AMP-activated protein kinase activates transcription  of the UCP3 and HKII genes in rat skeletal muscle

AMP-activated protein kinase (AMPK) has recently emerged as a key signaling protein in skeletal muscle, coordinating the activation of both glucose and fatty acid metabolism in response to increased cellular energy demand. To determine whether AMPK signaling may also regulate gene transcription in muscle, rats were given a single subcutaneous injection (1 mg/g) of the AMP analog 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR). AICAR injection activated ( P < 0.05) AMPK-α2 (∼2.5-fold) and transcription of the uncoupling protein-3 (UCP3, ∼4-fold) and hexokinase II (HKII, ∼10-fold) genes in both red and white skeletal muscle. However, AICAR injection also elicited ( P < 0.05) an acute drop (60%) in blood glucose and a sustained (2-h) increase in blood lactate, prompting concern regarding the specificity of AICAR on transcription. To maximize AMPK activation in muscle while minimizing potential systemic counterregulatory responses, a single-leg arterial infusion technique was employed in fully conscious rats. Relative to saline-infused controls, single-leg arterial infusion of AICAR (0.125, 0.5, and 2.5 μg · g−1 · min−1for 60 min) induced a dose-dependent increase (2- to 4-fold, P < 0.05) in UCP3 and HKII transcription in both red and white skeletal muscle. Importantly, AICAR infusion activated transcription only in muscle from the infused leg and had no effect on blood glucose or lactate levels. These data provide evidence that AMPK signaling is linked to the transcriptional regulation of select metabolic genes in skeletal muscle.

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Expression of Uncoupling Protein 3 and GLUT4 Gene in Skeletal Muscle of Preterm Newborns: Possible Control by AMP-Activated Protein Kinase

Pediatric Research ◽

10.1203/01.pdr.0000242301.64555.e2 ◽

2006 ◽

Vol 60 (5) ◽

pp. 569-575 ◽

Cited By ~ 8

Author(s):

Petr Brauner ◽

Pavel Kopecky ◽

Pavel Flachs ◽

Ondrej Kuda ◽

Jaroslav Vorlicek ◽

...

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Uncoupling Protein ◽

Uncoupling Protein 3 ◽

Amp Activated Protein Kinase ◽

Preterm Newborns

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Sex Differences in the Metabolic Effects of Testosterone in Sheep

Endocrinology ◽

10.1210/en.2011-1634 ◽

2012 ◽

Vol 153 (1) ◽

pp. 123-131 ◽

Cited By ~ 19

Author(s):

Scott D. Clarke ◽

Iain J. Clarke ◽

Alexandra Rao ◽

Michael A. Cowley ◽

Belinda A. Henry

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Uncoupling Protein ◽

Specific Effect ◽

Metabolic Effects ◽

Mrna Levels ◽

Nonesterified Fatty Acids ◽

Glucose Levels ◽

Amp Activated Protein Kinase ◽

The Brain

Adiposity is regulated in a sexually divergent manner. This is partly due to sex steroids, but the differential effects of androgens in males and females are unclear. We investigated effects of testosterone on energy balance in castrated male (n = 6) and female sheep (n = 4), which received 3 × 200 mg testosterone implants for 2 wk or blank implants (controls). Temperature probes were implanted into retroperitoneal fat and skeletal muscle. Blood samples were taken to measure metabolites and insulin. In males, muscle and fat biopsies were collected to measure uncoupling protein (UCP) mRNA and phosphorylation of AMP-activated protein kinase and Akt. Testosterone did not change food intake in either sex. Temperature in muscle was higher in males than females, and testosterone reduced heat production in males only. In fat, however, temperature was higher in the castrate males compared with females, and there was no effect of testosterone treatment in either sex. Preprandial glucose levels were lower, but nonesterified fatty acids were higher in females compared with males, irrespective of testosterone. In males, the onset of feeding increased UCP1 and UCP3 mRNA levels in skeletal muscle, without an effect of testosterone. During feeding, testosterone reduced glucose levels in males only but did not alter the phosphorylation of AMP-activated protein kinase or Akt in muscle. Thus, testosterone maintains lower muscle and fat temperatures in males but not females. The mechanism underlying this sex-specific effect of testosterone is unknown but may be due to sexual differentiation of the brain centers controlling energy expenditure.

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AMP-activated protein kinase phosphorylates transcription factors of the CREB family

Journal of Applied Physiology ◽

10.1152/japplphysiol.00900.2007 ◽

2008 ◽

Vol 104 (2) ◽

pp. 429-438 ◽

Cited By ~ 117

Author(s):

D. M. Thomson ◽

S. T. Herway ◽

N. Fillmore ◽

H. Kim ◽

J. D. Brown ◽

...

Keyword(s):

Skeletal Muscle ◽

Transcription Factors ◽

Protein Kinase ◽

Time Course ◽

Luciferase Reporter ◽

Hexokinase Ii ◽

Camp Response Element ◽

Response Element ◽

Compound C ◽

Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) has been identified as a regulator of gene transcription, increasing mitochondrial proteins of oxidative metabolism as well as hexokinase expression in skeletal muscle. In mice, muscle-specific knockout of LKB1, a component of the upstream kinase of AMPK, prevents contraction- and 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR)-induced activation of AMPK in skeletal muscle, and the increase in hexokinase II protein that is normally observed with chronic AICAR activation of AMPK. Since previous reports show a cAMP response element in the promoter region of the hexokinase II gene, we hypothesized that the cAMP-response element (CRE) binding protein (CREB) family of transcription factors could be targets of AMPK. Using radioisotopic kinase assays, we found that recombinant and rat liver and muscle AMPK phosphorylated CREB1 at the same site as cAMP-dependent protein kinase (PKA). AMPK was also found to phosphorylate activating transcription factor 1 (ATF1), CRE modulator (CREM), and CREB-like 2 (CREBL2), but not ATF2. Treatment of HEK-293 cells stably transfected with a CREB-driven luciferase reporter with AICAR increased luciferase activity approximately threefold over a 24-h time course. This increase was blocked with compound C, an AMPK inhibitor. In addition, AICAR-induced activation of AMPK in incubated rat epitrochlearis muscles resulted in an increase in both phospho-acetyl-CoA carboxylase and phospho-CREB. We conclude that CREB and related proteins are direct downstream targets for AMPK and are therefore likely involved in mediating some effects of AMPK on expression of genes having a CRE in their promoters.

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The many ways to regulate glucose transporter 4This paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

Applied Physiology Nutrition and Metabolism ◽

10.1139/h09-047 ◽

2009 ◽

Vol 34 (3) ◽

pp. 481-487 ◽

Cited By ~ 74

Author(s):

Amira Klip

Keyword(s):

Protein Kinase ◽

Glucose Uptake ◽

Energy Demand ◽

Glucose Transporter ◽

Peer Review Process ◽

Intrinsic Activity ◽

Hexokinase Ii ◽

The Many ◽

Energy Deprivation ◽

Amp Activated Protein Kinase

Glucose uptake into skeletal muscle is primarily mediated by glucose transporter 4 (GLUT4). The number of GLUT4 polypeptides at the surface of muscle cells rises rapidly in response to insulin, contraction, depolarization, or energy deprivation. However, distinct mechanisms underlie the gain in surface GLUT4 in each case. Insulin promotes its exocytosis to the membrane, regulating vesicle movement, tethering, docking, and fusion. In contrast, muscle contraction, depolarization, and energy demand reduce GLUT4 endocytosis. The signals involved in each case also differ. Insulin utilizes Akt, Rabs, and selective actin remodelling, whereas depolarization and energy deprivation engage AMP-activated protein kinase and Ca2+-dependent signals. GLUT4 internalizes via 2 major routes that involve dynamin, but only one requires clathrin. The clathrin-independent route is slowed down by energy deprivation, and is regulated by AMP-activated protein kinase. In addition to regulation of the exocytic and endocytic movement of GLUT4, glucose uptake is also modulated through changes in the transporter’s intrinsic activity. The glycolytic enzymes glyceraldehyde-3-dehydrogenase and hexokinase II contribute to such regulation, through differential binding to GLUT4.

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Energy-sensing and signaling by AMP-activated protein kinase in skeletal muscle

Journal of Applied Physiology ◽

10.1152/jappl.2001.91.3.1017 ◽

2001 ◽

Vol 91 (3) ◽

pp. 1017-1028 ◽

Cited By ~ 251

Author(s):

W. W. Winder

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Muscle Contraction ◽

Glucose Uptake ◽

Endurance Training ◽

Uncoupling Protein ◽

Energy Charge ◽

Oxidative Enzymes ◽

Energy Sensing ◽

Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is emerging as an important energy-sensing/signaling system in skeletal muscle. This kinase is activated allosterically by 5′-AMP and inhibited allosterically by creatine phosphate. Phosphorylation of AMPK by an upstream kinase, AMPK kinase (also activated allosterically by 5′-AMP), results in activation. It is activated in both rat and human muscle in response to muscle contraction, the extent of activation depending on work rate and muscle glycogen concentration. AMPK can also be activated chemically in resting muscle with 5-aminoimidazole-4-carboxamide-riboside, which enters the muscle and is phosphorylated to form ZMP, a nucleotide that mimics the effect of 5′-AMP. Once activated, AMPK is hypothesized to phosphorylate proteins involved in triggering fatty acid oxidation and glucose uptake. Evidence is also accumulating for a role of AMPK in inducing some of the adaptations to endurance training, including the increase in muscle GLUT-4, hexokinase, uncoupling protein 3, and some of the mitochondrial oxidative enzymes. It thus appears that AMPK has the capability of monitoring intramuscular energy charge and then acutely stimulating fat oxidation and glucose uptake to counteract the increased rates of ATP utilization during muscle contraction. In addition, this system may have the capability of enhancing capacity for ATP production when the muscle is exposed to endurance training.

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Isoleucine, a Blood Glucose-Lowering Amino Acid, Increases Glucose Uptake in Rat Skeletal Muscle in the Absence of Increases in AMP-Activated Protein Kinase Activity

Journal of Nutrition ◽

10.1093/jn/135.9.2103 ◽

2005 ◽

Vol 135 (9) ◽

pp. 2103-2108 ◽

Cited By ~ 71

Author(s):

Masako Doi ◽

Ippei Yamaoka ◽

Mitsuo Nakayama ◽

Shinji Mochizuki ◽

Kunio Sugahara ◽

...

Keyword(s):

Skeletal Muscle ◽

Blood Glucose ◽

Amino Acid ◽

Protein Kinase ◽

Glucose Uptake ◽

Kinase Activity ◽

Protein Kinase Activity ◽

Rat Skeletal Muscle ◽

Glucose Lowering ◽

Amp Activated Protein Kinase

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UCP-3 expression in skeletal muscle: effects of exercise, hypoxia, and AMP-activated protein kinase

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.2000.279.3.e622 ◽

2000 ◽

Vol 279 (3) ◽

pp. E622-E629 ◽

Cited By ~ 96

Author(s):

Min Zhou ◽

Bao-Zhen Lin ◽

Sean Coughlin ◽

Gino Vallega ◽

Paul F. Pilch

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Uncoupling Protein ◽

Fold Increase ◽

Treadmill Running ◽

Mitochondrial Transporter ◽

Edl Muscle ◽

Amp Activated Protein Kinase ◽

Carnitine Palmitoyltransferase 1

Uncoupling protein 3 (UCP-3), a member of the mitochondrial transporter superfamily, is expressed primarily in skeletal muscle where it may play a role in altering metabolic function under conditions of fuel depletion caused, for example, by fasting and exercise. Here, we show that treadmill running by rats rapidly (30 min) induces skeletal muscle UCP-3 mRNA expression (sevenfold after 200 min), as do hypoxia and swimming in a comparably rapid and substantial fashion. The expression of the mitochondrial transporters, carnitine palmitoyltransferase 1 and the tricarboxylate carrier, is unaffected under these conditions. Hypoxia and exercise-mediated induction of UCP-3 mRNA result in a corresponding four- to sixfold increase in rat UCP-3 protein. We treated extensor digitorum longus (EDL) muscle with 5′-amino-4-imidazolecarboxamide ribonucleoside (AICAR), a compound that activates AMP-activated protein kinase (AMPK), an enzyme known to be stimulated during exercise and hypoxia. Incubation of rat EDL muscle in vitro for 30 min with 2 mM AICAR causes a threefold increase in UCP-3 mRNA and a 1.5-fold increase of UCP-3 protein compared with untreated muscle. These data are consistent with the notion that activation of AMPK, presumably as a result of fuel depletion, rapidly regulates UCP-3 gene expression.

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