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Wong H, Yang D, Hill JS, Davis RC, Nikazy J, Schotz MC. A molecular biology-based approach to resolve the subunit orientation of lipoprotein lipase. Proc Natl Acad Sci U S A 1997; 94:5594-8. [PMID: 9159117 PMCID: PMC20823 DOI: 10.1073/pnas.94.11.5594] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/1996] [Accepted: 03/26/1997] [Indexed: 02/04/2023] Open
Abstract
The subunit orientation of a dimeric enzyme influences the mechanism of action and function. To determine the subunit arrangement of lipoprotein lipase (LPL), a molecular biology-based approach was initiated. An eight amino acid linker region was engineered between two LPL monomers and expressed in COS-7 cells. The resultant tandem-repeat molecule (LPLTR) was lipolytically active and had kinetic parameters, salt inhibition, cofactor-dependent activity, heparin-binding characteristics, and a functional unit size very similar to the expressed native human enzyme. By these criteria, LPLTR was the functional equivalent of native LPL. Considering the length of the linker peptide (no more than 24 A), monomers in the tethered molecule were restricted to a head-to-tail subunit arrangement. Since LPLTR demonstrated native enzyme-like properties while constrained to this subunit arrangement, these results provide the first compelling evidence that native LPL monomers are arranged in a head-to-tail subunit orientation within the active dimer. Thus, LPL function in physiology, lipolysis, and binding to cell-surface components must now be addressed with this subunit orientation in mind. The utility of the tandem-repeat approach to resolve the subunit arrangement of an obligate dimer has been demonstrated with LPL and could be generalized for use with other oligomeric enzymes.
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Affiliation(s)
- H Wong
- Lipid Research Laboratory, West Los Angeles Veterans Affairs Medical Center, Los Angeles, CA 90073, USA.
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2
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Sabugal R, Robert MQ, Julve J, Auwerx J, Llobera M, Peinado-Onsurbe J. Hepatic regeneration induces changes in lipoprotein lipase activity in several tissues and its re-expression in the liver. Biochem J 1996; 318 ( Pt 2):597-602. [PMID: 8809052 PMCID: PMC1217662 DOI: 10.1042/bj3180597] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We examined the expression of lipoprotein lipase (LPL) gene and LPL activity following a two-thirds hepatectomy and during liver regeneration. In most of the tissues studied, LPL activity increased a few hours after partial hepatectomy, but soon returned to normal levels. The greatest increase was found in the adrenal glands, plasma and liver. This increase in LPL activity in the liver could be partially due to an increase in the influx of the enzyme from extrahepatic tissues. There is, however, also a re-expression of LPL mRNA in the liver after partial hepatectomy (during the first hours). It is well known that LPL is expressed in the liver of neonatal animals, but progressively decreases during post-natal development, to reach adult levels around the time of weaning. Our results show by the first time that the remaining liver re-expresses LPL gene during the regeneration process and that the hepatocytes de-differentiate and acquire some of the neonatal characteristics. The increase in LPL mRNA will contribute to the rise in LPL activity after hepatectomy. This presence of LPL could enable the liver to take up fatty acids from the circulating triacylglycerols, which are needed as energetic and plastic substrates during the process of hepatic regeneration.
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Affiliation(s)
- R Sabugal
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Spain
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3
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Wilson DE, Hata A, Kwong LK, Lingam A, Shuhua J, Ridinger DN, Yeager C, Kaltenborn KC, Iverius PH, Lalouel JM. Mutations in exon 3 of the lipoprotein lipase gene segregating in a family with hypertriglyceridemia, pancreatitis, and non-insulin-dependent diabetes. J Clin Invest 1993; 92:203-11. [PMID: 8325986 PMCID: PMC293568 DOI: 10.1172/jci116551] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A proband with chylomicronemia, pancreatitis, and non-insulin-dependent diabetes (NIDDM) bears two different mutations in exon 3 of the lipoprotein lipase (LPL) gene: a missense mutation, 75Arg-->Ser, inherited through the paternal line and a truncation, 73Tyr-->Ter, through the maternal line. NIDDM appeared to be independently segregating. The R75S mutant was studied in extracts and media from transfected COS-1 cells. Detectable amounts of catalytically competent R75S LPL suggested destabilization of the active homodimer as with exon 5 mutants (Hata et al. 1992. J. Biol. Chem. 267:20132-20139). Hydrolysis of a short-chain fatty acid ester indicated that R75S does not directly affect activation of LPL by apoC-II. Subjects with NIDDM and wild-type LPL, and nondiabetic middle-aged carriers of the 73Tyr-->Ter truncation had moderate hypertriglyceridemia (260-521 mg/dl) and reduced high density lipoprotein cholesterol. A maternal aunt with NIDDM carried the truncation. Her phenotype (triglycerides of 5,300 mg/dl, eruptive xanthomatosis, and recurrent pancreatitis) was as severe as that in homozygotes or compound heterozygotes. We conclude: (a) diabetic carriers of dysfunctional LPL alleles are at risk for severe lipemia; and (b) the physiologic defects in NIDDM may be additive or synergistic with heterozygous LPL deficiency.
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Affiliation(s)
- D E Wilson
- Howard Hughes Medical Institute, University of Utah, Salt Lake City 84132
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4
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Enan E, Matsumura F. 2,3,7,8-Tetrachlorodibenzo-P-dioxin induced alterations in protein phosphorylation in guinea pig adipose tissue. JOURNAL OF BIOCHEMICAL TOXICOLOGY 1993; 8:89-99. [PMID: 8394938 DOI: 10.1002/jbt.2570080206] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
An in situ (explant tissue culture) model has been developed to study the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), hormones, and growth factors either alone or in combination. In our model system, the effect of TCDD on protein phosphorylation was greatly affected by the presence or the absence of externally added D-glucose. In the presence of a physiologically relevant level of glucose (13.3 mM), TCDD clearly stimulated protein phosphorylation as in the case of in vivo data. However, in the absence of D-glucose, TCDD clearly inhibited protein phosphorylation. On the other hand, TCDD reduced the glucose uptake activity in isolated adipose tissue either in the presence or absence of D-glucose (13.3 mM). Therefore, the TCDD-induced reduction of glucose transport does not appear to be related directly to the simultaneous rise in protein phosphorylation. For comparison, several agents which are known to affect protein phosphorylation were tested. These hormonal agents generally affected the TCDD-untreated adipose tissues in the manner expected from their known actions, indicating that this in situ model is an adequate system to study their independent actions. The TCDD-treated adipose tissue samples showed only mild or insignificant response to these hormonal stimuli. In terms of the changes in the pattern of protein phosphorylation activities, the action of TCDD appeared to resemble that of EGF and T3. Since under in situ conditions no agents such as EGF or T3 can be expected to be present, the observed TCDD-induced changes are suggestive of the basic intracellular changes in cellular activities. The types of TCDD-induced protein kinases appear to be protein tyrosine kinases and protein kinase C.
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Affiliation(s)
- E Enan
- Department of Environmental Toxicology, University of California, Davis 95616
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5
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Binding of lipoprotein lipase to heparin. Identification of five critical residues in two distinct segments of the amino-terminal domain. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)52896-9] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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6
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Oliver JD, Rogers MP. Effects of retinoic acid on lipoprotein lipase activity and mRNA level in vitro and in vivo. Biochem Pharmacol 1993; 45:579-83. [PMID: 8442757 DOI: 10.1016/0006-2952(93)90130-o] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This study was designed to determine whether all-trans retinoic acid altered lipoprotein lipase (LPL) activity and mRNA levels in vitro and tissue LPL mRNA levels in vivo. Incubation of adipocytes or adipose tissue for up to 12 hr with 10(-6) or 10(-5) M all-trans retinoic acid did not decrease LPL activity. There was no change in LPL mRNA levels following 3 hr incubation of adipocytes with all-trans retinoic acid. Feeding all-trans retinoic acid for 4 days led to a significant decrease in adipose tissue LPL activity but no change in heart enzyme activity. Retinoic acid did not alter the increase in heart LPL activity observed with fasting. There were no changes in LPL mRNA levels in adipose tissue, heart or liver. Retinoic acid does not have an acute direct effect on adipose tissue LPL activity. The observed decrease in adipose tissue LPL activity in vivo is not due to alterations in mRNA levels and may be a secondary effect of retinoic acid.
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Affiliation(s)
- J D Oliver
- Department of Biochemistry and Genetics, Medical School, The University, Newcastle upon Tyne, U.K
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7
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Hata A, Ridinger D, Sutherland S, Emi M, Kwong L, Shuhua J, Lubbers A, Guy-Grand B, Basdevant A, Iverius P. Missense mutations in exon 5 of the human lipoprotein lipase gene. Inactivation correlates with loss of dimerization. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)88676-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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8
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Mackay AG, Oliver JD, Rogers MP. Regulation of lipoprotein lipase activity and mRNA content in rat epididymal adipose tissue in vitro by recombinant tumour necrosis factor. Biochem J 1990; 269:123-6. [PMID: 2198021 PMCID: PMC1131540 DOI: 10.1042/bj2690123] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tumour necrosis factor (TNF) has previously been shown to decrease lipoprotein lipase (LPL) activity and mRNA levels in 3T3-L1 cells and in adipose tissue from rats and guinea pigs when injected in vivo, but not to alter LPL activity in human adipocytes incubated in vitro. The effect of recombinant human TNF on LPL activity and mRNA levels in rat epididymal adipose tissue incubated in vitro was examined. LPL activity and mRNA levels fell in adipose tissue taken from fed rats and incubated in Krebs-Henseleit bicarbonate medium with glucose. The addition of insulin and dexamethasone prevented these falls. TNF (400 ng/ml) produced a fall of approx. 50% in LPL activity after 2 h of incubation and of approx. 30% in LPL mRNA levels after 3 h. TNF did not decrease LPL activity in isolated adipocytes. These results demonstrate that rat adipose tissue incubated in vitro is responsive to TNF whereas isolated adipocytes are not.
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Affiliation(s)
- A G Mackay
- Department of Biochemistry and Genetics, University of Newcastle upon Tyne, U.K
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9
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McMaster J, Rogers MP, Sherratt HS, Shuster S. Effects of isotretinoin on lipid metabolism in the rat. Arch Dermatol Res 1989; 281:116-8. [PMID: 2774640 DOI: 10.1007/bf00426589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- J McMaster
- Department of Pharmacological Sciences, University of Newcastle upon Tyne, UK
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10
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Krakower GR, James RG, Arnaud C, Etienne J, Keller RH, Kissebah AH. Regional adipocyte precursors in the female rat. Influence of ovarian factors. J Clin Invest 1988; 81:641-8. [PMID: 3278003 PMCID: PMC442509 DOI: 10.1172/jci113367] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A flow cytometric immunofluorescence procedure utilizing a specific antibody to rat adipose tissue lipoprotein lipase (LPL) was developed to quantify differentiated and undifferentiated preadipocytes present in the adipose tissue vascular stroma. This method is highly sensitive and specific for cells capable of synthesizing LPL in significant quantities. Pubescence in female rats was associated with an increase in differentiated preadipocytes and in fat cell number with enlargement of the fat depots in the perirenal, parametrial, and the subcutaneous dorsal and femoral regions. A concomitant decline in the percentage of undifferentiated preadipocytes occurred in all but the femoral depot. Ovariectomy reduced pubertal adipose growth in the femoral and parametrial but not the dorsal or perirenal regions. Furthermore, the femoral undifferentiated preadipocyte pool was not preserved in the ovariectomized animals. Thus, ovarian factors influence the pubescence-associated regional preadipocyte differentiation and conversion to adipocytes. The femoral depot contains an ovarian-dependent infinite pool of fat cell precursors. These features could account for the association between ovarian hormones and body fat topography.
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Affiliation(s)
- G R Krakower
- Department of Medicine, Medical College of Wisconsin, Milwaukee 53226
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11
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Rogers MP. Effects of 2[5(4-chlorophenyl)pentyl]oxirane-2-carboxylate on lipoprotein lipase, adipose tissue lipolysis and glycerol phosphate acyltransferase in rats. Biochem Pharmacol 1987; 36:971-2. [PMID: 3566793 DOI: 10.1016/0006-2952(87)90193-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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12
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Vydelingum NA, AlQuadan F, Kissebah AH, Etienne J. Characterization of rat adipose tissue lipoprotein lipase using a monospecific antibody. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 876:399-412. [PMID: 3707976 DOI: 10.1016/0005-2760(86)90026-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An antibody to a highly pure enzyme preparation was developed to facilitate detailed studies of rat adipose tissue lipoprotein lipase regulation. Lipoprotein lipase was purified by heparin-Sepharose affinity chromatography followed by preparative isoelectric focusing. The enzyme migrated as a single broad band on SDS disc gel and two-dimensional gel electrophoresis with an apparent molecular mass of 67 000 and 62 000 Da, respectively. The amino acid composition of the purified rat enzyme was virtually identical to that of bovine milk. A major protein component with no lipase activity co-eluted with the enzyme from the affinity column, but was separated by the isoelectric focusing step. The molecular mass was slightly lower (58 000 Da) but the amino acid composition of this protein was similar to that of the enzyme. An antibody raised against the purified rat enzyme was highly potent and was effective in inhibiting rat heart lipoprotein lipase, but not the salt-resistant hepatic lipase. Analysis of crude acetone-ether adipose tissue preparation on SDS slab polyacrylamide gel coupled to Western blotting revealed five protein bands = (62 000, 56 000, 41 700, 22 500, 20 000 Da). Similarly, following affinity purification by immunoadsorption, the purified antibody reacted with five equivalent protein bands. Fluorescent concanavalin A binding data indicated that the 56 kDa band is a glycosylated form of lipoprotein lipase. Pretreatment of adipose tissue with proteinase inhibitors revealed that the lower molecular mass proteins (41 700 and 20 000 Da) were degradation products of lipoprotein lipase, and the 22 500 Da band could be accounted for by non-specific binding.
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13
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Odonkor JM, Rogers MP. Effects of ethyl-CPIB (clofibrate) on tissue lipoprotein lipase and plasma post-heparin lipolytic activity in rats. Biochem Pharmacol 1984; 33:1337-41. [PMID: 6370267 DOI: 10.1016/0006-2952(84)90189-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The role of LPL in reducing the serum triacylglycerol concentration was investigated in rats fed a high sucrose diet containing 0.25% (w/w) ethyl-CPIB. Compared with sucrose-fed controls, drug treatment resulted in a fall in adipose tissue LPL activity and a rise in enzyme activity in thigh and heart muscle. Serum post-heparin lipoprotein lipase activity after a high dose of heparin was lower in ethyl-CPIB-treated rats than controls, but after a low dose of heparin the values were similar. The amount of LPL activator was decreased by the drug. Thus, the low serum triacylglycerol concentration observed in the ethyl-CPIB-treated rats cannot be explained by changes in functional LPL activity. The plasma triacylglycerol-lowering effect of the drug could be explained by the observed decrease in triacylglyerol output by the liver.
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14
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Garfinkel AS, Kempner ES, Ben-Zeev O, Nikazy J, James SJ, Schotz MC. Lipoprotein lipase: size of the functional unit determined by radiation inactivation. J Lipid Res 1983. [DOI: 10.1016/s0022-2275(20)37945-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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Parkin SM, Speake BK, Robinson DS. Purification and characterization of rat adipose tissue lipoprotein lipase. Biochem J 1982; 207:485-95. [PMID: 7165705 PMCID: PMC1153888 DOI: 10.1042/bj2070485] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Lipoprotein lipase (EC 3.1.1.34) extracted from adipose tissue of glucose-fed rats with 5 mM-sodium barbital, pH 7.5, containing 20% (v/v) glycerol and 0.1% (v/v) Triton X-100, was partially purified by affinity chromatography on heparin linked to Sepharose 4B. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the partially purified enzyme preparation revealed the presence of two major Coomassie-staining bands (mol.wts. 62 000 and 56 000) as well as a number of minor bands. Treatment of partially purified enzyme with [1,3-3H]di-isopropyl fluorophosphate resulted in the incorporation of radiolabel into the band of mol.wt. 56 000, but not into the band of mol.wt. 62 000. Both the amount of the 56 000-mol.wt. polypeptide and the incorporation of [1,3-3H]di-isopropyl fluorophosphate into this band were greatly reduced in the enzyme preparations isolated from adipose tissue of 48 h-starved rats. whereas the amount of the 62 000-mol.wt. polypeptide was unaffected by starvation. Purification of lipoprotein lipase from adipose tissue of glucose-fed rats was also carried out using affinity chromatography on Sepharose 4B linked to heparin with low affinity for antithrombin-III. This procedure resulted in the presence of a single band of mol.wt. 56 000 on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. These results suggest that the polypeptide of mol.wt. 56 000 corresponds to the subunit of lipoprotein lipase, whereas the 62 000-mol.wt. polypeptide probably represents antithrombin-III.
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16
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Vannier C, Jansen H, Négrel R, Ailhaud G. Study of lipoprotein lipase content in Ob17 preadipocytes during adipose conversion. Immunofluorescent localization of the enzyme. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)33725-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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17
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Rogers MP, Hutchinson I. The effect in vitro of high-density lipoprotein on hydrolysis of triacylglycerol by lipoprotein lipase. Biochem J 1981; 200:453-6. [PMID: 7340847 PMCID: PMC1163558 DOI: 10.1042/bj2000453] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
In an incubation system in vitro with fully activated Intralipid as substrate, rat high-density lipoprotein inhibits the hydrolysis of triacylglycerol by lipoprotein lipase from rat adipose tissue, but does not inhibit hydrolysis by the enzyme from bovine milk. The pattern of inhibition suggests that substrate and high-density lipoprotein may compete for association with rat adipose-tissue lipoprotein lipase.
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18
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Parkin SM, Walker K, Ashby P, Robinson DS. Effects of glucose and insulin on the activation of lipoprotin lipase and on protein-synthesis in rat adipose tissue. Biochem J 1980; 188:193-9. [PMID: 6996676 PMCID: PMC1162555 DOI: 10.1042/bj1880193] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Glucose, and certain sugars that can readily be converted to glucose 6-phosphate, bring about an activation of adipose-tissue lipoprotein lipase when epididymal fat-bodies from starved rats are incubated in the presence of cycloheximide. Other substrates do not support the activation. If the tissue is preincubated in the presence of cycloheximide for longer than 2h, the ability of added glucose to activate the enzyme is lost. On the other hand, the addition of glucose still brings about an increase in lipoprotein lipase activity after preincubation in the absence of cycloheximide for as long as 4h. The magnitude of the increase in enzyme activity brought about by the addition of glucose is increased when protein synthesis is stimulated during the preincubation period by insulin. The results are interpreted in terms of the existence in adipose tissue of a proenzyme pool of lipoprotein lipase that is normally maintained by protein synthesis and that is converted to complete enzyme of higher specific activity by a process that specifically requires glucose.
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19
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Ashby P, Robinson DS. Effects of insulin, glucocorticoids and adrenaline on the activity of rat adipose-tissue lipoprotein lipids. Biochem J 1980; 188:185-92. [PMID: 6996675 PMCID: PMC1162554 DOI: 10.1042/bj1880185] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The lipoprotein lipase activity of epididymal fat-bodies from starved rats was measured during incubations at 37 degrees C in vitro. Protein synthesis independent activation of the enzyme, previously observed during incubations at 25 decrease C, also occurs at 37 degrees C. Protein-synthesis-dependent increases in the activity of the enzyme occur in the presence of insulin and are markedly potentiated by glucocorticoids. The effects on the activity of the enzyme of insulin alone, or in the presence of glucocorticoids, are correlated with its effects on total protein synthesis in the tissue. Adrenaline antagonizes the increase in activity of the enzyme brought about by insulin and abolishes the potentiation of insulin action by glucocorticoids. These changes may be due, at least in part, to its stimulation of inactivation of the enzyme in the tissue. It is suggested that changes in adipose-tissue lipoprotein lipase activity that occur with changes in nutritional status in vivo result from the combined effects of changes in plasma insulin and glucocorticoid concentrations.
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20
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Garratt CJ, Hubbard RE, Ponnudurai TB. Adipose tissue, obesity and insulin. PROGRESS IN MEDICINAL CHEMISTRY 1980; 17:105-49. [PMID: 7031767 DOI: 10.1016/s0079-6468(08)70158-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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21
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Spooner P, Chernick S, Garrison M, Scow R. Insulin regulation of lipoprotein lipase activity and release in 3T3-L1 adipocytes. Separation and dependence of hormonal effects on hexose metabolism and synthesis of RNA and protein. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86667-x] [Citation(s) in RCA: 123] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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22
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Vanhove A, Glangeaud MC, Breton M, Wolf C, Polonovski J. Separation of two molecular forms of rat adipose-tissue lipoprotein-lipase. Biochem Biophys Res Commun 1979; 89:664-70. [PMID: 486186 DOI: 10.1016/0006-291x(79)90681-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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23
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Ashby P, Bennett DP, Spencer IM, Robinson DS. Post-translational regulation of lipoprotein lipase activity in adipose tissue. Biochem J 1978; 176:865-72. [PMID: 747657 PMCID: PMC1186310 DOI: 10.1042/bj1760865] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Changes in adipose-tissue lipoprotein lipase activity that are independent of protein synthesis were investigated in an incubation system in vitro. Under appropriate conditions at 25 degrees C a progressive increase in the enzyme activity occurs that is energy-dependent. Part of the enzyme is rapidly inactivated when the tissue is incubated with adrenaline or adrenaline plus theophylline. The mechanism of this inactivation appears to be distinct from, and to follow, the activation of the enzyme. A hypothesis is presented to account for the results in terms of an activation of the enzyme during obligatory post-translational processing and a catecholamine-regulated inactivation of the enzyme as an alternative to secretion from the adipocyte.
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