Cardiovascular Research Advance Access [Accepted Manuscript] published online on May 28, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp166
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AMP-activated protein kinase confers protection against TNF-
-induced cardiac cell death
1 Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences
2 Department of Cellular and Physiological Sciences, The University of British Columbia, Vancouver, BC, Canada V6T 1Z3
AUTHOR FOR CORRESPONDENCE: Dr. B. Rodrigues, Division of Pharmacology and Toxicology, Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, B.C., Canada V6T 1Z3, TEL: (604) 822-4758; FAX: (604) 822-3035, E-mail: rodrigue{at}interchange.ubc.ca
Aims: Although a substantial role for 5’ adenosine monophosphate-activated protein kinase (AMPK) has been established in regulating cardiac metabolism, a less studied action of AMPK is its ability to prevent cardiac cell death. Using established AMPK activators like dexamethasone (DEX) or metformin (MET), the objective of the present study was to determine if AMPK activation prevents tumor necrosis factor-alpha (TNF-
) induced apoptosis in adult rat ventricular cardiomyocytes.
Methods: Cardiomyocytes were incubated with DEX, MET, or TNF- for varying durations (0-12 hr). TNF--induced cell damage was evaluated by measuring caspase-3 activity and Hoechst staining. Protein and gene estimation techniques were employed to determine the mechanisms mediating the effects of AMPK activators on TNF--induced cardiomyocyte apoptosis.
Results: Incubation of myocytes with TNF- for 8 hr increased caspase-3 activation and apoptotic cell death, an effect that was abrogated by DEX and MET. The beneficial effect of DEX and MET was associated with stimulation of AMPK, which led to a rapid and sustained increase in Bad phosphorylation. This event reduced the interaction between Bad and Bcl-xL, limiting cytochrome c release and caspase-3 activation. Addition of Compound C to inhibit AMPK reduced Bad phosphorylation and prevented the beneficial effects of AMPK against TNF--induced cytotoxicity.
Conclusion: Our data demonstrates that although DEX and MET are used as anti-inflammatory agents or insulin sensitizers, respectively, their common property to phosphorylate AMPK promotes cardiomyocyte cell survival through its regulation of Bad and the mitochondrial apoptotic mechanism.
KEYWORDS AMPK; Dexamethasone; Metformin; Cardiomyocyte; Apoptosis
Time for primary review: 28 Days
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