Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.34 (lipoprotein lipase)
 7,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An elevation of lipoprotein lipase (LPL) activity in adipose tissue is considered a possible cause of obesity. However, transgenic mice that overexpress the human LPL gene showed no increase in fat deposition as compared with controls. In the present study, we investigated effects of LPL on fat accumulation. Respiratory quotients and uptake of [3H] triolein by tissues (white and brown adipose tissue, and skeletal muscles) did not differ significantly for transgenic and non-transgenic mice. The mRNA levels of hormone-sensitive lipase (HSL) and HSL activity in adipose tissue during feeding were higher in LPL transgenic mice than in controls. Results suggest that the overexpression of LPL does not induce obesity by enhancing the hydrolysis of triglycerides in adipose tissue.
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PMID:Overexpression of human lipoprotein lipase increases hormone-sensitive lipase activity in adipose tissue of mice. 759 4

The effect of dietary octacosanol, a long-chain alcohol, on lipid metabolism was investigated in rats fed on a high-fat diet for 20 d. The addition of octacosanol (10 g/kg diet) to the high-fat diet led to a significant reduction (P < 0.05) in the perirenal adipose tissue weight without decrease of the cell number, suggesting that octacosanol may suppress lipid accumulation in this tissue, whereas no effect was seen in the epididymal adipose tissue weight and in the lipid content in liver. Octacosanol supplementation decreased the serum triacylglycerol concentration, and enhanced the concentration of serum fatty acids, probably through inhibition of hepatic phosphatidate phosphohydrolase (EC 3.1.3.4). Though the activity of hormone-sensitive lipase (EC 3.1.1.3) was not influenced by octacosanol, higher activities of lipoprotein lipase (EC 3.1.1.34) in the perirenal adipose tissue and the total oxidation rate of fatty acid in muscle were observed. Lipid absorption was not affected by the inclusion of octacosanol. Thus, the present results suggest that the dietary incorporation of octacosanol into a high-fat diet affects some aspects of lipid metabolism.
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PMID:Octacosanol affects lipid metabolism in rats fed on a high-fat diet. 776 66

We report the cloning of a complementary DNA for the mouse homolog of the very low density lipoprotein (VLDL)/apolipoprotein-E receptor (VLDLR), the deduced amino acid sequence of the protein, and the mapping of the gene encoding the receptor to mouse chromosome 19. Northern hybridization revealed that the VLDLR messenger RNA (mRNA) is most abundant in skeletal muscle, heart, kidney, and brain. It was also detected in lung and in low levels in liver, but it was not found in spleen or testes. Levels of VLDLR mRNA in mouse placenta increased from days 8-18 of gestation. The VLDLR mRNA was induced in 3T3-L1 cells undergoing differentiation into adipocytes. The increase in VLDLR mRNA paralleled the rise in lipoprotein lipase and hormone-sensitive lipase mRNAs. However, VLDLR and low density lipoprotein receptor-related protein were increased in the presence of retinoic acid, whereas the induction of lipoprotein lipase and hormone-sensitive lipase mRNAs was inhibited. Our observations demonstrate regulated expression of the VLDLR gene in placenta and adipocytes, where the receptor protein may play roles in the uptake of triglyceride-rich particles for storage of lipid (adipocytes) or for lipid transport to the fetus (placenta). The availability of a murine complementary DNA probe and the knowledge of the map position of the VLDLR gene in the mouse genome will facilitate studies on the function and regulation of this protein.
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PMID:Cloning of a complementary deoxyribonucleic acid encoding the murine homolog of the very low density lipoprotein/apolipoprotein-E receptor: expression pattern and assignment of the gene to mouse chromosome 19. 783 12

To investigate the factors controlling maternal depot fat accumulation during early pregnancy and net decrease during late pregnancy, the activity and mRNA expression of adipose tissue lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) were related to several other lipid metabolic parameters. Virgin control rats, pregnant rats (at days 12, 15, 19, and 21), and lactating rats (at days 5 and 10 postpartum) were studied. In adipose lumbar tissue of late pregnant rats, LPL activity decreased to about one-third that of the virgin control animals, with < 10% of initial LPL mRNA expressed as determined by Northern blots. HSL activity increased maximally 1.5-fold with a fourfold increase of HSL expression at days 12-15 of pregnancy and decreased to control levels after parturition. The HSL-to-LPL mRNA and activity ratios were enhanced from days 15 and 19 of pregnancy, respectively, and remained so even during lactation, mainly because of the marked lowering of the LPL values. This enhancement coincided with increments in plasma free fatty acids and glycerol levels indicating an increased depot fat breakdown. These results give no indication of an involvement of LPL and HSL gene expression changes in the accumulation of maternal depot during early pregnancy. In contrast, such changes could be responsible for the net breakdown of this fat depot during late gestation. Thus, during this physiological state, long-term (e.g., transcriptional) regulation of LPL and HSL gene expression could be an important mechanism for the control of adipose tissue mass breakdown during late gestation.
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PMID:Lipoprotein lipase and hormone-sensitive lipase activity and mRNA in rat adipose tissue during pregnancy. 802 24

Several lipases and their cofactors are involved in the absorption, transport, storage, and mobilization of lipids. As part of an effort to examine the role of these enzymes in plasma lipid metabolism and genetic susceptibility to atherosclerosis, we report the chromosomal mapping of their genes in mouse. Restriction fragment length variants for each gene were identified, typed in an interspecific cross, and tested for linkage to known chromosomal markers. The gene for pancreatic lipase resides on chromosome 19, while the gene for its cofactor, colipase, is on chromosome 17. A gene for a protein with sequence similarity to pancreatic lipase was tightly linked (no observed recombination) to the gene for pancreatic lipase, suggesting a gene cluster. The gene for hormone-sensitive lipase is near the gene cluster containing apolipoproteins C-II and E on chromosome 7. The gene for hepatic lipase is near the gene for apolipoprotein A-I on chromosome 9. The carboxyl ester lipase gene resides on chromosome 2. Previously, we have mapped the gene for lipoprotein lipase to chromosome 8. Thus, with the exception of pancreatic lipase and a related protein, these lipase genes, including several that are members of a gene family, are widely dispersed in the genome. Comparison of chromosomal locations for these genes in mouse and humans shows that the previously observed interspecies syntenies are preserved.
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PMID:Chromosomal localization of lipolytic enzymes in the mouse: pancreatic lipase, colipase, hormone-sensitive lipase, hepatic lipase, and carboxyl ester lipase. 810 16

There is net outward flow of fatty acids from adipose tissue in the fasted state but net inward flow and storage in the postprandial state. We investigated how this is regulated. Arteriovenous differences were measured across a subcutaneous adipose depot in six normal subjects before and for 5 h after a meal containing 80 g fat and 80 g carbohydrate. In five further experiments, insulin was infused at 40 mU.m-2.min-1 from 30 min after the meal, clamping the plasma glucose. Net transcapillary fatty acid flow changed from negative (outward flow from tissue to capillaries) in the postabsorptive state to consistently positive (net inward flow, implying fat storage) after the meal despite continued net efflux of fatty acids into venous blood. In the "clamped" experiments (with additional insulin), net fatty acid efflux in the venous blood was suppressed and positive transcapillary flux (storage) was more marked. Regulation of fatty acid flow appeared to depend on coordinated changes in hormone-sensitive lipase (HSL) and lipoprotein lipase (LPL) action and fatty acid esterification. Additional insulin caused no further suppression of HSL or activation of LPL but markedly stimulated fatty acid retention (presumed to represent esterification). In the absence of additional insulin, a high proportion of the fatty acids liberated by LPL are released into the venous plasma in both postabsorptive and postprandial states. We hypothesize that this "loss" of fatty acids is necessary to give precise control to the pathway of fat storage.
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PMID:Regulation of fatty acid movement in human adipose tissue in the postabsorptive-to-postprandial transition. 816 51

The review examines the mechanisms regulating the activities of the two key enzymes determining rates of glucose and fatty acid oxidation, i.e., the pyruvate dehydrogenase (PDH) complex and the carnitine palmitoyltransferase (CPT) system. The review also evaluates the regulatory importance of gene expression in the control of tissue fuel selection within the context of substrate competition between glucose and fatty acids. It identifies a strong indirect input of nutrient-gene interactions in the control of pyruvate oxidation through the regulated provision of pyruvate as a substrate for PDH and as an inhibitor of PDH kinase. Nutrient-gene interactions are also identified in relation to the regulation of CPT I activity by malonyl-CoA (inhibitor) and by the provision of long-chain acyl-CoA (substrate/activator), the latter via the hydrolysis of plasma or tissue triacylglycerol (by lipoprotein lipase and hormone-sensitive lipase, respectively). We discuss how such regulation is reinforced by long-term modulation of PDH kinase-specific activity and CPT I maximal activity. We also explore the role of mechanisms operating at the levels of the PDH complex and the CPT system that act to promote and accelerate a switch in fuel utilization once a committed change in nutrient supply has been established. In particular, we discuss the regulatory influences exerted by altered sensitivities of PDH kinase to inhibition by pyruvate and CPT I to inhibition by malonyl-CoA, respectively.
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PMID:Interactive regulation of the pyruvate dehydrogenase complex and the carnitine palmitoyltransferase system. 829 90

Obesity is a risk factor of atherosclerosis. The TG content of a fat cell is determined by the balance of lipogenesis from plasma FFA and glucose and lipolysis by hormone-sensitive lipase (HSL). Plasma FFA is produced by TG lipolysis by lipoprotein lipase (LPL). Insulin stimulates LPL activity and inhibits HSL activity. Therefore, hyperinsulinemia stimulates TG accumulation in fat cells. Insulin also stimulates fat cell proliferation. Hyperinsulinemia is a major factor for obesity. Portal FFA stimulates VLDL synthesis and gluconeogenesis and inhibits insulin degradation in the liver. Therefore, visceral obesity is important as a risk factor of atherosclerosis. However the increase of total adipose tissue mass is more important for blood pressure and cardiac performance.
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PMID:[Atherosclerotic and hemodynamic effects of obesity]. 841 92

The expression of genes coding for regulatory enzymes involved in the uptake, synthesis and mobilisation of lipid was measured in adipose tissue of cancer patients. Total RNA was isolated from subcutaneous adipose tissue of control and cancer patients and the various mRNAs measured by Northern blot analysis. The total lipoprotein lipase enzymic activity and the relative levels of the mRNAs for lipoprotein lipase and for fatty acid synthase were not significantly different between cancer patients and control patients. However, there was a significant two-fold increase in the relative level of mRNA for hormone-sensitive lipase (HSL) in adipose tissue of cancer patients compared with control patients. The cancer patients also exhibited a two-fold elevation in serum triacylglycerol levels and serum free fatty acid levels. There was a significant correlation between the serum free fatty acid level and expression of HSL mRNA in the adipose tissue. The serum levels of insulin and tumour necrosis factor-alpha were not different between cancer and control patients. The results suggest that at least one of the mechanisms for depletion of lipid from adipose tissue in cancer patients operates at the level of increased expression of mRNA of the lipolytic regulatory enzyme, hormone-sensitive lipase.
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PMID:Increased expression of the mRNA for hormone-sensitive lipase in adipose tissue of cancer patients. 842 28

The human hormone-sensitive lipase (HSL) gene encodes a 786-aa polypeptide (85.5 kDa). It is composed of nine exons spanning approximately 11 kb, with exons 2-5 clustered in a 1.1-kb region. The putative catalytic site (Ser423) and a possible lipid-binding region in the C-terminal part are encoded by exons 6 and 9, respectively. Exon 8 encodes the phosphorylation site (Ser551) that controls cAMP-mediated activity and a second site (Ser553) that is phosphorylated by 5'-AMP-activated protein kinase. Human HSL showed 83% identity with the rat enzyme and contained a 12-aa deletion immediately upstream of the phosphorylation sites with an unknown effect on the activity control. Besides the catalytic site motif (Gly-Xaa-Ser-Xaa-Gly) found in most lipases, HSL shows no homology with other known lipases or proteins, except for a recently reported unexpected homology between the region surrounding its catalytic site and that of the lipase 2 of Moraxella TA144, an antarctic psychrotrophic bacterium. The gene of lipase 2, which catalyses lipolysis below 4 degrees C, was absent in the genomic DNA of five other Moraxella strains living at 37 degrees C. The lipase 2-like sequence in HSL may reflect an evolutionarily conserved cold adaptability that might be of critical survival value when low-temperature-mobilized endogenous lipids are the primary energy source (e.g., in poikilotherms or hibernators). The finding that HSL at 10 degrees C retained 3- to 5-fold more of its 37 degrees C catalytic activity than lipoprotein lipase or carboxyl ester lipase is consistent with this hypothesis.
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PMID:Gene organization and primary structure of human hormone-sensitive lipase: possible significance of a sequence homology with a lipase of Moraxella TA144, an antarctic bacterium. 850 34


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