AICA riboside (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside) has been extensively used in cells to activate the AMPK (AMP-activated protein kinase), a metabolic sensor involved in cell energy homoeostasis. In the present study, we investigated the effects of AICA riboside on mitochondrial oxidative; phosphorylation. AICA riboside was found to dose-dependently inhibit the oligomycin-sensitive JO2 (oxygen consumption rate) of isolated rat hepatocytes. A decrease in Pi (inorganic phosphate), ATP, AMP and total adenine nucleotide contents was also observed with AICA riboside concentrations >0.1 mM. Interestingly, in hepatocytes from mice lacking both α1 and α2 AMPK catalytic subunits, basal JO2 and expression of several mitochondrial proteins were significantly reduced compared with wild-type mice, suggesting that mitochondrial biogenesis was perturbed. However, inhibition of JO2 by AICA riboside was still present in the mutant mice and thus was clearly not mediated by AMPK. In permeabilized hepatocytes, this inhibition was no longer evident, suggesting that it could be due to intracellular accumulation of Z nucleotides and/or loss of adenine nucleotides and Pi. ZMP did indeed inhibit respiration in isolated rat mitochondria through a direct effect on the respiratory-chain complex I. In addition, inhibition of JO2 by AICA riboside was also potentiated in cells incubated with fructose to deplete adenine nucleotides and Pi. We conclude that AICA riboside inhibits cellular respiration by an AMPK-independent mechanism that likely results from the combined intracellular Pi depletion and ZMP accumulation. Our data also demonstrate that the cellular effects of AICA riboside are not necessarily caused by AMPK activation and that their interpretation should be taken with caution.
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Research Article|
May 29 2007
AMP-activated protein kinase-independent inhibition of hepatic mitochondrial oxidative phosphorylation by AICA riboside
Bruno Guigas;
Bruno Guigas
1
*Université catholique de Louvain and Institute of Cellular Pathology, Hormone and Metabolic Research Unit, Brussels, Belgium
1To whom correspondence should be addressed (email: b.guigas@lumc.nl).
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Nellie Taleux;
Nellie Taleux
*Université catholique de Louvain and Institute of Cellular Pathology, Hormone and Metabolic Research Unit, Brussels, Belgium
†Bioénergétique Fondamentale et Appliquée INSERM-EMI0221, Université J. Fourier, Grenoble, France
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Marc Foretz;
Marc Foretz
‡Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris, France
§Inserm, U567, Paris, France
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Dominique Detaille;
Dominique Detaille
†Bioénergétique Fondamentale et Appliquée INSERM-EMI0221, Université J. Fourier, Grenoble, France
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Fabrizio Andreelli;
Fabrizio Andreelli
‡Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris, France
§Inserm, U567, Paris, France
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Benoit Viollet;
Benoit Viollet
‡Institut Cochin, Université Paris Descartes, CNRS (UMR 8104), Paris, France
§Inserm, U567, Paris, France
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Louis Hue
Louis Hue
*Université catholique de Louvain and Institute of Cellular Pathology, Hormone and Metabolic Research Unit, Brussels, Belgium
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Publisher: Portland Press Ltd
Received:
January 18 2007
Revision Received:
February 21 2007
Accepted:
February 27 2007
Accepted Manuscript online:
February 27 2007
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2007 Biochemical Society
2007
Biochem J (2007) 404 (3): 499–507.
Article history
Received:
January 18 2007
Revision Received:
February 21 2007
Accepted:
February 27 2007
Accepted Manuscript online:
February 27 2007
Citation
Bruno Guigas, Nellie Taleux, Marc Foretz, Dominique Detaille, Fabrizio Andreelli, Benoit Viollet, Louis Hue; AMP-activated protein kinase-independent inhibition of hepatic mitochondrial oxidative phosphorylation by AICA riboside. Biochem J 15 June 2007; 404 (3): 499–507. doi: https://doi.org/10.1042/BJ20070105
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