Prevention of export of anoxia/reoxygenation injury from ischemic to nonischemic cardiomyocytes via inhibition of endocytosis.
Myocardial infarct size is determined by the death of nonischemic border zone cardiomyocytes caused by export of injury signals from the infarct zone. The countermeasures to limit infarct size, therefore, should be aimed at nonselective blockade of most, if not all, injury signals from entering nonischemic cells. To test whether inhibition of endocytosis might limit infarct size, HL-1 cardiomyocytes were subjected to anoxia (6 h) and reoxygenation (1 h). Anoxic and reoxygenated cells showed a multifold increase in mitochondrial ROS production accompanied with upregulation of scavenger receptors lectin-like oxidized low-density lipoprotein receptor-1 and CD36 and stimulation of stress signals, including NADPH oxidase subunit p22(phox), SOD2, and beclin-1. Incubation of healthy cardiomyocytes in media from anoxic and reoxygenated cells (conditioned media) resulted in qualitatively similar responses, including increase in the generation of mitochondrial ROS, p22(phox), SOD2, and beclin-1. Anoxia and reoxygenation caused collapse of clathrin-mediated endocytosis and stimulation of macropinocytosis, whereas in cultures exposed to conditioned media, the activity of endocytosis was uniformly higher. Conditioned media also significantly aggravated cytotoxic effects of TNF-α and angiotensin II, and suppression of endocytosis reversed these trends, resulting in an overall increase of metabolic activity. Moreover, inhibition of endocytosis prevented binding of oxidized cellular fragments with greater efficiency than targeted neutralization of the scavenger receptor lectin-like oxidized low-density lipoprotein receptor-1. Many of the observations in HL-1 cardiomyocytes were confirmed in primary cardiomyocyte cultures. Our data suggest that endocytosis is upregulated in border zone cardiomyocytes, and inhibition of endocytosis may be an effective approach to prevent export of injury signals from the infarct zone.
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas; mkhaidakov@uams.edu.
Magomed
M
Khaidakov
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas; Division of Cardiology, Department of Internal Medicine, University of Rome "Tor Vergata," Rome, Italy; and.
Federico
F
Mercanti
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas;
Xianwei
X
Wang
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas;
Zufeng
Z
Ding
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas;
Yao
Y
Dai
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas; Division of Cardiology, Department of Internal Medicine, University of Rome "Tor Vergata," Rome, Italy; and.
Francesco
F
Romeo
Department of Vascular Physiology, National Cardiovascular Center Research Institute, Osaka, Japan.
Tatsuya
T
Sawamura
Central Arkansas Healthcare System and University of Arkansas for Medical Sciences, Little Rock, Arkansas;
Jawahar L
JL
Mehta
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D000071186:Beclin-1; D018955:CD36 Antigens / Q000378:metabolism; D002478:Cells, Cultured; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D000860:Hypoxia / Q000150:complications*; D051379:Mice; D023421:Models, Animal; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology* / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D000099156:Superoxide Dismutase 2
D000804:Angiotensin II; D051017:Apoptosis Regulatory Proteins; D000071186:Beclin-1; D018955:CD36 Antigens; D010100:Oxygen; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D014409:Tumor Necrosis Factor-alpha; D000099156:Superoxide Dismutase 2; C115010:Becn1 protein, mouse
anoxia; endocytosis injury export; lectin-like oxidized low-density lipoprotein receptor-1; myocardial infarction