Disruption of the ATP-binding cassette B7 (ABTM-1/ABCB7) induces oxidative stress and premature cell death in Caenorhabditis elegans

J Biol Chem. 2011 Jun 17;286(24):21304-14. doi: 10.1074/jbc.M110.211201. Epub 2011 Apr 4.

Abstract

X-linked sideroblastic anemia with ataxia (XLSA/A) is a rare inherited disorder characterized by mild anemia and ataxia. XLSA/A is caused by mutations in the ABCB7 gene, which encodes a member of the ATP-binding cassette transporter family. Studies in yeast, mammalian cells, and mice have shown that ABCB7 functions in the transport of iron-sulfur (Fe-S) clusters into the cytoplasm. To further investigate the mechanism of this disease, we have identified and characterized the Caenorhabditis elegans homologue of the ABCB7 gene, abtm-1. We have studied the function of abtm-1 using mutants and RNAi. abtm-1-depleted animals produce arrested embryos that have morphogenetic defects and unusual premature, putative apoptotic events. abtm-1(RNAi) animals also show accumulation of ferric iron and increased oxidative stress. Despite the increased level of oxidative stress in abtm-1(RNAi) animals, they have an increased life span. We observed accumulation of DAF-16/FOXO in the nuclei of affected animals and elevation of the expression of SOD-3, a well established target of DAF-16, which may explain the increased life span extension of these animals. abtm-1 is strongly expressed in tissues with a high energy demand, and abtm-1(RNAi) animals have phenotypes that reflect the need for abtm-1 in these tissues. Finally, we show that reducing the function of other genes involved in Fe-S cluster production produces similar phenotypic consequences to abtm-1 loss of function. Therefore, ablation of abtm-1 in C. elegans provides a model in which to investigate the mechanism underlying XLSA/A.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism*
  • ATP-Binding Cassette Transporters / physiology
  • Animals
  • Apoptosis
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / physiology*
  • Cell Death
  • Cytoplasm / metabolism
  • DNA, Complementary / metabolism
  • Frataxin
  • Gene Expression Regulation, Developmental*
  • Iron / metabolism
  • Iron-Binding Proteins / metabolism
  • Mitochondria / metabolism
  • Models, Biological
  • Oxidative Stress*
  • RNA Interference

Substances

  • ABTM-1 protein, C elegans
  • ATP-Binding Cassette Transporters
  • Caenorhabditis elegans Proteins
  • DNA, Complementary
  • Iron-Binding Proteins
  • Iron