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PubMed1987

Progression and regression of human coronary atherosclerosis. The role of lipoproteins, lipases and thyroid hormones in coronary lesion growth.

Relations between lipoprotein fractions, lipoprotein lipase activities, thyroid hormones and coronary lesion growth were studied among 35 male patients with severe coronary atherosclerosis, who had participated in the lipid lowering, dietary Leiden Intervention Trial. Coronary arteriographies were performed at the beginning of the study and 2 years later at termination. The coronary anatomy was quantitated with a computer-based analysis system to assess the progression rate of coronary atherosclerosis on the basis of the absolute arterial dimensions in a patient's coronary tree; for these purposes an absolute coronary score was computed. On the basis of the absolute coronary scores, the entire group of patients could be divided into a no lesion growth group (14 patients) and a progression group (21 patients). Lipoprotein fractions, lipoprotein lipases and thyroid hormones were determined at the end of the trial. No significant difference was found between the no lesion growth and progression groups of patients for total cholesterol (TC) and LDL-cholesterol (LDL-C). The VLDL-cholesterol (VLDL-C) and triglycerides (TG) were significantly higher (P less than 0.05) and HDL-C was almost significantly lower (P less than 0.10) in the progression group. Hepatic lipase (HL) values were significantly higher in the no lesion growth group, as compared to the progression group, whereas lipoprotein lipase (LPL) values were not significantly different. Triiodothyronine (T3) was significantly lower (P less than 0.01) in the progression group. Multivariate regression analysis showed HL to be the most important determinant of changes in coronary atherosclerotic lesions. T3 and HDL were also independently inversely related to coronary atherosclerotic lesion growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiocardiography↗

PubMed1990

C-terminal domain of apolipoprotein CII as both activator and competitive inhibitor of lipoprotein lipase.

In this study we have prepared peptides of the C-terminal domain of apolipoprotein CII (ApoCII) by a solid-peptide-synthesis technique and demonstrated that the C-terminal tetrapeptide, Lys-Gly-Glu-Glu, represents an inhibitor of lipoprotein lipase. The tetrapeptide not only inhibits the basal activity of lipoprotein lipase, but also blocks the activation effect of native ApoCII. The lengthening of this tetrapeptide resulted in a corresponding increase in affinity for lipoprotein lipase. This suggested that amino acids other than those of the C-terminal tetrapeptide also contribute to the binding affinity of ApoCII for lipoprotein lipase. On the basis of an essential requirement of the ApoCII terminal domain for binding to lipoprotein lipase, we suggest that the initial interaction of ApoCII, mediated via the C-terminal tetrapeptide, promotes the proper alignment of ApoCII with lipoprotein lipase, followed by the weak interaction of the ApoCII activator domain with the lipoprotein lipase activator site, enhancing the lipolysis process.

Amino Acid Sequence↗

PubMed1992

Dietary fish protein modulates high density lipoprotein cholesterol and lipoprotein lipase activity in rabbits.

To explore the pathways by which fish protein feeding influences HDL metabolism, postheparin plasma lipoprotein lipase and hepatic triglyceride lipase activities were measured in rabbits fed fish protein or soybean protein combined with corn oil or coconut oil in a 2 x 2 factorial arrangement. In addition to greater serum total and LDL-cholesterol concentrations, the elevated HDL cholesterol concentration caused by feeding fish protein, compared with soybean protein, was accompanied by lower VLDL triglycerides and parallel higher lipoprotein lipase activity in fish protein-fed rabbits. These results suggest an enhanced assembly of circulating HDL through promoted lipoprotein lipase activity in rabbits fed fish protein. Moreover, dietary proteins and lipids interacted with one another to alter HDL triglycerides and liver cholesterol concentrations. Diet-induced changes in lipoprotein lipase activity were, however, not related to insulinemia, which was unaltered by purified diet feeding. The present results suggest that fish protein may affect HDL metabolism through the modulation of lipoprotein lipase activity in rabbits.

Animals↗

PubMed2002

[Clinical significance of preheparin serum lipoprotein lipase mass in normocholesterolemic patients with coronary artery disease].

OBJECTIVES: Some normocholesterolemic patients have coronary artery disease (CAD) in Japan. This study evaluated the clinical significance of preheparin lipoprotein lipase mass as a risk factor for normocholesterolemic patients with CAD. METHODS: This study included 89 normocholesterolemic male patients with CAD (CAD group, 40 with stable organic angina pectoris, 19 with vasospastic angina pectoris, and 30 with acute myocardial infarction), and 13 normocholesterolemic males with normal coronary arteries (control group) with no stenotic lesion and negative reaction to intracoronary administration of acetylcholine. Preheparin lipoprotein lipase mass was measured by enzyme-linked immunosorbent assay. Coronary risk factors including preheparin lipoprotein lipase mass were compared between the two groups. Low-density lipoprotein (LDL) particle size and presence of midband were estimated by polyacrylamide gel disc electrophoresis. RESULTS: Mild hypertriglyceridemia and low high-density lipoprotein (HDL) cholesterolemia were observed in the CAD group, and small particle size LDL and presence of midband were also common in the CAD group. Preheparin lipoprotein lipase mass level was significantly lower in the CAD group than the control group (52 +/- 18 vs 40 +/- 13 ng/ml, p = 0.005) as well as in each type of patient in the CAD group. Multiple regression analysis showed that small particle size LDL, low preheparin lipoprotein lipase mass and smoking were independent risk factors for CAD (p < 0.001, p = 0.007, p = 0.037). Low preheparin lipoprotein lipase mass concentration was observed in the small particle size LDL group and/or the midband positive group. CONCLUSIONS: These results indicate that low preheparin lipoprotein lipase mass reflects insulin resistance and may be deeply involved in the progression of coronary arteriosclerosis.

Cholesterol↗

PubMed1983

The inhibitory effect of lipid peroxide on the activity of the membrane-bound and the solubilized lipoprotein lipase.

The effects of lipid peroxide (15-hydroperoxy arachidonic acid) on the activity of lipoprotein lipase was investigated. The activities were examined in 2 enzyme species: the lipoprotein lipase bound to the coronary vessels of the rat heart and that solubilized in the human post-heparin plasma. As a substrate, 3H-labelled human chylomicron was used. Lipid peroxide decreased the maximal velocity of the reaction between the chylomicron and lipoprotein lipase on the vascular surface. In the post-heparin plasma, the lipid peroxide decreased the maximal hydrolysis rate, but did not change the half life time in the unsaturated reaction. It is suggested that lipid peroxide directly damages a part of the membrane-bound lipoprotein lipase, and that the degeneration of cell membranes and the vasoconstriction caused by lipid peroxide will additionally disturb the hydrolysis of the plasma triglyceride on the vascular surface.

Animals↗

PubMed1996

Molecular characterization of quail apolipoprotein very-low-density lipoprotein II: disulphide-bond-mediated dimerization is not essential for inhibition of lipoprotein lipase.

As part of the avian reproductive effort, large quantities of triglyceride-rich very-low-density lipoprotein (VLDL) particles are transported by receptor-mediated endocytosis into the female germ cells. Although the oocytes are surrounded by a layer of granulosa cells harbouring high levels of active lipoprotein lipase, non-lipolysed VLDL is transported into the yolk. This is because VLDL particles from laying chickens are protected from lipolysis by apolipoprotein (apo)-VLDL-II, a potent dimeric lipoprotein lipase inhibitor [Schneider, Carroll, Severson and Nimpf (1990) J. Lipid Res. 31, 507-513]. To determine whether this protection depends on dimer formation and constitutes a general mechanism to ensure high levels of yolk triglycerides for embryonic utilization in birds, we have now molecularly characterized apo-VLDL-II in the Japanese quail, a frequently used avian species. Quail apo-VLDL-II shows 72% amino acid identity with the chicken protein, with most replacements being in the C-terminal region. Importantly, quail apo-VLDL-II lacks the single cysteine residue present eight residues from the C-terminus of chicken apo-VLDL-II, which is responsible for dimerization of the chicken lipoprotein lipase inhibitor. Nevertheless, monomeric quail and dimeric chicken apo-VLDL-II display, on a molar basis, identical inhibitory effects on lipoprotein lipase, underscoring the biological importance of their function. Furthermore secondary structure prediction of the 3'-untranslated region of the quail message supports a role for loop structures in the strictly oestrogen-dependent production of the lipoprotein lipase inhibitors. Our findings shed new light on the essential role of this small, hormonally regulated, protein in avian reproduction.

Amino Acid Sequence↗

PubMed1986

The lipoprotein lipase of white adipose tissue. Changes in the adipocyte cell-surface content of enzyme in response to extracellular effectors in vitro.

An indirect labelled-second-antibody cellular immunoassay for adipocyte surface lipoprotein lipase was used to assess the changes that occurred during the incubation of cells in the presence and absence of effectors. In the absence of any specific effectors, the amount of immunodetectable lipoprotein lipase present at the surface of adipocytes remained constant throughout the 4 h incubation period at 37 degrees C. Under such conditions total cellular enzyme activity also remained constant, with no activity appearing in the medium. In the presence of heparin, cell-surface immunodetectable lipoprotein lipase increased by up to 20%, whereas in the presence of cycloheximide they decreased by up to 60%. Thus the obvious turnover of enzyme from this cell-surface site was found to be relatively rapid and dependent for its replenishment, at least in part, on protein synthesis. In the presence of insulin alone, a substantial increase in cell-surface lipoprotein lipase protein occurred, only part of which was dependent on protein synthesis. The total cellular activity of lipoprotein lipase was unaffected by the presence of insulin. The insulin-dependent increase in cell-surface enzyme was potentiated somewhat in the presence of dexamethasone, which was not shown to exert any independent effect. Glucagon, adrenaline and theophylline all produced a significant decline in the cell-surface immunodetectable lipoprotein lipase, which in the case examined (adrenaline) was partially additive with regard to the independent effect of cycloheximide. Cell-surface immunodetectable lipoprotein lipase amounts were decreased significantly when cells were incubated in the presence of either colchicine or tunicamycin. The concerted way in which cell-surface lipoprotein lipase altered during the incubations of adipocytes in the presence of effectors suggested that the translocation of enzyme to and from this cellular site was dependent on hormonal action and the integrity of intracellular protein-transport mechanisms.

Adipose Tissue↗

PubMed1977

Influence of diet on adiposal lipoprotein lipase and hepatic triacylglyceride synthetase activities in the developing pullet (Gallus domesticus).

1. Lipoprotein lipase activity of the abdominal fat pad and hepatic triacylglyceride synthetase activity were determined at 2, 7.5, 9, 12.5 and 20 weeks of age. 2. Specific activity of lipoprotein lipase in fat pad was constant at 2-9 weeks, decreasing until 20 weeks. Hepatic triacylglyceride synthetase activity decreased from 2 to 12.5 weeks, increasing by 20 weeks. 3. Lipoprotein lipase activity was higher throughout 20 weeks and triacylglyceride synthetase activity was higher at 7.5 weeks with energy restricted diet. 4. An inverse relationship existed between fat pad weight and specific activity of lipoprotein lipase; higher activity in adipose tissue of energy restricted pullets may have been a function of smaller fat pad size.

Adipose Tissue↗

PubMed1984

Lipoprotein lipase--the molecule and its interactions.

The lipoprotein lipase molecule carries several functional sites. Three of these sites, for interaction with lipid interfaces, with activator protein, and with fatty acids, regulate the action of the enzyme's active site. Another, independent, site on the molecule anchors it to cell surface heparan sulfate and thus holds it in place at the endothelium. Together these properties allow for a fine-tuned regulation of the lipoprotein lipase reaction so that lipids are transported from the right particles, into the right tissues at the right rate.

Binding Sites↗

PubMed1987

The sequence of cDNA encoding lipoprotein lipase. A member of a lipase gene family.

cDNA clones corresponding to the entire coding region of mature lipoprotein lipase were identified by antibody screening of a mouse macrophage library and sequenced. The predicted amino acid sequence indicates that the mature protein contains 447 amino acids with a molecular weight of 50,314. Comparison of the nucleotide and amino acid sequence with those of rat hepatic lipase and porcine pancreatic lipase reveals extensive homology among the enzymes, indicating that they are members of a gene family of lipases. Most striking is a conservation of five disulfide bridges in all three enzymes, strongly suggesting that the enzymes have similar overall folding patterns. Lipoprotein lipase is also shown to be extraordinarily conserved among mouse, human, and bovine species. The mRNA for lipoprotein lipase is abundant in heart and adipose tissue but is also present in a wide variety of other tissues. There are two major species of mRNA in mouse and human tissues examined, 3.6 and 3.4 kilobases (kb) in size. Rat tissues, on the other hand, contain only the 3.6-kb species while bovine tissues contain an additional 1.7-kb species.

Amino Acid Sequence↗

PubMed1986

The hydrolysis of very low density lipoproteins and chylomicrons of intestinal origin by lipoprotein lipase in ruminants.

The hydrolysis by lipoprotein lipase of a very low density lipoprotein/chylomicron fraction, obtained from the intestinal lymph of sheep, has been studied in vitro. Rapid hydrolysis of triacylglycerols, with an accumulation of free fatty acids, was observed. After an initial lag period, phosphatidylcholine also was hydrolyzed. No specificity for particular fatty acids in the triacylglycerols (or phosphatidylcholines) was observed.

Animals↗

PubMed1997

Nitric oxide mediates down regulation of lipoprotein lipase activity induced by tumor necrosis factor-alpha in brown adipocytes.

We previously reported that tumor necrosis factor-alpha (TNF-alpha)/cachectin suppresses lipoprotein lipase activity and its gene expression in brown adipocytes differentiated in culture. Recent evidence suggests that the effect of TNF-alpha over various cells is related to the enhanced production of nitric oxide (NO). The present study examined whether the suppressive effect of TNF-alpha on lipoprotein lipase activity is mediated by production of NO in the brown adipocytes. A reverse transcription-polymerase chain reaction (RT-PCR) assay revealed that TNF-alpha caused a concentration- and time-dependent expression of inducible NO synthase in brown adipocytes. Increasing concentrations of TNF-alpha (0.5-50 ng/ml) for 24 h resulted in a concentration-dependent decrease in lipoprotein lipase activity with reciprocal increase in nitrite production in the medium. The suppressive effect of TNF-alpha on lipoprotein lipase activity was significantly prevented by NO synthase inhibitors, NG-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine, but not by D-NAME, an inactive isomer. Furthermore, 8-bromoguanosine 3',5'-cyclic monophosphate, cell permeant cGMP, suppressed lipoprotein lipase activity and 1 H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one, a selective inhibitor for soluble guanylate cyclase, restored the TNF-alpha-suppressed lipoprotein lipase activity. These results suggest that TNF-alpha stimulates brown adipocytes to express inducible NO synthase, followed by production of NO, which in turn mediates the suppressive effect of TNF-alpha on lipoprotein lipase activity. The effect of NO is mediated, at least partly, through production of cGMP.

Adipocytes↗

PubMed1985

Maturation and secretion of lipoprotein lipase in cultured adipose cells. I. Intracellular activation of the enzyme.

The intracellular pathway and the activation of lipoprotein lipase have been examined in differentiated Ob17 cells. These adipose cells were previously shown to secrete lipoprotein lipase during exposure to heparin. Treatment of the cells with cycloheximide and heparin leads to enzyme depletion, as shown by activity measurement and immunofluorescence microscopy. The repletion phase has been studied in the presence of monensin or carbonyl cyanide m-chlorophenylhydrazone, ionophores known to affect the intracellular transport of membrane and secretory proteins. Monensin-treated cells synthesize fully active lipoprotein lipase. Under these conditions the antigen accumulates in the Golgi apparatus and the heparin-stimulated enzyme release is extensively reduced. Carbonyl cyanide m-chlorophenylhydrazone-treated cells do not contain any enzyme activity but show detectable antigen which accumulates in the endoplasmic reticulum. Competition for binding to immobilized anti-lipoprotein lipase antibodies of mature and endoplasmic reticulum-sequestered antigens is observed. Carbonyl cyanide m-chlorophenylhydrazone removal is rapidly followed by a transient burst of enzyme activity and a redistribution of the antigen in the different subcellular compartments. Therefore, the results show that the activation of lipoprotein lipase is an intracellular event taking place after the enzyme exits from the endoplasmic reticulum and before it reaches the trans-Golgi cisternae.

Adipose Tissue↗

PubMed1993

Apolipoprotein E modulates low density lipoprotein retention by lipoprotein lipase anchored to the subendothelial matrix.

Lipoprotein lipase (lipase), a key enzyme in lipoprotein triglyceride metabolism, has been shown to markedly increase low density lipoprotein (LDL) retention by subendothelial matrix. In the present study we assessed the role that lipoprotein and matrix components play in retention of LDL by lipase anchored to the subendothelial matrix. Lipase addition to subendothelial matrix increased LDL retention by 66-fold. Scatchard analysis of LDL binding to lipase-containing matrix yielded an association constant of 12 nM. Exogenous addition of the matrix components, heparan sulfate and dermatan sulfate (i.e. chondroitin sulfate B), reduced LDL retention by greater than 90%. These glycosaminoglycans (GAGs) also reduced lipolytic activity associated with the matrix, suggesting that lipase was released from its binding sites on the matrix. In contrast, other matrix components (collagen, fibronectin, vitronectin, and chondroitin sulfate A) neither affected LDL release nor matrix lipolytic activity. Thus, heparan sulfate and dermatan sulfate function to anchor lipase to the subendothelial cell matrix. The effects of apolipoprotein E (apoE) and apoA-I were also examined. Preincubation of the subendothelial matrix with apoE, followed by washing, did not affect subsequent lipase binding to the matrix nor its ability to retain LDL. However, the direct addition of apoE alone or in combination with phospholipid liposomes decreased lipase-mediated LDL retention in a concentration-dependent fashion. Addition of apoA-I had no effect. Thus, in these studies apoE functions to displace LDL bound to lipase, but not lipase anchored to the matrix. To further examine the physiologic implications of this process, we assessed the ability of human apoE-rich and apoE-poor high density lipoproteins (HDL) to displace LDL from matrix-anchored lipase. ApoE-rich HDL reduced LDL retention dramatically (86% at 2.5 micrograms/ml). In contrast, apoE-poor HDL, at the highest concentration evaluated (400 micrograms/ml), decreased LDL retention by only 32%. Overall, these data suggest apoE and specifically apoE-containing HDL reduce the lipase-mediated retention of LDL by subendothelial matrix. This observation, in part could explain the protective effects of apoE and apoE-containing HDL against atherosclerosis.

Animals↗

PubMed1985

High muscle lipoprotein lipase activity in thyrotoxic patients.

Serum lipoprotein metabolism was studied in 7 women before and after treatment for thyrotoxicosis. Of the lipoprotein lipids, the triglyceride concentration in the low density lipoproteins (LDL) (P less than 0.01) and the cholesterol concentration in both LDL (P less than 0.01) and the high density lipoproteins (HDL) (P less than 0.05) increased significantly during treatment. These changes were accompanied by increases in apolipoprotein B (P less than 0.01) and A-I (P less than 0.05) concentrations in serum. Muscle lipoprotein lipase activity (LPLA) was increased in the thyrotoxic state by 46% (P less than 0.05) compared with the value after the patients had been rendered euthyroid, but adipose tissue LPLA was only 8% higher (ns) in the former state. The capacity for removal of exogenous fat, as determined by the fractional elimination rate (K2) at an iv fat tolerance test, was 23% higher in the thyrotoxic than in the euthyroid state (ns). It is suggested that the increase in muscle LPLA in the thyrotoxic state may be due to enhanced sensitivity to catecholamines. This may contribute to the increased capacity for plasma triglyceride turnover in thyrotoxicosis.

Adipose Tissue↗

PubMed1982

Binding of lipoprotein lipase to the cell surface is essential for the transmembrane transport of chylomicron cholesteryl ester.

Four cell types, F1 rat heart cells, rat preadipocytes, human skin fibroblasts and bovine endothelial cells, were used to investigate whether surface binding of lipoprotein lipase was essential in the transmembrane transport of chylomicron cholesteryl ester. Exposure of F1 heart cells to colchicine resulted in decrease in endogenous surface-bound lipoprotein lipase and a concomitant fall in the uptake of chylomicron cholesteryl linoleyl ether, a nondegradable analog of cholesteryl ester. Uptake of chylomicron cholesteryl linoleyl ether was enhanced by addition of milk lipoprotein lipase and this enhancement also persisted in the presence of colchicine. The drug did not reduce surface binding to the enzyme. Milk lipoprotein lipase was bound to the cell surface of the different cell types and its fate during chase in enzyme-free medium was determined. The t 1/2 of surface-bound enzyme in endothelial cells and in F1 heart cells was about 2 h; it was 4 h in skin fibroblasts. The decrease in surface-bound lipoprotein lipase was accompanied by a parallel fall in the binding and uptake of chylomicron cholesteryl linoleyl ether by the various cell types examined. This decrease in the uptake of cholesteryl linoleyl ether occurred even though lipoprotein lipase activity in the medium was present, as evidenced by the hydrolysis of [14C]triacylglycerol. Release of surface-bound endogenous or exogenous lipoprotein lipase by heparin was accompanied by almost complete elimination of uptake of cholesteryl linoleyl ether in presence of complete hydrolysis of [14C]triacylglycerol. The present results indicate that the transmembrane transport of cholesteryl ester is catalyzed by lipoprotein lipase only when the enzyme is bound to the cell membrane.

Adipose Tissue↗

PubMed1979

Lipolysis and lipid movement in a membrane model. Action of lipoprotein lipase.

The action of purified bovine milk lipoprotein lipase on tri[3H]oleoylglycerol and the effect of albumin on movement of lipolytic products at an argon-water interface were studied in a specially designed tricomparted trough. The amount of trioleoylglycerol applied was 14 times that needed to cover the surface of the aqueous subphase (0.1 M Tris . HCl, pH 7.4) with a monolayer. It is concluded that trioleoylglycerol was present in lenses on the surface of the aqueous subphase, that hydrolysis by lipoprotein lipase occurred in or near the lipid/argon-water interface, and that lipolytic products immediately located and spread throughout the interface, displacing substances with lower spreading pressures from the interface. Addition of albumin to the aqueous subphase accelerated markedly the desorption of oleic acid and monooleoylglycerol from the interface and thereby enhanced lipolysis. When albumin was not contiguous with the site of hydrolysis, oleic acid and monooleoylglycerol readily moved in the interface to the area of contact with albumin where they were desorbed from the interface. These findings support the hypothesis of transport of lipolytic products by lateral movement in cell membranes.

Animals↗

PubMed1985

Monoclonal antibodies to avian lipoprotein lipase. Purification of the enzyme by immunoaffinity chromatography.

Three monoclonal antibodies to avian lipoprotein lipase have been isolated by fusing spleen cells from immunized BALB/c mice with myeloma P3X-63 Ag 8. The antibodies were detected by their ability to bind immobilized lipoprotein lipase in enzyme-linked immunosorbent assay (ELISA) and by immunoprecipitation of purified enzyme in the presence of second (rabbit anti-mouse) antibodies. Two of these antibodies, CAL1-7 and CAL1-11, inhibited catalytic activity, whereas with CAL1-2 interaction with lipoprotein lipase could be demonstrated only in ELISA and in Western blot assays following denaturation of the enzyme with sodium dodecyl sulfate. An immunoadsorbent column was prepared by coupling immunopurified CAL1-11 to Sepharose-4B. When acetone powder extracts of adipose tissue were applied on the column, 70% of the catalytic activity bound to the matrix. Effective elution was achieved with 1.8 M NaCl, 40% glycerol, 5% acetone, 20 mM Chaps (3[(3-cholamidopropyl)dimethylammonio]propanesulfonate), 0.5 mM EDTA, 1 mM phosphate (pH 6.5). After concentration of the active fractions on a heparin-Sepharose 4B column, the purified enzyme was obtained with an overall recovery of 25%. Sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrates that the preparation is homogeneous with a major band at Mr 60900. Thus, avian adipose lipoprotein lipase has been purified by a one-step immunoaffinity followed by a concentrating step on heparin-Sepharose 4B.

Animals↗