Mammalian target of rapamycin inhibition attenuates myocardial ischaemia–reperfusion injury in hypertrophic heart

Mammalian target of rapamycin inhibition attenuates myocardial ischaemia–reperfusion injury in... Pathological cardiac hypertrophy aggravated myocardial infarction and is causally related to autophagy dysfunction and increased oxidative stress. Rapamycin is an inhibitor of serine/threonine kinase mammalian target of rapamycin (mTOR) involved in the regulation of autophagy as well as oxidative/nitrative stress. Here, we demonstrated that rapamycin ameliorates myocardial ischaemia reperfusion injury by rescuing the defective cytoprotective mechanisms in hypertrophic heart. Our results showed that chronic rapamycin treatment markedly reduced the phosphorylated mTOR and ribosomal protein S6 expression, but not Akt in both normal and aortic‐banded mice. Moreover, chronic rapamycin treatment significantly mitigated TAC‐induced autophagy dysfunction demonstrated by prompted Beclin‐1 activation, elevated LC3‐II/LC3‐I ratio and increased autophagosome abundance. Most importantly, we found that MI/R‐induced myocardial injury was markedly reduced by rapamycin treatment manifested by the inhibition of myocardial apoptosis, the reduction of myocardial infarct size and the improvement of cardiac function in hypertrophic heart. Mechanically, rapamycin reduced the MI/R‐induced iNOS/gp91phox protein expression and decreased the generation of NO and superoxide, as well as the cytotoxic peroxynitrite. Moreover, rapamycin significantly mitigated MI/R‐induced endoplasmic reticulum stress and mitochondrial impairment demonstrated by reduced Caspase‐12 activity, inhibited CHOP activation, decreased cytoplasmic Cyto‐C release and preserved intact mitochondria. In addition, inhibition of mTOR also enhanced the phosphorylated ERK and eNOS, and inactivated GSK3β, a pivotal downstream target of Akt and ERK signallings. Taken together, these results suggest that mTOR signalling protects against MI/R injury through autophagy induction and ERK‐mediated antioxidative and anti‐nitrative stress in mice with hypertrophic myocardium. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Cellular and Molecular Medicine Wiley

Mammalian target of rapamycin inhibition attenuates myocardial ischaemia–reperfusion injury in hypertrophic heart

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Publisher
Wiley Subscription Services, Inc., A Wiley Company
Copyright
Copyright © 2018 John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine
ISSN
1582-1838
eISSN
1582-4934
D.O.I.
10.1111/jcmm.13451
Publisher site
See Article on Publisher Site

Abstract

Pathological cardiac hypertrophy aggravated myocardial infarction and is causally related to autophagy dysfunction and increased oxidative stress. Rapamycin is an inhibitor of serine/threonine kinase mammalian target of rapamycin (mTOR) involved in the regulation of autophagy as well as oxidative/nitrative stress. Here, we demonstrated that rapamycin ameliorates myocardial ischaemia reperfusion injury by rescuing the defective cytoprotective mechanisms in hypertrophic heart. Our results showed that chronic rapamycin treatment markedly reduced the phosphorylated mTOR and ribosomal protein S6 expression, but not Akt in both normal and aortic‐banded mice. Moreover, chronic rapamycin treatment significantly mitigated TAC‐induced autophagy dysfunction demonstrated by prompted Beclin‐1 activation, elevated LC3‐II/LC3‐I ratio and increased autophagosome abundance. Most importantly, we found that MI/R‐induced myocardial injury was markedly reduced by rapamycin treatment manifested by the inhibition of myocardial apoptosis, the reduction of myocardial infarct size and the improvement of cardiac function in hypertrophic heart. Mechanically, rapamycin reduced the MI/R‐induced iNOS/gp91phox protein expression and decreased the generation of NO and superoxide, as well as the cytotoxic peroxynitrite. Moreover, rapamycin significantly mitigated MI/R‐induced endoplasmic reticulum stress and mitochondrial impairment demonstrated by reduced Caspase‐12 activity, inhibited CHOP activation, decreased cytoplasmic Cyto‐C release and preserved intact mitochondria. In addition, inhibition of mTOR also enhanced the phosphorylated ERK and eNOS, and inactivated GSK3β, a pivotal downstream target of Akt and ERK signallings. Taken together, these results suggest that mTOR signalling protects against MI/R injury through autophagy induction and ERK‐mediated antioxidative and anti‐nitrative stress in mice with hypertrophic myocardium.

Journal

Journal of Cellular and Molecular MedicineWiley

Published: Jan 1, 2018

Keywords: ; ; ; ;

References

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