• Asian-Australasian Journal of Animal Sciences
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• v.21 no.5
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• pp.715-722
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• 2008

There are marked variations in the activity of lipoprotein lipase (LPL) among adipose depots. The aim of this study was to compare the mechanisms of 24 h of fasting on LPL regulation between epididymal (EPI) adipocytes and mesenteric (MES) adipocytes in rats. 1-Day fasting consistently decreased activities of heparin-releasable LPL, total extractable LPL and cellular LPL markedly in both EPI and MES fat pads. LPL activity in MES fat pads was relatively lower than in the EPI fat pads. Consistent with data on LPL activity, the levels of expression of LPL mRNA in both nutritional states were lower in MES than EPI adipose tissue and isolated adipocytes. The decreased LPL activity after 1 day of fasting in MES adipocytes was explained mainly by a 50% decrease in the relative abundance of LPL mRNA level and a parallel 50% decrease in relative rate of LPL synthesis. In contrast, fasting of 1 day in EPI adipocytes decreased total LPL activity by 47% but did not affect LPL mRNA level or relative rate of LPL synthesis. A decrease in overall protein synthesis contributed to the decreased LPL activity after 1 day fasting both in EPI and MES adipocytes. In MES adipocytes the decrease in LPL activity, LPL mRNA and LPL synthesis were comparable, but in EPI adipocytes the changes in LPL activity were substantially larger than the changes in LPL mRNA level and LPL synthesis. Therefore, fasting decreased fat cell size, LPL activity, LPL mRNA level and relative rate of LPL synthesis in rats, and these effects were more marked in the MES adipocytes. These results clearly demonstrate the regional variations in the metabolic response of adipose tissue and LPL functions to fasting.

• Preventive Nutrition and Food Science
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• v.4 no.2
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• pp.139-144
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• 1999

Lipoprotein lipase (LPL) I san enzyme that catalyzed the hydrolysis of triacylglycerols of chylomicrons and VLDL to produce 20acylglycerols and fatty acids. The enzyme, LPL, is localized on the surface of the capillary endothelium and is widely distributed in extrahepatic tissues including heart, skeletal muscle and adipose tissue. LPL has been isolated from boving milk by affinity chromatography on heparin-separose in 2 M NaCL, 5mM barbital buffer, pH 7.4. To elucidate the lipid-binding regin, LPL was digested with trypsin and then separated by gel filtration. Lipid binding region of LPL has been investigated by recombining LPL peptides with DMPC vesicles. Proteolytic LPL fragments with DMPC were reassembled and stabilized by cholate. Lipid-binding region of LPL was identified by a PTH-automated protein sequencer, as AQQHYPVSAGYTK. The analysis of the secondary structure of the lipid-binding peptides revealed a higher probability of $\alpha$-helix structure compared to the whole LPL protein. The prediction of hydrophobicity of lipid -binding region was highly hydrophobic (-1.1) compared to LPL polypetide(-0.4).

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.3
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• pp.355-361
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• 1995

Lipoprotein lipase(LPL) is an acylglycerol hydrolase and is the extrahepatic enzyme responsible for the hydrolysis of triglyceride-rich plasma lipoproteins. LPL has been isolated from bovine milk by affinity chromatography on heparin-sepharose in 2M NaCl, 5mM barbital buffer, pH 7.4. Para-nitrophenyl butyrate(PNPB) was used as a substrate for the determination of LPL activity. Molecular weight of LPL was 55KD on 10% SDS-PAGE. When the effects of heparin on LPL activation were compared, LPL activity of heparin added group increased approximately 5 times higher than that of heparin non-added groups. These results indicated that heparin involved in the stabilization of LPL structure that led to increase enzyme activity. Furthermore, LPL activity increased about 4 times compared to the absence of heparin at various pH. LPL was stabilized when heparin was added either low or high salt concentrations. With the presence of heparin, NaCl concentration did not affect LPL activity at pH range 6∼9.

• Korean Journal of Food Science and Technology
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• v.47 no.2
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• pp.246-253
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• 2015

In this study, we evaluated the lipoprotein lipase (LPL) inhibitory activity of 11 water extracts derived from Cinnamomum cassia Blume, Sarcodon aspratus, Cordyceps militaris, Crataegus pinnatifida Bunge, Corni fructus, Allium cepa, Coix lacryma-jobi, Plantago asiatica L., Lentinus edodes, Rosa rugosa, and Foeniculum fructus. The results of the LPL secretion and activity assay showed Sarcodon aspratus (NE) extract have an LPL secretion inhibitory acitivity. The cause of reduction in LPL secretion after NE treatment was investigated using molecular biology methods. NE treatment affected the LPL content in cells, but did not affect LPL mRNA expression. It also increased the mRNA expression level of sortilin-related receptor LDLR class A (SorLA), a receptor that induces endocytosis and intracellular trafficking of LPL. Finally, cell fractionation revealed that NE treatment induced the expression of CCAAT-enhancer-binding protein beta ($C/EBP{\beta}$), a SorLA transcription factor, in the nuclei of 3T3-L1 adipocytes. These results show that NE's anti-obesity effect involves inhibition of LPL secretion through $C/EBP{\beta}$-mediated induction of SorLA expression.

• BMB Reports
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• v.34 no.4
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• pp.329-333
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• 2001

Active lipoprotein lipase (LPL) is known as a noncovalent homodimer of identical subunits, and dissociation of the dimer to a monomeric form renders the lipase inactive. In this study, the oligomerization status of LPL in human and rat plasma was investigated. The LPL activity was barely detectable in the control rat and human plasma. After the injection of heparin, the total lipolytic activity of plasma was rapidly increased, and reached its maximum in 30 min. Changes of the LPL protein correlated well with those of lipolytic activity. The LPL protein that is released by heparin into both human and rat plasma was active and dimeric in the sucrose density gradient ultracentrifugation. In control rat plasma, LPL was inactive, and a great fraction was present as an aggregate. However, the inactive LPL protein in the control human plasma retained the dimeric state, indicating that dimerization can be an entity independent of the catalytic activity of LPL. The released LPL is transported as a complex with lipoproteins in plasma. Lipoprotein profiles, determined by NaBr ultracentrifugation, exhibited typical LDL- and HDL-mammal patterns in humans and rats, respectively, with a smaller amount of the LDL fraction observed in rats. The difference in the lipoprotein profiles might influence the fate of the released LPL in plasma.

• BMB Reports
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• v.35 no.5
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• pp.518-523
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• 2002

Nordihydroguaiaretic acid (NDGA), an inhibitor of lipoxygenase, inhibits the secretion of proteins and causes the redistribution of resident Golgi proteins into the endoplasmic reticulum (ER). In this study, the effect of NDGA on lipoprotein lipase (LPL) secretion was investigated in 3T3-L1 adipocytes, and compared with those of brefeldin A (BFA), a well-known fungal metabolite that exhibits similar ER-Golgi redistribution. Both BFA and NDGA blocked secretions of LPL. In the presence of BFA, the active and dimeric LPL was accumulated in adipocytes. After endoglycosidase H (endo H) digestion, the proportion of LPL subunits with partially endo H-sensitive oligosaccharide was significantly increased with BFA. However, in the presence of NDGA, the cellular LPL became inactive, and only the endo H-sensitive fraction of the LPL subunit was observed. An increase of the aggregated forms was observed in the fractions of the sucrose-density gradient ultracentrifugation. These properties of LPL in the NDGA-treated cells were similar to those of LPL that is retained in ER, and the effects of NDGA could not be reversed by BFA. These results indicate that the inhibitory mechanism of NDGA on the LPL secretion is functionally different from the ER-Golgi redistribution that is induced by BFA.

• BMB Reports
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• v.33 no.2
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• pp.148-154
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• 2000

The glycation process plays an important role in accelerated atherosclerosis in diabetes, and the uptake of atherogenic lipoproteins by macrophage in the intima of the vessel wall leads to foam cell formation, an early sign of atherosclerosis. Besides the lipolytic action on the plasma triglyceride component, lipoprotein lipase (LPL) has been reported to enhance the cholesterol uptake by arterial wall cells. In this study, some properties of LPL-mediated low-density lipoprotein (LDL) uptake and the effect of LDL glycation were investigated in RAW 264.7 cell, a murine macrophage cell line. In the presence of LPL, $^{125}I$-LDL binding to RAW 264.7 cells was increased in a dose-dependent manner. At concentrations greater than $20\;{\mu}g/ml$ of LPL, LPL-mediated LDL binding was increased about 17-fold, achieving saturation. Without LPL, both very low-density lipoprotein (VLDL) and high-density lipoprotein (HDL) were ineffective in blocking the binding of $^{125}I$-LDL to Cells. However, LPL-enhanced LDL binding was inhibited about 50% by the presence of VLDL, while no significant effect was observed with HDL. Heat inactivation of LPL caused a 30% decrease of LDL binding. In the presence of LPL, the cells took up 40% of cell-bound native LDL. No significant difference was observed in cell binding between native and glycated LDL. However, the uptake of glycated LDL was significantly greater than that of native LDL, reaching to 70% of the total cell bound glycated LDL. These results indicate that LPL can cause the significant enhancement of LDL uptake by RAW 264.7 cells and the enhanced uptake of glycated LDL in the presence of LPL might play an important role in the accelerated atherogenesis in diabetic patients.

• Journal of Soil and Groundwater Environment
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• v.22 no.3
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• pp.42-49
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• 2017

TOUGH2 was used to simulate the migration of $CO_2$ injected into a sandy aquifer. A series of numerical simulations was performed to investigate the effects of a low-permeability layer (LPL) embedded in the aquifer on the injection rate and the pressure distribution of $CO_2$. The results show that the size and location of the LPL greatly affected the spread of $CO_2$. The pressure difference between two points in the aquifer, one each below and above the LPL, increased as the size of the LPL increased, showing a critical value at 200 m, above which the size effect was diminished. The location of the LPL with respect to the injection well also affected the migration of $CO_2$. When the injection well was at the center of the LPL, the injection rate of $CO_2$ decreased by 5.0% compared to the case with no LPL. However, when the injection well was at the edge of the LPL, the injection rate was decreased by only 1.6%. The vertical distance between the injection point and the LPL also affected the injection rate. The closer the LPL was to the injection point, the lower the injection rate was, by up to 8.3%. Conclusively, in planning geologic storage of $CO_2$, the optimal location of the injection well should be determined considering the distribution of the LPL in the aquifer.

• Journal of Nutrition and Health
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• v.48 no.1
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• pp.9-18
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• 2015

Purpose: Poncirus trifoliata has been reported to have anti-inflammatory, antioxidant, and immune activities. However, its anti-obesity activity and the mechanism by which the water extract of dried, immature fruit of Poncirus trifoliata (PF-W) acts are not clear. This study suggests a potential mechanism associated with the anti-obesity activity of PF-W. Methods: We measured the effect of PF-W on lipoprotein lipase (LPL) regulation using enzyme-linked immunosorbent assay (ELISA) and an activity assay. The LPL regulation mechanism was examined by reverse transcription polymerase chain reaction (RT-PCR) to measure the mRNA expression of biomarkers related to protein transport and by western blot for analysis of the protein expression of the transcription factor CCAAT-enhancer-binding protein ($C/EBP{\beta}$). Results: The total polyphenol and flavonoid content of PF-W was $52.15{\pm}4.02$ and $6.56{\pm}0.47mg/g$, respectively. PF-W treatment decreased LPL content in media to $58{\pm}5%$ of that in control adipocyte media, and increased LPL content to $117{\pm}3.5%$ of that in control adipocytes, but did not affect the mRNA expression of LPL. PF-W also increased the mRNA expression of sortilin-related receptor (SorLA), a receptor that induces endocytosis and intracellular trafficking of LPL, in a concentration- and time-dependent manner. Finally, cell fractionation revealed that PF-W treatment induced the expression of $C/EBP{\beta}$, a SorLA transcription factor, in the nuclei of 3T3-L1 adipocytes. Conclusion: The LPL secretion and activity assay showed PF-W to be an LPL secretion inhibitor, and these results suggest the potential mechanism of PF-W involving inhibition of LPL secretion through $C/EBP{\beta}$-mediated induction of SorLA expression.

• Journal of Nutrition and Health
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• v.10 no.4
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• pp.10-18
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• 1977

Activities of lipoprotein lipase (LPL) and hormone-sensitive lipase (HSL) in adipose tissue, accumulation of carcass fat, and serum triglyceride have been determined in meal-fed (MF) and ad libitum-fed (AD) rats. At each feeding frequency, the animals received diets providing total fat as 15% or 30% of calories and polyunsaturated fatty acids (PUFA) as 2.5% or 11% of calories. The food intake of the MF rats was 75% of that consumed by the AD rats but MF rat utilized their food more efficiently, as evidenced by weight gain per 100 Kcal consumed. Meal feeding, as contrasted to ad libitum feeding, resulted in greater activities of both LPL and HSL. This suggested a higher turnover of fat in the adipose tissue of MF rats. In AD rats, body fat was significantly correlated with LPL and the ratio of LPL/HSL. Meal feeding significantly increased the ratio of LPL/HSL, indicating a greater capacity for energy storage and fat deposition in the MF rat. However, at the limited caloric intake, MF rats failed to realize this potential; there was no significant difference in percentage of body fat at the two feeding frequencies. Body fat deposition was greater in rats fed the 30% fat diet, as compared with the 15% diet, regardless of the rate of food ingestion. This was coupled with a higher ratio of LPL/HSL. The significant correlation of serum triglycerides with body fat and with the ratio of LPL/HSL in AD rats suggests that LPL activity and fat deposition may be controlled by the concentration of circulating triglycerides. Both serum triglycerides and adipose LPL activity were significantly reduced when the diet contained high levels of PUFA. The percentage of body fat was also lower in animals whose intake of PUFA was high.