scholarly journals Regulation of protein synthesis associated with skeletal muscle hypertrophy by insulin-, amino acid- and exercise-induced signalling

2004 ◽  
Vol 63 (2) ◽  
pp. 351-356 ◽  
Author(s):  
Douglas R. Bolster ◽  
Leonard S. Jefferson ◽  
Scot R. Kimball
Keyword(s):  
Skeletal Muscle ◽  
Signal Transduction ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Ribosome Biogenesis ◽  
Muscle Hypertrophy ◽  
Current Knowledge ◽  
Signal Transduction Pathway ◽  
Mrna Translation ◽  
Transduction Pathway

Although insulin, amino acids and exercise individually activate multiple signal transduction pathways in skeletal muscle, one pathway, the phosphatidylinositol 3-kinase (PI3K)–mammalian target of rapamycin (mTOR) signalling pathway, is a target of all three. Activation of the PI3K–mTOR signal transduction pathway results in both acute (i.e. occurring in minutes to hours) and long-term (i.e. occurring in hours to days) up-regulation of protein synthesis through modulation of multiple steps involved in mediating the initiation of mRNA translation and ribosome biogenesis respectively. In addition, changes in gene expression through altered patterns of mRNA translation promote cell growth, which in turn promotes muscle hypertrophy. The focus of the present discussion is to review current knowledge concerning the mechanism(s) through which insulin, amino acids and resistance exercise act to activate the PI3K–mTOR signal transduction pathway and thereby enhance the rate of protein synthesis in muscle.

scholarly journals Regulation of Ribosome Biogenesis in Skeletal Muscle Hypertrophy

Physiology ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 30-42 ◽  
Author(s):  
Vandré Casagrande Figueiredo ◽  
John J. McCarthy
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Ribosome Biogenesis ◽  
Muscle Hypertrophy ◽  
Muscle Growth ◽  
Translational Efficiency ◽  
Resistance Exercise Training ◽  
Skeletal Muscle Growth ◽  
Skeletal Muscle Hypertrophy ◽  
Important Regulator

The ribosome is the enzymatic macromolecular machine responsible for protein synthesis. The rates of protein synthesis are primarily dependent on translational efficiency and capacity. Ribosome biogenesis has emerged as an important regulator of skeletal muscle growth and maintenance by altering the translational capacity of the cell. Here, we provide evidence to support a central role for ribosome biogenesis in skeletal muscle growth during postnatal development and in response to resistance exercise training. Furthermore, we discuss the cellular signaling pathways regulating ribosome biogenesis, discuss how myonuclear accretion affects translational capacity, and explore future areas of investigation within the field.

Role of Amino Acids and Peptides in the Molecular Signaling in Skeletal Muscle after Resistance Exercise

2007 ◽  
Vol 17 (s1) ◽  
pp. S47-S57 ◽  
Author(s):  
René Koopman
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Translation Initiation ◽  
Intracellular Signaling ◽  
Muscle Protein ◽  
Mrna Translation ◽  
Molecular Signaling ◽  
Stimulation Of

Resistance exercise can effectively result in an increase in muscle mass, or hypertrophy, which generally becomes apparent after several weeks of training. Muscle hypertrophy requires muscle protein synthesis to exceed protein breakdown during an extended time period. It has been firmly established that the interaction between exercise and nutrition (i.e., protein intake) is necessary to attain net protein accretion in skeletal muscle. The stimulation of protein synthesis is caused in part by stimulation of mRNA translation initiation. There is relatively little information on the response of intracellular signaling controlling mRNA translation to exercise and nutrition, especially in humans, but the available data in humans seem to suggest that a single bout of resistance exercise does not substantially enhance PI-3 kinase/mTOR signaling during the first 2 h after exercise. Moreover, it is demonstrated that the ingestion of protein or amino acids after exercise is crucial to further stimulate molecular signaling that controls translation initiation. The aim of this review is to provide an overview of the intracellular signaling related to translational control and to provide a summary of the current knowledge about the response of the signaling pathways controlling the anabolic response to exercise and nutrient intake in vivo in humans.

Translational control of c-MYC by rapamycin promotes terminal myeloid differentiation

Blood ◽  
2008 ◽  
Vol 112 (6) ◽  
pp. 2305-2317 ◽  
Author(s):  
Meaghan Wall ◽  
Gretchen Poortinga ◽  
Katherine M. Hannan ◽  
Richard B. Pearson ◽  
Ross D. Hannan ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Cell Growth ◽  
Protein Stability ◽  
Translational Control ◽  
Terminal Differentiation ◽  
Signal Transduction Pathway ◽  
Mrna Translation ◽  
Polymorphonuclear Neutrophils ◽  
Myeloid Differentiation ◽  
Transduction Pathway

Abstract c-MYC inhibits differentiation and regulates the process by which cells acquire biomass, cell growth. Down-regulation of c-MYC, reduced cell growth, and decreased activity of the PI3K/AKT/mTORC1 signal transduction pathway are features of the terminal differentiation of committed myeloid precursors to polymorphonuclear neutrophils. Since mTORC1 regulates growth, we hypothesized that pharmacological inhibition of mTORC1 by rapamycin may reverse the phenotypic effects of c-MYC. Here we show that granulocytes blocked in their ability to differentiate by enforced expression of c-MYC can be induced to differentiate by reducing exogenous c-MYC expression through rapamycin treatment. Rapamycin also reduced expression of endogenous c-MYC and resulted in enhanced retinoid-induced differentiation. Total cellular c-Myc mRNA and c-MYC protein stability were unchanged by rapamycin, however the amount of c-Myc mRNA associated with polysomes was reduced. Therefore rapamycin limited expression of c-MYC by inhibiting c-Myc mRNA translation. These findings suggest that mTORC1 could be targeted to promote terminal differentiation in myeloid malignancies characterized by dysregulated expression of c-MYC.

A purinergic signal transduction pathway in mammalian skeletal muscle cells in culture

2002 ◽  
Vol 443 (5) ◽  
pp. 731-738 ◽  
Author(s):  
Julianna Cseri ◽  
Henrietta Szappanos ◽  
Gyula Szigeti ◽  
Zoltán Csernátony ◽  
László Kovács ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Signal Transduction ◽  
Signal Transduction Pathway ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Mammalian Skeletal Muscle ◽  
Transduction Pathway ◽  
Cells In Culture

scholarly journals c-Myc overexpression increases ribosome biogenesis and protein synthesis independent of mTORC1 activation in mouse skeletal muscle

2021 ◽  
Author(s):  
Takahiro Mori ◽  
Satoru Ato ◽  
Jonas R. Knudsen ◽  
Carlos Henriquez-Olguin ◽  
Zhencheng Li ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Skeletal Muscles ◽  
Ribosome Biogenesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mrna Translation ◽  
Adeno Associated Virus ◽  
Mtorc1 Signaling ◽  
Mtorc1 Activation

High-intensity muscle contractions (HiMC) are known to increase c-Myc expression which is known to stimulate ribosome biogenesis and protein synthesis in most cells. However, while c-Myc mRNA transcription and c-Myc mRNA translation have been shown to be upregulated following resistance exercise concomitantly with increased ribosome biogenesis, this has not been tested directly. We investigated the effect of adeno-associated virus (AAV)-mediated c-Myc overexpression, with or without fasting or percutaneous electrical stimulation-induced HiMC, on ribosome biogenesis and protein synthesis in adult mouse skeletal muscles. AAV-mediated overexpression of c-Myc in mouse skeletal muscles for 2 weeks increased the DNA polymerase subunit POL1 mRNA, 45S-pre-rRNA, total RNA, and muscle protein synthesis without altering mechanistic target of rapamycin complex 1 (mTORC1) signaling under both ad libitum and fasted conditions. RNA-seq analyses revealed that c-Myc overexpression mainly regulated ribosome biogenesis-related biological processes. The protein synthesis response to c-Myc overexpression mirrored the response with HiMC. No additional effect of combining c-Myc overexpression and HiMC was observed. Our results suggest that c-Myc overexpression is sufficient to stimulate skeletal muscle ribosome biogenesis and protein synthesis without activation of mTORC1. Therefore, the HiMC-induced increase in c-Myc may contribute to ribosome biogenesis and increased protein synthesis following HiMC.

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