The Friedreich's ataxia protein frataxin modulates DNA base excision repair in prokaryotes and mammals

Biochem J. 2010 Nov 15;432(1):165-72. doi: 10.1042/BJ20101116.

Abstract

DNA-repair mechanisms enable cells to maintain their genetic information by protecting it from mutations that may cause malignant growth. Recent evidence suggests that specific DNA-repair enzymes contain ISCs (iron-sulfur clusters). The nuclearencoded protein frataxin is essential for the mitochondrial biosynthesis of ISCs. Frataxin deficiency causes a neurodegenerative disorder named Friedreich's ataxia in humans. Various types of cancer occurring at young age are associated with this disease, and hence with frataxin deficiency. Mice carrying a hepatocyte-specific disruption of the frataxin gene develop multiple liver tumours for unresolved reasons. In the present study, we show that frataxin deficiency in murine liver is associated with increased basal levels of oxidative DNA base damage. Accordingly, eukaryotic V79 fibroblasts overexpressing human frataxin show decreased basal levels of these modifications, while prokaryotic Salmonella enterica serotype Typhimurium TA104 strains transformed with human frataxin show decreased mutation rates. The repair rates of oxidative DNA base modifications in V79 cells overexpressing frataxin were significantly higher than in control cells. Lastly, cleavage activity related to the ISC-independent repair enzyme 8-oxoguanine glycosylase was found to be unaltered by frataxin overexpression. These findings indicate that frataxin modulates DNA-repair mechanisms probably due to its impact on ISC-dependent repair proteins, linking mitochondrial dysfunction to DNA repair and tumour initiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Cells, Cultured
  • DNA Damage*
  • DNA Glycosylases / metabolism
  • DNA Repair / genetics*
  • Fibroblasts / metabolism
  • Fibroblasts / pathology
  • Friedreich Ataxia / genetics*
  • Friedreich Ataxia / metabolism
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Humans
  • Iron-Binding Proteins / genetics*
  • Iron-Binding Proteins / metabolism
  • Iron-Sulfur Proteins / metabolism
  • Liver Neoplasms / genetics
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology
  • Mammals / genetics
  • Mammals / metabolism
  • Mice
  • Mice, Knockout
  • Mutation
  • Oxidative Stress
  • Prokaryotic Cells / metabolism
  • Salmonella enterica / genetics
  • Transfection

Substances

  • Iron-Binding Proteins
  • Iron-Sulfur Proteins
  • frataxin
  • DNA Glycosylases
  • oxoguanine glycosylase 1, human