Reduced carbohydrate availability enhances exercise-induced p53 signaling in human skeletal muscle: implications for mitochondrial biogenesis

2013 ◽  
Vol 304 (6) ◽  
pp. R450-R458 ◽  
Author(s):  
Jonathan D. Bartlett ◽  
Jari Louhelainen ◽  
Zafar Iqbal ◽  
Andrew J. Cochran ◽  
Martin J. Gibala ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Biogenesis ◽  
Repeated Measures ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Oxidative Capacity ◽  
Pyruvate Dehydrogenase Kinase ◽  
Repeated Measures Design ◽  
P53 Signaling ◽  
Exercise Induced

The mechanisms that regulate the enhanced skeletal muscle oxidative capacity observed when training with reduced carbohydrate (CHO) availability are currently unknown. The aim of the present study was to test the hypothesis that reduced CHO availability enhances p53 signaling and expression of genes associated with regulation of mitochondrial biogenesis and substrate utilization in human skeletal muscle. In a repeated-measures design, muscle biopsies (vastus lateralis) were obtained from eight active males before and after performing an acute bout of high-intensity interval running with either high (HIGH) or low CHO availability (LOW). Resting muscle glycogen (HIGH, 467 ± 19; LOW, 103 ± 9 mmol/kg dry wt) was greater in HIGH compared with LOW ( P < 0.05). Phosphorylation (P-) of ACCSer79 (HIGH, 1.4 ± 0.4; LOW, 2.9 ± 0.9) and p53Ser15 (HIGH, 0.9 ± 0.4; LOW, 2.6 ± 0.8) was higher in LOW immediately postexercise and 3 h postexercise, respectively ( P < 0.05). Before and 3 h postexercise, mRNA content of pyruvate dehydrogenase kinase 4, mitochondrial transcription factor A, cytochrome- c oxidase IV, and PGC-1α were greater in LOW compared with HIGH ( P < 0.05), whereas carnitine palmitoyltransferase-1 showed a trend toward significance ( P = 0.09). However, only PGC-1α expression was increased by exercise ( P < 0.05), where three-fold increases occurred independently of CHO availability. We conclude that the exercise-induced increase in p53 phosphorylation is enhanced in conditions of reduced CHO availability, which may be related to upstream signaling through AMPK. Given the emergence of p53 as a molecular regulator of mitochondrial biogenesis, such nutritional modulation of contraction-induced p53 activation has implications for both athletic and clinical populations.

scholarly journals Investigating human skeletal muscle physiology with unilateral exercise models: when one limb is more powerful than two

2017 ◽  
Vol 42 (6) ◽  
pp. 563-570 ◽  
Author(s):  
Martin J. MacInnis ◽  
Chris McGlory ◽  
Martin J. Gibala ◽  
Stuart M. Phillips
Keyword(s):  
Skeletal Muscle ◽  
Repeated Measures ◽  
Statistical Power ◽  
Human Skeletal Muscle ◽  
Capillary Density ◽  
Muscle Physiology ◽  
Repeated Measures Design ◽  
Confounding Variables ◽  
Direct Sampling ◽  
Wide Range

Direct sampling of human skeletal muscle using the needle biopsy technique can facilitate insight into the biochemical and histological responses resulting from changes in exercise or feeding. However, the muscle biopsy procedure is invasive, and analyses are often expensive, which places pragmatic restraints on sample sizes. The unilateral exercise model can serve to increase statistical power and reduce the time and cost of a study. With this approach, 2 limbs of a participant are randomized to 1 of 2 treatments that can be applied almost concurrently or sequentially depending on the nature of the intervention. Similar to a typical repeated measures design, comparisons are made within participants, which increases statistical power by reducing the amount of between-person variability. A washout period is often unnecessary, reducing the time needed to complete the experiment and the influence of potential confounding variables such as habitual diet, activity, and sleep. Variations of the unilateral exercise model have been employed to investigate the influence of exercise, diet, and the interaction between the 2, on a wide range of variables including mitochondrial content, capillary density, and skeletal muscle hypertrophy. Like any model, unilateral exercise has some limitations: it cannot be used to study variables that potentially transfer across limbs, and it is generally limited to exercises that can be performed in pairs of treatments. Where appropriate, however, the unilateral exercise model can yield robust, well-controlled investigations of skeletal muscle responses to a wide range of interventions and conditions including exercise, dietary manipulation, and disuse or immobilization.

scholarly journals Effect of N-acetylcysteine infusion on exercise-induced modulation of insulin sensitivity and signaling pathways in human skeletal muscle

2015 ◽  
Vol 309 (4) ◽  
pp. E388-E397 ◽  
Author(s):  
Adam J. Trewin ◽  
Leonidas S. Lundell ◽  
Ben D. Perry ◽  
Kim Vikhe Patil ◽  
Alexander V. Chibalin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Insulin Sensitivity ◽  
Repeated Measures ◽  
Insulin Action ◽  
Human Skeletal Muscle ◽  
Protein Signaling ◽  
Insulin Stimulation ◽  
Double Blind ◽  
Exercise Induced ◽  
Muscle Biopsies

—Reactive oxygen species (ROS) produced in skeletal muscle may play a role in potentiating the beneficial responses to exercise; however, the effects of exercise-induced ROS on insulin action and protein signaling in humans has not been fully elucidated. Seven healthy, recreationally active participants volunteered for this double-blind, randomized, repeated-measures crossover study. Exercise was undertaken with infusion of saline (CON) or the antioxidant N-acetylcysteine (NAC) to attenuate ROS. Participants performed two 1-h cycling exercise sessions 7–14 days apart, 55 min at 65% V̇o2peak plus 5 min at 85%V̇o2peak, followed 3 h later by a 2-h hyperinsulinemic euglycemic clamp (40 mIU·min−1·m2) to determine insulin sensitivity. Four muscle biopsies were taken on each trial day, at baseline before NAC infusion (BASE), after exercise (EX), after 3-h recovery (REC), and post-insulin clamp (PI). Exercise, ROS, and insulin action on protein phosphorylation were evaluated with immunoblotting. NAC tended to decrease postexercise markers of the ROS/protein carbonylation ratio by −13.5% ( P = 0.08) and increase the GSH/GSSG ratio twofold vs. CON ( P < 0.05). Insulin sensitivity was reduced (−5.9%, P < 0.05) by NAC compared with CON without decreased phosphorylation of Akt or AS160. Whereas p-mTOR was not significantly decreased by NAC after EX or REC, phosphorylation of the downstream protein synthesis target kinase p70S6K was blunted by 48% at PI with NAC compared with CON ( P < 0.05). We conclude that NAC infusion attenuated muscle ROS and postexercise insulin sensitivity independent of Akt signaling. ROS also played a role in normal p70S6K phosphorylation in response to insulin stimulation in human skeletal muscle.

scholarly journals Forty high-intensity interval training sessions blunt exercise-induced changes in the nuclear protein content of PGC-1α and p53 in human skeletal muscle

2019 ◽  
Author(s):  
Cesare Granata ◽  
Rodrigo S.F. Oliveira ◽  
Jonathan P. Little ◽  
David J. Bishop
Keyword(s):  
Skeletal Muscle ◽  
Protein Content ◽  
Mitochondrial Biogenesis ◽  
Exercise Intensity ◽  
High Intensity ◽  
Human Skeletal Muscle ◽  
Interval Training ◽  
High Intensity Interval Training ◽  
High Intensity Interval ◽  
Exercise Induced

ABSTRACTExercise-induced increases in peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and p53 protein content in the nucleus mediate the initial phase of exercise-induced mitochondrial biogenesis. Here we investigated if exercise-induced increases in these and other markers of mitochondrial biogenesis were altered after 40 sessions of twice-daily high-volume high-intensity interval training (HVT) in human skeletal muscle. Vastus lateralis muscle biopsies were collected from 10 healthy recreationally active participants before, immediately post, and 3h after a session of HIIE performed at the same absolute exercise intensity before and after HVT (Pre-HVT and Post-HVT, respectively). The protein content of common markers of exercise-induced mitochondrial biogenesis were assessed in nuclear- and cytosolic-enriched fractions by immunoblotting; mRNA contents of key transcription factors and mitochondrial genes were assessed by qPCR. Despite exercise-induced increases in PGC-1α, p53, and plant homeodomain finger-containing protein 20 (PHF20) protein content, the phosphorylation of p53 and acetyl-CoA carboxylase (p-p53Ser15 and p-ACCSer79, respectively), and PGC-1α mRNA Pre-HVT, no significant changes were observed Post-HVT. Forty sessions of twice-daily high-intensity interval training blunted all of the measured exercise-induced molecular events associated with mitochondrial biogenesis that were observed Pre-HVT. Future studies should determine if this loss relates to the decrease in relative exercise intensity, habituation to the same exercise stimulus, or a combination of both.

Activation of skeletal muscle calpain-3 by eccentric exercise in humans does not result in its translocation to the nucleus or cytosol

2011 ◽  
Vol 111 (5) ◽  
pp. 1448-1458 ◽  
Author(s):  
Robyn M. Murphy ◽  
Kristian Vissing ◽  
Heidy Latchman ◽  
Cedric Lamboley ◽  
Michael J. McKenna ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Eccentric Exercise ◽  
Repeated Measures ◽  
Human Skeletal Muscle ◽  
Exercise Intervention ◽  
Calpain 3 ◽  
Functional Consequences ◽  
Exercise Induced ◽  
Post Hoc ◽  
Exercise In Humans

The skeletal muscle-specific calpain-3 protease is likely involved in muscle repair, although the mechanism is not known. Physiological activation of calpain-3 occurs 24 h following eccentric exercise in humans. Functional consequences of calpain-3 activation are not known; however, calpain-3 has been suggested to be involved in nuclear signaling via NF-κB. To test this and help identify how/where calpain-3 acts, we investigated whether calpain-3 autolysis (hence, activation) following eccentric exercise results in translocation from its normal myofibrillar location to the nucleus or the cytosol. In resting human skeletal muscle, the majority (87%) of calpain-3 was present in myofibrillar fractions, with only a small proportion (<10%) in an autolyzed state. Enriched nuclear fractions contained ∼8% of the total calpain-3, which was present in a predominantly (>80%) autolyzed state. Using freshly dissected human muscle fibers to identify freely diffusible proteins, we showed that only ∼5% of the total calpain-3 pool was cytosolic. At 3 and 24 h following eccentric step exercise, there was an ∼70% increase in autolysis in whole muscle samples ( n = 11, P < 0.05, by 1-way ANOVA with repeated measures and Newman-Keuls post hoc analysis). This exercise-induced autolysis was attributed to myofibrillar-bound calpain-3, since neither the amount of calpain-3 nor the proportion autolyzed was significantly changed in enriched nuclear or cytosolic fractions following the exercise intervention. We present a model for calpain-3 localization at rest and following activation in human skeletal muscle and suggest that the functional importance of calpain-3 remains predominantly tightly associated with its localization within the myofibrillar compartment.

Looking beyond PGC-1α: emerging regulators of exercise-induced skeletal muscle mitochondrial biogenesis and their activation by dietary compounds

2020 ◽  
Vol 45 (1) ◽  
pp. 11-23 ◽  
Author(s):  
Hashim Islam ◽  
David A. Hood ◽  
Brendon J. Gurd
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Biogenesis ◽  
Respiratory Function ◽  
Human Skeletal Muscle ◽  
Ppar Gamma ◽  
Master Regulator ◽  
Mechanistic Insight ◽  
Simplistic Notion ◽  
Exercise Induced ◽  
Insight Into

Despite its widespread acceptance as the “master regulator” of mitochondrial biogenesis (i.e., the expansion of the mitochondrial reticulum), peroxisome proliferator-activated receptor (PPAR) gamma coactivator-1 alpha (PGC-1α) appears to be dispensable for the training-induced augmentation of skeletal muscle mitochondrial content and respiratory function. In fact, a number of regulatory proteins have emerged as important players in skeletal muscle mitochondrial biogenesis and many of these proteins share key attributes with PGC-1α. In an effort to move past the simplistic notion of a “master regulator” of mitochondrial biogenesis, we highlight the regulatory mechanisms by which nuclear factor erythroid 2-related factor 2 (Nrf2), estrogen-related receptor gamma (ERRγ), PPARβ, and leucine-rich pentatricopeptide repeat-containing protein (LRP130) may contribute to the control of skeletal muscle mitochondrial biogenesis. We also present evidence supporting/refuting the ability of sulforaphane, quercetin, and epicatechin to promote skeletal muscle mitochondrial biogenesis and their potential to augment mitochondrial training adaptations. Targeted activation of specific pathways by these compounds may allow for greater mechanistic insight into the molecular pathways controlling mitochondrial biogenesis in human skeletal muscle. Dietary activation of mitochondrial biogenesis may also be useful in clinical populations with basal reductions in mitochondrial protein content, enzyme activities, and/or respiratory function as well as individuals who exhibit a blunted skeletal muscle responsiveness to contractile activity. Novelty The existence of redundant pathways leading to mitochondrial biogenesis refutes the simplistic notion of a “master regulator” of mitochondrial biogenesis. Dietary activation of specific pathways may provide greater mechanistic insight into the exercise-induced mitochondrial biogenesis in human skeletal muscle.

scholarly journals Decreased transcriptional corepressor p107 is associated with exercise-induced mitochondrial biogenesis in human skeletal muscle

2017 ◽  
Vol 5 (5) ◽  
pp. e13155 ◽  
Author(s):  
Debasmita Bhattacharya ◽  
Mia Ydfors ◽  
Meghan C. Hughes ◽  
Jessica Norrbom ◽  
Christopher G. R. Perry ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Biogenesis ◽  
Human Skeletal Muscle ◽  
Transcriptional Corepressor ◽  
Exercise Induced

scholarly journals Angiogenesis-related ultrastructural changes to capillaries in human skeletal muscle in response to endurance exercise

2015 ◽  
Vol 119 (10) ◽  
pp. 1118-1126 ◽  
Author(s):  
Oliver Baum ◽  
Jennifer Gübeli ◽  
Sebastian Frese ◽  
Eleonora Torchetti ◽  
Corinna Malik ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cross Sections ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Capillary Density ◽  
Volume Density ◽  
Ultrastructural Changes ◽  
Vastus Lateralis Muscle ◽  
Before And After ◽  
Exercise Induced

The ultrastructure of capillaries in skeletal muscle was morphometrically assessed in vastus lateralis muscle (VL) biopsies taken before and after exercise from 22 participants of two training studies. In study 1 (8 wk of ergometer training), light microscopy revealed capillary-fiber (C/F) ratio (+27%) and capillary density (+16%) to be higher ( P ≤ 0.05) in postexercise biopsies than in preexercise biopsies from all 10 participants. In study 2 (6 mo of moderate running), C/F ratio and capillary density were increased (+23% and +20%; respectively, P ≤ 0.05) in VL biopsies from 6 angiogenesis responders (AR) after training, whereas 6 nonangiogenesis responders (NR) showed nonsignificant changes in these structural indicators (−4%/−4%, respectively). Forty capillary profiles per participant were evaluated by point and intersection counting on cross sections after transmission electron microscopy. In study 1, volume density (Vv) and mean arithmetic thickness (T) of endothelial cells (ECs; +19%/+17%, respectively) and pericytes (PCs; +20%/+21%, respectively) were higher ( P ≤ 0.05), whereas Vv and T of the pericapillary basement membrane (BM) were −23%/−22% lower ( P ≤ 0.05), respectively, in posttraining biopsies. In study 2, exercise-related differences between AR and NR-groups were found for Vv and T of PCs (AR, +26%/+22%, respectively, both P ≤ 0.05; NR, +1%/−3%, respectively, both P > 0.05) and BM (AR, −14%/−13%, respectively, both P ≤ 0.05; NR, −9%/−11%, respectively, P = 0.07/0.10). Vv and T of ECs were higher (AR, +16%/+18%, respectively; NR, +6% /+6%, respectively; all P ≤ 0.05) in both groups. The PC coverage was higher (+13%, P ≤ 0.05) in VL biopsies of individuals in the AR group but nonsignificantly altered (+3%, P > 0.05) in those of the NR group after training. Our study suggests that intensified PC mobilization and BM thinning are related to exercise-induced angiogenesis in human skeletal muscle, whereas training per se induces EC-thickening.

scholarly journals Forty high-intensity interval training sessions blunt exercise-induced changes in the nuclear protein content of PGC-1α and p53 in human skeletal muscle

2020 ◽  
Vol 318 (2) ◽  
pp. E224-E236 ◽  
Author(s):  
Cesare Granata ◽  
Rodrigo S. F. Oliveira ◽  
Jonathan P. Little ◽  
David J. Bishop
Keyword(s):  
Skeletal Muscle ◽  
Protein Content ◽  
Mitochondrial Biogenesis ◽  
Exercise Intensity ◽  
High Intensity ◽  
Human Skeletal Muscle ◽  
Interval Training ◽  
High Intensity Interval Training ◽  
High Intensity Interval ◽  
Exercise Induced

Exercise-induced increases in peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and p53 protein content in the nucleus mediate the initial phase of exercise-induced mitochondrial biogenesis. Here, we investigated whether exercise-induced increases in these and other markers of mitochondrial biogenesis were altered after 40 sessions of twice-daily high-volume, high-intensity interval training (HVT) in human skeletal muscle. Vastus lateralis muscle biopsies were collected from 10 healthy recreationally active participants before, immediately postexercise, and 3 h after a session of high-intensity interval exercise (HIIE) performed at the same absolute exercise intensity before and after HVT (pre-HVT and post-HVT, respectively). The protein content of common markers of exercise-induced mitochondrial biogenesis was assessed in nuclear- and cytosolic-enriched fractions by immunoblotting; mRNA contents of key transcription factors and mitochondrial genes were assessed by qPCR. Despite exercise-induced increases in PGC-1α, p53, and plant homeodomain finger-containing protein 20 (PHF20) protein content, the phosphorylation of p53 and acetyl-CoA carboxylase (p-p53 Ser15 and p-ACC Ser79, respectively), and PGC-1α mRNA Pre-HVT, no significant changes were observed post-HVT. Forty sessions of twice-daily high-intensity interval training blunted all of the measured exercise-induced molecular events associated with mitochondrial biogenesis that were observed pre-HVT. Future studies should determine whether this loss relates to the decrease in relative exercise intensity, habituation to the same exercise stimulus, or a combination of both.

scholarly journals Human skeletal muscle HSP70 response to training in highly trained rowers

1999 ◽  
Vol 86 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Yuefei Liu ◽  
Sabine Mayr ◽  
Alexandra Opitz-Gress ◽  
Claudia Zeller ◽  
Werner Lormes ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Heat Shock ◽  
Heat Shock Protein 70 ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Human Muscle ◽  
Muscle Sample ◽  
Exercise Induced ◽  
The Right

Previous studies have demonstrated exercise-induced heat shock protein 70 (HSP70) in animals. The purpose of this study was to investigate human skeletal muscle HSP70 response to rowing training. Ten male rowers trained for 4 wk with different forms, durations, and intensities of exercise. Biopsy was performed in the right musculus vastus lateralis before training and at the end of each week. HSP70 in 5 μg of total protein from the muscle sample was determined by using Western blot and immunodetection with chemiluminescence technique, by means of laser densitometer referring to a series of known standard HSP70. Compared with pretraining (100%), HSP70 increased during training (181, 405, 456, and 363% from the first to fourth training week, respectively) with the maximum HSP70 production at the end of second training week. Thus HSP70 is induced in highly trained human muscle by long-term training.

Human skeletal muscle pyruvate dehydrogenase kinase activity increases after a low-carbohydrate diet

1998 ◽  
Vol 275 (6) ◽  
pp. E980-E986 ◽  
Author(s):  
Sandra J. Peters ◽  
Timothy A. St. Amand ◽  
Richard A. Howlett ◽  
George J. F. Heigenhauser ◽  
Lawrence L. Spriet
Keyword(s):  
Skeletal Muscle ◽  
Pyruvate Dehydrogenase ◽  
Human Skeletal Muscle ◽  
Citrate Synthase ◽  
Vastus Lateralis ◽  
Active Form ◽  
Pyruvate Dehydrogenase Kinase ◽  
Acid Oxidation ◽  
Low Carbohydrate Diet ◽  
Low Carbohydrate

To characterize human skeletal muscle enzymatic adaptation to a low-carbohydrate, high-fat, and high-protein diet (LCD), subjects consumed a eucaloric diet consisting of 5% of the total energy intake from carbohydrate, 63% from fat, and 33% from protein for 6 days compared with their normal diet (52% carbohydrate, 33% fat, and 14% protein). Biopsies were taken from the vastus lateralis before and after 3 and 6 days on a LCD. Intact mitochondria were extracted from fresh muscle and analyzed for pyruvate dehydrogenase (PDH) kinase, total PDH, and carnitine palmitoyltransferase I activities and mitochondrial ATP production rate (using carbohydrate and fat substrates). β-Hydroxyacyl CoA dehydrogenase, active PDH (PDHa), and citrate synthase activities were also measured on whole muscle homogenates. PDH kinase (PDHK) was calculated as the absolute value of the apparent first-order rate constant of the inactivation of PDH in the presence of 0.3 mM Mg2+-ATP. PDHK increased dramatically from 0.10 ± 0.02 min−1 to 0.35 ± 0.09 min−1 at 3 days and 0.49 ± 0.06 min−1 after 6 days. Resting PDHa activity decreased from 0.63 ± 0.17 to 0.17 ± 0.04 mmol ⋅ min−1 ⋅ kg−1after 6 days on the diet, whereas total PDH activity did not change. Activities for all other enzymes were unaltered by the LCD. In summary, severe deficiency of dietary carbohydrate combined with a twofold increase in dietary fat and protein caused a rapid three- to fivefold increase in PDHK activity in human skeletal muscle. The increased PDHK activity downregulated the amount of PDH in its active form at rest and decreased carbohydrate metabolism. However, an increase in the activities of enzymes involved in fatty acid oxidation did not occur.

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