Apoprotein-independent binding of chylomicron remnants to rat liver membranes

Borensztajn, Jayme; Kotlar, T J; Chang, Suyi

doi:10.1042/bj2790769

Cited by 16 publications

(18 citation statements)

References 39 publications

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“…The inhibitory effect ofchloroquine, which blocks the receptormediated lysosomal degradation of lipoproteins, was not complete with either the remnant-like particles used here or native remnants [2], suggesting that their uptake could also partially proceed via a receptor-unrelated process. In this regard, phospholipid-mediated uptake [16] had been suggested. Indeed, after phospholipolysis of chylomicron remnants by HL, their uptake by isolated hepatocytes is doubled [2].…”

Section: Discussionmentioning

confidence: 99%

“…Several types of receptor may account for the latter: the apoB,E lowdensity lipoprotein receptor and specific apoE receptor(s) which include the a2-macroglobulin/low-density-lipoprotein receptorrelated protein [9][10][11][12][13] and/or a remnant receptor [14] that may be the lipolysis-stimulated receptor [15]. An apoE-independent pathway for remnant uptake has also been advocated [16], mediated by remnant phospholipid composition and HL remodelling of these compounds [2,7,8]. LPL was shown to be a ligand for triacylglycerol-rich lipoproteins [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

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Hepatic lipase may act as a ligand in the uptake of artificial chylomicron remnant-like particles by isolated rat hepatocytes.

Diard

Malewiak

Lagrange

et al. 1994

Biochemical Journal

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hepatic lipase may act as a ligand in the uptake of artificial chylomicron remnant-like particles by isolated rat hepatocytes.

Diard

Malewiak

Lagrange

et al. 1994

Biochemical Journal

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“…This uptake might have been mediated by the apo E present on the surface of the lipoproteins. Previous work from this laboratory suggested, however, that apo E might not be necessary for the uptake of chylomicron remnants by hepatocytes [17,18]. To investigate this possibility further, hepatocytes isolated from mice lacking apo E were incubated with labelled apo E-free chylomicrons, also obtained from mice lacking apo E, in the presence and absence of LPL.…”

Section: Effect Of Lpl On the Recognition Of Apo E-free Chylomicrons mentioning

confidence: 98%

The role of lipoprotein lipase and apoprotein E in the recognition of chylomicrons and chylomicron remnants by cultured isolated mouse hepatocytes

Chang

Maeda

Borensztajn

1996

Biochemical Journal

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Lipoprotein lipase (LPL) has been proposed to play a role in the uptake of chylomicron remnants by hepatocytes by mediating the binding of these lipoproteins to cell-surface glycosaminoglycans and to the low-density-lipoprotein receptor-related protein (LRP). This proposal is based on studies that examined the binding of chylomicrons to HepG2 cells, fibroblasts and Chinese hamster ovary cells in culture, in the presence of large amounts of LPL [Beisiegel (1995) Curr. Opin. Lipidol. 6, 117-122]. We have investigated whether LPL attached to the surface of chylomicrons enhances the binding and uptake of these lipoproteins to isolated hepatocytes maintained in culture. Bovine milk LPL was bound to mouse chylomicrons, double-labelled in vivo with [3H]retinol (in retinyl esters) and with [14C]palmitic acid (in triacylglycerols), collected from the mesenteric lymph of normal mice and from mice lacking the apoprotein E (apo E) gene. Normal chylomicrons (containing apo E) and apo E-free chylomicrons, with or without bound LPL, were incubated with cultured hepatocytes isolated from mice lacking the apo E gene. At 0 degree C LPL did not enhance the binding of the normal or apo E-free chylomicrons by the hepatocytes. When incubations were performed at 37 degrees C the triacylglycerols of normal and apo E-free chylomicrons were hydrolysed by LPL and there was a significant uptake of [14C]fatty acids and [3H]retinol by the hepatocytes. The addition of heparin or lactoferrin, a known inhibitor of hepatic uptake of chylomicron remnants, to the incubation medium inhibited the uptake of [3H]retinol, present in the lipoprotein core, but not the uptake of the [14C]fatty acids. We conclude that: (1) LPL attached to chylomicrons in amounts sufficient to effectively hydrolyse their core triacylglycerols does not enhance the binding of these lipoproteins to the surface of isolated hepatocytes; (2) the recognition and uptake of chylomicrons by hepatocytes requires that these lipoproteins be first hydrolysed by LPL; and (3) the uptake of lipolysed chylomicrons (remnants) by hepatocytes does not require the mediation of apo E.

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“…Several hepatic receptors may be involved in the clearance of chylomicron remnants, among others the low density lipoprotein receptor related protein‐α 2 ‐macroglobulin (LRP‐α 2 M) receptor [6,7], a parenchymal liver cell remnant receptor [8], the asialoglycoprotein receptor [9], the lipolysis stimulated receptor [10] and the LDL receptor [11], have been reported to play a role in the clearance of chylomicron remnants. In addition, apolipoprotein independent binding of chylomicron remnants to liver membranes was found in vitro , suggesting that phospholipids also participate in chylomicron remnant recognition by the liver [12]. Recently, the VLDL receptor, a new member of the LDL receptor supergene family, has been recognized as a physiological receptor for chylomicron remnants [13].…”

Section: Introductionmentioning

confidence: 99%

Delayed chylomicron remnant clearance in subjects with heterozygous familial hypercholesterolaemia

Cabezas¹,

Bruin

Westerveld³

et al. 1998

Journal of Internal Medicine

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Objectives. To study the role of the LDL receptor in the clearance of chylomicron remnants in humans. Design. Chylomicron remnant clearance was studied in five untreated subjects with heterozygous familial hypercholesterolaemia (FH) and nine normolipidaemic controls, by oral retinyl palmitate-fat loading tests. Fasting plasma triglycerides (TG), which are important determinators of chylomicron and remnant clearance, were not significantly different between FH (1.76 Ϯ 0.32 mmol L Ϫ1 , mean Ϯ SEM) and controls (1.26 Ϯ 0.18 mmol L Ϫ1 ). Chylomicrons (Sf Ͼ 1000) and their remnants (Sf Ͻ 1000) were separated by flotation and their clearance was estimated by calculating the area under the 24 h-retinyl palmitate curve (AUC-RP). The factors determining chylomicron and remnant clearance were studied by univariate and multiple regression analysis. Results. Triglyceride clearance in plasma, Sf Ͼ 1000 fractions and Sf Ͻ 1000 fractions was not significantly different between FH subjects and controls. In subjects with heterozygous FH, chylomicron remnant clearance was two-fold delayed (AUC-RP, 49.39 Ϯ 11.61 h.mg L Ϫ1 ) compared to controls (27.45 Ϯ 3.95 h.mg L Ϫ1 ; P = 0.048). Moreover, 28.4% higher fasting plasma TG in FH resulted in 44.4% higher areas under the remnant-curves compared to controls. The clearance of chylomicron RP was associated to plasma apo E (␤ = 0.73, P = 0.011), plasma LDL cholesterol (␤ = 0.62, P = 0.018) and plasma TG (␤ = 0.58, P = 0.029). The clearance of remnant RP was associated to the diagnosis (FH vs. non-FH), but not to the well-known determinants of remnant clearance like plasma TG. Conclusions. The clearance of chylomicrons and large remnants isolated in the Sf Ͼ fraction depends primarily on the apo B, E (LDL) receptor and to a lesser extent on plasma triglycerides. The clearance of smaller chylomicron remnants isolated in the Sf Ͻ 1000 depends to a large extent on the apo B, E (LDL) receptor.

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Apoprotein-independent binding of chylomicron remnants to rat liver membranes

Cited by 16 publications

References 39 publications

Hepatic lipase may act as a ligand in the uptake of artificial chylomicron remnant-like particles by isolated rat hepatocytes.

Hepatic lipase may act as a ligand in the uptake of artificial chylomicron remnant-like particles by isolated rat hepatocytes.

The role of lipoprotein lipase and apoprotein E in the recognition of chylomicrons and chylomicron remnants by cultured isolated mouse hepatocytes

Delayed chylomicron remnant clearance in subjects with heterozygous familial hypercholesterolaemia

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