Woods, A. et al. Ca2+/calmodulin-dependent protein kinase kinase- acts upstream of AMP-activated protein kinase in mammalian cells. Cell Metab. 2, 21-33

Cellular Stress Group, MRC Clinical Sciences Centre, Imperial College, Hammersmith Hospital, Du Cane Road, London W12 0NN, United Kingdom.
Cell Metabolism (Impact Factor: 17.57). 08/2005; 2(1):21-33. DOI: 10.1016/j.cmet.2005.06.005
Source: PubMed


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.

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Available from: Richard Heath, Oct 02, 2015
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    • "We induced energy stress in HEK293 (expressing empty vector or FLAG SENP1) by subjecting the cells to low-glucose conditions, low glucose together with glycolysis inhibitor 2-DG, or treatment with phenformin (a biguanide compound that inhibits complex 1 of the mitochondria). CAMKK inhibitor STO-609 was included in the treatment regimen since CAMKKb can compensate for LKB1 by phosphorylating AMPK on the same site (Woods et al., 2005). Interestingly, immunoprecipitation of LKB1 revealed an increase in SUMO1 modification of LKB1 as the intracellular ATP levels declined (Figures 1C and S1D). "
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    ABSTRACT: SUMOylation has been implicated in cellular stress adaptation, but its role in regulating liver kinase B1 (LKB1), a major upstream kinase of the energy sensor AMP-activated protein kinase (AMPK), is unknown. Here, we show that energy stress triggers an increase in SUMO1 modification of LKB1, despite a global reduction in both SUMO1 and SUMO2/3 conjugates. During metabolic stress, SUMO1 modification of LKB1 lysine 178 is essential in promoting its interaction with AMPK via a SUMO-interacting motif (SIM) essential for AMPK activation. The LKB1 K178R SUMO mutant had defective AMPK signaling and mitochondrial function, inducing death in energy-deprived cells. These results provide additional insight into how LKB1-AMPK signaling is regulated during energy stress, and they highlight the critical role of SUMOylation in maintaining the cell's energy equilibrium. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 07/2015; 12(5). DOI:10.1016/j.celrep.2015.07.002 · 8.36 Impact Factor
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    • "LKB1 protein, the major kinase activating AMPK, was decreased in a dose-dependent manner (Fig. 5B and C). However, it did not contradict AMPK activation because other kinases, such as CaMKKβ, may account for the activation [23]. This finding was consistent with the inhibition of neurite growth, in which LKB1 positively regulates axon formation during neuronal polarization [37]. "
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    ABSTRACT: As a widely used anti-bacterial agent and a metabolic inhibitor as well as AMP-activated protein kinase (AMPK) activator, berberine (BBR) has been shown to cross the blood-brain barrier. Its efficacy has been investigated in various disease models of the central nervous system. Neurite outgrowth is critical for nervous system development and is a highly energy-dependent process regulated by AMPK-related pathways. In the present study, we aimed to investigate the effects of BBR on AMPK activation and neurite outgrowth in neurons. The neurite outgrowth of primary rat cortical neurons at different stages of polarization was monitored after exposure of BBR. Intracellular energy level, AMPK activation and polarity-related pathways were also inspected. The results showed that BBR suppressed neurite outgrowth and affected cytoskeleton stability in the early stages of neuronal polarization, which was mediated by lowered energy status and AMPK activation. Liver kinase B1 and PI3K-Akt-GSK3β signaling pathways were also involved. In addition, mitochondrial dysfunction and endoplasmic reticulum stress contributed to the lowered energy status induced by BBR. This study highlighted the knowledge of the complex activities of BBR in neurons and corroborated the significance of energy status during the neuronal polarization. Copyright © 2015. Published by Elsevier Inc.
    Experimental Cell Research 04/2015; 334(2). DOI:10.1016/j.yexcr.2015.04.006 · 3.25 Impact Factor
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    • "The same phosphorylation could occur through a different upstream molecule, such as calcium ions that activate CaMKKb (Hawley et al., 2005; Hurley et al., 2005; Woods et al., 2005). "
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    ABSTRACT: AMP-activated protein kinase (AMPK), whose activity is a critical determinant of cell health, serves a fundamental role in integrating extracellular and intracellular nutrient information into signals that regulate various metabolic processes. Despite the importance of AMPK, its specific roles within the different intracellular spaces remain unresolved, largely due to the lack of real-time, organelle-specific AMPK activity probes. Here, we present a series of molecular tools that allows for the measurement of AMPK activity at the different subcellular localizations and that allows for the rapid induction of AMPK inhibition. We discovered that AMPKα1, not AMPKα2, was the subunit that preferentially conferred spatial specificity to AMPK, and that inhibition of AMPK activity at the mitochondria was sufficient for triggering cytosolic ATP increase. These findings suggest that genetically encoded molecular probes represent a powerful approach for revealing the basic principles of the spatiotemporal nature of AMPK regulation. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 04/2015; 12(4). DOI:10.1016/j.celrep.2015.03.057 · 8.36 Impact Factor
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