scholarly journals AMPK directly inhibits NDPK through a phosphoserine switch to maintain cellular homeostasis

2012 ◽  
Vol 23 (2) ◽  
pp. 381-389 ◽  
Author(s):  
Rob U. Onyenwoke ◽  
Lawrence J. Forsberg ◽  
Lucy Liu ◽  
Tyisha Williams ◽  
Oscar Alzate ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Phosphorylation Site ◽  
Nucleoside Diphosphate Kinase ◽  
Ampk Activation ◽  
Cellular Energy ◽  
Energy Sensor ◽  
Energy Deprivation ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is a key energy sensor that regulates metabolism to maintain cellular energy balance. AMPK activation has also been proposed to mimic benefits of caloric restriction and exercise. Therefore, identifying downstream AMPK targets could elucidate new mechanisms for maintaining cellular energy homeostasis. We identified the phosphotransferase nucleoside diphosphate kinase (NDPK), which maintains pools of nucleotides, as a direct AMPK target through the use of two-dimensional differential in-gel electrophoresis. Furthermore, we mapped the AMPK/NDPK phosphorylation site (serine 120) as a functionally potent enzymatic “off switch” both in vivo and in vitro. Because ATP is usually the most abundant cellular nucleotide, NDPK would normally consume ATP, whereas AMPK would inhibit NDPK to conserve energy. It is intriguing that serine 120 is mutated in advanced neuroblastoma, which suggests a mechanism by which NDPK in neuroblastoma can no longer be inhibited by AMPK-mediated phosphorylation. This novel placement of AMPK upstream and directly regulating NDPK activity has widespread implications for cellular energy/nucleotide balance, and we demonstrate in vivo that increased NDPK activity leads to susceptibility to energy deprivation–induced death.

scholarly journals Activation of AMPK under Hypoxia: Many Roads Leading to Rome

2020 ◽  
Vol 21 (7) ◽  
pp. 2428 ◽  
Author(s):  
Franziska Dengler
Keyword(s):  
Current Knowledge ◽  
Protective Action ◽  
Energy Levels ◽  
Hypoxia Inducible Factor ◽  
Protective Effects ◽  
Ampk Activation ◽  
Cellular Energy ◽  
Energy Sensor ◽  
Atp Supply ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is known as a pivotal cellular energy sensor, mediating the adaptation to low energy levels by deactivating anabolic processes and activating catabolic processes in order to restore the cellular ATP supply when the cellular AMP/ATP ratio is increased. Besides this well-known role, it has also been shown to exert protective effects under hypoxia. While an insufficient supply with oxygen might easily deplete cellular energy levels, i.e., ATP concentration, manifold other mechanisms have been suggested and are heavily disputed regarding the activation of AMPK under hypoxia independently from cellular AMP concentrations. However, an activation of AMPK preceding energy depletion could induce a timely adaptation reaction preventing more serious damage. A connection between AMPK and the master regulator of hypoxic adaptation via gene transcription, hypoxia-inducible factor (HIF), has also been taken into account, orchestrating their concerted protective action. This review will summarize the current knowledge on mechanisms of AMPK activation under hypoxia and its interrelationship with HIF.

scholarly journals Dissecting the Role of 5′-AMP for Allosteric Stimulation, Activation, and Deactivation of AMP-activated Protein Kinase

2006 ◽  
Vol 281 (43) ◽  
pp. 32207-32216 ◽  
Author(s):  
Marianne Suter ◽  
Uwe Riek ◽  
Roland Tuerk ◽  
Uwe Schlattner ◽  
Theo Wallimann ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Phosphatase ◽  
Energy Homeostasis ◽  
Adenine Nucleotides ◽  
Enzyme Preparations ◽  
Activity Measurements ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is a heterotrimeric protein kinase that is crucial for cellular energy homeostasis of eukaryotic cells and organisms. Here we report on the activation of AMPK α1β1γ1 and α2β2γ1 by their upstream kinases (Ca2+/calmodulin-dependent protein kinase kinase-β and LKB1-MO25α-STRADα), the deactivation by protein phosphatase 2Cα, and on the extent of stimulation of AMPK by its allosteric activator AMP, using purified recombinant enzyme preparations. An accurate high pressure liquid chromatography-based method for AMPK activity measurements was established, which allowed for direct quantitation of the unphosphorylated and phosphorylated artificial peptide substrate, as well as the adenine nucleotides. Our results show a 1000-fold activation of AMPK by the combined effects of upstream kinase and saturating concentrations of AMP. The two AMPK isoforms exhibit similar specific activities (6 μmol/min/mg) and do not differ significantly by their responsiveness to AMP. Due to the inherent instability of ATP and ADP, it proved impossible to assay AMPK activity in the absolute absence of AMP. However, the half-maximal stimulatory effect of AMP is reached below 2 μm. AMP does not appear to augment phosphorylation by upstream kinases in the purified in vitro system, but deactivation by dephosphorylation of AMPK α-subunits at Thr-172 by protein phosphatase 2Cα is attenuated by AMP. Furthermore, it is shown that neither purified NAD+ nor NADH alters the activity of AMPK in a concentration range of 0–300 μm, respectively. Finally, evidence is provided that ZMP, a compound formed in 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside-treated cells to activate AMPK in vivo, allosterically activates purified AMPK in vitro, but compared with AMP, maximal activity is not reached. These data shed new light on physiologically important aspects of AMPK regulation.

scholarly journals Regulation of the energy sensor AMP-activated protein kinase by antigen receptor and Ca2+ in T lymphocytes

2006 ◽  
Vol 203 (7) ◽  
pp. 1665-1670 ◽  
Author(s):  
Peter Tamás ◽  
Simon A. Hawley ◽  
Rosemary G. Clarke ◽  
Kirsty J. Mustard ◽  
Kevin Green ◽  
...  
Keyword(s):  
Protein Kinase ◽  
T Lymphocytes ◽  
Energy Homeostasis ◽  
Antigen Receptor ◽  
Adenosine Monophosphate ◽  
Ampk Activation ◽  
Serine Kinase ◽  
Cellular Energy ◽  
Amp Activated Protein Kinase ◽  
Stimulation Of

The adenosine monophosphate (AMP)–activated protein kinase (AMPK) has a crucial role in maintaining cellular energy homeostasis. This study shows that human and mouse T lymphocytes express AMPKα1 and that this is rapidly activated in response to triggering of the T cell antigen receptor (TCR). TCR stimulation of AMPK was dependent on the adaptors LAT and SLP76 and could be mimicked by the elevation of intracellular Ca2+ with Ca2+ ionophores or thapsigargin. AMPK activation was also induced by energy stress and depletion of cellular adenosine triphosphate (ATP). However, TCR and Ca2+ stimulation of AMPK required the activity of Ca2+–calmodulin-dependent protein kinase kinases (CaMKKs), whereas AMPK activation induced by increased AMP/ATP ratios did not. These experiments reveal two distinct pathways for the regulation of AMPK in T lymphocytes. The role of AMPK is to promote ATP conservation and production. The rapid activation of AMPK in response to Ca2+ signaling in T lymphocytes thus reveals that TCR triggering is linked to an evolutionally conserved serine kinase that regulates energy metabolism. Moreover, AMPK does not just react to cellular energy depletion but also anticipates it.

scholarly journals Effects of AMP-Activated Protein Kinase in Cerebral Ischemia

2009 ◽  
Vol 30 (3) ◽  
pp. 480-492 ◽  
Author(s):  
Jun Li ◽  
Louise D McCullough
Keyword(s):  
Protein Kinase ◽  
In Vivo Studies ◽  
Ampk Activation ◽  
Vigorous Exercise ◽  
Nitric Oxide Signaling ◽  
Reductase Inhibitors ◽  
Amp Activated Protein Kinase ◽  
The Brain

AMP-activated protein kinase (AMPK) is a serine threonine kinase that is highly conserved through evolution. AMPK is found in most mammalian tissues including the brain. As a key metabolic and stress sensor/effector, AMPK is activated under conditions of nutrient deprivation, vigorous exercise, or heat shock. However, it is becoming increasingly recognized that changes in AMPK activation not only signal unmet metabolic needs, but also are involved in sensing and responding to ‘cell stress’, including ischemia. The downstream effect of AMPK activation is dependent on many factors, including the severity of the stressor as well as the tissue examined. This review discusses recent in vitro and in vivo studies performed in the brain/neuronal cells and vasculature that have contributed to our understanding of AMPK in stroke. Recent data on the potential role of AMPK in angiogenesis and neurogenesis and the interaction of AMPK with 3-hydroxy-3-methy-glutaryl-CoA reductase inhibitors (statins) agents are highlighted. The interaction between AMPK and nitric oxide signaling is also discussed.

scholarly journals ANTI-DIABETIC EFFECTS OF GLUCOMANNO-OLIGOSACCHARIDES VIA AMPK ACTIVATION IN C2C12 MYOTUBES

2021 ◽  
Vol 59 (4) ◽  
pp. 467
Author(s):  
Thien Truong Do ◽  
Nu Thi Tran ◽  
Que Nguyet Thi Do ◽  
Nhi Thi Y Tran
Keyword(s):  
C2c12 Myotubes ◽  
Control Group ◽  
Ampk Activation ◽  
Independent Manner ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Ampk Phosphorylation ◽  
Amp Activated Protein Kinase

Abstract-HCTN7. In this paper, antidiabetic activities of glucomanno-oligosaccharides (GMO) in vitro and in vivo were investigated. GMO significantly increased AMP-activated protein kinase (AMPK) phosphorylation in a concentration-independent manner. Treatment with 100μg/ml and 50μg/ml of GMO for 1 hour caused 1.47-fold and 1.81-fold phosphorylation of AMPK, respectively. Oral administration of GMO (6g/kg-1 of body weight day-1) lowered blood glucose levels (p < 0.05) at 120 min as compared to control group. These results suggested that GMO exhibited anti-diabetic effects via activation of AMPK and could be useful for diabetes prevention

scholarly journals Modulation of Renal Injury by Variable Expression of Myo-Inositol Oxygenase (MIOX) via Perturbation in Metabolic Sensors

Biomedicines ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 217
Author(s):  
Isha Sharma ◽  
Fei Deng ◽  
Yashpal S. Kanwar
Keyword(s):  
Renal Injury ◽  
Energy Homeostasis ◽  
Chronic Renal Disease ◽  
Mitochondrial Dynamics ◽  
Peroxisome Proliferator ◽  
Tubular Injury ◽  
Variable Expression ◽  
Cellular Energy

Obesity is associated with perturbations in cellular energy homeostasis and consequential renal injury leading to chronic renal disease (CKD). Myo-inositol oxygenase (MIOX), a tubular enzyme, alters redox balance and subsequent tubular injury in the settings of obesity. Mechanism(s) for such adverse changes remain enigmatic. Conceivably, MIOX accentuates renal injury via reducing expression/activity of metabolic sensors, which perturb mitochondrial dynamics and, if sustained, would ultimately contribute towards CKD. In this brief communication, we utilized MIOX-TG (Transgenic) and MIOXKO mice, and subjected them to high fat diet (HFD) administration. In addition, ob/ob and ob/MIOXKO mice of comparable age were used. Mice fed with HFD had increased MIOX expression and remarkable derangements in tubular injury biomarkers. Decreased expression of p-AMPKα (phospho AMP-activated protein kinase) in the tubules was also observed, and it was accentuated in MIOX-TG mice. Interestingly, ob/ob mice also had decreased p-AMPKα expression, which was restored in ob/MIOXKO mice. Parallel changes were observed in Sirt1/Sirt3 (silent mating type information regulation 2 homolog), and expression of other metabolic sensors, i.e., PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator 1-alpha) and Yin Yang (YY-1). In vitro experiments with tubular cells subjected to palmitate-BSA and MIOX-siRNA had results in conformity with the in vivo observations. These findings link the biology of metabolic sensors to MIOX expression in impaired cellular energy homeostasis with exacerbation/amelioration of renal injury.

scholarly journals A novel physical and functional association between nucleoside diphosphate kinase A and AMP-activated protein kinase α1 in liver and lung

2005 ◽  
Vol 392 (1) ◽  
pp. 201-209 ◽  
Author(s):  
Russell M. Crawford ◽  
Kate J. Treharne ◽  
O. Giles Best ◽  
Richmond Muimo ◽  
Claudia E. Riemen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Mammalian Cells ◽  
Nucleoside Diphosphate Kinase ◽  
Cell Types ◽  
Acid Synthesis ◽  
Cellular Fatty Acid ◽  
Energy Status ◽  
Amp Activated Protein Kinase

Nucleoside diphosphate kinase (NDPK, NM23/awd) belongs to a multifunctional family of highly conserved proteins (∼16–20 kDa) containing two well-characterized isoforms (NM23-H1 and -H2; also known as NDPK A and B). NDPK catalyses the conversion of nucleoside diphosphates into nucleoside triphosphates, regulates a diverse array of cellular events and can act as a protein histidine kinase. AMPK (AMP-activated protein kinase) is a heterotrimeric protein complex that responds to cellular energy status by switching off ATP-consuming pathways and switching on ATP-generating pathways when ATP is limiting. AMPK was first discovered as an activity that inhibited preparations of ACC1 (acetyl-CoA carboxylase), a regulator of cellular fatty acid synthesis. We report that NM23-H1/NDPK A and AMPK α1 are associated in cytosol from two different tissue sources: rat liver and a human lung cell line (Calu-3). Co-immunoprecipitation and binding assay data from both cell types show that the H1/A (but not H2/B) isoform of NDPK is associated with AMPK complexes containing the α1 (but not α2) catalytic subunit. Manipulation of NM23-H1/NDPK A nucleotide transphosphorylation activity to generate ATP (but not GTP) enhances the activity of AMPK towards its specific peptide substrate in vitro and also regulates the phosphorylation of ACC1, an in vivo target for AMPK. Thus novel NM23-H1/NDPK A-dependent regulation of AMPK α1-mediated phosphorylation is present in mammalian cells.

AMP kinase (PRKAA1)

2014 ◽  
Vol 67 (9) ◽  
pp. 758-763 ◽  
Author(s):  
Sukriti Krishan ◽  
Des R Richardson ◽  
Sumit Sahni
Keyword(s):  
Energy Homeostasis ◽  
Atp Synthesis ◽  
Cellular Growth ◽  
Α Subunit ◽  
Cellular Energy ◽  
Therapeutic Drugs ◽  
Energy Sensor ◽  
Energy Consuming ◽  
Cardiac Disorders ◽  
Amp Activated Protein Kinase

The PRKAA1 gene encodes the catalytic α-subunit of 5′ AMP-activated protein kinase (AMPK). AMPK is a cellular energy sensor that maintains energy homeostasis within the cell and is activated when the AMP/ATP ratio increases. When activated, AMPK increases catabolic processes that increase ATP synthesis and inhibit anabolic processes that require ATP. Additionally, AMPK also plays a role in activating autophagy and inhibiting energy consuming processes, such as cellular growth and proliferation. Due to its role in energy metabolism, it could act as a potential target of many therapeutic drugs that could be useful in the treatment of several diseases, for example, diabetes. Moreover, AMPK has been shown to be involved in inhibiting tumour growth and metastasis, and has also been implicated in the pathology of neurodegenerative and cardiac disorders. Hence, a better understanding of AMPK and its role in various pathological conditions could enable the development of strategies to use it as a therapeutic target.

scholarly journals Development of hepatic fibrosis occurs normally in AMPK-deficient mice

2009 ◽  
Vol 118 (6) ◽  
pp. 411-420 ◽  
Author(s):  
Alain Da Silva Morais ◽  
Jorge Abarca-Quinones ◽  
Bruno Guigas ◽  
Benoit Viollet ◽  
Peter Stärkel ◽  
...  
Keyword(s):  
Liver Fibrosis ◽  
Hepatic Fibrosis ◽  
In Vitro Studies ◽  
Cellular Energy ◽  
Wound Healing Response ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase ◽  
Deficient Mice

Inhibition or blockade of HSCs (hepatic stellate cells), the main matrix-producing cells involved in the wound-healing response, represents an attractive strategy for the treatment of liver fibrosis. In vitro studies have shown that activation of AMPK (AMP-activated protein kinase), a key player in the regulation of cellular energy homoeostasis, inhibits proliferation of myofibroblasts derived from HSCs. If AMPK is a true regulator of fibrogenesis then defective AMPK activity would enhance fibrogenesis and hepatic fibrosis. To test this, in the present work, in vitro studies were performed on mouse primary HSCs treated or not with the AMPK activator AICAR (5-amino-4-imidazolecarboxamide ribonucleotide) or isolated from mice lacking the AMPKα1 catalytic subunit (AMPKα1−/−) or their littermates (AMPKα1+/+). Liver fibrosis was induced in vivo in AMPKα1−/− and AMPKα1+/+ mice by repeated injections of CCl4 (carbon tetrachloride). During culture activation of HSCs, AMPK protein and activity significantly increased and regulatory AMPKγ3 mRNA was specifically up-regulated. Stimulation of AMPK activity by AICAR inhibited HSC proliferation, as expected, as well as collagen α1(I) expression. Importantly, AMPKα1 deletion inhibited proliferation of HSCs, but not fibrogenesis, in vivo. Moreover, AMPKα1 deletion was not associated with enhanced CCl4-induced fibrosis in vivo. In conclusion, our present findings demonstrate that HSC transdifferentiation is associated with increased AMPK activity that could relate to the stabilization of AMPK complex by the γ3 subunits. Activation of AMPK in HSCs inhibits in vitro fibrogenesis. By contrast, low AMPK activity does not prevent HSC activation in vitro nor in in vivo fibrosis.

scholarly journals Tumor protein D52 (TPD52) affects cancer cell metabolism by negatively regulating AMPK

2021 ◽  
Author(s):  
Yali Chen ◽  
Changmin Peng ◽  
Wei Tan ◽  
Jia Yu ◽  
Jacqueline Zayas ◽  
...  
Keyword(s):  
Energy Homeostasis ◽  
Kinase Activity ◽  
Cell Metabolism ◽  
Stable Complex ◽  
Metabolic Defects ◽  
Energy Stress ◽  
Cancer Cell Metabolism ◽  
Amp Activated Protein Kinase

AbstractThe AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, with deregulation leading to cancer and other diseases. When intracellular ATP levels decrease during energy stress, AMPK is phosphorylated and activated through AMP binding. However, how this pathway is dysregulated in cancer remains unclear. Here, we find that tumor protein D52 (TPD52), initially identified to be overexpressed in many human cancers, forms a stable complex with AMPK in cancer cells. TPD52 directly interacts with AMPKα and inhibits AMPKα kinase activity in vitro and in vivo. We generated TPD52 transgenic mice, and found that overexpression of TPD52 leads to AMPK inhibition and multiple metabolic defects in mice. Together, our results shed new light on AMPK regulation and on our understanding of the etiology of cancers with TPD52 overexpression.

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