• BMB Reports
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• 제34권4호
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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.

• Preventive Nutrition and Food Science
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• 제4권2호
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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).

• Asian-Australasian Journal of Animal Sciences
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• 제14권11호
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• pp.1592-1597
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• 2001

Sixteen pigs from 2 distinct genetic lines (LGAH and VFIL) obtained after eight generations of divergent selection for high (H) and low (L) lean tissue growth rate with ad-libitum feeding (LGA) and voluntary feed intake (VF1), respectively, were used in this study. The objectives of this investigation were to establish appropriate working conditions for the postheparin plasma lipoprotein lipase (LPL) assay and to study relationships between fat deposition and plasma lipids, very low density lipoprotein (VLDL) lipids, VLDL-subfractions and postheparin plasma LPL activity in growing pigs. Four preliminary experiments were performed to determine the appropriate working conditions for the postheparin plasma LPL assays. Postheparin plasma preincubated with SDS (20-50 mM) at $26^{\circ}C$ for 45 minutes inhibited hepatic lipase activity. A total of $2{\mu}l$ VLDL/assay produced maximum stimulation of LPL activity. Postheparin plasma protein and increasing incubation time contributed an optimum response. LGAH pigs had a significantly higher proportion subtraction 2 than VFIL pigs. No differences were observed in postheparin plasma LPL activity and backfat thickness for two lines of pigs. There were positive correlations between backfat thickness and proportion of subtractions 2 and postheparin plasma LPL activity but the results were not statistically significant. Backfat thickness was not statistically correlated with proportion of subtraction 2 and postheparin plasma LPL activity in a multiple regression analysis. It is believed that the apolipoprotein E, which is present in higher quantities in VLDL-subfraction 2 plays an important role for clearing VLDL triacylglycerol into adipose tissue. LPL activity of pigs can be measured by using postheparin plasma technique. If the relationships of backfat thickness and VLDL-subfraction 2 and postheparin plasma LPL activity can be established, it suggests that these parameters could be used as indicators in selection programmes. Further experiments need to be conducted by using larger sample size and different breed of pigs with greater differences in backfat thicknesses to confirm these trends.

• 한국식품영양과학회지
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• 제24권3호
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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.

• BMB Reports
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• 제33권2호
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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.

• 한국식품과학회지
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• 제47권2호
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• pp.246-253
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• 2015

본 연구에는 항비만소재로 연구되어진 11종의 소재를 대상으로 lipoprotein lipase (LPL)의 억제효능을 확인하고자 배양배지내 LPL의 함량과 LPL 효소활성을 측정하였다. 그 결과 3T3-L1 adipocyte에서 LPL의 분비를 억제하는 소재로 능이추출물(NE)을 선택할 수 있었다. 선택된 NE의 폴리페놀과 플라보노이드 함량을 측정한 결과 $16.61{\pm}0.44mg/g$과 $6.58{\pm}0.01mg/g$이 각각 확인되었다. NE의 LPL 분비억제기작을 확인하기위해 먼저 세포내 LPL단백질의 함량과 mRNA 발현을 확인하였다. 그 결과 함량이 감소했던 배양배지와는 다르게 NE를 처리한 3T3-L1 adipocyte의 세포내 LPL은 유의하게 증가한 것을 확인할 수 있었으며 mRNA의 발현에는 영향이 없음을 관찰할 수 있었다. 이를 바탕으로 생성된 LPL 단백질의 exocytosis에 문제가 발생했을 것으로 유추하고 다양한 단백질 이동 관련 유전자의 발현을 확인하였다. 그 결과 LPL의 이동과 분해에 관여하여 세포내 LPL의 활성을 조절하는 것으로 알려진 SorLA의 발현이 증가하는 것을 확인하고 이를 조절하는 transcription factor의 발현과 nuclear로의 이동에 NE가 미치는 영향을 검토하였다. 그 결과 NE를 처리함으로써 SorLA promoter에 작용하는 $C/EBP{\beta}$의 단백질 발현이 nuclear에서 증가하는 것을 확인할 수 있었다. 본 연구를 통해 NE가 SorLA 유전자의 transcription factor인 $C/EBP{\beta}$의 단백질 발현을 nuclear에서 증가시킴으로서 결과적으로 LPL의 분비억제가 가능함을 확인할 수 있었으며 이는 NE의 항비만 효과기전을 설명하는 기초자료를 제공하는 것이라 사료된다.

• BMB Reports
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• 제35권5호
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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.

• Asian-Australasian Journal of Animal Sciences
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• 제21권5호
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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.

• BMB Reports
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• 제32권3호
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• pp.311-316
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• 1999

Studies in adipocytes indicate that secretion of active lipoprotein lipase (LPL) was strictly regulated by a quality control system in the endoplasmic reticulum (ER). However, there has been no report about the ER chaperones participating in the folding and assembly of LPL. Many chaperones are known to bind unfolded proteins and dissociate from them through the ATP-hydrolyzing reaction. In this study, putative ER chaperones for LPL were determined by affinity chromatography using denatured LPL as an affinity ligand and elution with ATP. BiP, grp94, calreticulin, and another 50 kDa K-D-E-L protein in the ER of rat adipose tissue were bound to denatured LPL and eluted by ATP. Calnexin was bound to denatured LPL; however, it was not eluted by ATP but by acetic acid. These results indicate that, at least, BiP, grp94, calreticulin, calnexin, and the unidentified 50 kDa protein might act as putative chaperones for the proper folding and assembly of LPL in ER.

• 한국자원식물학회지
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• 제24권2호
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• pp.181-188
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• 2011

본 연구는 회향종자 물 추출물이 비만과 관련된 지질대사를 조절하는 효소들 가운데 lipoprotein lipase(LPL), acyl-CoA synthetase(ACS), hormone sensitive lipase(HSL)의 활성에 미치는 효과를 알아보았다. 정상 마우스에서 회향종자 물 추출물의 LPL 활성은 최고 21.9% 억제되었고, ACS와 HSL의 효소 활성은 각각 151.8%, 174.0% 증가되었다. 고지방식이 유도 비만 마우스에서 LPL은 12.0% 활성이 억제되었으며, ACS와 HSL은 742.0%, 134.4% 활성이 증가하였다. 결과적으로 회향종자 물 추출물이 효과적으로 세포내로 지방산의 유입을 억제하며, 유입된 지방산을 에너지원으로 사용하는 대사과정을 활성화시킴으로서 항비만 효능을 갖는다는 것을 추정할 수 있다.