AMPK: A Key Sensor of Fuel and Energy Status in Skeletal Muscle

Physiology ◽  
2006 ◽  
Vol 21 (1) ◽  
pp. 48-60 ◽  
Author(s):  
D. Grahame Hardie ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Signaling Pathway ◽  
Recent Work ◽  
Metabolic Changes ◽  
Energy Status ◽  
Upstream Kinase ◽  
Amp Activated Protein Kinase

Contraction induces marked metabolic changes in muscle, and the AMP-activated protein kinase (AMPK) is a good candidate to explain these effects. Recent work using a muscle-specific knockout of the upstream kinase, LKB1, has confirmed that the LKB1→AMPK cascade is the signaling pathway responsible for many of these effects.

Possible involvement of the α1 isoform of 5′AMP-activated protein kinase in oxidative stress-stimulated glucose transport in skeletal muscle

2004 ◽  
Vol 287 (1) ◽  
pp. E166-E173 ◽  
Author(s):  
Taro Toyoda ◽  
Tatsuya Hayashi ◽  
Licht Miyamoto ◽  
Shin Yonemitsu ◽  
Masako Nakano ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Transport ◽  
Activation Process ◽  
Dependent Manner ◽  
Upstream Kinase ◽  
Metabolic Stresses ◽  
Amp Activated Protein Kinase

Recent studies have suggested that 5′AMP-activated protein kinase (AMPK) is activated in response to metabolic stresses, such as contraction, hypoxia, and the inhibition of oxidative phosphorylation, which leads to insulin-independent glucose transport in skeletal muscle. In the present study, we hypothesized that acute oxidative stress increases the rate of glucose transport via an AMPK-mediated mechanism. When rat epitrochlearis muscles were isolated and incubated in vitro in Krebs buffer containing the oxidative agent H2O2, AMPKα1 activity increased in a time- and dose-dependent manner, whereas AMPKα2 activity remained unchanged. The activation of AMPKα1 was associated with phosphorylation of AMPK Thr172, suggesting that an upstream kinase is involved in the activation process. H2O2-induced AMPKα1 activation was blocked in the presence of the antioxidant N-acetyl-l-cysteine (NAC), and H2O2 significantly increased the ratio of oxidized glutathione to glutathione (GSSG/GSH) concentrations, a sensitive marker of oxidative stress. H2O2 did not cause an increase in the conventional parameters of AMPK activation, such as AMP and AMP/ATP. H2O2 increased 3- O-methyl-d-glucose transport, and this increase was partially, but significantly, blocked in the presence of NAC. Results were similar when the muscles were incubated in a superoxide-generating system using hypoxanthine and xanthine oxidase. Taken together, our data suggest that acute oxidative stress activates AMPKα1 in skeletal muscle via an AMP-independent mechanism and leads to an increase in the rate of glucose transport, at least in part, via an AMPKα1-mediated mechanism.

The role of AMP-activated protein kinase in the coordination of skeletal muscle turnover and energy homeostasis

2012 ◽  
Vol 303 (5) ◽  
pp. C475-C485 ◽  
Author(s):  
Anthony M. J. Sanchez ◽  
Robin B. Candau ◽  
Alfredo Csibi ◽  
Allan F. Pagano ◽  
Audrey Raibon ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Energy Homeostasis ◽  
Therapeutic Potential ◽  
Energy Status ◽  
Muscle Plasticity ◽  
Glucose And Lipid Metabolism ◽  
Muscle Homeostasis ◽  
Amp Activated Protein Kinase

The AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase that acts as a sensor of cellular energy status switch regulating several systems including glucose and lipid metabolism. Recently, AMPK has been implicated in the control of skeletal muscle mass by decreasing mTORC1 activity and increasing protein degradation through regulation of ubiquitin-proteasome and autophagy pathways. In this review, we give an overview of the central role of AMPK in the control of skeletal muscle plasticity. We detail particularly its implication in the control of the hypertrophic and atrophic signaling pathways. In the light of these cumulative and attractive results, AMPK appears as a key player in regulating muscle homeostasis and the modulation of its activity may constitute a therapeutic potential in treating muscle wasting syndromes in humans.

scholarly journals Effects of 3-phosphoglycerate and other metabolites on the activation of AMP-activated protein kinase by LKB1-STRAD-MO25

2007 ◽  
Vol 292 (2) ◽  
pp. E400-E407 ◽  
Author(s):  
W. J. Ellingson ◽  
D. G. Chesser ◽  
W. W. Winder
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Contraction ◽  
Ampk Phosphorylation ◽  
Mouse Protein ◽  
Skeletal Muscle Contraction ◽  
Upstream Kinase ◽  
Fructose 1,6 Bisphosphate ◽  
Allosteric Mechanisms ◽  
Amp Activated Protein Kinase

Skeletal muscle contraction results in the phosphorylation and activation of the AMP-activated protein kinase (AMPK) by an upstream kinase (AMPKK). The LKB1-STE-related adaptor (STRAD)-mouse protein 25 (MO25) complex is the major AMPKK in skeletal muscle; however, LKB1-STRAD-MO25 activity is not increased by muscle contraction. This relationship suggests that phosphorylation of AMPK by LKB1-STRAD-MO25 during skeletal muscle contraction may be regulated by allosteric mechanisms. In this study, we tested an array of metabolites including, glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-bisphosphate, 3-phosphoglycerate (3-PG), glucose 1-phosphate, glucose 1,6-bisphosphate, ADP, carnitine, acetylcarnitine, IMP, inosine, and ammonia for allosteric regulation. ADP inhibited both AMPK and LKB1-STRAD-MO25 actions, but probably is not important physiologically because of the low free ADP inside the muscle fiber. We found that 3-PG stimulated LKB1-STRAD-MO25 activity and allowed for increased AMPK phosphorylation. 3-PG did not stimulate LKB1-STRAD-MO25 activity toward the peptide substrate LKB1tide. These results have identified 3-PG as an AMPK-specific regulator of AMPK phosphorylation and activation by LKB1-STRAD-MO25.

scholarly journals Evidence against regulation of AMP-activated protein kinase and LKB1/STRAD/MO25 activity by creatine phosphate

2006 ◽  
Vol 290 (4) ◽  
pp. E661-E669 ◽  
Author(s):  
Eric B. Taylor ◽  
William J. Ellingson ◽  
Jeremy D. Lamb ◽  
David G. Chesser ◽  
Cori L. Compton ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Contraction ◽  
Rat Liver ◽  
Creatine Phosphate ◽  
Energy Status ◽  
Skeletal Muscle Contraction ◽  
Ampk Activity ◽  
Allosteric Mechanisms ◽  
Amp Activated Protein Kinase

Muscle contraction results in phosphorylation and activation of the AMP-activated protein kinase (AMPK) by an AMPK kinase (AMPKK). LKB1/STRAD/MO25 (LKB1) is the major AMPKK in skeletal muscle; however, the activity of LKB1 is not increased by muscle contraction. This finding suggests that phosphorylation of AMPK by LKB1 is regulated by allosteric mechanisms. Creatine phosphate is depleted during skeletal muscle contraction to replenish ATP. Thus the concentration of creatine phosphate is an indicator of cellular energy status. A previous report found that creatine phosphate inhibits AMPK activity. The purpose of this study was to determine whether creatine phosphate would inhibit 1) phosphorylation of AMPK by LKB1 and 2) AMPK activity after phosphorylation by LKB1. We found that creatine phosphate did not inhibit phosphorylation of either recombinant or purified rat liver AMPK by LKB1. We also found that creatine phosphate did not inhibit 1) active recombinant α1β1γ1 or α2β2γ2 AMPK, 2) AMPK immunoprecipitated from rat liver extracts by either the α1 or α2 subunit, or 3) AMPK chromatographically purified from rat liver. Inhibition of skeletal muscle AMPK by creatine phosphate was greatly reduced or eliminated with increased AMPK purity. In conclusion, these results suggest that creatine phosphate is not a direct regulator of LKB1 or AMPK activity. Creatine phosphate may indirectly modulate AMPK activity by replenishing ATP at the onset of muscle contraction.

Influence of AMP-activated protein kinase and calcineurin on metabolic networks in skeletal muscle

2008 ◽  
Vol 295 (3) ◽  
pp. E545-E552 ◽  
Author(s):  
Yun Chau Long ◽  
Juleen R. Zierath
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Protein Kinase ◽  
Mitochondrial Gene ◽  
Oxidative Capacity ◽  
Substrate Utilization ◽  
Peroxisome Proliferator ◽  
Energy Status ◽  
Peroxisome Proliferator Activated Receptor ◽  
Amp Activated Protein Kinase

Skeletal muscle fibers differ considerably in their metabolic and physiological properties. Skeletal muscle displays a high degree of metabolic flexibility, which allows the myofibers to adapt to various physiological demands by shifting energy substrate utilization. Transcriptional events play a pivotal role in the metabolic adaptations of skeletal muscle. The expression of genes essential for skeletal muscle glucose and lipid metabolism is tightly coordinated in support of a shift in substrate utilization. AMP-activated protein kinase (AMPK) and calcineurin (a calcium-regulated serine/threonine protein phosphatase) regulate skeletal muscle metabolic gene expression programs in response to changes in the energy status and levels of neuronal input, respectively. AMPK and calcineurin activate transcriptional regulators such as peroxisome proliferator-activated receptor-γ coactivator-1α and myocyte enhancer factor as well as increase skeletal muscle oxidative capacity and mitochondrial gene expression. Activation of either the AMPK or calcineurin pathway can also enhance the glycogen storage capacity and insulin sensitivity in skeletal muscle. Characterization of pathways governing skeletal muscle metabolism offers insight into physiological and pharmacological strategies to prevent or ameliorate peripheral insulin resistance associated with metabolic disorders such as type 2 diabetes.

Chronic activation of AMP-activated protein kinase increases monocarboxylate transporter 2 and 4 expression in skeletal muscle

2017 ◽  
Vol 95 (8) ◽  
pp. 3552
Author(s):  
E. M. England ◽  
H. Shi ◽  
S. K. Matarneh ◽  
E. M. Oliver ◽  
E. T. Helm ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Monocarboxylate Transporter ◽  
Chronic Activation ◽  
Amp Activated Protein Kinase

scholarly journals Antidiabetic and Antihyperlipidemic Effects ofClitocybe nudaon Glucose Transporter 4 and AMP-Activated Protein Kinase Phosphorylation in High-Fat-Fed Mice

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Mei-Hsing Chen ◽  
Cheng-Hsiu Lin ◽  
Chun-Ching Shih
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Transporter ◽  
Body Weight Gain ◽  
Glucose Production ◽  
Hypolipidemic Effect ◽  
Glucose Transporter 4 ◽  
High Fat ◽  
Hepatic Expression ◽  
Amp Activated Protein Kinase

The objective of this study was to evaluate the antihyperlipidemic and antihyperglycemic effects and mechanism of the extract ofClitocybe nuda(CNE), in high-fat- (HF-) fed mice. C57BL/6J was randomly divided into two groups: the control (CON) group was fed with a low-fat diet, whereas the experimental group was fed with a HF diet for 8 weeks. Then, the HF group was subdivided into five groups and was given orally CNE (including C1: 0.2, C2: 0.5, and C3: 1.0 g/kg/day extracts) or rosiglitazone (Rosi) or vehicle for 4 weeks. CNE effectively prevented HF-diet-induced increases in the levels of blood glucose, triglyceride, insulin (P<0.001,P<0.01,P<0.05, resp.) and attenuated insulin resistance. By treatment with CNE, body weight gain, weights of white adipose tissue (WAT) and hepatic triacylglycerol content were reduced; moreover, adipocytes in the visceral depots showed a reduction in size. By treatment with CNE, the protein contents of glucose transporter 4 (GLUT4) were significantly increased in C3-treated group in the skeletal muscle. Furthermore, CNE reduces the hepatic expression of glucose-6-phosphatase (G6Pase) and glucose production. CNE significantly increases protein contents of phospho-AMP-activated protein kinase (AMPK) in the skeletal muscle and adipose and liver tissues. Therefore, it is possible that the activation of AMPK by CNE leads to diminished gluconeogenesis in the liver and enhanced glucose uptake in skeletal muscle. It is shown that CNE exhibits hypolipidemic effect in HF-fed mice by increasing ATGL expression, which is known to help triglyceride to hydrolyze. Moreover, antidiabetic properties of CNE occurred as a result of decreased hepatic glucose production via G6Pase downregulation and improved insulin sensitization. Thus, amelioration of diabetic and dyslipidemic states by CNE in HF-fed mice occurred by regulation of GLUT4, G6Pase, ATGL, and AMPK phosphorylation.

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