α-Enolase plays a catalytically independent role in doxorubicin-induced cardiomyocyte apoptosis and mitochondrial dysfunction

J Mol Cell Cardiol. 2015 Feb:79:92-103. doi: 10.1016/j.yjmcc.2014.11.007. Epub 2014 Nov 15.

Abstract

Background: α-Enolase is a glycolytic enzyme with "second jobs" beyond its catalytic activity. However, its possible contribution to cardiac dysfunction remains to be determined. The present study aimed to investigate the role of α-enolase in doxorubicin (Dox)-induced cardiomyopathy as well as the underlying mechanisms.

Experimental approaches: The expression of α-enolase was detected in rat hearts and primary cultured rat cardiomyocytes with or without Dox administration. An adenovirus carrying short-hairpin interfering RNA targeting α-enolase was constructed and transduced specifically into the heart by intramyocardial injection. Heart function, cell apoptosis and mitochondrial function were measured following Dox administration. In addition, by using gain- and loss-of-function approaches to regulate α-enolase expression in primary cultured rat cardiomyocytes, we investigated the role of endogenous, wide type and catalytically inactive mutant α-enolase in cardiomyocyte apoptosis and ATP generation. Furthermore, the involvement of α-enolase in AMPK phosphorylation was also studied.

Key results: The mRNA and protein expression of cardiac α-enolase was significantly upregulated by Dox. Genetic silencing of α-enolase in rat hearts and cultured cardiomyocytes attenuated Dox-induced apoptosis and mitochondrial dysfunction. In contrast, overexpression of wide-type or catalytically inactive α-enolase in cardiomyocytes mimicked the detrimental role of Dox in inducing apoptosis and ATP reduction. AMPK dephosphorylation was further demonstrated to be involved in the proapoptotic and ATP-depriving effects of α-enolase.

Conclusion: Our findings provided the evidence that α-enolase has a catalytically independent role in inducing cardiomyocyte apoptosis and mitochondrial dysfunction, which could be at least partially contributed to the inhibition of AMPK phosphorylation.

Keywords: AMPK; Apoptosis; Cardiomyocyte; Doxorubicin; Mitochondria; α-Enolase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Adenoviridae / metabolism
  • Adenylate Kinase / metabolism
  • Animals
  • Apoptosis / drug effects*
  • Biocatalysis / drug effects
  • Cell Respiration / drug effects
  • Cells, Cultured
  • Down-Regulation / drug effects
  • Doxorubicin / pharmacology*
  • Energy Metabolism / drug effects
  • Enzyme Activation / drug effects
  • Gene Silencing / drug effects
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Myocardium / enzymology
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / enzymology*
  • Phosphopyruvate Hydratase / metabolism*
  • Phosphorylation / drug effects
  • Rats, Sprague-Dawley
  • Up-Regulation / drug effects

Substances

  • Doxorubicin
  • Adenosine Triphosphate
  • Adenylate Kinase
  • Phosphopyruvate Hydratase