation (P less than 0.001); the IgG Index failed to show similar differences. However, combining the apo E and IgG indices gave maximum discrimination between controls, MS patients in remission, and those in exacerbation. This study suggests that apo E measurements should be included in the laboratory evaluation of MS patients.

scholarly journals Apolipoprotein E in Cerebrospinal Fluid: Relation to Phenotype and Plasma Apolipoprotein E Concentrations

1999 ◽  
Vol 45 (4) ◽  
pp. 497-504 ◽  
Author(s):  
Kazuyoshi Yamauchi ◽  
Minoru Tozuka ◽  
Tetsuo Nakabayashi ◽  
Mitsutoshi Sugano ◽  
Hiroya Hidaka ◽  
...  
Keyword(s):  
Cerebrospinal Fluid ◽  
Detection Limit ◽  
Apolipoprotein E ◽  
Nervous Tissue ◽  
Central Nervous Tissue ◽  
Apo E ◽  
The Mean ◽  
Apoe Phenotype ◽  
Plasma Apolipoprotein ◽  
Number Of Cells

Abstract Background: Apolipoprotein (apo) E may be related to the development of Alzheimer disease, but data on apoE in cerebrospinal fluid (CSF) are limited. The aim of the present study was to measure apoE in CSF and relate its concentrations to apoE phenotype and CSF lipids. Methods: We adapted an assay for CSF apoE sensitivity using an ELISA. It allowed us to measure CSF apoE with sufficient reproducibility and precision. Results: The within- and between-run CVs were <7%, and the detection limit was 0.025 mg/L. No cross-reaction was found for other apolipoproteins. No significant differences related to sex or apoE phenotype were observed in the CSF apoE concentration. The mean CSF apoE concentration was significantly higher in the 0–5 year group (n = 6; 18.47 ± 1.14 mg/L, mean ± SD) than in the >5 year group (n = 34; 8.82 ± 3.31 mg/L). The mean concentrations of total cholesterol (TC) and phospholipid (PL) in CSF were 2.68 ± 2.16 and 6.50 ± 2.84 mg/L (n = 52), respectively. Although no significant differences in TC or PL in the CSF were found with respect to sex or age, the concentrations in subjects with the apoE phenotype E4/E3 were significantly lower than in those with E3/E3 and E3/E2. The concentrations of apoE, TC, and PL in CSF did not correlate with those in plasma. The time-related fluctuations in CSF apoE were independent of those in total protein and IgG. CSF apoE was significantly correlated with TC and PL concentrations in the CSF, but not with the number of cells in the CSF. Conclusions: These findings support the idea that apoE and lipids are unable to cross the blood-brain barrier and that their concentrations in CSF may reflect production in central nervous tissue.

Abstract 429: Structural Stability of Streptococcal Serum Opacity Factor

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Corina Rosales ◽  
Baiba K Gillard ◽  
Dedipya Yelamanchili ◽  
Antonio M Gotto ◽  
Henry J Pownall
Keyword(s):  
Disulfide Bonds ◽  
Plasma Cholesterol ◽  
Ldl Receptor ◽  
Density Lipoprotein ◽  
Cholesterol Levels ◽  
Serum Opacity Factor ◽  
Apo E ◽  
Plasma High Density

Despite its putative cardioprotective qualities, raising plasma high density lipoprotein-cholesterol (HDL-C) levels via pharmacologic means has failed to add protection against atherosclerosis, particularly when used as co-therapy with a statin. Two scenarios argue against the raising-plasma-HDL-is-better hypothesis and suggest that enhancing the final RCT step, hepatic cholesterol disposal, is a better cardioprotective strategy. First, probucol prevents CVD events and increases survival in humans and reduces CVD in SR-BI/apo E DKO mice. Despite its anti atherogenic properties, probucol lowers plasma HDL-C levels. Second, SR-BI over expressing vs. WT mice have lower plasma HDL-C but less atherosclerosis whereas the converse is true in SR-BI KO mice, suggesting that increasing HDL-C disposal is a rational cardioprotective strategy. One possible agent for therapeutic development is streptococcal serum opacity factor (SOF), a 100 kDa protein that clouds human serum via a novel HDL-targeting mechanism. SOF diverts HDL-CE to the LDL receptor and to bile acid secretion in vitro and in vivo, increases plasma HDL-C clearance in mice in an apo E-, LDLR-dependent mechanism thereby increasing hepatic CE uptake and reducing plasma cholesterol levels. SOF is active at 10 -14 M. Given its novel mechanism and potent reduction of plasma cholesterol levels in mice, we studied the structure and stability of SOF using its activity as a marker of its integrity versus several physicochemical challenges—extremes of pH, the denaturant, guanidinium chloride, heat, and ionic strength. SOF was highly resistant to all of these challenges. SOF has only one cysteine so it cannot be stabilized by internal disulfide bonds. Thus, SOF is an unusually stable protein that undergoes reversible unfolding-folding when challenged with a variety of physicochemical perturbants. These studies have helped us identify optimal conditions for crystallizing SOF for X-ray structure analysis.

Receptor interactions controlling lipoprotein metabolism

1985 ◽  
Vol 63 (8) ◽  
pp. 898-905 ◽  
Author(s):  
Karl H. Weisgraber ◽  
Thomas L. Innerarity ◽  
Stanley C. Rall Jr. ◽  
Robert W. Mahley
Keyword(s):  
Receptor Binding ◽  
Cholesterol Metabolism ◽  
Ldl Receptor ◽  
Lipoprotein Metabolism ◽  
Binding Domain ◽  
Cholesterol Homeostasis ◽  
Lipoprotein Receptor ◽  
Receptor Binding Domain ◽  
Apo B ◽  
Apo E

Lipoprotein receptors play a central role in lipoprotein metabolism and a major role in cholesterol homeostasis. The most completely characterized lipoprotein receptor is the LDL (low density lipoprotein) or apo-B,E(LDL) receptor. The apo-B,E(LDL) receptor is present on both hepatic and extrahepatic cells and is responsible for the metabolism of a major portion of plasma LDL. Binding and internalization of LDL particles by this receptor initiates a series of intracellular events, resulting in the regulation of cellular cholesterol metabolism. In addition to the apo-B on LDL interacting with the apo-B,E(LDL) receptor, the apo-E on apo-E-containing lipoproteins is also capable of interacting and regulating intracellular cholesterol metabolism. The liver has also been shown to contain a second distinct lipoprotein receptor that is specific for apo-E. This receptor has been demonstrated on hepatic membranes from humans, dogs, and swine and is referred to as the apo-E receptor. This receptor may be responsible for the clearance of chylomicron remnants from plasma by the liver and may participate in reverse cholesterol transport. Thus, apo-E is a major determinant in lipoprotein metabolism and cholesterol homeostasis. The receptor binding properties of apo-E are well characterized, and a series of structural variants, several with lipoprotein binding defects, have been identified. Studies of the binding activity of these receptor-defective apo-E variants have helped to define the receptor binding domain of apo-E. These results, in conjunction with receptor binding studies with various apo-E fragments and with an apo-E monoclonal antibody that inhibits receptor binding, have demonstrated that the receptor binding domain is located in the center of the molecule between residues 140 and 160.

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