Human hepatic triglyceride lipase: cDNA cloning, amino acid sequence and expression in a cultured cell line

Stahnke, Gisela; Sprengel, Rolf; Augustin, J.; Will, Hans

doi:10.1111/j.1432-0436.1987.tb00150.x

Cited by 88 publications

(44 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A significantly greater increase of specific activity by EL-N116A (177 6 40%) versus wild-type EL (100 6 22%) was also observed toward HDL 2 . However, no significant change of specific activity by EL-N116A (136 6 36%) was observed versus wild-type EL (100 6 21%) toward HDL 3 .…”

Section: Effect Of Disruption Of N-linked Glycosylation At Asn-116 Ofmentioning

confidence: 89%

“…This would not be a surprise, because phylogenetic analyses of the lipase superfamily suggest that HL has a greater divergence from both EL and LPL than EL and LPL have from each other (27,28). It is interesting that the carbohydrate at Asn-116 of EL appears to inhibit activity toward LDL and HDL 2 but not toward HDL 3 . Thus, the presence of N-linked glycosylation at Asn-116 of EL may have evolved in its divergence from LPL, in part as a means to direct greater specificity of EL in vivo away from apolipoprotein B-containing lipoproteins and toward HDL.…”

Section: Discussionmentioning

confidence: 99%

“…Endothelial lipase (EL) belongs to a superfamily of lipases (EC 3.1.1.3) that includes LPL and HL (1)(2)(3)(4)(5)(6). These three lipases have both triglyceride (TG) lipase and phospholipase activity, but EL has relatively more phospholipase activity compared with LPL, which has predominantly TG lipase activity (7).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo

Brown

Miller

Griffon

et al. 2007

Journal of Lipid Research

View full text Add to dashboard Cite

We previously identified that four of five putative N-linked glycosylation sites of human endothelial lipase (EL) are utilized and suggested that the substitution of asparagine-116 (Asn-116) with alanine (Ala) (N116A) increased the hydrolytic activity of EL. The current study demonstrates that mutagenesis of either Asn-116 to threonine (Thr) or Thr-118 to Ala also disrupted the glycosylation of EL and enhanced catalytic activity toward synthetic substrates by 3-fold versus wild-type EL. Furthermore, we assessed the hydrolysis of native lipoprotein lipids by EL-N116A. EL-N116A exhibited a 5-fold increase in LDL hydrolysis and a 1.8-fold increase in HDL 2 hydrolysis. Consistent with these observations, adenovirus-mediated expression of EL-N116A in mice significantly reduced the levels of both LDL and HDL cholesterol beyond the reductions observed by the expression of wild-type EL alone. Finally, we introduced Asn-116 of EL into the analogous positions within LPL and HL, resulting in N-linked glycosylation at this site. Glycosylation at this site suppressed the LPL hydrolysis of synthetic substrates, LDL, HDL 2 , and HDL 3 but had little effect on HL activity. These data suggest that N-linked glycosylation at Asn-116 reduces the ability of EL to hydrolyze lipids in LDL and HDL 2 .-Brown, R. J., G. C. Miller, N. Griffon, C. J. Long, and D. J. Rader. Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo. J. Lipid Res. 2007Res. . 48: 1132Res. -1139. Supplementary key words lipaseEndothelial lipase (EL) belongs to a superfamily of lipases (EC 3.1.1.3) that includes LPL and HL (1-6). These three lipases have both triglyceride (TG) lipase and phospholipase activity, but EL has relatively more phospholipase activity compared with LPL, which has predominantly TG lipase activity (7). Overexpression of EL in mice was shown to significantly reduce high density lipoprotein cholesterol (HDL-C) (1,8,9), whereas loss-of-function studies in mice result in significantly elevated plasma 10,11).In vitro and in vivo studies using chimeric proteins of LPL and HL have shown that the differences in substrate specificity between these two lipases are governed by a 22 amino acid loop, or "lid domain," within the N-terminal domain of the respective lipases that covers the catalytic site (12)(13)(14). The shorter 19 amino acid lid domain within EL partially contributes to its substrate specificity (15); other elements affecting substrate specificity remain to be elucidated.Human EL is translated as a 500 amino acid 57 kDa peptide that is processed into a mature 480 amino acid protein with an apparent molecular mass of 68 kDa after the loss of its signal peptide and the addition of N-linked glycosylation (1, 2). EL has five putative N-linked glycosylation sites [identified by the presence of asparagine-X-serine/threonine (Asn-Xaa-Ser/Thr) motifs]. We previously reported that four of the five sites, specifically are utilized (16). Abolishment of N-linke...

show abstract

Section: Effect Of Disruption Of N-linked Glycosylation At Asn-116 Ofmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo

Brown

Miller

Griffon

et al. 2007

Journal of Lipid Research

View full text Add to dashboard Cite

show abstract

“…The recombinant adenoviruses HL-rAdV, HL-145G-rAdV, and Lucif-rAdV, containing the human HL cDNA, 27 the mutant HL-145G cDNA, 20 or firefly luciferase, 28 respectively, were generated as first described by McGrory et al 29 and adapted as published previously. 13 Briefly, cDNAs were subcloned into a shuttle vector (pAdl2-HL) containing CMV promoter and enhancer elements as well as the SV40 polyadenylation signal.…”

Section: Recombinant Adenovirusmentioning

confidence: 99%

In Vivo Evidence for Both Lipolytic and Nonlipolytic Function of Hepatic Lipase in the Metabolism of HDL

Dugi

Amar

Haudenschild

et al. 2000

ATVB

View full text Add to dashboard Cite

Abstract-To investigate the in vivo role that hepatic lipase (HL) plays in HDL metabolism independently of its lipolytic function, recombinant adenovirus (rAdV) expressing native HL, catalytically inactive HL (HL-145G), and luciferase control was injected in HL-deficient mice. At day 4 after infusion of 2ϫ10 8 plaque-forming units of rHL-AdV and rHL-145G-AdV, similar plasma concentrations were detected in postheparin plasma (HLϭ8.4Ϯ0.8 g/mL and HL-145Gϭ8.3Ϯ0.8 g/mL). Mice expressing HL had significant reductions of cholesterol (Ϫ76%), phospholipids (PL; Ϫ68%), HDL cholesterol (Ϫ79%), apolipoprotein (apo) A-I (Ϫ45%), and apoA-II (Ϫ59%; PϽ0.05 for all), whereas mice expressing HL-145G decreased their cholesterol (Ϫ49%), PL (Ϫ40%), HDL cholesterol (Ϫ42%), and apoA-II (Ϫ89%; PϽ0.005 for all) but had no changes in apoA-I. The plasma kinetics of 125 I-labeled apoA-I HDL, 131 I-labeled apoA-II HDL, and Key Words: hepatic lipase Ⅲ HDL metabolism Ⅲ lipolysis Ⅲ nonlipolytic function H epatic lipase (HL) is a 66-kDa lipolytic enzyme that is synthesized primarily by the liver. 1 It is anchored to the vascular endothelium present in the liver, ovaries, and adrenals via heparan sulfate proteoglycans and can be released into the circulation by the infusion of heparan sulfate. 2 HL hydrolyzes triglycerides and phospholipids present in chylomicron remnants, IDL, and HDL. Through its function as a lipolytic enzyme, HL plays a major role in the metabolism of circulating plasma lipoproteins.Several lines of evidence demonstrate the important role of HL in HDL metabolism. Patients with a genetic deficiency of HL have increased plasma levels of HDL cholesterol and phospholipids. 3,4 Increased HDL is also a hallmark of HLdeficient states induced by infusion of anti-HL antibodies 5,6 or genetic manipulation 7 or naturally present in different animal models. 8 Conversely, increased expression of HL in transgenic mice 9,10 and rabbits 11 significantly decreases plasma HDL concentrations. Similarly, adenovirus-mediated expression of human HL leads to marked reductions in HDL cholesterol [12][13][14] in different mouse models.In addition to its enzymatic action as a lipase, recent in vitro studies have suggested a separate role for HL in cellular lipoprotein metabolism by serving as a ligand that mediates the binding and uptake of lipoproteins via proteoglycans and/or receptor pathways. HL enhances the binding and/or uptake of chylomicrons, chylomicron remnants, and ␤-VLDL to different cell types in vitro, [15][16][17][18] a process that appears to require proteoglycans. 17 Most of these studies have investigated the HL-mediated interaction of apolipoprotein (apo)Bcontaining lipoproteins with cell surface receptors and/or proteoglycans. However, HL may play a similar role in promoting the cellular binding of HDL. [17][18][19] In the present article, we investigate, using recombinant adenovirus, potential mechanisms by which HL contributes to the metabolism of HDL in vivo by expressing native HL and catalytically inactive HL (HL-145G) in HL...

show abstract

“…Both lipoprotein lipase and hepatic lipase are synthesized and secreted by parenchymal cells and are bound specifically to the endothelial-cell lining [10][11][12][13][14][15]. It is generally assumed that both hepatic lipase and lipoprotein lipase are bound to heparan sulphates at the endothelium [15][16][17][18]. A heparan sulphate proteoglycan and a heparin-releasable lipoprotein-lipase-binding protein (HRP) have been identified as the binding sites for lipoprotein lipase in bovine aortic endothelial cells [19,20].…”

Section: Introductionmentioning

confidence: 99%

Rat liver contains a limited number of binding sites for hepatic lipase

Schoonderwoerd

Verhoeven

Jansen

1994

Biochemical Journal

View full text Add to dashboard Cite

The binding of hepatic lipase to rat liver was studied in an ex vivo perfusion model. The livers were perfused with media containing partially purified rat hepatic lipase or bovine milk lipoprotein lipase. The activity of the enzymes was determined in the perfusion media before and after passage through the liver. During perfusion with a hepatic-lipase-containing medium the lipase activity in the medium did not change, indicating that there was no net binding of lipase by the liver. In contrast, more than 80% of the lipoprotein .lipase was removed from the medium. This lipoprotein lipase activity could be recovered into the perfusion medium completely by heparin perfusion of the liver. If livers, first depleted of hepatic lipase by heparin, were subsequent perfused with a hepatic-lipase-containing medium, 90 + 24 m-units of the lipase activity was bound per g of liver (up to 1000 m-units/total liver). However, heparin treatment of the liver decreases the ability of the liver to re-bind hepatic lipase by 80 %. Perfusion of rat livers with 0.3 M NaCl released 60 % of the lipase activity into the medium. Upon subsequent perfusion of these livers with hepatic-lipase-containing media, 541 + 164 munits of hepatic lipase could be bound per g of liver (up to 5000 m-units/total liver). The binding of hepatic lipase was also studied in livers of corticotropin (ACTH)-pre-treated rats. In these rats also, hepatic lipase bound only to livers which had been pre-perfused with heparin or 0.3 M NaCl. After heparin pre-perfusion, 88 + 12 m-units of hepatic lipase could be bound per g of liver, similar to that with livers of control rats not treated with ACTH. After prior salt perfusion, however, the capacity of the livers of ACTH-pre-treated rats to bind hepatic lipase was 212 + 60 m-units/g of liver. This is less than in livers of control rats (541 + 164 m-units/g of liver). These results indicate that in rat liver the binding ofhepatic lipase is heterogeneous in character and consists of heparin-resistant and heparin-sensitive components. The hepatic-lipase binding capacity of the liver is saturable and fully utilized under various conditions. The heparin-sensitive binding capacity is lowered in ACTH-treated rats, whereas the heparin-resistant binding is unaffected. We postulate that the functional hepatic lipase activity can be regulated by changes in the binding capacity of the liver.

show abstract

Human hepatic triglyceride lipase: cDNA cloning, amino acid sequence and expression in a cultured cell line

Cited by 88 publications

References 47 publications

Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo

Glycosylation of endothelial lipase at asparagine-116 reduces activity and the hydrolysis of native lipoproteins in vitro and in vivo

In Vivo Evidence for Both Lipolytic and Nonlipolytic Function of Hepatic Lipase in the Metabolism of HDL

Rat liver contains a limited number of binding sites for hepatic lipase

Contact Info

Product

Resources

About