Oxidative stress stimulates autophagic flux during ischemia/reperfusion.
Autophagy is a bulk degradation process in which cytosolic proteins and organelles are degraded through lysosomes. To evaluate autophagic flux in cardiac myocytes, we generated adenovirus and cardiac-specific transgenic mice harboring tandem fluorescent mRFP-GFP-LC3. Starvation significantly increased the number of mRFP-GFP-LC3 dots representing both autophagosomes and autolysosomes per cell, suggesting that autophagic flux is increased in cardiac myocytes. H(2)O(2) significantly increased autophagic flux, which was attenuated in the presence of N-2-mercaptopropionyl glycine (MPG), an antioxidant, suggesting that oxidative stress stimulates autophagy in cardiac myocytes. Myocardial ischemia/reperfusion (I/R) increased both autophagosomes and autolysosomes, thereby increasing autophagic flux. Treatment with MPG attenuated I/R-induced increases in oxidative stress, autophagic flux, and Beclin-1 expression, accompanied by a decrease in the size of myocardial infarction (MI)/area at risk (AAR), suggesting that oxidative stress plays an important role in mediating autophagy and myocardial injury during I/R. MI/AAR after I/R was significantly reduced in beclin1(+/-) mice, whereas beclin1(+/-) mice treated with MPG exhibited no additional reduction in the size of MI/AAR after I/R. These results suggest that oxidative stress plays an important role in mediating autophagy during I/R, and that activation of autophagy through oxidative stress mediates myocardial injury in response to I/R in the mouse heart.
Hariharan
Nirmala
N
Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, UMDNJ, New Jersey Medical School, New Jersey, USA.
Zhai
Peiyong
P
Sadoshima
Junichi
J
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D001343:Autophagy; D000071186:Beclin-1; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D008822:Mice, Transgenic; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D013217:Starvation; D008625:Tiopronin / Q000494:pharmacology
D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; C115010:Becn1 protein, mouse; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D006861:Hydrogen Peroxide; D008625:Tiopronin
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