ABCG1 is involved in vitamin E efflux

Biochim Biophys Acta. 2014 Dec;1841(12):1741-51. doi: 10.1016/j.bbalip.2014.10.003.

Abstract

Vitamin E membrane transport has been shown to involve the cholesterol transporters SR-BI, ABCA1 and NPC1L1. Our aim was to investigate the possible participation of another cholesterol transporter in cellular vitamin E efflux: ABCG1. In Abcgl-deficient mice, vitamin E concentration was reduced in plasma lipoproteins whereas most tissues displayed a higher vitamin E content compared to wild-type mice. α- and γ-tocopherol efflux was increased in CHO cells overexpressing human ABCG1 compared to control cells. Conversely, α- and γ- tocopherol efflux was decreased in ABCG1-knockdown human cells (Hep3B hepatocytes and THP-1 macro- phages). Interestingly, α- and γ-tocopherol significantly downregulated ABCG1 and ABCA1 expression levels in Hep3B and THP-1, an effect confirmed in vivo in rats given vitamin E for 5 days. This was likely due to reduced LXR activation by oxysterols, as Hep3B cells and rat liver treated with vitamin E displayed a significantly reduced content in oxysterols compared to their respective controls. Overall, the present study reveals for the first time that ABCG1 is involved in cellular vitamin E efflux.

MeSH terms

  • ATP Binding Cassette Transporter 1 / genetics
  • ATP Binding Cassette Transporter 1 / metabolism
  • ATP Binding Cassette Transporter, Subfamily G, Member 1
  • ATP-Binding Cassette Transporters / deficiency
  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Animals
  • Biological Transport
  • CHO Cells
  • Chromans / metabolism
  • Cricetinae
  • Cricetulus
  • Down-Regulation
  • Humans
  • Lipoproteins / deficiency
  • Lipoproteins / metabolism*
  • Liver / metabolism
  • Liver X Receptors
  • Macrophages / metabolism
  • Mice, Inbred C57BL
  • Organ Specificity
  • Orphan Nuclear Receptors / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / metabolism
  • Rats
  • Transfection
  • Vitamin E / metabolism*

Substances

  • ABCA1 protein, mouse
  • ABCG1 protein, human
  • ABCG1 protein, mouse
  • ATP Binding Cassette Transporter 1
  • ATP Binding Cassette Transporter, Subfamily G, Member 1
  • ATP-Binding Cassette Transporters
  • Chromans
  • Lipoproteins
  • Liver X Receptors
  • Orphan Nuclear Receptors
  • RNA, Messenger
  • RNA, Small Interfering
  • Vitamin E
  • 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid