Transportomics: screening for substrates of ABC transporters in body fluids using vesicular transport assays

FASEB J. 2012 Feb;26(2):738-47. doi: 10.1096/fj.11-195743. Epub 2011 Oct 27.

Abstract

The ATP-binding cassette (ABC) genes encode the largest family of transmembrane proteins. ABC transporters translocate a wide variety of substrates across membranes, but their physiological function is often incompletely understood. We describe a new method to study the substrate spectrum of ABC transporters: We incubate extracts of mouse urine with membrane vesicles prepared from Spodoptera frugiperda Sf9 insect cells overproducing an ABC transporter and determine the compounds transported into the vesicles by LC/MS-based metabolomics. We illustrate the power of this simple "transportomics" approach using ABCC2, a protein present at sites of uptake and elimination. We identified many new substrates of ABCC2 in urine. These included glucuronides of plant-derived xenobiotics, a class of compounds to which humans are exposed on a daily basis. Moreover, we show that the excretion of these compounds in vivo depends on ABCC2: compared to wild-type mice, the urinary excretion of several glucuronides was increased up to 20-fold in Abcc2(-/-) mice. Transportomics has broad applicability, as it is not restricted to urine and can be applied to other ATP-dependent transport proteins as well.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • Animals
  • Biological Transport, Active
  • Body Fluids / metabolism
  • Glucuronides / metabolism
  • Glucuronides / urine
  • Humans
  • Kinetics
  • Metabolome
  • Mice
  • Mice, Knockout
  • Multidrug Resistance-Associated Proteins / deficiency
  • Multidrug Resistance-Associated Proteins / genetics
  • Multidrug Resistance-Associated Proteins / metabolism
  • Phytoestrogens / metabolism
  • Phytoestrogens / urine
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Xenobiotics / metabolism
  • Xenobiotics / urine

Substances

  • ATP-Binding Cassette Transporters
  • Glucuronides
  • Multidrug Resistance-Associated Proteins
  • Phytoestrogens
  • Recombinant Proteins
  • Xenobiotics
  • multidrug resistance-associated protein 2