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PubMed1995

Exercise induces human lipoprotein lipase gene expression in skeletal muscle but not adipose tissue.

Lipoprotein lipase (LPL) is regulated by exercise in humans, but the effects of exercise on LPL expression in different tissues and the molecular mechanisms involved are unclear. We assessed the effects of 5-13 consecutive days of supervised exercise on tissue LPL expression as well as fasting plasma lipids and lipoproteins in 32 sedentary, weight-stable adult men. In skeletal muscle, exercise training increased the mean LPL mRNA level by 117% (P = 0.037), LPL protein mass by 53% (P = 0.038), and total LPL enzyme activity by 35% (P = 0.025). In adipose tissue, mean LPL mRNA, protein mass, and activity did not change. Exercise decreased triglycerides [from 172 +/- 4.3 to 127 +/- 3.2 (SE) mg/dl, P = 0.002], total cholesterol (from 188 +/- 1.2 to 181 +/- 1.0 mg/dl, P = 0.011), and very low-density lipoprotein-cholesterol (from 30.1 +/- 0.9 to 22.0 +/- 0.8, P = 0.004) and increased high-density lipoprotein cholesterol (HDL-C; from 43.4 +/- 0.35 to 45.0 +/- 0.37, P = 0.030) and HDL2-C (from 6.6 +/- 0.21 to 7.7 +/- 0.19, P = 0.021). Changes in muscle but not adipose tissue heparin-releasable LPL activity were inversely correlated (r = -0.435, P < 0.034) with changes in triglycerides. These data suggest the existence of an exercise stimulus intrinsic to skeletal muscle, which raises LPL activity in part by pretranslational mechanisms, a process that contributes to the improvement in circulating lipids seen with physical activity.

Adipose Tissue↗
PubMed1983

Transfer of cholesteryl linoleyl ether from phosphatidylcholine and phosphatidylethanolamine liposomes to cultured cells catalyzed by lipoprotein lipase.

Unilamellar liposomes prepared from purified phospholipids (phosphatidylcholine, phosphatidylethanolamine or sphingomyelin) and labeled cholesteryl linoleyl ether were used to study lipoprotein lipase-catalyzed transfer of cholesteryl ester into cells in culture. In mesenchymal rat heart cell cultures, the transfer of cholesteryl linoleyl ether and cholesteryl linoleate was similar and related to the activity of endogenously produced lipoprotein lipase. In human skin fibroblasts transfer of labeled cholesteryl linoleyl ether was proportional to the concentration of milk lipoprotein lipase added to the incubation medium. Liposomes prepared from phosphatidylcholine or phosphatidylethanolamine were much better donors of cholesteryl ether to normal and apolipoprotein E-B receptor-negative fibroblasts and to endothelial cells than those prepared from sphingomyelin. Lysophosphatidylcholine was formed during incubation with milk lipoprotein lipase but was not considered to be directly responsible for the lipoprotein lipase-catalyzed transfer of cholesteryl ether. This conclusion was drawn because in the absence of lipoprotein lipase addition of lysophosphatidylcholine to liposomes, or almost complete phospholipolysis by phospholipase A2, did not result in the transfer of cholesteryl linoleyl ether from liposomes to cells. Attachment of lipoprotein lipase to the cell surface was mandatory for the transfer of cholesteryl ether and could be prevented by heparin. High density apolipoprotein reduced also the transfer of cholesteryl linoleyl ether, even though it did not interfere with the binding of labeled milk lipoprotein lipase to cultured fibroblasts. The present results provide evidence that lipoprotein lipase, and not the products of phospholipid hydrolysis, is the ligand for the non-apolipoprotein E-B receptor-mediated transfer of cholesteryl ester to cells.

Animals↗
PubMed1988

Human hepatic lipase. Cloned cDNA sequence, restriction fragment length polymorphisms, chromosomal localization, and evolutionary relationships with lipoprotein lipase and pancreatic lipase.

Human hepatic lipase is an important enzyme in high density lipoprotein (HDL) metabolism, being implicated in the conversion of HDL2 to HDL3. Three human hepatic lipase cDNA clones were identified in two lambda gt11 libraries from human liver. The cDNA-derived amino acid sequence predicts a protein of 476 amino acid residues, preceded by a 23-residue signal peptide. Four potential N-glycosylation sites are identified, two of which are conserved in rat hepatic lipase. On alignment with human, mouse, and bovine lipoprotein lipase, the same two sites were also conserved in lipoprotein lipase in all three species. Stringent conservation of the cysteine residues was also evident. Comparative analysis of amino acid sequences shows that hepatic lipase evolves at a rapid rate, 2.07 x 10(-9) substitutions/site/year, about four times that in lipoprotein lipase and half that in pancreatic lipase. Further, hepatic lipase and pancreatic lipase appear to be evolutionarily closer to each other than either of them is to lipoprotein lipase. Southern blot analysis revealed high frequency restriction fragment length polymorphisms of the hepatic lipase gene for the enzymes HindIII and MspI. these polymorphisms will be useful for haplotype and linkage analysis of the hepatic lipase gene. Using cloned human hepatic lipase cDNA as a hybridization probe, we performed Southern blot analysis of a panel of 13 human-rodent somatic cell hybrids. Concordance analysis of the various hybrid clones indicates that the hepatic lipase gene is located on the long arm of human chromosome 15. Analysis of hybrids containing different translocations of chromosome 15 localized the gene to the region 15q15----q22.

Amino Acids↗
PubMed1996

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

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 seen early, before the age of 40 and often before 20 years of age. In the total cohort these changes included an elevation in the mean very low density (VLDL) and intermediate density lipoprotein (IDL) triglyceride (+69%; P = 0.01 and +40%; P = 0.001) and cholesterol (+51%; P = 0.03 and +67%; P = 0.007) and apoB levels but decreased HDL2 and HDL3 cholesterol, (-32%; P = 0.01 and -15%; P = 0.002 respectively). While the lipid compositions of VLDL and IDL were similar between heterozygotes and controls, the low density (LDL) and high density lipoproteins (HDL) of carriers were triglyceride enriched. Heterozygotes also had a markedly lower apoC-III ratio (apoC-III in supernatant/apoC-III in heparin precipitate) (1.46 vs. 3.86 P = 1 x 10(-4)) indicating a substantial enrichment of VLDL and IDL with apoC-III and depletion of HDL apoC-III supporting this ratio as an effective index for efficiency of lipolysis. LpA-I was markedly reduced (0.34 vs. 0.43 P = 1 x 10(-5)) showing that levels of this particle are partly dependent on LPL catalytic activity. Heterozygotes manifest from an early age with a markedly reduced HDL, LpA-I, apoC-III ratio and an increased TC/HDLc ratio which would predict a relatively increased risk of premature coronary artery disease, compared to their normal siblings.

Adult↗
PubMed2004

A role for lipoprotein lipase during synaptic remodeling in the adult mouse brain.

Lipoprotein lipase (LPL) is a member of a lipase family known to hydrolyze triglyceride molecules found in lipoprotein particles. This particular lipase also has a role in the binding of lipoprotein particles to different cell-surface receptors. LPL has been identified in the brain but has no specific function yet. This study aimed at elucidating the role of LPL in the brain in response to injury. Mice were subjected to hippocampal deafferentation using the entorhinal cortex lesion and mRNA and protein expression were assessed over a time-course of degeneration/reinnervation. Hippocampal LPL levels peaked at 2 days post-lesion (DPL) both at the mRNA and protein levels. No change was observed for receptors of the LDL-receptor family or RAP at DPL 2 in the hippocampus but the glia-specific syndecan-4 was found to be significantly upregulated at DPL 2. These results suggest that LPL is involved in the recycling of cholesterol and lipids released from degenerating terminals after a lesion through a syndecan-4-dependent pathway.

Animals↗
PubMed1983

Hypertriacylglycerolemia and adipose tissue lipoprotein lipase activity in the Nagase analbuminemic rat.

In Nagase analbuminemic rats, serum triacylglycerol levels were significantly elevated. This abnormality was accompanied by decreased adipose tissue fat stores, and both were more marked in female than in male rats. Parametrial adipose tissue lipoprotein lipase activity was determined in normally fed female rats. When expressed per mg protein, the activity in analbuminemic rats was only 35% of that in control rats. The activity in analbuminemic rats, however, could be increased as in control rats by refeeding starved animals with a fat-free and carbohydrate-rich diet, and the peak values recorded were the same with the two groups. Treatment of animals with streptozotocin lowered adipose tissue lipoprotein lipase activity in both groups to similar levels. These results suggest that hypertriacylglycerolemia associated with analbuminemia may be caused, at least in part, by altered hormonal control of adipose tissue lipoprotein lipase activity.

Adipose Tissue↗
PubMed1999

Fatty acid alcohol ester-synthesizing activity of lipoprotein lipase.

The fatty acid alcohol ester-synthesizing activity of lipoprotein lipase (LPL) was characterized using bovine milk LPL. Synthesizing activities were determined in an aqueous medium using oleic acid or trioleylglycerol as the acyl donor and equimolar amounts of long-chain alcohols as the acyl acceptor. When oleic acid and hexadecanol emulsified with gum arabic were incubated with LPL, palmityl oleate was synthesized, in a time- and dose-dependent manner. Apo-very low density lipoprotein (apoVLDL) stimulated LPL-catalyzed palmityl oleate synthesis. The apparent equilibrium ratio of fatty acid alcohol ester/oleic acid was estimated using a high concentration of LPL and a long (20 h) incubation period. The equilibrium ratio was affected by the incubation pH and the alcohol chain length. When the incubation pH was below pH 7.0 and long chain fatty acyl alcohols were used as substrates, the fatty acid alcohol ester/free fatty acid equilibrium ratio favored ester formation, with an apparent equilibrium ratio of fatty acid alcohol ester/fatty acid of about 0.9/0.1. The equilibrium ratio decreased sharply at alkaline pH (above pH 8.0). The ratio also decreased when fatty alcohols with acyl chains shorter than dodecanol were used. When a trioleoylglycerol/fatty acyl alcohol emulsion was incubated with LPL, fatty acid alcohol esters were synthesized in a dose- and time-dependent fashion. Fatty acid alcohol esters were easily synthesized from trioleoylglycerol when fatty alcohols with acyl chains longer than dodecanol were used, but synthesis was decreased with fatty alcohols with acyl chain lengths shorter than decanol, and little synthesizing activity was detected with shorter-chain fatty alcohols such as butanol or ethanol.

Animals↗
PubMed1996

Brefeldin A enables synthesis of active lipoprotein lipase in cld/cld and castanospermine-treated mouse brown adipocytes via translocation of Golgi components to endoplasmic reticulum.

Brown adipocytes cultured from newborn combined-lipase-deficient (cld/cld) mice and castanospermine (CST)-treated 3T3-L1 adipocytes synthesize lipoprotein lipase (LPL) which is inactive and retained in the endoplasmic reticulum (ER) [Masuno, Blanchette-Mackie, Chernick and Scow (1990) J.Biol. Chem. 265, 1628-1638; Masuno, Blanchette-Mackie, Schultz, Spaeth, Scow and Okuda (1992) J. Lipid Res.33, 1343-1349]. Brefeldin A (BFA), which is known to block protein transport from ER and translocate Golgi components to ER, was used here to study the effect of translocated Golgi enzymes on LPL retained in ER of cld/cld and CST-treated mouse brown adipocytes. Brown adipocytes cultured from newborn normal mice contained 3000-5000 m-units of LPL activity/mg of DNA and secreted 35 m-units of LPL activity/mg of DNA per h. BFA at 10 micrograms/ml doubled LPL activity in normal cells within 2 h as it stopped completely secretion of active LPL. LPL in mouse cells has two N-oligosaccharide chains per subunit. Analyses with SDS/PAGE and immunoblotting showed that about one-third of LPL subunits in untreated normal cells were totally endo-beta-N-acetylglucosaminidase (endo H)-resistant, one-third were partially endo H-resistant, and one-third were totally endo H-sensitive. BFA decreased to zero the proportion of subunits which were totally endo H-resistant, while it increased the proportion which were partially endo H-resistant. Thus, BFA blocked processing of one oligosaccharide chain per subunit to endo H-resistance. Sucrose-gradient centrifugation studies showed that BFA increased the proportion of LPL subunits in normal cells which were present as active dimers. LPL activity in cld/cld adipocytes was 120 m-units/mg of DNA and that in normal adipocytes treated with CST was 430 m-units/mg of DNA. Most LPL subunits in such cells were totally endo H-sensitive and some were partially endo H-resistant, but none were totally endo H-resistant. Some of the subunits, in both cld/cld and CST-treated cells, were present as inactive LPL dimers. BFA increased LPL activity in cld/cld cells to 2100 m-units/mg of DNA and that in CST-treated cells to 2600 m-units/mg of DNA within 2 h. BFA increased in both groups the proportion of LPL subunits which were partially endo H-resistant. BFA also increased the proportion which were present as active dimers. Immunofluorescence studies in normal and cld/cld adipocytes showed that BFA caused retention of LPL in large tubular and spherical structures and in ER, but not in Golgi. When BFA was withdrawn and protein synthesis was blocked with cycloheximide, LPL in normal cells was transferred to Golgi within 30 min and disappeared within 60 min, whereas LPL in cld/cld cells was retained in large vesicles and ER. The findings indicate that BFA enabled synthesis of active LPL in cld/cld and CST-treated cells via translocation of Golgi components to ER. Also, cld/cld cells synthesized LPL which could be processed to active lipase and the enzymes needed for activation of the lipase were present in Golgi of such cells. Production of inactive LPL in cld/cld adipocytes probably results from their inability to transport LPL from ER to Golgi.

Adipocytes↗
PubMed1988

Lipoprotein pattern and plasma lipoprotein lipase activities in patients with primary biliary cirrhosis. Relationship with increase of HDL2 fraction in Lp-X-positive and Lp-X-negative subjects.

Plasma lipids, apoprotein A-I and B in serum and in lipoprotein fractions (VLDL + LDL, HDL2, and HDL3) obtained by preparative ultracentrifugation, as well as postheparin lipoprotein lipase activity (H-TGL and LPL) were evaluated in 17 subjects with primary biliary cirrhosis (stage II and III) subdivided into two groups according to the presence or absence of lipoprotein X (Lp-X). A reduction in total lipoprotein lipase activity was observed in both patient groups, compared to controls (P less than 0.01); the hepatic lipoprotein lipase was significantly reduced (P less than 0.01) only in the Lp-X-positive group. The lipid (477.8 +/- 154.3 vs 239.6 +/- 51.1; P less than 0.01) and protein (147.4 +/- 37.1 vs 83.3 +/- 19.7; P less than 0.01) masses in the VLDL + LDL fraction of the Lp-X-positive group were increased compared to controls. In the same group, the HDL2 fraction also showed an increase in lipid (186.6 +/- 80.0 vs 77.9 +/- 21.6; P less than 0.01) and protein (133.9 +/- 60.0 vs 67.9 +/- 16.5; P less than 0.01) masses; in addition, the HDL2 percent lipid composition was different in the two patient groups, showing a decrease in esterified cholesterol (20.4 +/- 3.6 vs 25.7 +/- 2.2; P less than 0.01) and an increase in phospholipids (59.2 +/- 2.9 vs 54.8 +/- 2.6; p less than 0.01) in the Lp-X-positive group.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoproteins B↗
PubMed1995

Expression in mouse embryos and in adult mouse brain of three members of the amyloid precursor protein family, of the alpha-2-macroglobulin receptor/low density lipoprotein receptor-related protein and of its ligands apolipoprotein E, lipoprotein lipase, alpha-2-macroglobulin and the 40,000 molecular weight receptor-associated protein.

We have analysed by northern blotting and by in situ hybridization the expression patterns of eight different genes during the second half of mouse embryonic development and in adult mouse brain: we compared the messenger RNA levels of amyloid precursor protein and of the two amyloid precursor protein-like proteins 1 and 2 and we have analysed expression of apolipoprotein E and of its main receptor in brain, the alpha-2-macroglobulin/low density lipoprotein receptor-related protein and three other ligands: the proteinase inhibitor alpha-2-macroglobulin, the modifying enzyme lipoprotein lipase and the 44,000 molecular weight heparin binding protein, a ligand of unknown function. During embryogenesis the temporal expression pattern differs considerably for the three members of the amyloid precursor proteins. Total embryo messenger RNA levels of amyloid precursor protein and amyloid precursor protein-like protein 2 increased progressively, while amyloid precursor protein-like protein 1 messenger RNA showed a burst of synthesis between days 10 and 13 post-coitum. Significantly, expression of the alpha-2-macroglobulin/low density lipoprotein receptor-related protein and of its associated protein, the 44,000 molecular weight heparin binding protein, exhibited their most important increase very similar to that of amyloid precursor protein-like protein 1, between days 10 and 13 post-coitum. Apolipoprotein E, lipoprotein lipase and alpha-2-macroglobulin messenger RNA levels in total embryos increased progressively, beginning most pronounced at days 13, 15 and 17, respectively. In mouse embryos, in situ hybridization established amyloid precursor protein, amyloid precursor protein-like protein 2 and alpha-2-macroglobulin/low density lipoprotein receptor-related protein messenger RNA to be expressed in most organs, with the notable exception of the liver, while expression of the other studied proteins was much more restricted. Among adult mouse tissues, the genes investigated were expressed very prominently in brain, except for lipoprotein lipase and for the complete absence of alpha-2-macroglobulin messenger RNA. In adult mouse brain, the cortex and hippocampus exhibited strong signals for most genes analysed. Exceptions are lipoprotein lipase and apolipoprotein E messenger RNAs, and the absent alpha-2-macroglobulin messenger RNA. Several interesting features, similarities as well as differences, between brain tissue sections hybridized with probes for amyloid precursor protein, amyloid precursor protein-like proteins 1 and 2 and between alpha-2-macroglobulin/low density lipoprotein receptor-related protein and heparin binding protein-44 were observed and are described. The results are further discussed in view of the known or anticipated physiological functions of the proteins examined and of their possible role in the etiology of Alzheimer's disease.

Amyloid beta-Protein Precursor↗
PubMedDate not supplied

Chronic alpha 1-adrenergic blockade, serum triacylglycerols, and tissue lipoprotein lipase activity in rats fed diets high in starch or sucrose.

This study was designed to assess the individual and interactive effects of types of dietary carbohydrate and of chronic alpha 1-adrenergic blockade on some of the determinants of triacylglycerol metabolism in the rat. Specifically, dietary starch and sucrose were given chronically, with or without prazosin mixed with the diet. Serum lipid concentrations and the activity of lipoprotein lipase in several tissues were evaluated 3 h after a voluntary meal consisting of a diet that has been consumed chronically. Postprandial serum triacylglycerol levels were significantly higher (88%, P less than 0.05) after the ingestion of a meal high in sucrose than after a meal high in starch. Prazosin interacted significantly with dietary carbohydrates (P less than 0.03), in that the blocker did not affect triacylglycerol levels in starch-fed rats but greatly diminished their concentration in sucrose-fed animals. Postprandial measurement of lipoprotein lipase in epididymal white adipose tissue, brown adipose tissue, and vastus lateralis muscle showed that enzyme activity in these specific tissues was not affected by the type of dietary carbohydrate. Prazosin significantly decreased lipoprotein lipase activity in brown adipose tissue regardless of the diet, but it did not affect enzyme activity in the other tissues evaluated. These findings demonstrate that the influence of alpha 1-adrenergic blockade on triacylglycerol metabolism can be modulated by dietary components. They further suggest that, in the postprandial state, prazosin did not affect triacylglycerol concentrations by modulating total tissue activity of lipoprotein lipase, at least in the organs that were probed in this study.

Adipose Tissue, Brown↗
PubMed2004

Macrophage-derived lipoprotein lipase increases aortic atherosclerosis in cholesterol-fed Tg rabbits.

Lipoprotein lipase (LPL) produced by macrophages is upregulated in the atherosclerotic lesions; however, it is not fully understood whether increased macrophage-derived LPL is pro-atherogenic. To examine the hypothesis that macrophage-derived LPL in the arterial wall enhances atherosclerotic lesion formation, we generated transgenic (Tg) rabbits that express the human LPL transgene under the control of the human scavenger receptor enhancer/promoter, which drives macrophage-specific expression of the human LPL gene. We fed Tg and non-Tg littermate rabbits a diet containing 0.3% cholesterol for 16 weeks and compared their lipoproteins and aortic atherosclerosis. We found that there was no difference in plasma lipid or lipoprotein profiles between Tg and non-Tg rabbits; however, atherosclerotic lesions were significantly increased in Tg compared to non-Tg rabbits. There was a 1.4-fold increase in total aortic en face lesions and a 2-fold increase in intimal lesions evaluated by image analysis system. Furthermore, immunohistochemical staining revealed that the increased atherosclerotic lesions present in Tg rabbits were characterized by marked accumulation of macrophage-derived foam cells and frequently associated with the deposition of oxidized LDL. These results support the notion that macrophage-derived LPL in the arterial wall is pro-atherogenic, possibly via the enhancement of foam cell formation during atherogenesis.

Animals↗
PubMed1994

Beef tallow diet decreases lipoprotein lipase activities in brown adipose tissue, heart, and soleus muscle by reducing sympathetic activities in rats.

Effects of dietary fats consisting of different fatty acids on lipoprotein lipase activities in the interscapular brown adipose tissue, heart, and soleus muscle, and on body fat accumulation were studied in rats. Sprague-Dawley male rats were meal-fed an isoenergetic diet based on either beef tallow or safflower oil for 8 weeks. Lipoprotein lipase activities in the interscapular brown adipose tissue, heart, and soleus muscle before and after a meal were lower in the beef tallow diet group than in the safflower oil diet group. Body fat accumulation was greater in the beef tallow diet group than in the safflower oil diet group. The norepinephrine turnover rats in the interscapular brown adipose tissue, heart, and soleus muscle were lower in the beef tallow diet group. beta-Adrenergic receptor bindings were determined with [125I]iodocyanopindolol. Binding affinities of beta-adrenergic receptor in the interscapular brown adipose tissue, heart, and soleus muscle were lower in the beef tallow diet group probably resulted from lower membrane fluidities. These results suggest that intake of the beef tallow diet promotes body fat accumulation by reducing the lipoprotein lipase activities resulting from lower sympathetic activities in the brown adipose tissue, heart, and skeletal muscle.

Adipose Tissue, Brown↗
PubMed1998

Analysis of heparin-binding sites in human lipoprotein lipase using synthetic peptides.

Synthetic nonbasic peptides based on the type I repeats of thrombospondin (TSP) and four peptides corresponding to the predicted basic clusters in lipoprotein lipase (LPL) have been analyzed for heparin binding. In the present report we examine the structural requirement for the binding of these peptides to heparin-Sepharose column. The peptide containing the sequence Phe-Ser-Trp-Ser-Asp-Trp-Trp-Ser (residues 388-395 in lipoprotein lipase, which include the consensus TSP type I sequence) showed strong binding to heparin. Both the first and second Trp residues in this sequence were essential for tight heparin binding. Substitution of either of the Trp residues by an Ala resulted in the complete loss of heparin binding. The peptides representing the four basic cluster regions of lipoprotein lipase showed variable heparin binding. Strong retention was observed for peptides representing cluster 1 (residues 261-287) and cluster 3 (residues 147-151) peptides followed by cluster 2 (residues 290-302) peptide. A peptide corresponding to LPL cluster 4 (residues 405-414) did not show binding to heparin column. The present study confirms the presence of specific heparin-binding sites in LPL. Furthermore, this study also demonstrates the potential use of synthetic peptides to investigate the interaction between peptides and heparin as an alternative approach to site-directed mutagenesis in selected regions of large protein molecules. The affinity of these peptides toward heparin can be explored to block molecular interactions at these specific sites or to carry and deliver other coupled molecules at the site(s) of attachment of these peptides for therapeutic applications.

Amino Acid Sequence↗
PubMed1982

Lipoprotein lipase activity of adipose tissue, skeletal muscle and post-heparin plasma in primary endogenous hypertriglyceridaemia: relation to lipoprotein pattern and to obesity.

The lipoprotein lipase (LPL) activity was determined from heparin eluates of adipose tissue and skeletal muscle and from post-heparin plasma of sixty-five males with hypertriglyceridaemia and of seventy males with normal serum lipid levels. The patients were subgrouped by their lipoprotein concentrations into types 2b, 4 and 5. The mean LPL activity of adipose tissue (per tissue weight) of nonobese type 2b, 4 and 5 patients was reduced to 54%, 41% and 13%, respectively, of the corresponding value of normolipidaemic men. On the other hand, among obese hyperglyceridaemic men only those with type 5 showed a decreased LPL activity in adipose tissue (44%). The mean skeletal muscle LPL was subnormal in nonobese type 4 (55%) and in type 5 patients (34%) but was normal in type 2b and in obese type 4 patients. The post-heparin plasma LPL activity was significantly reduced in all nonobese hyperglyceridaemic groups but was normal in obese patients apart from cases with type 5 who had low values. One exceptional subject with type 5 had high post-heparin plasma LPL activity. It is concluded that a low LPL activity may be a crucial factor in the pathogenesis of hypertriglyceridaemia in nonobese subjects and in patients having type 5 disorder.

Adipose Tissue↗
PubMed1990

A sandwich-enzyme immunoassay for the quantification of lipoprotein lipase and hepatic triglyceride lipase in human postheparin plasma using monoclonal antibodies to the corresponding enzymes.

We have developed a sandwich-enzyme immunoassay (EIA) for the quantification of lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) in human postheparin plasma (PHP) using monoclonal antibodies (MAbs) directed against the corresponding enzymes purified from human PHP. The sandwich-EIA for LPL was performed by using the combination of two distinct types of anti-LPL MAbs that recognize different epitopes on the LPL molecule. The immunoreactive mass of LPL was specifically measured using a beta-galactosidase-labeled anti-LPL MAb as an enzyme-linked MAb, an anti-LPL MAb linked with the bacterial cell wall as an insolubilized MAb, and purified human PHP-LPL as a standard. The sandwich-EIA for HTGL was carried out by using two distinct anti-HTGL MAbs that recognize different epitopes on HTGL. The limit of detection was 20 ng/ml for LPL and 60 ng/ml for HTGL. Each method yielded a coefficient of variation of less than 6% in intra- and inter-assays, and a high concentration of triglyceride did not interfere with the assays. The average recovery of purified human PHP-LPL and -HTGL added to human PHP samples was 98.8% and 97.5%, respectively. The immunoreactive masses of LPL and HTGL in PHP samples, obtained at a heparin dose of 30 IU/kg, from 34 normolipidemic and 20 hypertriglyceridemic subjects were quantified by the sandwich-EIA. To assess the reliability of the measured mass values, they were compared with the corresponding enzyme activities measured by selective immunoinactivation assay using rabbit anti-human PHP-LPL and -HTGL polyclonal antisera. Both assay methods yielded a highly significant correlation in either normolipidemic (r = 0.945 for LPL; r = 0.932 for HTGL) or hypertriglyceridemic subjects (r = 0.989 for LPL; r = 0.954 for HTGL). The normal mean (+/- SD) level of lipoprotein lipase mass and activity in postheparin plasma was 223 +/- 66 ng/ml and 10.1 +/- 2.9 mumol/h per ml, and that of hepatic triglyceride lipase mass and activity was 1456 +/- 469 ng/ml and 26.4 +/- 8.7 mumol/h per ml, respectively. The present sandwich-enzyme immunoassay methods make it possible to study the molecular nature of LPL and HTGL in PHP from patients with either primary or secondary hyperlipoproteinemia.

Adult↗
PubMed2005

Post-heparin plasma lipoprotein lipase, but not hepatic lipase activity, is related to plasma adiponectin in type 2 diabetic patients and healthy subjects.

The aim of this study was to determine the relationships of plasma adiponectin with post-heparin plasma lipoprotein lipase (LPL) and hepatic lipase (HL) activities, and to evaluate whether plasma adiponectin contributes to diabetes-associated dyslipidaemia. Plasma adiponectin, post-heparin plasma lipase activities, lipoproteins and insulin sensitivity (hyperinsulinaemic euglycaemic clamp) were measured in 24 male type 2 diabetic patients and 24 age-matched healthy men. Plasma triglycerides (P < 0.01) and apolipoprotein B levels (P < 0.01) were higher, and HDL cholesterol was lower (P < 0.05) in type 2 diabetic patients. Plasma adiponectin, as well as LPL and HL activities were not significantly different between diabetic and healthy subjects. Multiple regression analysis showed that LPL activity was positively related with plasma adiponectin (P < 0.05). In contrast, HL activity was positively related with body mass index (P < 0.02) and waist/hip ratio (P < 0.05, multiple r = 0.74), but not with plasma adiponectin. Plasma adiponectin was positively associated with insulin sensitivity (P = 0.001), age (P < 0.02) and LPL activity (P < 0.05, multiple r = 0.64), but not with the presence of diabetes and HL activity. Plasma triglycerides were negatively related with LPL activity (P = 0.002) and positively with the diabetic state (P = 0.001, multiple r = 0.58). HDL cholesterol was positively related with plasma adiponectin (P = 0.003) and negatively with HL activity (P < 0.02) as well as with the presence of diabetes (P = 0.05, multiple r = 0.59). We conclude that post-heparin plasma LPL activity, but not HL activity, is related with plasma adiponectin. Plasma adiponectin appears to be a determinant of plasma triglycerides via an effect on LPL activity. It seems unlikely that plasma adiponectin predicts the effects of the diabetic state as such on high plasma triglycerides and low HDL cholesterol.

Case-Control Studies↗
PubMed1992

Postnatal development of plasma-lipid-clearing enzymes (lipoprotein lipase, hepatic lipase and lecithin:cholesterol acyl transferase) and lipid profiles in suckling rats.

We examined the activity of plasma circulating lipoprotein lipase and hepatic lipase, lecithin:cholesterol acyl transferase (LCAT), as well as lipid profiles in Sprague-Dawley rats from 1 day until 29 days of age. Plasma lipoprotein lipase activity peaked between ages 5 and 15 days and decreased after weaning, while plasma hepatic lipase activity remained constantly low during the suckling period and increased after weaning. No statistically significant difference in LCAT activity was seen from birth until weaning. Plasma triglycerides, as well as free fatty acids, decreased significantly after birth. Total plasma cholesterol increased during the suckling period and decreased after weaning. HDL cholesterol increased after the first 10 days of life, and free cholesterol remained constant after an initial decrease from birth to the 5th day of life. In conclusion, the enzymes associated with the metabolism of triglycerides, cholesterols and phospholipids are well developed in the rat shortly after birth.

Animals↗