PIKfyve: a new fish in the growing pool of AMPK substrates

2013 ◽  
Vol 455 (2) ◽  
pp. e1-e3
Author(s):  
James S. V. Lally ◽  
Gregory R. Steinberg
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Muscle Contractions ◽  
Whole Body ◽  
Glucose Homoeostasis ◽  
Increase Glucose Uptake ◽  
Biochemical Journal ◽  
Complex Events ◽  
Amp Activated Protein Kinase

Skeletal muscle is critical for whole-body glucose homoeostasis. Insulin and muscle contractions induced by exercise can increase glucose uptake through distinct intracellular signalling pathways involving PKB (protein kinase B)/Akt and AMPK (AMP-activated protein kinase) respectively. Whereas the proximal events governing these processes are becoming well understood, less is known about the regulation of the complex events necessary for the control of glucose uptake at the plasma membrane. In recent years, a number of common targets of AMPK and PKB/Akt have emerged as important components controlling glucose uptake, but the necessary phosphorylation events required for the control of glucose uptake have remained more elusive. In the current issue of the Biochemical Journal, Liu et al. identify that PIKfyve, a phosphoinositide phosphate kinase, is required for contraction-stimulated glucose uptake. They demonstrate that AMPK directly phosphorylates PIKfyve at Ser307, the same site as PKB/Akt, and that phosphorylation is increased in response to muscle contractions. These data provide compelling evidence for a new AMPK substrate that converges with PKB/Akt signalling and may be critical for the control of glucose uptake in skeletal muscle.

AMP-activated protein kinase activity and glucose uptake in rat skeletal muscle

2001 ◽  
Vol 280 (5) ◽  
pp. E677-E684 ◽  
Author(s):  
Nicolas Musi ◽  
Tatsuya Hayashi ◽  
Nobuharu Fujii ◽  
Michael F. Hirshman ◽  
Lee A. Witters ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Muscle Contractions ◽  
Treadmill Running ◽  
Dependent Manner ◽  
Rat Skeletal Muscle ◽  
Amp Activated Protein Kinase ◽  
Dose Dependent

The AMP-activated protein kinase (AMPK) has been hypothesized to mediate contraction and 5-aminoimidazole-4-carboxamide 1-β-d-ribonucleoside (AICAR)-induced increases in glucose uptake in skeletal muscle. The purpose of the current study was to determine whether treadmill exercise and isolated muscle contractions in rat skeletal muscle increase the activity of the AMPKα1 and AMPKα2 catalytic subunits in a dose-dependent manner and to evaluate the effects of the putative AMPK inhibitors adenine 9-β-d-arabinofuranoside (ara-A), 8-bromo-AMP, and iodotubercidin on AMPK activity and 3- O-methyl-d-glucose (3-MG) uptake. There were dose-dependent increases in AMPKα2 activity and 3-MG uptake in rat epitrochlearis muscles with treadmill running exercise but no effect of exercise on AMPKα1 activity. Tetanic contractions of isolated epitrochlearis muscles in vitro significantly increased the activity of both AMPK isoforms in a dose-dependent manner and at a similar rate compared with increases in 3-MG uptake. In isolated muscles, the putative AMPK inhibitors ara-A, 8-bromo-AMP, and iodotubercidin fully inhibited AICAR-stimulated AMPKα2 activity and 3-MG uptake but had little effect on AMPKα1 activity. In contrast, these compounds had absent or minimal effects on contraction-stimulated AMPKα1 and -α2 activity and 3-MG uptake. Although the AMPKα1 and -α2 isoforms are activated during tetanic muscle contractions in vitro, in fast-glycolytic fibers, the activation of AMPKα2-containing complexes may be more important in regulating exercise-mediated skeletal muscle metabolism in vivo. Development of new compounds will be required to study contraction regulation of AMPK by pharmacological inhibition.

Exercise and MEF2–HDAC interactions

2007 ◽  
Vol 32 (5) ◽  
pp. 852-856 ◽  
Author(s):  
Sean L. McGee
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Nuclear Export ◽  
Energy Homeostasis ◽  
Whole Body ◽  
Positive Health ◽  
Exercise Induced ◽  
Amp Activated Protein Kinase ◽  
Body Energy ◽  
Skeletal Muscle Adaptations

Exercise increases the metabolic capacity of skeletal muscle, which improves whole-body energy homeostasis and contributes to the positive health benefits of exercise. This is, in part, mediated by increases in the expression of a number of metabolic enzymes, regulated largely at the level of transcription. At a molecular level, many of these genes are regulated by the class II histone deacetylase (HDAC) family of transcriptional repressors, in particular HDAC5, through their interaction with myocyte enhancer factor 2 transcription factors. HDAC5 kinases, including 5′-AMP-activated protein kinase and protein kinase D, appear to regulate skeletal muscle metabolic gene transcription by inactivating HDAC5 and inducing HDAC5 nuclear export. These mechanisms appear to participate in exercise-induced gene expression and could be important for skeletal muscle adaptations to exercise.

AICA riboside increases AMP-activated protein kinase, fatty acid oxidation, and glucose uptake in rat muscle

1997 ◽  
Vol 273 (6) ◽  
pp. E1107-E1112 ◽  
Author(s):  
G. F. Merrill ◽  
E. J. Kurth ◽  
D. G. Hardie ◽  
W. W. Winder
Keyword(s):  
Skeletal Muscle ◽  
Fatty Acid ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Fatty Acid Oxidation ◽  
Fold Increase ◽  
Acid Oxidation ◽  
Acetyl Coa Carboxylase ◽  
Malonyl Coa ◽  
Amp Activated Protein Kinase

5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) has previously been reported to be taken up into cells and phosphorylated to form ZMP, an analog of 5′-AMP. This study was designed to determine whether AICAR can activate AMP-activated protein kinase (AMPK) in skeletal muscle with consequent phosphorylation of acetyl-CoA carboxylase (ACC), decrease in malonyl-CoA, and increase in fatty acid oxidation. Rat hindlimbs were perfused with Krebs-Henseleit bicarbonate containing 4% bovine serum albumin, washed bovine red blood cells, 200 μU/ml insulin, and 10 mM glucose with or without AICAR (0.5–2.0 mM). Perfusion with medium containing AICAR was found to activate AMPK in skeletal muscle, inactivate ACC, and decrease malonyl-CoA. Hindlimbs perfused with 2 mM AICAR for 45 min exhibited a 2.8-fold increase in fatty acid oxidation and a significant increase in glucose uptake. No difference was observed in oxygen uptake in AICAR vs. control hindlimb. These results provide evidence that decreases in muscle content of malonyl-CoA can increase the rate of fatty acid oxidation.

Muscle-specific overexpression of wild type and R225Q mutant AMP-activated protein kinase γ3-subunit differentially regulates glycogen accumulation

2006 ◽  
Vol 291 (3) ◽  
pp. E557-E565 ◽  
Author(s):  
Haiyan Yu ◽  
Michael F. Hirshman ◽  
Nobuharu Fujii ◽  
Jason M. Pomerleau ◽  
Lauren E. Peter ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Glycogen Content ◽  
Specific Activity ◽  
Glycogen Synthase ◽  
Underlying Mechanism ◽  
Wild Type ◽  
Glycogen Accumulation ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is a heterotrimeric complex that works as an energy sensor to integrate nutritional and hormonal signals. The naturally occurring R225Q mutation in the γ3-subunit in pigs is associated with abnormally high glycogen content in skeletal muscle. Becauses skeletal muscle accounts for most of the body's glucose uptake, and γ3 is specifically expressed in skeletal muscle, it is important to understand the underlying mechanism of this mutation in regulating glucose and glycogen metabolism. Using skeletal muscle-specific transgenic mice overexpressing wild type γ3 (WTγ3) and R225Q mutant γ3 (MUTγ3), we show that both WTγ3 and MUTγ3 mice have 1.5- to 2-fold increases in muscle glycogen content. In WTγ3 mice, increased glycogen content was associated with elevated total glycogen synthase activity and reduced glycogen phosphorylase activity, whereas alterations in activities of these enzymes could not explain elevated glycogen in MUTγ3 mice. Basal, 5-aminoimidazole- AICAR- and phenformin-stimulated AMPKα2 isoform-specific activities were decreased only in MUTγ3 mice. Basal rates of 2-DG glucose uptake were decreased in both WTγ3 and MUTγ3 mice. However, AICAR- and phenformin-stimulated 2-DG glucose uptake were blunted only in MUTγ3 mice. In conclusion, expression of either wild type or mutant γ3-subunit of AMPK results in increased glycogen concentrations in muscle, but the mechanisms underlying this alteration appear to be different. Furthermore, mutation of the γ3-subunit is associated with decreases in AMPKα2 isoform-specific activity and impairment in AICAR- and phenformin-stimulated skeletal muscle glucose uptake.

Characterization of the role of the AMP-activated protein kinase in the stimulation of glucose transport in skeletal muscle cells

2002 ◽  
Vol 363 (1) ◽  
pp. 167-174 ◽  
Author(s):  
Lee G.D. FRYER ◽  
Fabienne FOUFELLE ◽  
Kay BARNES ◽  
Stephen A. BALDWIN ◽  
Angela WOODS ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Transport ◽  
Phorbol Ester ◽  
Hyperosmotic Stress ◽  
Amp Activated Protein Kinase ◽  
Stimulation Of ◽  
Constitutively Active

Stimulation of AMP-activated protein kinase (AMPK) in skeletal muscle has been correlated with an increase in glucose transport. Here, we demonstrate that adenoviral-mediated expression of a constitutively active mutant of AMPKα leads to activation of glucose transport in a skeletal-muscle cell line, similar to that seen following treatment with 5-amino-imidazolecarboxamide (AICA) riboside, hyperosmotic stress or insulin. In contrast, expression of a dominant-negative form of AMPK blocked the stimulation of glucose transport by both AICA riboside and hyperosmotic stress, but was without effect on either insulin or phorbol-ester-stimulated transport. These results demonstrate that activation of AMPK is sufficient for stimulation of glucose uptake into muscle cells, and is a necessary component of the AICA riboside- and hyperosmotic-stress-induced pathway leading to increased glucose uptake. On the other hand, AMPK is not required in the insulin- or phorbol-ester-mediated pathways. Long-term (5 days) expression of the constitutively active AMPK mutant increased protein expression of GLUT1, GLUT4 and hexokinase II, consistent with previous reports on the chronic treatment of rats with AICA riboside. Expression of constitutively active AMPK had no detectable effect on p38 mitogen-activated protein kinase levels, although interestingly the level of protein kinase B was decreased. These results demonstrate that long-term activation of AMPK is sufficient to cause increased expression of specific proteins in muscle. Our results add further support to the hypothesis that long-term activation of AMPK is involved in the adaptive response of muscle to exercise training.

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