8-oxo-dGTPase, which prevents oxidative stress-induced DNA damage, increases in the mitochondria from failing hearts.
BACKGROUND
Reactive oxygen species (ROS) can cause an oxidative modification of nucleotides, such as 8-oxo-7,8-dihydrodeoxyguanosine triphosphate (8-oxo-dGTP), which can lead to defects in DNA replication. The misincorporation of 8-oxo-dGTP into DNA is prevented by 8-oxo-dGTPase, which hydrolyzes 8-oxo-dGTP into 8-oxo-dGMP. The changes in this defensive system have not yet been examined in failing hearts, in which the generation of ROS increases.


RESULTS
Myocardial infarction (MI) was created in mice by ligating the left coronary artery. Four weeks later, the left ventricle was dilated and contractility was diminished on echocardiography. The generation of ROS, as measured by electron spin resonance spectroscopy with 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, increased in the noninfarcted left ventricle from MI mice. The formation of thiobarbituric acid-reactive substances also increased in the mitochondria from MI mice. 8-Oxo-dGTPase was detected in the mitochondrial fractions isolated from MI mice using a Western blot analysis with an antibody to its human homologue (hMTH1). Immunohistochemistry showed positive staining for hMTH1 was localized in the cardiac myocytes.


CONCLUSIONS
The level of 8-oxo-dGTPase increased in the mitochondria isolated from post-MI hearts as oxidative stress increased, thus suggesting that a preventive mechanism is activated against ROS-induced DNA damage. As a result, 8-oxo-dGTPase is considered a useful marker of mitochondrial oxidative stress in heart failure.
Tsutsui
H
H
Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. prehiro@cardiol.med.kyushu-u.ac.jp
Ide
T
T
Shiomi
T
T
Kang
D
D
Hayashidani
S
S
Suematsu
N
N
Wen
J
J
Utsumi
H
H
Hamasaki
N
N
Takeshita
A
A
D000818:Animals; D015153:Blotting, Western; D004249:DNA Damage; D045643:DNA Repair Enzymes; D004452:Echocardiography; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D019169:Jurkat Cells; D008168:Lung / Q000254:growth & development; D008297:Male; D051379:Mice; D008929:Mitochondria, Heart / Q000378:metabolism*; D009203:Myocardial Infarction / Q000378:metabolism*; D009929:Organ Size; D018384:Oxidative Stress / Q000502:physiology*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D010744:Phosphoric Monoester Hydrolases; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes