Reevaluation of the role of the multidrug-resistant P-glycoprotein in cellular cholesterol homeostasis

J Lipid Res. 2006 Jan;47(1):51-8. doi: 10.1194/jlr.M500255-JLR200. Epub 2005 Oct 7.

Abstract

The multidrug resistance P-glycoprotein (P-gp) was recently proposed to redistribute cholesterol in the plasma membrane, suggesting that P-gp could modulate cholesterol efflux to cholesterol acceptors. To address this hypothesis and to reevaluate the role of P-gp in cholesterol homeostasis, we first analyzed the role of P-gp expression on cholesterol efflux in P-gp stably transfected drug-selected LLC-MDR1 cells. Cholesterol efflux to methyl-beta-cyclodextrin (CD) was 4-fold higher in LLC-MDR1 cells compared with control LLC-PK1 cells, indicating that the accessible pool of plasma membrane cholesterol was increased by P-gp expression. However, using the P-gp-inducible cells lines HeLa MDR-Tet and 77.1 MDR-Tet, cholesterol efflux to CD, apolipoprotein A-I, or HDL was not associated with P-gp expression. In addition, we did not observe any effect of P-gp expression on cellular free and esterified cholesterol content, cholesteryl ester uptake from LDL and HDL particles, or acyl-CoA:cholesterol acyltransferase activity. Therefore, we conclude that P-gp expression does not play a major role in cholesterol homeostasis in P-gp-inducible cells and that the effects of P-gp on cholesterol homeostasis previously described in drug-selected cells might result from non-P-gp pathways that were also induced by selection for drug resistance.

Publication types

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

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / deficiency
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / genetics
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism*
  • Animals
  • Cell Line
  • Cholesterol / metabolism*
  • HeLa Cells
  • Homeostasis
  • Humans
  • LLC-PK1 Cells
  • Membrane Lipids / metabolism
  • Mice
  • Mice, Knockout
  • Promoter Regions, Genetic / drug effects
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Swine
  • Tetracycline / pharmacology
  • Transfection

Substances

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Membrane Lipids
  • Recombinant Proteins
  • Cholesterol
  • Tetracycline