scholarly journals Regulation of the Growth of Multinucleated Muscle Cells by an Nfatc2-Dependent Pathway

2001 ◽  
Vol 153 (2) ◽  
pp. 329-338 ◽  
Author(s):  
Valerie Horsley ◽  
Bret B. Friday ◽  
Sarah Matteson ◽  
Kristy Miller Kegley ◽  
Jonathan Gephart ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Muscle Size ◽  
Growth Defect ◽  
Activated T Cells ◽  
Cross Sectional ◽  
Development And Differentiation ◽  
Muscle Cultures

The nuclear factor of activated T cells (NFAT) family of transcription factors regulates the development and differentiation of several tissue types. Here, we examine the role of NFATC2 in skeletal muscle by analyzing adult NFATC2−/− mice. These mice exhibit reduced muscle size due to a decrease in myofiber cross-sectional area, suggesting that growth is blunted. Muscle growth was examined during regeneration after injury, wherein NFATC2-null myofibers form normally but display impaired growth. The growth defect is intrinsic to muscle cells, since the lack of NFATC2 in primary muscle cultures results in reduced cell size and myonuclear number in myotubes. Retroviral-mediated expression of NFATC2 in the mutant cells rescues this cellular phenotype. Myonuclear number is similarly decreased in NFATC2−/− mice. Taken together, these results implicate a novel role for NFATC2 in skeletal muscle growth. We demonstrate that during growth of multinucleated muscle cells, myoblasts initially fuse to form myotubes with a limited number of nuclei and that subsequent nuclear addition and increases in myotube size are controlled by a molecular pathway regulated by NFATC2.

scholarly journals FGF-2–dependent signaling activated in aged human skeletal muscle promotes intramuscular adipogenesis

2021 ◽  
Vol 118 (37) ◽  
pp. e2021013118 ◽  
Author(s):  
Sebastian Mathes ◽  
Alexandra Fahrner ◽  
Umesh Ghoshdastider ◽  
Hannes A. Rüdiger ◽  
Michael Leunig ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transcriptional Activation ◽  
Human Skeletal Muscle ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Adeno Associated Virus ◽  
Adult Skeletal Muscle

Aged skeletal muscle is markedly affected by fatty muscle infiltration, and strategies to reduce the occurrence of intramuscular adipocytes are urgently needed. Here, we show that fibroblast growth factor-2 (FGF-2) not only stimulates muscle growth but also promotes intramuscular adipogenesis. Using multiple screening assays upstream and downstream of microRNA (miR)-29a signaling, we located the secreted protein and adipogenic inhibitor SPARC to an FGF-2 signaling pathway that is conserved between skeletal muscle cells from mice and humans and that is activated in skeletal muscle of aged mice and humans. FGF-2 induces the miR-29a/SPARC axis through transcriptional activation of FRA-1, which binds and activates an evolutionary conserved AP-1 site element proximal in the miR-29a promoter. Genetic deletions in muscle cells and adeno-associated virus–mediated overexpression of FGF-2 or SPARC in mouse skeletal muscle revealed that this axis regulates differentiation of fibro/adipogenic progenitors in vitro and intramuscular adipose tissue (IMAT) formation in vivo. Skeletal muscle from human donors aged >75 y versus <55 y showed activation of FGF-2–dependent signaling and increased IMAT. Thus, our data highlights a disparate role of FGF-2 in adult skeletal muscle and reveals a pathway to combat fat accumulation in aged human skeletal muscle.

scholarly journals The Possible Role of Complete Loss of Myostatin in Limiting Excessive Proliferation of Muscle Cells (C2C12) via Activation of MicroRNAs

2019 ◽  
Vol 20 (3) ◽  
pp. 643 ◽  
Author(s):  
Peixuan Huang ◽  
Daxin Pang ◽  
Kankan Wang ◽  
Aishi Xu ◽  
Chaogang Yao ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Muscle Growth ◽  
Interaction Network ◽  
Muscle Cells ◽  
Complete Loss ◽  
Skeletal Muscle Growth ◽  
Excessive Proliferation ◽  
Mouse Myoblast

Myostatin (MSTN) is a member of the TGF-β superfamily that negatively regulates skeletal muscle growth and differentiation. However, the mechanism by which complete MSTN deletion limits excessive proliferation of muscle cells remains unclear. In this study, we knocked out MSTN in mouse myoblast lines using a Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR/Cas9) system and sequenced the mRNA and miRNA transcriptomes. The results show that complete loss of MSTN upregulates seven miRNAs targeting an interaction network composed of 28 downregulated genes, including TGFB1, FOS and RB1. These genes are closely associated with tumorigenesis and cell proliferation. Our study suggests that complete loss of MSTN may limit excessive cell proliferation via activation of miRNAs. These data will contribute to the treatment of rhabdomyosarcoma (RMS).

Calcineurin differentially regulates maintenance and growth of phenotypically distinct muscles

2002 ◽  
Vol 282 (5) ◽  
pp. C984-C992 ◽  
Author(s):  
Patrick O. Mitchell ◽  
Stephen T. Mills ◽  
Grace K. Pavlath
Keyword(s):  
Skeletal Muscle ◽  
Cyclosporin A ◽  
Human Health ◽  
Muscle Growth ◽  
Growth Conditions ◽  
Muscle Size ◽  
Molecular Pathways ◽  
Adult Skeletal Muscle ◽  
Growth Differential

Adequate muscle mass is critical for human health. The molecular pathways regulating maintenance and growth of adult skeletal muscle are little understood. Calcineurin (CN) is implicated as a key signaling molecule in hypertrophy. Whether CN is involved in all forms of muscle growth or in different muscles is unknown. Here, we examine the role of CN in regulating maintenance of muscle size and growth of atrophied muscle in the soleus (slow) and plantaris (fast). The CN inhibitor cyclosporin A (CsA) differentially affects muscle growth and maintenance depending on muscle phenotype. The plantaris is more severely affected by CsA than the soleus in both growth conditions. One-week vs. 2-wk CsA treatment suggests that both CN-dependent and CN-independent growth occur in the atrophied soleus, whereas plantaris growth appears to be totally CN dependent. Our results suggest that CN regulates multiple types of muscle growth, depending both on muscle phenotype and stage of myofiber growth. Differential expression of components of the CN pathway occurs and may contribute to the differences between muscles.

scholarly journals Prostaglandin F2α stimulates growth of skeletal muscle cells via an NFATC2-dependent pathway

2003 ◽  
Vol 161 (1) ◽  
pp. 111-118 ◽  
Author(s):  
Valerie Horsley ◽  
Grace K. Pavlath
Keyword(s):  
Skeletal Muscle ◽  
Cell Growth ◽  
Cell Size ◽  
Muscle Cell ◽  
Muscle Growth ◽  
Prostaglandin F2α ◽  
Muscle Cells ◽  
Receptor Activation ◽  
Activated T Cells ◽  
Fp Receptor

Skeletal muscle growth requires multiple steps to form large multinucleated muscle cells. Molecules that stimulate muscle growth may be therapeutic for muscle loss associated with aging, injury, or disease. However, few factors are known to increase muscle cell size. We demonstrate that prostaglandin F2α (PGF2α) as well as two analogues augment muscle cell size in vitro. This increased myotube size is not due to PGF2α-enhancing cell fusion that initially forms myotubes, but rather to PGF2α recruiting the fusion of cells with preexisting multinucleated cells. This growth is mediated through the PGF2α receptor (FP receptor). As the FP receptor can increase levels of intracellular calcium, the involvement of the calcium-regulated transcription factor nuclear factor of activated T cells (NFAT) in mediating PGF2α-enhanced cell growth was examined. We show that NFAT is activated by PGF2α, and the isoform NFATC2 is required for PGF2α-induced muscle cell growth and nuclear accretion, demonstrating the first intersection between prostaglandin receptor activation and NFAT signaling. Given this novel role for PGF2α in skeletal muscle cell growth, these studies raise caution that extended use of drugs that inhibit PG production, such as nonsteroidal antiinflammatory drugs, may be deleterious for muscle growth.

scholarly journals The Recent Understanding of the Neurotrophin's Role in Skeletal Muscle Adaptation

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Kunihiro Sakuma ◽  
Akihiko Yamaguchi
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Disorders ◽  
Muscle Fibers ◽  
Brain Disorders ◽  
Muscle Adaptation ◽  
Bdnf Mrna ◽  
Pathological Conditions ◽  
Development And Differentiation ◽  
And Function

This paper summarizes the various effects of neurotrophins in skeletal muscle and how these proteins act as potential regulators of the maintenance, function, and regeneration of skeletal muscle fibers. Increasing evidence suggests that this family of neurotrophic factors influence not only the survival and function of innervating motoneurons but also the development and differentiation of myoblasts and muscle fibers. Muscle contractions (e.g., exercise) produce BDNF mRNA and protein in skeletal muscle, and the BDNF seems to play a role in enhancing glucose metabolism and may act for myokine to improve various brain disorders (e.g., Alzheimer's disease and major depression). In adults with neuromuscular disorders, variations in neurotrophin expression are found, and the role of neurotrophins under such conditions is beginning to be elucidated. This paper provides a basis for a better understanding of the role of these factors under such pathological conditions and for treatment of human neuromuscular disease.

IL-4 and IL-13 upregulate arginase I expression by cAMP and JAK/STAT6 pathways in vascular smooth muscle cells

2000 ◽  
Vol 279 (1) ◽  
pp. C248-C256 ◽  
Author(s):  
Liu Hua Wei ◽  
Aaron T. Jacobs ◽  
Sidney M. Morris ◽  
Louis J. Ignarro
Keyword(s):  
Cell Proliferation ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Protein Levels ◽  
Ifn Γ ◽  
Arginase Ii ◽  
Arginase I

The objectives of this study were to determine whether rat aortic smooth muscle cells (RASMC) express arginase and to elucidate the possible mechanisms involved in the regulation of arginase expression. The results show that RASMC contain basal arginase I (AI) activity, which is significantly enhanced by stimulating the cells with either interleukin (IL)-4 or IL-13, but arginase II (AII) expression was not detected under any condition studied here. We further investigated the signal transduction pathways responsible for AI induction. AI mRNA and protein levels were enhanced by addition of forskolin (1 μM) and inhibited by H-89 (30 μM), suggesting positive regulation of AI by a protein kinase A pathway. Genistein (10 μg/ml) and sodium orthovanadate (Na3VO4; 10 μM) were used to investigate the role of tyrosine phosphorylation in the control of AI expression. Genistein inhibited, whereas Na3VO4enhanced the induction of AI by IL-4 or IL-13. Along with immunoprecipitation and immunoblot analyses, these data implicate the JAK/STAT6 pathway in AI regulation. Dexamethasone (Dex) and interferon (IFN)-γ were investigated for their effects on AI induction. Dex (1 μM) and IFN-γ (100 U/ml) alone had no effect on basal AI expression in RASMC, but both reduced AI induction by IL-4 and IL-13. In combination, Dex and IFN-γ abolished AI induction by IL-4 and IL-13. Finally, both IL-4 and IL-13 significantly increased RASMC DNA synthesis as monitored by [3H]thymidine incorporation, demonstrating that upregulation of AI is correlated with an increase in cell proliferation. Blockade of AI induction by IFN-γ, H-89, or genistein also blocked the increase in cell proliferation. These observations are consistent with the possibility that upregulation of AI might play an important role in the pathophysiology of vascular disorders characterized by excessive smooth muscle growth.

scholarly journals Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis

2020 ◽  
Author(s):  
Emma L Watson ◽  
Thomas J Wilkinson ◽  
Tom F O’Sullivan ◽  
Luke A Baker ◽  
Douglas W Gould ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Vitamin D ◽  
Vitamin D Deficiency ◽  
Exercise Capacity ◽  
Muscle Mass ◽  
Ex Vivo ◽  
Muscle Size ◽  
Cross Sectional ◽  
Cross Sectional Analysis ◽  
Sectional Analysis

AbstractEvidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients. This is a secondary cross-sectional analysis of previously published interventional study, with ex vivo follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3ml/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n=20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors. In vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with was seen with the total form. Ex vivo, 1α,25(OH)2D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter. This early preliminary work suggests that vitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.

scholarly journals Expression Levels of Long Non-Coding RNAs Change in Models of Altered Muscle Activity and Muscle Mass

2020 ◽  
Vol 21 (5) ◽  
pp. 1628 ◽  
Author(s):  
Keisuke Hitachi ◽  
Masashi Nakatani ◽  
Shiori Funasaki ◽  
Ikumi Hijikata ◽  
Mizuki Maekawa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Skeletal Muscle Mass ◽  
Muscle Size ◽  
Skeletal Muscle Atrophy ◽  
Myostatin Gene ◽  
Expression Levels ◽  
Non Coding Rnas

Skeletal muscle is a highly plastic organ that is necessary for homeostasis and health of the human body. The size of skeletal muscle changes in response to intrinsic and extrinsic stimuli. Although protein-coding RNAs including myostatin, NF-κβ, and insulin-like growth factor-1 (IGF-1), have pivotal roles in determining the skeletal muscle mass, the role of long non-coding RNAs (lncRNAs) in the regulation of skeletal muscle mass remains to be elucidated. Here, we performed expression profiling of nine skeletal muscle differentiation-related lncRNAs (DRR, DUM1, linc-MD1, linc-YY1, LncMyod, Neat1, Myoparr, Malat1, and SRA) and three genomic imprinting-related lncRNAs (Gtl2, H19, and IG-DMR) in mouse skeletal muscle. The expression levels of these lncRNAs were examined by quantitative RT-PCR in six skeletal muscle atrophy models (denervation, casting, tail suspension, dexamethasone-administration, cancer cachexia, and fasting) and two skeletal muscle hypertrophy models (mechanical overload and deficiency of the myostatin gene). Cluster analyses of these lncRNA expression levels were successfully used to categorize the muscle atrophy models into two sub-groups. In addition, the expression of Gtl2, IG-DMR, and DUM1 was altered along with changes in the skeletal muscle size. The overview of the expression levels of lncRNAs in multiple muscle atrophy and hypertrophy models provides a novel insight into the role of lncRNAs in determining the skeletal muscle mass.

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