scholarly journals Overload-mediated skeletal muscle hypertrophy is not impaired by loss of myofiber STAT3

2017 ◽  
Vol 313 (3) ◽  
pp. C257-C261 ◽  
Author(s):  
Joaquín Pérez-Schindler ◽  
Mary C. Esparza ◽  
James McKendry ◽  
Leigh Breen ◽  
Andrew Philp ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Signal Pathways ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Adaptive Growth ◽  
Stat3 Phosphorylation ◽  
Transcription 3

Although the signal pathways mediating muscle protein synthesis and degradation are well characterized, the transcriptional processes modulating skeletal muscle mass and adaptive growth are poorly understood. Recently, studies in mouse models of muscle wasting or acutely exercised human muscle have suggested a potential role for the transcription factor signal transducer and activator of transcription 3 (STAT3), in adaptive growth. Hence, in the present study we sought to define the contribution of STAT3 to skeletal muscle adaptive growth. In contrast to previous work, two different resistance exercise protocols did not change STAT3 phosphorylation in human skeletal muscle. To directly address the role of STAT3 in load-induced (i.e., adaptive) growth, we studied the anabolic effects of 14 days of synergist ablation (SA) in skeletal muscle-specific STAT3 knockout (mKO) mice and their floxed, wild-type (WT) littermates. Plantaris muscle weight and fiber area in the nonoperated leg (control; CON) was comparable between genotypes. As expected, SA significantly increased plantaris weight, muscle fiber cross-sectional area, and anabolic signaling in WT mice, although interestingly, this induction was not impaired in STAT3 mKO mice. Collectively, these data demonstrate that STAT3 is not required for overload-mediated hypertrophy in mouse skeletal muscle.

scholarly journals Advances in the Role of Leucine-Sensing in the Regulation of Protein Synthesis in Aging Skeletal Muscle

2021 ◽  
Vol 9 ◽  
Author(s):  
Yan Zhao ◽  
Jason Cholewa ◽  
Huayu Shang ◽  
Yueqin Yang ◽  
Xiaomin Ding ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Therapeutic Potential ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Trna Synthetase ◽  
Limiting Factor ◽  
Anabolic Resistance ◽  
Age Related

Skeletal muscle anabolic resistance (i.e., the decrease in muscle protein synthesis (MPS) in response to anabolic stimuli such as amino acids and exercise) has been identified as a major cause of age-related sarcopenia, to which blunted nutrition-sensing contributes. In recent years, it has been suggested that a leucine sensor may function as a rate-limiting factor in skeletal MPS via small-molecule GTPase. Leucine-sensing and response may therefore have important therapeutic potential in the steady regulation of protein metabolism in aging skeletal muscle. This paper systematically summarizes the three critical processes involved in the leucine-sensing and response process: (1) How the coincidence detector mammalian target of rapamycin complex 1 localizes on the surface of lysosome and how its crucial upstream regulators Rheb and RagB/RagD interact to modulate the leucine response; (2) how complexes such as Ragulator, GATOR, FLCN, and TSC control the nucleotide loading state of Rheb and RagB/RagD to modulate their functional activity; and (3) how the identified leucine sensor leucyl-tRNA synthetase (LARS) and stress response protein 2 (Sestrin2) participate in the leucine-sensing process and the activation of RagB/RagD. Finally, we discuss the potential mechanistic role of exercise and its interactions with leucine-sensing and anabolic responses.

Beyond muscle hypertrophy: why dietary protein is important for endurance athletes

2014 ◽  
Vol 39 (9) ◽  
pp. 987-997 ◽  
Author(s):  
Daniel R. Moore ◽  
Donny M. Camera ◽  
Jose L. Areta ◽  
John A. Hawley
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Dietary Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Recovery Period ◽  
Essential Element ◽  
Skeletal Muscle Protein ◽  
Muscle Remodelling

Recovery from the demands of daily training is an essential element of a scientifically based periodized program whose twin goals are to maximize training adaptation and enhance performance. Prolonged endurance training sessions induce substantial metabolic perturbations in skeletal muscle, including the depletion of endogenous fuels and damage/disruption to muscle and body proteins. Therefore, increasing nutrient availability (i.e., carbohydrate and protein) in the post-training recovery period is important to replenish substrate stores and facilitate repair and remodelling of skeletal muscle. It is well accepted that protein ingestion following resistance-based exercise increases rates of skeletal muscle protein synthesis and potentiates gains in muscle mass and strength. To date, however, little attention has focused on the ability of dietary protein to enhance skeletal muscle remodelling and stimulate adaptations that promote an endurance phenotype. The purpose of this review is to critically discuss the results of recent studies that have examined the role of dietary protein for the endurance athlete. Our primary aim is to consider the results from contemporary investigations that have advanced our knowledge of how the manipulation of dietary protein (i.e., amount, type, and timing of ingestion) can facilitate muscle remodelling by promoting muscle protein synthesis. We focus on the role of protein in facilitating optimal recovery from, and promoting adaptations to strenuous endurance-based training.

scholarly journals Exercise-Induced Muscle Damage and Hypertrophy: A Closer Look Reveals the Jury is Still Out

2018 ◽  
Author(s):  
Brad Jon Schoenfeld ◽  
Bret Contreras
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Training ◽  
Muscle Damage ◽  
Muscle Hypertrophy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Hypertrophy ◽  
Exercise Induced

This letter is a response to the paper by Damas et al (2017) titled, “The development of skeletal muscle hypertrophy through resistance training: the role of muscle damage and muscle protein synthesis,” which, in part, endeavored to review the role of exercise-induced muscle damage on muscle hypertrophy. We feel there are a number of issues in interpretation of research and extrapolation that preclude drawing the inference expressed in the paper that muscle damage neither explains nor potentiates increases in muscle hypertrophy. The intent of our letter is not to suggest that a causal role exists between hypertrophy and microinjury. Rather, we hope to provide balance to the evidence presented and offer the opinion that the jury is still very much out as to providing answers on the topic.

scholarly journals MicroRNAs in Skeletal Muscle and Hints on Their Potential Role in Muscle Wasting During Cancer Cachexia

2020 ◽  
Vol 10 ◽  
Author(s):  
Gioacchino P. Marceca ◽  
Giovanni Nigita ◽  
Federica Calore ◽  
Carlo M. Croce
Keyword(s):  
Skeletal Muscle ◽  
Cancer Cachexia ◽  
Muscle Wasting ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Phenotypic Alteration ◽  
Specific Tumor ◽  
Non Coding Rnas

Cancer-associated cachexia is a heterogeneous, multifactorial syndrome characterized by systemic inflammation, unintentional weight loss, and profound alteration in body composition. The main feature of cancer cachexia is represented by the loss of skeletal muscle tissue, which may or may not be accompanied by significant adipose tissue wasting. Such phenotypic alteration occurs as the result of concomitant increased myofibril breakdown and reduced muscle protein synthesis, actively contributing to fatigue, worsening of quality of life, and refractoriness to chemotherapy. According to the classical view, this condition is primarily triggered by interactions between specific tumor-induced pro-inflammatory cytokines and their cognate receptors expressed on the myocyte membrane. This causes a shift in gene expression of muscle cells, eventually leading to a pronounced catabolic condition and cell death. More recent studies, however, have shown the involvement of regulatory non-coding RNAs in the outbreak of cancer cachexia. In particular, the role exerted by microRNAs is being widely addressed, and several mechanistic studies are in progress. In this review, we discuss the most recent findings concerning the role of microRNAs in triggering or exacerbating muscle wasting in cancer cachexia, while mentioning about possible roles played by long non-coding RNAs and ADAR-mediated miRNA modifications.

scholarly journals Ribosome biogenesis adaptation in resistance training-induced human skeletal muscle hypertrophy

2015 ◽  
Vol 309 (1) ◽  
pp. E72-E83 ◽  
Author(s):  
Vandre C. Figueiredo ◽  
Marissa K. Caldow ◽  
Vivien Massie ◽  
James F. Markworth ◽  
David Cameron-Smith ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Training ◽  
Ribosome Biogenesis ◽  
Muscle Hypertrophy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
D1 Protein ◽  
Transcriptional Level ◽  
Cross Sectional ◽  
Before And After

Resistance training (RT) has the capacity to increase skeletal muscle mass, which is due in part to transient increases in the rate of muscle protein synthesis during postexercise recovery. The role of ribosome biogenesis in supporting the increased muscle protein synthetic demands is not known. This study examined the effect of both a single acute bout of resistance exercise (RE) and a chronic RT program on the muscle ribosome biogenesis response. Fourteen healthy young men performed a single bout of RE both before and after 8 wk of chronic RT. Muscle cross-sectional area was increased by 6 ± 4.5% in response to 8 wk of RT. Acute RE-induced activation of the ERK and mTOR pathways were similar before and after RT, as assessed by phosphorylation of ERK, MNK1, p70S6K, and S6 ribosomal protein 1 h postexercise. Phosphorylation of TIF-IA was also similarly elevated following both RE sessions. Cyclin D1 protein levels, which appeared to be regulated at the translational rather than transcriptional level, were acutely increased after RE. UBF was the only protein found to be highly phosphorylated at rest after 8 wk of training. Also, muscle levels of the rRNAs, including the precursor 45S and the mature transcripts (28S, 18S, and 5.8S), were increased in response to RT. We propose that ribosome biogenesis is an important yet overlooked event in RE-induced muscle hypertrophy that warrants further investigation.

scholarly journals The Role of the IGF-1 Signaling Cascade in Muscle Protein Synthesis and Anabolic Resistance in Aging Skeletal Muscle

2019 ◽  
Vol 6 ◽  
Author(s):  
Richie D. Barclay ◽  
Nicholas A. Burd ◽  
Christopher Tyler ◽  
Neale A. Tillin ◽  
Richard W. Mackenzie
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Signaling Cascade ◽  
Anabolic Resistance

scholarly journals Precocious glucocorticoid exposure reduces skeletal muscle satellite cells in the fetal rat

2017 ◽  
Vol 232 (3) ◽  
pp. 561-572 ◽  
Author(s):  
Ganga Gokulakrishnan ◽  
Xiaoyan Chang ◽  
Ryan Fleischmann ◽  
Marta L Fiorotto
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cell ◽  
Progenitor Cell ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Pregnant Rats ◽  
Cross Sectional ◽  
Muscle Progenitor Cell ◽  
Fetal Muscle

Perinatal skeletal muscle growth rates are a function of protein and myonuclear accretion. Precocious exposure of the fetus to glucocorticoids (GLC) in utero impairs muscle growth. Reduced muscle protein synthesis rates contribute to this response, but the consequences for myonuclear hyperplasia are unknown. To test the hypothesis that blunting of Pax7+ muscle progenitor cell proliferative activity by GLC in vivo also contributes to reduced fetal muscle growth, pregnant rats were administered dexamethasone (DEX: 1 mg/L drinking water) from embryonic day (ED) 13 to ED21. Their responses were compared to pair-fed (PF) and ad libitum-fed controls (CON). Bromodeoxyuridine (BrdU) was administered before delivery to measure myonuclear accretion. Fetal hind limb and diaphragm muscles were collected at term and analyzed for myofiber cross-sectional area (CSA), total and BrdU+ myonuclei, Pax7+ nuclei, MyoD and myogenin protein and mRNA abundance and myosin heavy chain (MyHC) isoform composition. Mean fiber CSA, myonuclei/myofiber and Pax7+ nuclei/myofiber ratios were reduced in DEX compared to those in CON and PF muscles; CSA/myonucleus, BrdU+/total myonuclei and BrdU+ myonuclei/Pax7+ nuclei were similar among groups. Myogenin abundance was reduced and MyHC-slow was increased in DEX fetuses. The data are consistent with GLC inhibition of muscle progenitor cell proliferation limiting satellite cell and myonuclear accretion. The response of PF-fed compared to CON muscles indicated that decreased food consumption by DEX dams contributed to the smaller myofiber CSA but did not affect Pax7+ nuclear accretion. Thus, the effect on satellite cell reserve and myonuclear number also contributes to the blunting of fetal muscle growth by GLC.

Sign in / Sign up

Export Citation Format

Share Document