title: Ectopic expression of the human MutT-type Nudix hydrolase, hMTH1, confers enhanced tolerance to oxidative stress in arabidopsis.
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.
authors.affiliation: Department of Food and Nutritional Science, College of Bioscience and Biotechnology, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi, 487-8501 Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Yoshimura
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, Nakamachi, Nara, 631-8505 Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Ogawa
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, Nakamachi, Nara, 631-8505 Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Tsujimura
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, Nakamachi, Nara, 631-8505 Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ishikawa
authors.affiliation: Department of Advanced Bioscience, Faculty of Agriculture, Kinki University, Nakamachi, Nara, 631-8505 Japan shigeoka@nara.kindai.ac.jp.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Shigeoka
mesh_terms: D017209:Apoptosis; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D002470:Cell Survival; D002736:Chloroplasts / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D053938:DNA Fragmentation; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006540:Herbicides / Q000494:pharmacology; D006358:Hot Temperature; D006801:Humans; D008928:Mitochondria / Q000502:physiology; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D036226:Seedlings / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology; D013312:Stress, Physiological; D019076:Transgenes
chemical_list: D006540:Herbicides; D010744:Phosphoric Monoester Hydrolases; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes; D010269:Paraquat
keywords: 8-Oxo-dGTP; MTH1; Nudix hydrolase; Oxidative stress; Oxidized nucleotide