Endocytosis is not required for the selective lipid uptake mediated by murine SR-BI

Biochim Biophys Acta. 2005 May 1;1734(1):44-51. doi: 10.1016/j.bbalip.2005.02.007. Epub 2005 Mar 9.

Abstract

The scavenger receptor class B, type I (SR-BI) mediates the cellular selective uptake of cholesteryl esters and other lipids from high-density lipoproteins (HDL) and low-density lipoproteins (LDL). This process, unlike classical receptor-mediated endocytosis, does not result in lipoprotein degradation. Instead, the lipid depleted particles are released into the medium. Here we show that selective lipid uptake mediated by murine SR-BI can be uncoupled from the endocytosis of HDL or LDL particles. We found that blocking selective lipid uptake by incubating cells with the small chemical inhibitors BLT-1 or BLT-4 did not affect endocytosis of HDL. Similarly, blocking endocytosis by hyperosmotic sucrose or K+ depletion did not prevent selective lipid uptake from HDL or LDL. These findings suggest that mSR-BI-mediated selective uptake occurs at the cell surface upon the association of lipoproteins with mSR-BI and does not require endocytosis of HDL or LDL particles.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • CD36 Antigens
  • CHO Cells
  • Cricetinae
  • Endocytosis / drug effects*
  • Endocytosis / physiology
  • Humans
  • Lipid Metabolism*
  • Lipoproteins, HDL / metabolism
  • Lipoproteins, LDL / metabolism
  • Mice
  • Naphthalenes / pharmacology*
  • Osmotic Pressure / drug effects
  • Potassium / metabolism
  • Receptors, Immunologic / metabolism*
  • Receptors, Scavenger
  • Scavenger Receptors, Class B
  • Sucrose / pharmacology
  • Urea / analogs & derivatives*
  • Urea / pharmacology*

Substances

  • (1-(2-methoxy-phenyl)-3-naphthalen-2-yl-urea)
  • CD36 Antigens
  • Lipoproteins, HDL
  • Lipoproteins, LDL
  • Naphthalenes
  • Receptors, Immunologic
  • Receptors, Scavenger
  • SCARB1 protein, human
  • Scavenger Receptors, Class B
  • Sucrose
  • Urea
  • Potassium