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Abstract 357: Activation of Autophagic Flux Blunts Cardiac Ischemia/Reperfusion Injury

Authors: Geoffrey W Cho; Min Xie; Yongli Kong; Dan L Li; Xiang L Luo; Francisco Altamirano; Cyndi Morales; +8 Authors

Abstract 357: Activation of Autophagic Flux Blunts Cardiac Ischemia/Reperfusion Injury

Abstract

Background: Reperfusion injury accounts for a significant portion of myocardial damage in acute coronary syndromes. Autophagy, a process of cell catabolism, plays a vital role in the heart’s response to stress. We have reported that re-induction of ischemia/reperfusion (I/R)-suppressed cardiomyocyte autophagy with histone deacetylase (HDAC) inhibitors affords significant cardioprotection. However, as HDACs govern many processes and may have off-target effects, we set out to modulate autophagy in a manner independent of HDAC activity. Here, we hypothesized that induction of autophagy with a novel agent, Tat-Beclin, at the time of reperfusion, will reduce I/R injury and rescue cardiac function. Methods: Wild type and ATG7 (protein required for autophagic flux) knockout mice were randomized among 3 treatment groups prior to surgical I/R injury [45 min LAD artery ligation; 24h reperfusion]: vehicle control (VC), Tat-Scrambled (TS), or Tat-Beclin (TB). Each agent was delivered at coronary reperfusion. To define molecular mechanisms, cultured adult and neonatal rat ventricular cardiomyocytes (ARVMs/NRVMs) were subjected to simulated I/R. Results: Induction of cardiomyocyte autophagy at reperfusion reduced infarct size 20.1% (±6.3%, n=23, p<0.02 vs VC). This treatment was associated with improved systolic function (declines in fractional shortening: 19.8±3.7% VC; 18.7±2.1% TS; 8.5±1.7% TB, n=11, p<0.01 vs VC). In NRVMs subjected to I/R injury, cell death was reduced 41% (±6%, n=12, p<0.001 vs VC). Improvements correlated with increased autophagic flux measured by the marker LC3-II, particularly at the infarct border zone. Additional data suggested that autophagy rescues I/R injury through reduction of oxidative stress. ATG7 KO mice or NRVM depleted of ATG7 (RNAi) manifested significantly less cardioprotection. Conclusion: Direct induction of cardiomyocyte autophagy reduces infarct size and declines in contractile function. Autophagy rescues I/R injury in part through reduction of oxidative stress. Critically, this cardioprotection was observed when intervention occurred at the time of reperfusion, the clinically relevant context.

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
0
Average
Average
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