The impact of a 48-h fast on SIRT1 and GCN5 in human skeletal muscle

The present study examined the impact of a 48 h fast on the expression and activation status of SIRT1 and GCN5, the relationship between SIRT1/GCN5 and the gene expression of PGC-1α, and the PGC-1α target PDK4 in the skeletal muscle of 10 lean healthy men (age, 22.0 ± 1.5 years; peak oxygen uptake, 47.2 ± 6.7 mL/(min·kg)). Muscle biopsies and blood samples were collected 1 h postprandial (Fed) and following 48 h of fasting (Fasted). Plasma insulin (Fed, 80.8 ± 47.9 pmol/L; Fasted, not detected) and glucose (Fed, 4.36 ± 0.86; Fasted, 3.74 ± 0.25 mmol/L, p = 0.08) decreased, confirming participant adherence to fasting. Gene expression of PGC-1α decreased (p < 0.05, –24%), while SIRT1 and PDK4 increased (p < 0.05, +11% and +1023%, respectively), and GCN5 remained unchanged. No changes were observed for whole-muscle protein expression of SIRT1, GCN5, PGC-1α, or COX IV. Phosphorylation of SIRT1, AMPKα, ACC, p38 MAPK, and PKA substrates as well as nuclear acetylation status was also unaltered. Additionally, nuclear SIRT1 activity, GCN5, and PGC-1α content remained unchanged. Preliminary findings derived from regression analysis demonstrate that changes in nuclear GCN5 and SIRT1 activity/phosphorylation may contribute to the control of PGC-1α, but not PDK4, messenger RNA expression following fasting. Collectively, and in contrast with previous animal studies, our data are inconsistent with the altered activation status of SIRT1 and GCN5 in response to 48 h of fasting in human skeletal muscle.

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Effect of Local Cold Application During Exercise on Gene Expression Related to Mitochondrial Homeostasis

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2020-0387 ◽

2020 ◽

Author(s):

Ben Meister ◽

Christopher Collins ◽

Mark L McGlynn ◽

Dustin Russel Slivka

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Inhibitory Effect ◽

Local Cooling ◽

Cold Environments ◽

Mitochondrial Homeostasis ◽

Muscle Cooling ◽

Exercise Induced ◽

The Impact

Exercise training increases mitochondrial content in active skeletal muscle. Previous work suggests that mitochondrial-related genes respond favorably to exercise in cold environments. However, the impact of localized tissue cooling is unknown. The purpose is to determine the impact of local muscle cooling during endurance exercise on human skeletal muscle mitochondrial-related gene expression. Twelve subjects (age 28±6 y) cycled at 65% Wpeak. One leg was cooled (C) for 30 minutes before and during exercise with a thermal wrap while the other leg was wrapped but not cooled, room temperature (RT). Muscle biopsies were taken from each VL before and 4 hours post-exercise for the analysis of gene expression. Muscle temperature was lower in C (29.2±0.7°C) than RT (34.1±0.3°C) after pre-cooling for 30 minutes before exercise (p<0.001) and remained lower after exercise in C (36.9±0.5) than RT (38.4±0.2, p<0.001). PGC-1α and NRF1 mRNA expression were lower in C (p=0.012 and p=0.045, respectively) than RT at 4-h post. There were no temperature related differences in other genes (p>0.05). These data suggest that local cooling has an inhibitory effect on exercise-induced PGC-1α and NRF1 expression in human skeletal muscle. Those considering using local cooling during exercise should consider other systemic cooling options. Novelty Bullets • Local cooling has an inhibitory effect on exercise-induced PGC-1α and NRF1 expression in human skeletal muscle. • Local cooling may lead to a less robust exercise stimulus compared to standard conditions.

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Knockdown of the E3 Ubiquitin ligase UBR5 and its role in skeletal muscle anabolism

10.1101/2020.06.05.116145 ◽

2020 ◽

Cited By ~ 2

Author(s):

Daniel C. Turner ◽

David C. Hughes ◽

Leslie M. Baehr ◽

Robert A. Seaborne ◽

Mark Viggars ◽

...

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Muscle Mass ◽

Ubiquitin Ligase ◽

Muscle Protein ◽

E3 Ubiquitin Ligase ◽

Skeletal Muscle Atrophy ◽

Human Myotubes ◽

The Impact

AbstractUBR5 is an E3-ubiquitin-ligase positively associated with anabolism, hypertrophy and recovery from atrophy in skeletal muscle. The precise mechanisms underpinning UBR5’s role in the regulation of skeletal muscle mass remain unknown. The present study aimed to elucidate these mechanisms by silencing the UBR5 gene in-vitro and in-vivo. The siRNA-induced reduction (−77%) in UBR5 gene expression in human myotubes was prevented by mechanical loading, suggesting that UBR5 gene expression may be regulated via mechano-transduction signalling. Therefore, we electroporated a UBR5-RNAi plasmid into mouse tibialis anterior muscle in-vivo to investigate the impact of reduced UBR5 on mechano-transduction signalling MEK/ERK/p90RSK and Akt/p70S6K/4E-BP1/rpS6 pathways. Seven days post UBR5 RNAi electroporation, while reductions in overall muscle mass were not detected, mean CSA of GFP-positive fibers was reduced (−9.5%) and the number of large fibers was lower versus the control. Importantly, UBR5-RNAi significantly reduced total RNA, muscle protein synthesis, ERK1/2 and Akt phosphorylation. Whilst p90RSK phosphorylation significantly increased, total p90RSK protein levels demonstrated a 45% reduction with UBR5-RNAi. Finally, these early signalling events after 7 days of UBR5 knockdown culminated in significant reductions in muscle mass (−4.6%) and larger reductions in fiber CSA (−18.5%) after 30 days. This was associated with increased levels of the phosphatase, PP2Ac, and inappropriate chronic elevation of p70S6K and rpS6 between 7 and 30 days, and corresponding reductions in eIF4e. This study demonstrates UBR5 plays an important role in anabolism/hypertrophy, whereby knockdown of UBR5 culminates in skeletal muscle atrophy.

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Faculty Opinions recommendation of Age influences DNA methylation and gene expression of COX7A1 in human skeletal muscle.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1116308.572315 ◽

2008 ◽

Author(s):

Kyong Soo Park ◽

Soo Heon Kwak

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Dna Methylation ◽

Human Skeletal Muscle

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Exercise training increases branched-chain oxoacid dehydrogenase kinase content in human skeletal muscle

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00115.2007 ◽

2007 ◽

Vol 293 (3) ◽

pp. R1335-R1341 ◽

Cited By ~ 18

Author(s):

Krista R. Howarth ◽

Kirsten A. Burgomaster ◽

Stuart M. Phillips ◽

Martin J. Gibala

Keyword(s):

Skeletal Muscle ◽

Exercise Training ◽

Protein Content ◽

Human Skeletal Muscle ◽

Acute Exercise ◽

Citrate Synthase ◽

Muscle Protein ◽

Moderate Intensity ◽

Main Effect ◽

Branched Chain

The branched-chain oxoacid dehydrogenase complex (BCOAD) is rate determining for the oxidation of branched-chain amino acids (BCAAs) in skeletal muscle. Exercise training blunts the acute exercise-induced activation of BCOAD (BCOADa) in human skeletal muscle (McKenzie S, Phillips SM, Carter SL, Lowther S, Gibala MJ, Tarnopolsky MA. Am J Physiol Endocrinol Metab 278: E580–E587, 2000); however, the mechanism is unknown. We hypothesized that training would increase the muscle protein content of BCOAD kinase, the enzyme responsible for inactivation of BCOAD by phosphorylation. Twenty subjects [23 ± 1 yr; peak oxygen uptake (V̇o2peak) = 41 ± 2 ml·kg−1·min−1] performed 6 wk of either high-intensity interval or continuous moderate-intensity training on a cycle ergometer ( n = 10/group). Before and after training, subjects performed 60 min of cycling at 65% of pretraining V̇o2peak, and needle biopsy samples (vastus lateralis) were obtained before and immediately after exercise. The effect of training was demonstrated by an increased V̇o2peak, increased citrate synthase maximal activity, and reduced muscle glycogenolysis during exercise, with no difference between groups (main effects, P < 0.05). BCOADa was lower after training (main effect, P < 0.05), and this was associated with a ∼30% increase in BCOAD kinase protein content (main effect, P < 0.05). We conclude that the increased protein content of BCOAD kinase may be involved in the mechanism for reduced BCOADa after exercise training in human skeletal muscle. These data also highlight differences in models used to study the regulation of skeletal muscle BCAA metabolism, since exercise training was previously reported to increase BCOADa during exercise and decrease BCOAD kinase content in rats (Fujii H, Shimomura Y, Murakami T, Nakai N, Sato T, Suzuki M, Harris RA. Biochem Mol Biol Int 44: 1211–1216, 1998).

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Promoter-specific regulation of PPARGC1A gene expression in human skeletal muscle

Journal of Molecular Endocrinology ◽

10.1530/jme-15-0150 ◽

2015 ◽

Vol 55 (2) ◽

pp. 159-168 ◽

Cited By ~ 12

Author(s):

Daniil V Popov ◽

Evgeny A Lysenko ◽

Tatiana F Vepkhvadze ◽

Nadia S Kurochkina ◽

Pavel A Maknovskii ◽

...

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Human Skeletal Muscle ◽

Stop Codon ◽

Constitutive Expression ◽

Alternative Promoter ◽

Specific Expression ◽

Post Exercise ◽

Specific Regulation ◽

Intensity Of Exercise

The goal of this study was to identify unknown transcription start sites of thePPARGC1A(PGC-1α) gene in human skeletal muscle and investigate the promoter-specific regulation ofPGC-1αgene expression in human skeletal muscle. Ten amateur endurance-trained athletes performed high- and low-intensity exercise sessions (70 min, 70% or 50%o2max). High-throughput RNA sequencing and exon–exon junction mapping were applied to analyse muscle samples obtained at rest and after exercise.PGC-1αpromoter-specific expression and activation of regulators of PGC-1α gene expression (AMPK, p38 MAPK, CaMKII, PKA and CREB1) after exercise were evaluated using qPCR and western blot. Our study has demonstrated that during post-exercise recovery, human skeletal muscle expresses thePGC-1αgene via two promoters only. As previously described, the additional exon 7a that contains a stop codon was found in all samples. Importantly, only minor levels of other splice site variants were found (and not in all samples). Constitutive expressionPGC-1αgene occurs via the canonical promoter, independent of exercise intensity and exercise-induced increase of AMPKThr172phosphorylation level. Expression ofPGC-1αgene via the alternative promoter is increased of two orders after exercise. This post-exercise expression is highly dependent on the intensity of exercise. There is an apparent association between expression via the alternative promoter and activation of CREB1.

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Regulation of PPARGC1A gene expression in trained and untrained human skeletal muscle

Physiological Reports ◽

10.14814/phy2.13543 ◽

2017 ◽

Vol 5 (23) ◽

pp. e13543 ◽

Cited By ~ 8

Author(s):

Daniil V. Popov ◽

Evgeny A. Lysenko ◽

Pavel A. Makhnovskii ◽

Nadia S. Kurochkina ◽

Olga L. Vinogradova

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Human Skeletal Muscle

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Sex-Related Differences in Gene Expression in Human Skeletal Muscle

PLoS ONE ◽

10.1371/journal.pone.0001385 ◽

2008 ◽

Vol 3 (1) ◽

pp. e1385 ◽

Cited By ~ 79

Author(s):

Stephen Welle ◽

Rabi Tawil ◽

Charles A. Thornton

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Human Skeletal Muscle

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Knockdown of the E3 ubiquitin ligase UBR5 and its role in skeletal muscle anabolism

AJP Cell Physiology ◽

10.1152/ajpcell.00432.2020 ◽

2021 ◽

Vol 320 (1) ◽

pp. C45-C56

Author(s):

David C. Hughes ◽

Daniel C. Turner ◽

Leslie M. Baehr ◽

Robert A. Seaborne ◽

Mark Viggars ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Ubiquitin Ligase ◽

Fluorescent Protein ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Tibialis Anterior Muscle ◽

E3 Ubiquitin Ligase ◽

Skeletal Muscle Atrophy ◽

The Impact

UBR5 is an E3 ubiquitin ligase positively associated with anabolism, hypertrophy, and recovery from atrophy in skeletal muscle. The precise mechanisms underpinning UBR5’s role in the regulation of skeletal muscle mass remain unknown. The present study aimed to elucidate these mechanisms by silencing the UBR5 gene in vivo. To achieve this aim, we electroporated a UBR5-RNAi plasmid into mouse tibialis anterior muscle to investigate the impact of reduced UBR5 on anabolic signaling MEK/ERK/p90RSK and Akt/GSK3β/p70S6K/4E-BP1/rpS6 pathways. Seven days after UBR5 RNAi electroporation, although reductions in overall muscle mass were not detected, the mean cross-sectional area (CSA) of green fluorescent protein (GFP)-positive fibers were reduced (−9.5%) and the number of large fibers were lower versus the control. Importantly, UBR5-RNAi significantly reduced total RNA, muscle protein synthesis, ERK1/2, Akt, and GSK3β activity. Although p90RSK phosphorylation significantly increased, total p90RSK protein levels demonstrated a 45% reduction with UBR5-RNAi. Finally, these early events after 7 days of UBR5 knockdown culminated in significant reductions in muscle mass (−4.6%) and larger reductions in fiber CSA (−18.5%) after 30 days. This was associated with increased levels of phosphatase PP2Ac and inappropriate chronic elevation of p70S6K and rpS6 between 7 and 30 days, as well as corresponding reductions in eIF4e. This study demonstrates that UBR5 plays an important role in anabolism/hypertrophy, whereby knockdown of UBR5 culminates in skeletal muscle atrophy.

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