Enhancing macroautophagy protects against ischemia/reperfusion injury in cardiac myocytes

Research output: Contribution to journalArticle

Abstract

Cardiac myocytes undergo programmed cell death as a result of ischemia/reperfusion (I/R). One feature of I/R injury is the increased presence of autophagosomes. However, to date it is not known whether macroautophagy functions as a protective pathway, contributes to programmed cell death, or is an irrelevant event during cardiac I/R injury. We employed simulated I/R of cardiac HL-1 cells as an in vitro model of I/R injury to the heart. To assess macroautophagy, we quantified autophagosome generation and degradation (autophagic flux), as determined by steady-state levels of autophagosomes in relation to lysosomal inhibitor-mediated accumulation of autophagosomes. We found that I/R impaired both formation and downstream lysosomal degradation of autophagosomes. Overexpression of Beclin1 enhanced autophagic flux following I/R and significantly reduced activation of pro-apoptotic Bax, whereas RNA interference knockdown of Beclin1 increased Bax activation. Bcl-2 and Bcl-xL were protective against I/R injury, and expression of a Beclin1 Bcl-2/-x L binding domain mutant resulted in decreased autophagic flux and did not protect against I/R injury. Overexpression of Atg5, a component of the autophagosomal machinery downstream of Beclin1, did not affect cellular injury, whereas expression of a dominant negative mutant of Atg5 increased cellular injury. These results demonstrate that autophagic flux is impaired at the level of both induction and degradation and that enhancing autophagy constitutes a powerful and previously uncharacterized protective mechanism against I/R injury to the heart cell.

Original languageEnglish (US)
Pages (from-to)29776-29787
Number of pages12
JournalJournal of Biological Chemistry
Volume281
Issue number40
DOIs
StatePublished - Oct 6 2006
Externally publishedYes

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Autophagy
Reperfusion Injury
Cardiac Myocytes
Fluxes
Reperfusion
Cell death
Ischemia
Degradation
Chemical activation
Cell Death
Machinery
Wounds and Injuries
RNA
RNA Interference
Autophagosomes
Beclin-1

ASJC Scopus subject areas

  • Biochemistry

Cite this

Enhancing macroautophagy protects against ischemia/reperfusion injury in cardiac myocytes. / Hamacher-Brady, Anne; Brady, Nathan Ryan; Gottlieb, Roberta A.

In: Journal of Biological Chemistry, Vol. 281, No. 40, 06.10.2006, p. 29776-29787.

Research output: Contribution to journalArticle

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