Abstract
AMP-activated protein kinase (AMPK) is the downstream component of a kinase cascade that plays a pivotal role in energy homeostasis. Activation of AMPK requires phosphorylation of threonine 172 (T172) within the T loop region of the catalytic alpha subunit. Recently, LKB1 was shown to activate AMPK. Here we show that AMPK is also activated by Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK). Overexpression of CaMKKbeta in mammalian cells increases AMPK activity, whereas pharmacological inhibition of CaMKK, or downregulation of CaMKKbeta using RNA interference, almost completely abolishes AMPK activation. CaMKKbeta isolated from rat brain or expressed in E. coli phosphorylates and activates AMPK in vitro. In yeast, CaMKKbeta expression rescues a mutant strain lacking the three kinases upstream of Snf1, the yeast homolog of AMPK. These results demonstrate that AMPK is regulated by at least two upstream kinases and suggest that AMPK may play a role in Ca(2+)-mediated signal transduction pathways.
Publication types
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Research Support, N.I.H., Extramural
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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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3T3 Cells
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AMP-Activated Protein Kinases
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Adenosine Monophosphate / metabolism
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Animals
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Benzimidazoles / pharmacology
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Calcium / metabolism*
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Calcium-Calmodulin-Dependent Protein Kinase Kinase
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Enzyme Activation / drug effects
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Fibroblasts
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HeLa Cells
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Humans
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Hydrogen Peroxide / pharmacology
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Ionomycin / pharmacology
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Isoenzymes / metabolism
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Isoquinolines / pharmacology
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Mice
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Multienzyme Complexes / metabolism*
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Naphthalimides
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Phosphorylation
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Protein Serine-Threonine Kinases / deficiency
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Rats
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / metabolism
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Signal Transduction / drug effects
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Sorbitol / pharmacology
Substances
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Benzimidazoles
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Isoenzymes
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Isoquinolines
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Multienzyme Complexes
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Naphthalimides
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STO 609
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Adenosine Monophosphate
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Sorbitol
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Ionomycin
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Hydrogen Peroxide
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SNF1-related protein kinases
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Protein Serine-Threonine Kinases
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Stk11 protein, mouse
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CAMKK2 protein, human
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Calcium-Calmodulin-Dependent Protein Kinase Kinase
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Camkk2 protein, mouse
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Camkk2 protein, rat
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AMP-Activated Protein Kinases
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Calcium