AMPK-Mediated AS160 Phosphorylation in Skeletal Muscle Is Dependent on AMPK Catalytic and Regulatory Subunits
- Jonas T. Treebak1,
- Stephan Glund2,
- Atul Deshmukh2,
- Ditte K. Klein1,
- Yun Chau Long2,
- Thomas E. Jensen1,
- Sebastian B. Jørgensen1,
- Benoit Viollet3,
- Leif Andersson4,
- Dietbert Neumann5,
- Theo Wallimann5,
- Erik A. Richter1,
- Alexander V. Chibalin2,
- Juleen R. Zierath2 and
- Jørgen F.P. Wojtaszewski1
- 1Department of Human Physiology, Institute of Exercise and Sport Sciences, Copenhagen Muscle Research Centre, University of Copenhagen, Copenhagen, Denmark
- 2Department of Molecular Medicine and Surgery, Section Integrative Physiology, Karolinska Institute, Stockholm, Sweden
- 3René Descartes University, Institute Cochin, Paris, France
- 4Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala Biomedical Center, Uppsala, Sweden
- 5Swiss Federal Institute of Technology, Zurich, Switzerland
- Address correspondence and reprint requests to Juleen R. Zierath, Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institute, von Eulers väg 4, 4th Floor, S-171 77 Stockholm, Sweden. E-mail: juleen.zierath{at}ki.se
Abstract
AMP-activated protein kinase (AMPK) is a heterotrimeric protein that regulates glucose transport mediated by cellular stress or pharmacological agonists such as 5-aminoimidazole-4-carboxamide 1 β-d-ribonucleoside (AICAR). AS160, a Rab GTPase-activating protein, provides a mechanism linking AMPK signaling to glucose uptake. We show that AICAR increases AMPK, acetyl-CoA carboxylase, and AS160 phosphorylation by insulin-independent mechanisms in isolated skeletal muscle. Recombinant AMPK heterotrimeric complexes (α1β1γ1 and α2β2γ1) phosphorylate AS160 in a cell-free assay. In mice deficient in AMPK signaling (α2 AMPK knockout [KO], α2 AMPK kinase dead [KD], and γ3 AMPK KO), AICAR effects on AS160 phosphorylation were severely blunted, highlighting that complexes containing α2 and γ3 are necessary for AICAR-stimulated AS160 phosphorylation in intact skeletal muscle. Contraction-mediated AS160 phosphorylation was also impaired in α2 AMPK KO and KD but not γ3 AMPK KO mice. Our results implicate AS160 as a downstream target of AMPK.
- ACC, acetyl-CoA carboxylase
- AICAR, 5-aminoimidazole-4-carboxamide 1 β-d-ribonucleoside
- AMPK, AMP-activated protein kinase
- CaMKK, calmodulin-dependent protein kinase kinase
- EDL, extensor digitorum longus
- GST, glutathione S-transferase
- PAS, phospho-Akt substrate
- TSC, tuberous sclerosis complex
Footnotes
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J.T.T., S.G., and A.D. contributed equally to this work.
See related article by Kramer et al., p. 2067.
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- Accepted March 23, 2006.
- Received February 7, 2006.
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