Evidence against a role for insulin-signaling proteins PI 3-kinase and Akt in insulin resistance in human skeletal muscle induced by short-term GH infusion

2005 ◽  
Vol 288 (1) ◽  
pp. E194-E199 ◽  
Author(s):  
Niels Jessen ◽  
Christian B. Djurhuus ◽  
Jens O. L. Jørgensen ◽  
Lasse S. Jensen ◽  
Niels Møller ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Signaling ◽  
Infusion Rate ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Fold Increase ◽  
Saline Infusion ◽  
Short Term ◽  
The Impact

Prolonged growth hormone (GH) excess is known to be associated with insulin resistance, but the underlying mechanisms remain unknown. The aim of this study was to assess the impact of GH on insulin-stimulated glucose metabolism and insulin signaling in human skeletal muscle. In a cross-over design, eight healthy male subjects (age 26.0 ± 0.8 yr and body mass index 24.1 ± 0.5 kg/m2) were infused for 360 min with either GH (Norditropin, 45 ng·kg−1·min−1) or saline. During the final 180 min of the infusion, a hyperinsulinemic euglycemic clamp was performed (insulin infusion rate: 1.2 mU·kg−1·min−1). Muscle biopsies from vastus lateralis were taken before GH/saline administration and after 60 min of hyperinsulinemia. GLUT4 content and insulin signaling, as assessed by insulin receptor substrate (IRS)-1-associated phosphatidylinositol 3-kinase and Akt activity were determined. GH levels increased to a mean (±SE) level of 20.0 ± 2.3 vs. 0.5 ± 0.2 μg/l after saline infusion ( P < 0.01). During GH infusion, the glucose infusion rate during hyperinsulinemia was reduced by 38% ( P < 0.01). In both conditions, free fatty acids were markedly suppressed during hyperinsulinemia. Despite skeletal muscle insulin resistance, insulin still induced a similar ∼3-fold rise in IRS-1-associated PI 3-kinase activity (269 ± 105 and 311 ± 71% compared with baseline, GH vs. saline). GH infusion did not change Akt protein expression, and insulin caused an ∼13-fold increase in Akt activity (1,309 ± 327 and 1,287 ± 173%) after both GH and saline infusion. No difference in total GLUT4 content was noted (114.7 ± 7.4 and 107.6 ± 16.7 arbitrary units, GH vs. saline, compared with baseline). In conclusion, insulin resistance in skeletal muscle induced by short-term GH administration is not associated with detectable changes in the upstream insulin-signaling cascade or reduction in total GLUT4. Yet unknown mechanisms in insulin signaling downstream of Akt may be responsible.

Effect of exercise and training on phospholemman phosphorylation in human skeletal muscle

2011 ◽  
Vol 301 (3) ◽  
pp. E456-E466 ◽  
Author(s):  
Boubacar Benziane ◽  
Ulrika Widegren ◽  
Sergej Pirkmajer ◽  
Jan Henriksson ◽  
Nigel K. Stepto ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Acute Exercise ◽  
Vastus Lateralis ◽  
Exercise Bout ◽  
Short Term ◽  
Atpase Subunit ◽  
Acute Bout ◽  
Subunit Expression ◽  
The Impact

Phospholemman (PLM, FXYD1) is a partner protein and regulator of the Na+-K+-ATPase (Na+-K+ pump). We explored the impact of acute and short-term training exercise on PLM physiology in human skeletal muscle. A group of moderately trained males ( n = 8) performed a 1-h acute bout of exercise by utilizing a one-legged cycling protocol. Muscle biopsies were taken from vastus lateralis at 0 and 63 min (non-exercised leg) and 30 and 60 min (exercised leg). In a group of sedentary males ( n = 9), we determined the effect of a 10-day intense aerobic cycle training on Na+-K+-ATPase subunit expression, PLM phosphorylation, and total PLM expression as well as PLM phosphorylation in response to acute exercise (1 h at ∼72% V̇o2peak). Biopsies were taken at rest, immediately following, and 3 h after an acute exercise bout before and at the conclusion of the 10-day training study. PLM phosphorylation was increased both at Ser63 and Ser68 immediately after acute exercise (75%, P < 0.05, and 30%, P < 0.05, respectively). Short-term training had no adaptive effect on PLM phosphorylation at Ser63 and Ser68, nor was the total amount of PLM altered posttraining. The protein expressions of α1-, α2-,and β1-subunits of Na+-K+-ATPase were increased after training (113%, P < 0.05, 49%, P < 0.05, and 27%, P < 0.05, respectively). Whereas an acute bout of exercise increased the phosphorylation of PKCα/βII on Thr638/641 pre- and posttraining, phosphorylation of PKCζ/λ on Thr403/410 was increased in response to acute exercise only after the 10-day training. In conclusion, we show that only acute exercise, and not short-term training, increases phosphorylation of PLM on Ser63 and Ser68, and data from one-legged cycling indicate that this effect of exercise on PLM phosphorylation is not due to systemic factors. Our results provide evidence that phosphorylation of PLM may play a role in the acute regulation of the Na+-K+-ATPase response to exercise.

Eccentric exercise markedly increases c-Jun NH2-terminal kinase activity in human skeletal muscle

1999 ◽  
Vol 87 (5) ◽  
pp. 1668-1673 ◽  
Author(s):  
Marni D. Boppart ◽  
Doron Aronson ◽  
Lindsay Gibson ◽  
Ronenn Roubenoff ◽  
Leslie W. Abad ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Eccentric Exercise ◽  
Intracellular Signaling ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Fold Increase ◽  
Mitogen Activated Protein Kinase ◽  
Eccentric Contractions ◽  
Vastus Lateralis Muscle

Eccentric contractions require the lengthening of skeletal muscle during force production and result in acute and prolonged muscle injury. Because a variety of stressors, including physical exercise and injury, can result in the activation of the c-Jun NH2-terminal kinase (JNK) intracellular signaling cascade in skeletal muscle, we investigated the effects of eccentric exercise on the activation of this stress-activated protein kinase in human skeletal muscle. Twelve healthy subjects (7 men, 5 women) completed maximal concentric or eccentric knee extensions on a KinCom isokinetic dynamometer (10 sets, 10 repetitions). Percutaneous needle biopsies were obtained from the vastus lateralis muscle 24 h before exercise (basal), immediately postexercise, and 6 h postexercise. Whereas both forms of exercise increased JNK activity immediately postexercise, eccentric contractions resulted in a much higher activation (15.4 ± 4.5 vs. 3.5 ± 1.4-fold increase above basal, eccentric vs. concentric). By 6 h after exercise, JNK activity decreased back to baseline values. In contrast to the greater activation of JNK with eccentric exercise, the mitogen-activated protein kinase kinase 4, the immediate upstream regulator of JNK, was similarly activated by concentric and eccentric exercise. Because the activation of JNK promotes the phosphorylation of a variety of transcription factors, including c-Jun, the results from this study suggest that JNK may be involved in the molecular and cellular adaptations that occur in response to injury-producing exercise in human skeletal muscle.

Effect of short-term, high-intensity exercise training on human skeletal muscle citrate synthase maximal activity: single versus multiple bouts per session

2019 ◽  
Vol 44 (12) ◽  
pp. 1391-1394
Author(s):  
Martin J. MacInnis ◽  
Lauren E. Skelly ◽  
F. Elizabeth Godkin ◽  
Brian J. Martin ◽  
Thomas R. Tripp ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
High Intensity ◽  
Human Skeletal Muscle ◽  
Citrate Synthase ◽  
Vastus Lateralis ◽  
Maximal Activity ◽  
High Intensity Exercise ◽  
Short Term ◽  
Significant Difference

The legs of 9 men (age 21 ± 2 years, 45 ± 4 mL/(kg·min)) were randomly assigned to complete 6 sessions of high-intensity exercise training, involving either one or four 5-min bouts of counterweighted, single-leg cycling. Needle biopsies from vastus lateralis revealed that citrate synthase maximal activity increased after training in the 4-bout group (p = 0.035) but not the 1-bout group (p = 0.10), with a significant difference between groups post-training (13%, p = 0.021). Novelty Short-term training using brief intense exercise requires multiple bouts per session to increase mitochondrial content in human skeletal muscle.

Subcellular fractionation reveals HSP72 does not associate with SERCA in human skeletal muscle following damaging eccentric and concentric exercise

2014 ◽  
Vol 116 (11) ◽  
pp. 1503-1511 ◽  
Author(s):  
Noni T. Frankenberg ◽  
Graham D. Lamb ◽  
Kristian Vissing ◽  
Robyn M. Murphy
Keyword(s):  
Skeletal Muscle ◽  
Protein Content ◽  
Human Skeletal Muscle ◽  
Physiological Stress ◽  
Vastus Lateralis ◽  
Tight Binding ◽  
Fold Increase ◽  
Subcellular Fractionation ◽  
Vastus Lateralis Muscle ◽  
Type I

Through its upregulation and/or translocation, heat shock protein 72 (HSP72) is involved in protection and repair of key proteins after physiological stress. In human skeletal muscle we investigated HSP72 protein after eccentric (ECC1) and concentric (CONC) exercise and repeated eccentric exercise (ECC2; 8 wk later) and whether it translocated from its normal cytosolic location to membranes/myofibrils. HSP72 protein increased ∼2-fold 24 h after ECC1, with no apparent change after CONC or ECC2. In resting (nonstressed) human skeletal muscle the total pool of HSP72 protein was present almost exclusively in the cytosolic fraction, and after each exercise protocol the distribution of HSP72 protein remained unaltered. Overall, the amount of HSP72 protein in the cytosol increased 24 h after ECC1, matching the fold increase that was measured in total HSP72 protein. To better ascertain the capabilities and limitations of HSP72, using quantitative Western blotting we determined the HSP72 protein content to be 11.4 μmol/kg wet weight in resting human vastus lateralis muscle, which is comprised of Type I (slow-twitch) and Type II (fast-twitch) fibers. HSP72 protein content was similar in individual Type I or II fiber segments. After physiological stress, HSP72 content can increase and, although the functional consequences of increased amounts of HSP72 protein are poorly understood, it has been shown to bind to and protect protein pumps like SERCA and Na+-K+-ATPase. Given no translocation of cytosolic HSP72, these findings suggest eccentric contractions, unlike other forms of stress such as heat, do not trigger tight binding of HSP72 to its primary membrane-bound target proteins, in particular SERCA.

Seven days of exercise increase GLUT-4 protein content in human skeletal muscle

1995 ◽  
Vol 79 (6) ◽  
pp. 1936-1938 ◽  
Author(s):  
J. A. Houmard ◽  
M. S. Hickey ◽  
G. L. Tyndall ◽  
K. E. Gavigan ◽  
G. L. Dohm
Keyword(s):  
Skeletal Muscle ◽  
Exercise Training ◽  
Protein Content ◽  
Human Skeletal Muscle ◽  
Glucose Transporter ◽  
Vastus Lateralis ◽  
Cycle Ergometer ◽  
Maximal Heart Rate ◽  
Short Term ◽  
Glut 4

Insulin-responsive glucose transporter (GLUT-4) content increases by 1.8-fold in skeletal muscle with 14 wk of exercise training [Houmard et al. Am. J. Physiol. 264 (Endocrinol. Metab. 27): E896-E901, 1993]. The purpose of this study was to determine whether more short-term training (7 days) increases GLUT-4 protein content in human skeletal muscle. Seven sedentary men [25.0 +/- 1.1 (SE) yr, 44.1 +/- 2.2 ml.kg-1.min-1 maximal O2 uptake, 14.9 +/- 2.1% body fat] were examined before and after 7 days of cycle ergometer training (1 h/day, 76 +/- 2% maximal heart rate). Needle biopsy samples from the vastus lateralis were used to determine GLUT-4 protein content. Muscle GLUT-4 increased (P < 0.05) by an average of 2.8 +/- 0.5-fold with 7 days of training. GLUT-4 content in skeletal muscle thus increases substantially with short-term exercise training.

Malleability of human skeletal muscle Na+-K+-ATPase pump with short-term training

2004 ◽  
Vol 97 (1) ◽  
pp. 143-148 ◽  
Author(s):  
H. J. Green ◽  
D. J. Barr ◽  
J. R. Fowles ◽  
S. D. Sandiford ◽  
J. Ouyang
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Aerobic Power ◽  
Vastus Lateralis ◽  
Peak Oxygen Consumption ◽  
Rapid Adaptation ◽  
Ouabain Binding ◽  
Short Term ◽  
Power Peak ◽  
Phosphatase Assay

To investigate the hypothesis that short-term submaximal training would result in changes in Na+-K+-ATPase content, activity, and isoform distribution in skeletal muscle, seven healthy, untrained men [peak aerobic power (peak oxygen consumption; V̇o2 peak) = 45.6 ml·kg−1·min−1 (SE 5.4)] cycled for 2 h/day at 60–65% V̇o2 peak for 6 days. Muscle tissue, sampled from the vastus lateralis before training (0 days) and after 3 and 6 days of training and analyzed for Na+-K+-ATPase content, as assessed by the vanadate facilitated [3H]ouabain-binding technique, was increased ( P < 0.05) at 3 days (294 ± 8.6 pmol/g wet wt) and 6 days (308 ± 15 pmol/g wet wt) of training compared with 0 days (272 ± 9.7 pmol/g wet wt). Maximal Na+-K+-ATPase activity as evaluated by the 3- O-methylfluorescein phosphatase assay was increased ( P < 0.05) by 6 days (53.4 ± 5.9 nmol·h−1·mg protein−1) but not by 3 days (35.9 ± 4.5 nmol·h−1·mg protein−1) compared with 0 days (37.8 ± 3.7 nmol·h−1·mg protein−1) of training. Relative isoform distribution, measured by Western blot techniques, indicated increases ( P < 0.05) in α2-content by 3 days and β1-content by 6 days of training. These results indicate that prolonged aerobic exercise represents a potent stimulus for the rapid adaptation of Na+-K+-ATPase content, isoform, and activity characteristics.

scholarly journals The Influence of Physical Activity on the Bioactive Lipids Metabolism in Obesity-Induced Muscle Insulin Resistance

Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1665
Author(s):  
Monika Imierska ◽  
Adam Kurianiuk ◽  
Agnieszka Błachnio-Zabielska
Keyword(s):  
Physical Activity ◽  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Insulin Signaling ◽  
Biologically Active ◽  
Bioactive Lipids ◽  
Glucose Levels ◽  
Insulin Dependent ◽  
Lipids Metabolism ◽  
The Impact

High-fat diet consumption and lack of physical activity are important risk factors for metabolic disorders such as insulin resistance and cardiovascular diseases. Insulin resistance is a state of a weakened response of tissues such as skeletal muscle, adipose tissue, and liver to insulin, which causes an increase in blood glucose levels. This condition is the result of inhibition of the intracellular insulin signaling pathway. Skeletal muscle is an important insulin-sensitive tissue that accounts for about 80% of insulin-dependent glucose uptake. Although the exact mechanism by which insulin resistance is induced has not been thoroughly understood, it is known that insulin resistance is most commonly associated with obesity. Therefore, it is believed that lipids may play an important role in inducing insulin resistance. Among lipids, researchers’ attention is mainly focused on biologically active lipids: diacylglycerols (DAG) and ceramides. These lipids are able to regulate the activity of intracellular enzymes, including those involved in insulin signaling. Available data indicate that physical activity affects lipid metabolism and has a positive effect on insulin sensitivity in skeletal muscles. In this review, we have presented the current state of knowledge about the impact of physical activity on insulin resistance and metabolism of biologically active lipids.

Creatine Supplementation: A Comparison of Loading and Maintenance Protocols on Creatine Uptake by Human Skeletal Muscle

2003 ◽  
Vol 13 (1) ◽  
pp. 97-111 ◽  
Author(s):  
David Preen ◽  
Brian Dawson ◽  
Carmel Goodman ◽  
John Beilby ◽  
Simon Ching
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Effective Means ◽  
Creatine Supplementation ◽  
Whole Body ◽  
Physically Active ◽  
Treatment Conditions ◽  
Creatine Uptake ◽  
The Impact

The purposes of this investigation were first to determine the impact of 3 different creatine (Cr) loading procedures on skeletal muscle total Cr (TCr) accumulation and, second, to evaluate the effectiveness of 2 maintenance regimes on retaining intramuscular TCr stores, in the 6 weeks following a 5-day Cr loading program (20 g · day−1). Eighteen physically active male subjects were divided into 3 equal groups and administered either: (a) Cr (4 X 5 g · day−1 X 5 days), (b) Glucose+Cr (1 g · kg−1 of body mass twice per day), or (c) Cr in conjunction with 60 min of daily muscular (repeated-sprint) exercise. Following the 5-day loading period, subjects were reassigned to 3 maintenance groups and ingested either 0 g · day−1, 2 g · day−1 or 5 g · day−1 of Cr for a period of 6 weeks. Muscle biopsy samples (vastus lateralis) were taken pre- and post-loading as well as post-maintenance and analyzed for skeletal muscle ATP, phosphocreatine (PCr), Cr, and TCr concentrations. Twenty-four hour urine samples were collected for each of the loading days and last 2 maintenance days, and used to determine whole body Cr retention. Post-loading TCr stores were significantly (p < .05) increased in all treatment conditions. The Glucose+Cr condition produced a greater elevation (p < .05) in TCr concentrations (25%) than the Cr Only (16%) or Exercise+Cr (18%) groups. Following the maintenance period, muscle TCr stores were still similar to post-loading values for both the 2 g · day−1 and 5 g · day−1 conditions. Intramuscular TCr values for the 0 g · day−1 condition were significantly lower than the other conditions after the 6-week period. Although not significantly different from pre-loading concentrations, muscle TCr for the 0 g · day−1 group had not fully returned to baseline levels at 6 weeks post-loading. The data suggests that Glucose+Cr (but with a much smaller glucose intake than currently accepted) is potentially the most effective means of elevating TCr accumulation in human skeletal muscle. Furthermore, after 5 days of Cr loading, elevated muscle TCr concentrations can be maintained by the ingestion of small daily Cr doses (2-5 g) for a period of 6 weeks and that TCr concentrations may take longer than currently accepted to return to baseline values after such a Cr loading regime.

scholarly journals Kinome Profiling Reveals Abnormal Activity of Kinases in Skeletal Muscle From Adults With Obesity and Insulin Resistance

2019 ◽  
Vol 105 (3) ◽  
pp. 644-659
Author(s):  
Yue Qi ◽  
Xiangmin Zhang ◽  
Berhane Seyoum ◽  
Zaher Msallaty ◽  
Abdullah Mallisho ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Protein Kinases ◽  
Insulin Signaling ◽  
Human Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Kinase Activity ◽  
Metabolic Diseases ◽  
Muscle Insulin Resistance ◽  
Skeletal Muscle Insulin Resistance

Abstract Context Obesity-related insulin resistance (OIR) is one of the main contributors to type 2 diabetes and other metabolic diseases. Protein kinases are implicated in insulin signaling and glucose metabolism. Molecular mechanisms underlying OIR involving global kinase activities remain incompletely understood. Objective To investigate abnormal kinase activity associated with OIR in human skeletal muscle. Design Utilization of stable isotopic labeling-based quantitative proteomics combined with affinity-based active enzyme probes to profile in vivo kinase activity in skeletal muscle from lean control (Lean) and OIR participants. Participants A total of 16 nondiabetic adults, 8 Lean and 8 with OIR, underwent hyperinsulinemic-euglycemic clamp with muscle biopsy. Results We identified the first active kinome, comprising 54 active protein kinases, in human skeletal muscle. The activities of 23 kinases were different in OIR muscle compared with Lean muscle (11 hyper- and 12 hypo-active), while their protein abundance was the same between the 2 groups. The activities of multiple kinases involved in adenosine monophosphate–activated protein kinase (AMPK) and p38 signaling were lower in OIR compared with Lean. On the contrary, multiple kinases in the c-Jun N-terminal kinase (JNK) signaling pathway exhibited higher activity in OIR vs Lean. The kinase-substrate–prediction based on experimental data further confirmed a potential downregulation of insulin signaling (eg, inhibited phosphorylation of insulin receptor substrate-1 and AKT1/2). Conclusions These findings provide a global view of the kinome activity in OIR and Lean muscle, pinpoint novel specific impairment in kinase activities in signaling pathways important for skeletal muscle insulin resistance, and may provide potential drug targets (ie, abnormal kinase activities) to prevent and/or reverse skeletal muscle insulin resistance in humans.

scholarly journals Insulin resistance after a 72-h fast is associated with impaired AS160 phosphorylation and accumulation of lipid and glycogen in human skeletal muscle

2012 ◽  
Vol 302 (2) ◽  
pp. E190-E200 ◽  
Author(s):  
M. H. Vendelbo ◽  
B. F. F. Clasen ◽  
J. T. Treebak ◽  
L. Møller ◽  
T. Krusenstjerna-Hafstrøm ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Lipid Oxidation ◽  
Glucose Uptake ◽  
Lipid Content ◽  
Insulin Signaling ◽  
Insulin Action ◽  
Human Skeletal Muscle ◽  
Substrate Oxidation ◽  
Underlying Mechanisms

During fasting, human skeletal muscle depends on lipid oxidation for its energy substrate metabolism. This is associated with the development of insulin resistance and a subsequent reduction of insulin-stimulated glucose uptake. The underlying mechanisms controlling insulin action on skeletal muscle under these conditions are unresolved. In a randomized design, we investigated eight healthy subjects after a 72-h fast compared with a 10-h overnight fast. Insulin action on skeletal muscle was assessed by a hyperinsulinemic euglycemic clamp and by determining insulin signaling to glucose transport. In addition, substrate oxidation, skeletal muscle lipid content, regulation of glycogen synthesis, and AMPK signaling were assessed. Skeletal muscle insulin sensitivity was reduced profoundly in response to a 72-h fast and substrate oxidation shifted to predominantly lipid oxidation. This was associated with accumulation of both lipid and glycogen in skeletal muscle. Intracellular insulin signaling to glucose transport was impaired by regulation of phosphorylation at specific sites on AS160 but not TBC1D1, both key regulators of glucose uptake. In contrast, fasting did not impact phosphorylation of AMPK or insulin regulation of Akt, both of which are established upstream kinases of AS160. These findings show that insulin resistance in muscles from healthy individuals is associated with suppression of site-specific phosphorylation of AS160, without Akt or AMPK being affected. This impairment of AS160 phosphorylation, in combination with glycogen accumulation and increased intramuscular lipid content, may provide the underlying mechanisms for resistance to insulin in skeletal muscle after a prolonged fast.

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