ATP-binding cassette transporter A1 expression disrupts raft membrane microdomains through its ATPase-related functions

J Biol Chem. 2006 Nov 24;281(47):36091-101. doi: 10.1074/jbc.M602247200. Epub 2006 Sep 19.

Abstract

ATP-binding cassette transporter A1 (ABCA1) is known to mediate cholesterol efflux to lipid-poor apolipoprotein A-I. In addition, ABCA1 has been shown to influence functions of the plasma membrane, such as endocytosis and phagocytosis. Here, we report that ABCA1 expression results in a significant redistribution of cholesterol and sphingomyelin from rafts to non-rafts. Caveolin, a raft/caveolae marker also redistributes from punctate caveolae-like structures to the general area of the plasma membrane upon ABCA1 expression. Furthermore, we observed significant reduction of Akt activation in ABCA1-expressing cells, consistent with raft disruption. Cholesterol content in the plasma membrane is, however, not altered. Moreover, we provide evidence that a non-functional ABCA1 with mutation in an ATP-binding domain, A937V, fails to redistribute cholesterol, sphingomyelin, or caveolin. A937V also fails to influence Akt activation. Finally, we show that apolipoprotein A-I preferentially associates with non-raft membranes in ABCA1-expressing cells. Our results thus demonstrate that ABCA1 causes a change in overall lipid packing of the plasma membrane, likely through its ATPase-related functions. Such reorganization by ABCA1 effectively expands the non-raft membrane fractions and, consequentially, pre-conditions cells for cholesterol efflux.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter 1
  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / physiology*
  • Animals
  • Caveolin 1 / biosynthesis
  • Cell Membrane / metabolism
  • Cholesterol / metabolism
  • Cricetinae
  • Endocytosis
  • Membrane Microdomains / chemistry*
  • Membrane Transport Proteins / chemistry
  • Microscopy, Fluorescence
  • Phospholipids / chemistry
  • Phosphorylation
  • Proto-Oncogene Proteins c-akt / metabolism
  • Transferrin / metabolism

Substances

  • ATP Binding Cassette Transporter 1
  • ATP-Binding Cassette Transporters
  • Caveolin 1
  • Membrane Transport Proteins
  • Phospholipids
  • Transferrin
  • Cholesterol
  • Proto-Oncogene Proteins c-akt