Scavenger receptor BI-mediated selective uptake is required for the remodeling of high density lipoprotein by endothelial lipase

J Biol Chem. 2009 Mar 6;284(10):6093-100. doi: 10.1074/jbc.M807683200. Epub 2009 Jan 9.

Abstract

Endothelial lipase (EL) is a negative regulator of high density lipoprotein (HDL) cholesterol plasma levels, and scavenger receptor BI (SR-BI) is involved in remodeling of HDL. The present study investigates the requirement of SR-BI for the effects of EL-mediated phospholipid hydrolysis on HDL metabolism in vivo. In vitro, selective uptake from EL-modified HDL was 129% higher than selective uptake from control HDL in SR-BI-overexpressing cells (p=0.01). In vivo overexpression of human EL by means of recombinant adenovirus decreased HDL plasma levels significantly (p<0.01). Fast protein liquid chromatography analysis and agarose gel electrophoresis revealed that EL expression resulted in the generation of small pre-beta HDL particles in wild-type mice, whereas in SR-BI-/- mice small HDL were preferentially removed. In kinetic experiments the fractional catabolic rate (FCR) of HDL cholesteryl ester increased by 110% (p<0.001), and the FCR of HDL apolipoproteins increased by 64% (p<0.001) in response to EL overexpression in wild-type mice. In SR-BI-/- mice a similar increase in the HDL apolipoprotein FCR occurred (p<0.001); however, there was no further increase in HDL cholesteryl ester catabolism. The apparent whole body selective uptake was increased 3-fold by EL in wild-type mice (p<0.001), whereas there was no selective uptake in SR-BI knock-out mice. EL overexpression increased hepatic selective uptake as well as holoparticle uptake (each p<0.01) in wild-type mice, whereas in SR-BI knock-out mice only holoparticle uptake increased (p<0.01). Our results indicate that SR-BI-mediated selective uptake of HDL cholesteryl ester is essential for the remodeling of large alpha-migrating HDL particles by EL.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Cholesterol Esters / genetics
  • Cholesterol Esters / metabolism*
  • Humans
  • Kinetics
  • Lipase / genetics
  • Lipase / metabolism*
  • Lipoproteins, HDL / genetics
  • Lipoproteins, HDL / metabolism*
  • Liver / metabolism*
  • Mice
  • Mice, Knockout
  • Scavenger Receptors, Class B / genetics
  • Scavenger Receptors, Class B / metabolism*

Substances

  • Cholesterol Esters
  • HDL cholesteryl ester
  • Lipoproteins, HDL
  • SCARB1 protein, human
  • Scarb1 protein, mouse
  • Scavenger Receptors, Class B
  • LIPG protein, human
  • Lipase
  • Lipg protein, mouse