Ectopic Expression of the Human MutT-type Nudix Hydrolase, hMTH1, Confers Enhanced Tolerance to Oxidative Stress in Arabidopsis

Plant Cell Physiol. 2014 Sep;55(9):1534-43. doi: 10.1093/pcp/pcu083. Epub 2014 Jun 12.

Abstract

Oxidized nucleotides produced by oxidative stress cause DNA mutations and the production of abnormal proteins. Thus, mammalian cells have developed multiple MutT-type Nudix hydrolases that exhibit pyrophosphohydrolase activity toward oxidized nucleotides in the cytosol, mitochondria and nucleus. On the other hand, AtNUDX1 is the only MutT-type Nudix hydrolase in the cytosol of Arabidopsis plants. To clarify the physiological significance of the defenses against oxidatively induced DNA damage in plant organelles, we analyzed the effects of the ectopic expression of the human MutT-type Nudix hydrolase, hMTH1, which was localized in the cytosol (cyt-hMTH1), chloroplasts (chl-hMTH1) and mitochondria (mit-hMTH1) of Arabidopsis cells, on tolerance to oxidative stress. Tolerance to oxidative stress caused by heating and paraquat (PQ) treatment was higher in the mit-hMTH1 and chl-hMTH1 plants than in the control and cyt-hMTH1 plants. The accumulation of H2O2 and the frequency of dead cells were lower in the mit-hMTH1 and chl-hMTH1 plants under stressful conditions. The poly(ADP-ribosyl)ation (PAR) reaction, which regulates repair systems for damaged DNA, was activated in the mit-hMTH1 and chl-hMTH1 plants under heat stress and PQ treatment. Furthermore, DNA fragmentation, which caused programmed cell death, was clearly suppressed in the mit-hMTH1 and chl-hMTH1 plants under heat stress. These results demonstrated that the ectopic expression of hMTH1 in the chloroplasts and mitochondria of Arabidopsis enhanced oxidative stress tolerance by activating the PAR reaction and suppressing programmed cell death.

Keywords: 8-Oxo-dGTP; MTH1; Nudix hydrolase; Oxidative stress; Oxidized nucleotide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis
  • Arabidopsis / drug effects
  • Arabidopsis / enzymology
  • Arabidopsis / genetics
  • Arabidopsis / physiology*
  • Cell Survival
  • Chloroplasts / physiology
  • Cytosol / metabolism
  • DNA Fragmentation
  • DNA Repair Enzymes / genetics
  • DNA Repair Enzymes / metabolism*
  • Gene Expression
  • Herbicides / pharmacology
  • Hot Temperature
  • Humans
  • Mitochondria / physiology
  • Oxidative Stress
  • Paraquat / pharmacology
  • Phosphoric Monoester Hydrolases / genetics
  • Phosphoric Monoester Hydrolases / metabolism*
  • Protein Transport
  • Seedlings / drug effects
  • Seedlings / enzymology
  • Seedlings / genetics
  • Seedlings / physiology
  • Stress, Physiological*
  • Transgenes

Substances

  • Herbicides
  • Phosphoric Monoester Hydrolases
  • 8-oxodGTPase
  • DNA Repair Enzymes
  • Paraquat