Abstract
The AMP-activated protein kinase (AMPK) in rat skeletal and cardiac muscle is activated by vigorous exercise and ischaemic stress. Under these conditions AMPK phosphorylates and inhibits acetyl-coenzyme A carboxylase causing increased oxidation of fatty acids. Here we show that AMPK co-immunoprecipitates with cardiac endothelial NO synthase (eNOS) and phosphorylates Ser-1177 in the presence of Ca2+-calmodulin (CaM) to activate eNOS both in vitro and during ischaemia in rat hearts. In the absence of Ca2+-calmodulin, AMPK also phosphorylates eNOS at Thr-495 in the CaM-binding sequence, resulting in inhibition of eNOS activity but Thr-495 phosphorylation is unchanged during ischaemia. Phosphorylation of eNOS by the AMPK in endothelial cells and myocytes provides a further regulatory link between metabolic stress and cardiovascular function.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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AMP-Activated Protein Kinases
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Amino Acid Sequence
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Animals
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Aorta
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Calmodulin / metabolism
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Cattle
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Endothelium, Vascular / cytology
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Endothelium, Vascular / enzymology*
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Enzyme Activation
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Kinetics
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Liver / enzymology
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Molecular Sequence Data
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Multienzyme Complexes / metabolism*
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Myocardial Ischemia / enzymology
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Myocardium / enzymology
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Nitric Oxide Synthase / metabolism*
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Nitric Oxide Synthase Type III
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Phosphorylation
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Precipitin Tests
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Protein Binding
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Protein Kinases / metabolism*
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Protein Serine-Threonine Kinases*
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Rats
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Recombinant Proteins / metabolism
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Serine / metabolism
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Threonine / metabolism
Substances
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Calmodulin
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Multienzyme Complexes
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Recombinant Proteins
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Threonine
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Serine
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Nitric Oxide Synthase
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Nitric Oxide Synthase Type III
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Nos3 protein, rat
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Protein Kinases
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Protein Serine-Threonine Kinases
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AMP-Activated Protein Kinases