Journal of Lipid Research (Jul 1999)

Hepatic lipase promotes the selective uptake of high density lipoprotein-cholesteryl esters via the scavenger receptor B1

  • Gilles Lambert,
  • Michael B. Chase,
  • Klaus Dugi,
  • Andre Bensadoun,
  • H. Bryan Brewer, Jr.,
  • Silvia Santamarina-Fojo

Journal volume & issue
Vol. 40, no. 7
pp. 1294 – 1303

Abstract

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Hepatic lipase (HL) plays a major role in high-density lipoprotein (HDL) metabolism both as a lipolytic enzyme and as a ligand. To investigate whether HL enhances the uptake of HDL-cholesteryl ester (CE) via the newly described scavenger receptor BI (SR-BI), we measured the effects of expressing HL and SR-BI on HDL-cell association as well as uptake of 125I-labeled apoA-I and [3H]CE-HDL, by embryonal kidney 293 cells. As expected, HDL cell association and CE selective uptake were increased in SR-BI transfected cells by 2- and 4-fold, respectively, compared to controls (P < 0.001). Cells transfected with HL alone or in combination with SR-BI expressed similar amounts of HL, 20% of which was bound to cell surface proteoglycans. HL alone increased HDL cell association by 2-fold but had no effect on HDL-CE uptake in 293 cells. However, in cells expressing SR-BI, HL further enhanced the selective uptake of CE from HDL by 3-fold (P < 0.001). To determine whether the lipolytic and/or ligand function of HL are required in this process, we generated a catalytically inactive form of HL (HL-145G). Cells co-transfected with HL-145G and SR-BI increased their HDL cell association and HDL-CE selective uptake by 1.4-fold compared to cells expressing SR-BI only (P < 0.03). Heparin abolished the effect of HL-145G on SR-BI-mediated HDL-CE selective uptake. Thus, the enhanced uptake of HDL-CE by HL is mediated by both its ligand role, which requires interaction with proteoglycans, and by lipolysis with subsequent HDL particle remodeling. These results establish HL as a major modulator of SR-BI mediated selective uptake of HDL-CE.—Lambert, G., M. B. Chase, K. Dugi, A. Bensadoun, H. B. Brewer, Jr., and S. Santamarina-Fojo. Hepatic lipase promotes the selective uptake of high density lipoprotein-cholesteryl esters via the scavenger receptor B1. J. Lipid Res. 1999. 40: 1294–1303.

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