The macrophage cholesterol exporter ABCA1 functions as an anti-inflammatory receptor

J Biol Chem. 2009 Nov 20;284(47):32336-43. doi: 10.1074/jbc.M109.047472. Epub 2009 Sep 25.

Abstract

ATP-binding cassette transporter A1 (ABCA1) is a cell membrane protein that exports excess cholesterol from cells to apolipoprotein (apo) A-I, the major protein in high density lipoproteins. Genetic studies have shown that ABCA1 protects against cardiovascular disease. The interaction of apoA-I with ABCA1 promotes cholesterol removal and activates signaling molecules, such as Janus kinase 2 (JAK2), that optimize the lipid export activity of ABCA1. Here we show that the ABCA1-mediated activation of JAK2 also activates STAT3, which is independent of the lipid transport function of ABCA1. ABCA1 contains two candidate STAT3 docking sites that are required for the apoA-I/ABCA1/JAK2 activation of STAT3. The interaction of apoA-I with ABCA1-expressing macrophages suppressed the ability of lysopolysaccaride to induce the inflammatory cytokines interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha, which was reversed by silencing STAT3 or ABCA1. Thus, the apoA-I/ABCA1 pathway in macrophages functions as an anti-inflammatory receptor through activation of JAK2/STAT3. These findings implicate ABCA1 as a direct molecular link between the cardioprotective effects of cholesterol export from arterial macrophages and suppressed inflammation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • ATP Binding Cassette Transporter 1
  • ATP-Binding Cassette Transporters / metabolism*
  • Animals
  • Anti-Inflammatory Agents / metabolism*
  • Cholesterol / metabolism
  • Cricetinae
  • Gene Silencing
  • Humans
  • Interleukin-1beta / metabolism
  • Interleukin-6 / metabolism
  • Lipids / chemistry
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred C57BL
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • ABCA1 protein, human
  • ATP Binding Cassette Transporter 1
  • ATP-Binding Cassette Transporters
  • Anti-Inflammatory Agents
  • Interleukin-1beta
  • Interleukin-6
  • Lipids
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Tumor Necrosis Factor-alpha
  • Cholesterol