scholarly journals Androgen receptor polyglutamine repeat length affects receptor activity and C2C12 cell development

2011 ◽  
Vol 43 (20) ◽  
pp. 1135-1143 ◽  
Author(s):  
Ryan L. Sheppard ◽  
Espen E. Spangenburg ◽  
Eva R. Chin ◽  
Stephen M. Roth
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Androgen Receptor ◽  
Transcriptional Activity ◽  
C2c12 Cell ◽  
Repeat Length ◽  
C2c12 Cells ◽  
Expression Vectors ◽  
Polyglutamine Repeat ◽  
Fusion Index

Testosterone (T) has an anabolic effect on skeletal muscle and is believed to exert its local effects via the androgen receptor (AR). The AR harbors a polymorphic stretch of glutamine repeats demonstrated to inversely affect receptor transcriptional activity in prostate and kidney cells. The effects of AR glutamine repeat length on skeletal muscle are unknown. In this study we examined the effect of AR CAG repeat length on AR function in C2C12 cells. AR expression vectors harboring 14, 24, and 33 CAG repeats were used to assess AR transcriptional activity. C2C12 cell proliferation, differentiation, gene expression, myotube formation, and myonuclear fusion index were assessed. Transcriptional activity increased with increasing repeat length and in response to testosterone (AR14 = 3.91 ± 0.26, AR24 = 25.21 ± 1.72, AR33 = 36.08 ± 3.22 relative light units; P < 0.001). Ligand activation was increased for AR33 (2.10 ± 0.04) compared with AR14 (1.54 ± 0.09) and AR24 (1.57 ± 0.05, P < 0.001). AR mRNA expression was elevated in each stably transfected line. AR33 cell proliferation (20,512.3 ± 1,024.0) was decreased vs. AR14 (27,604.17 ± 1,425.3; P < 0.001) after 72 h. Decreased CK activity in AR14 cells (54.9 ± 2.9 units/μg protein) in comparison to AR33 (70.8 ± 8.1) ( P < 0.05) was noted. The myonuclear fusion index was lower for AR14 (15.21 ± 3.24%) and AR33 (9.97 ± 3.14%) in comparison to WT (35.07 ± 5.60%, P < 0.001). AR14 and AR33 cells also displayed atypical myotube morphology. RT-PCR revealed genotype differences in myostatin and myogenin expression. We conclude that AR polyglutamine repeat length is directly associated with transcriptional activity and alters the growth and development of C2C12 cells. This polymorphism may contribute to the heritability of muscle mass in humans.

scholarly journals Diverse Action of Selected Statins on Skeletal Muscle Cells—An Attempt to Explain the Protective Effect of Geranylgeraniol (GGOH) in Statin-Associated Myopathy (SAM)

2019 ◽  
Vol 8 (5) ◽  
pp. 694 ◽  
Author(s):  
Anna Jaśkiewicz ◽  
Beata Pająk ◽  
Magdalena Łabieniec-Watała ◽  
Clara De Palma ◽  
Arkadiusz Orzechowski
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Cell Viability ◽  
Mitochondrial Respiration ◽  
Molecular Mechanisms ◽  
Caspase 3 ◽  
C2c12 Cell ◽  
Muscle Cells ◽  
C2c12 Cells ◽  
Calpain Inhibitor

The present study is centered on molecular mechanisms of the cytoprotective effect of geranylgeraniol (GGOH) in skeletal muscle harmed by statin-associated myopathy (SAM). GGOH via autophagy induction was purportedly assumed to prevent skeletal muscle viability impaired by statins, atorvastatin (ATR) or simvastatin (SIM). The C2C12 cell line was used as the ‘in vitro’ model of muscle cells at different stages of muscle formation, and the effect of ATR or SIM on the cell viability, protein expression and mitochondrial respiration were tested. Autophagy seems to be important for the differentiation of muscle cells; however, it did not participate in the observed GGOH cytoprotective effects. We showed that ATR- and SIM-dependent loss in cell viability was reversed by GGOH co-treatment, although GGOH did not reverse the ATR-induced drop in the cytochrome c oxidase protein expression level. It has been unambiguously revealed that the mitochondria of C2C12 cells are not sensitive to SIM, although ATR effectively inhibits mitochondrial respiration. GGOH restored proper mitochondria functioning. Apoptosis might, to some extent, explain the lower viability of statin-treated myotubes as the pan-caspase inhibitor, N-Benzyloxycarbonyl-Val-Ala-Asp(O-Me) fluoromethyl ketone (Z-VAD-FMK), partly reversed ATR- or SIM-induced cytotoxic effects; however, it does not do so in conjunction with caspase-3. It appears that the calpain inhibitor, N-Acetyl-L-leucyl-L-leucyl-L-norleucinal (ALLM), restored the viability that was reduced by ATR and SIM (p < 0.001). GGOH prevents SAM, in part, as a consequence of a caspase-3 independent pathway, probably by calpain system inactivation.

scholarly journals Osteocalcin Induces Proliferation via Positive Activation of the PI3K/Akt, P38 MAPK Pathways and Promotes Differentiation Through Activation of the GPRC6A-ERK1/2 Pathway in C2C12 Myoblast Cells

2017 ◽  
Vol 43 (3) ◽  
pp. 1100-1112 ◽  
Author(s):  
Suifeng Liu ◽  
Feng Gao ◽  
Lei Wen ◽  
Min Ouyang ◽  
Yi Wang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
P38 Mapk ◽  
C2c12 Cell ◽  
C2c12 Cells ◽  
Myoblast Differentiation ◽  
C2c12 Myoblast ◽  
C2c12 Myoblasts ◽  
Mapk Phosphorylation ◽  
Mapk Pathways ◽  
Myoblast Cells

Background/Aims: Sarcopenia is characterized by an age-related decline in skeletal muscle plus low muscle strength and/or physical performance. Despite the clinical significance of sarcopenia, the molecular pathways underlying sarcopenia remain elusive. The recent demonstration that undercarboxylated osteocalcin (ucOC) favours muscle function related to insulin sensitivity and glucose metabolism raises the question of whether this hormone may also regulate muscle mass. The present study explored the promotive effects of ucOC in proliferation and differentiation processes of C2C12 myoblasts as well as the possible signalling pathways involved. Methods: The effects of exogenous ucOC on C2C12 myoblasts proliferation were assessed using CCK8 and immunohistological staining assays. C2C12 cells were pretreated with PI3K/Akt or P38 MAPK inhibitors to investigate the possible involvement of the PI3K/Akt and P38 MAPK pathways in proliferation. The levels of Akt, phosphorylated-Akt (p-Akt), P38, and phosphorylated-P38 (p-P38) were measured by Western Blotting. The effects of ucOC on myoblast differentiation were quantified by morphological analysis. A silencing experiment was conducted in which the expression of GPRC6A in C2C12 myoblasts was modified. The expression of GPRC6A, myosin heavy chain (MyHC) and the related ERK1/2 signalling pathway in C2C12 myoblasts were monitored by qRT-PCR and Western Blotting. Results: We showed that treatment with exogenous ucOC stimulated the priming of C2C12 myoblasts proliferation. Inhibition of Akt phosphorylation by wortmannin or inhibition of P38 MAPK phosphorylation by SB203580 decreased C2C12 cell proliferation. Wortmannin also reduced P38 MAPK phosphorylation, whereas SB203580 did not affect Akt activation. Furthermore, ucOC promoted C2C12 myoblast differentiation. Inhibition of ERK1/2 phosphorylation with U0126 decreased C2C12 cell differentiation. Finally, GPRC6A expression was substantially increased after ucOC treatment of C2C12 cells. GPRC6A silencing inhibited Akt, P38 MAPK phosphorylation in C2C12 cells, and ERK1/2 phosphorylation in C2C12 myotubes; GPRC6A silencing also decreased cell proliferation, decreased cell differentiation, and downregulated MyHC expression. Conclusions: The present data suggest that ucOC induces myoblast proliferation via sequential activation of the PI3K/Akt and p38 MAPK pathways in C2C12 myoblast cells. Moreover, ucOC enhances myogenic differentiation via a mechanism involving GPRC6A-ERK1/2 signalling.

scholarly journals Identification of CXCL11 as part of chemokine network controlling skeletal muscle development

2021 ◽  
Author(s):  
Malte Puchert ◽  
Christian Koch ◽  
Konstanze Zieger ◽  
Jürgen Engele
Keyword(s):  
Skeletal Muscle ◽  
Muscle Development ◽  
C2c12 Cell ◽  
C2c12 Cells ◽  
Muscle Fibres ◽  
Skeletal Muscle Development ◽  
Functional Studies ◽  
Adult Rat ◽  
Limb Muscles ◽  
Chemokine Cxcl12

AbstractThe chemokine, CXCL12, and its receptors, CXCR4 and CXCR7, play pivotal roles during development and maintenance of limb muscles. CXCR7 additionally binds CXCL11, which uses CXCR3 as its prime receptor. Based on this cross-talk, we investigate whether CXCL11 would likewise affect development and/or function of skeletal muscles. Western blotting and immunolabelling demonstrated the developmentally restricted expression of CXCL11 in rat limb muscles, which was contrasted by the continuous expression of its receptors in proliferating and differentiating C2C12 cells as well as in late embryonic to adult rat limb muscle fibres. Consistent with a prime role in muscle formation, functional studies identified CXCL11 as a potent chemoattractant for undifferentiated C2C12 cells and further showed that CXCL11 does neither affect myoblast proliferation and differentiation nor metabolic/catabolic pathways in formed myotubes. The use of selective receptor antagonists unravelled complementary effects of CXCL11 and CXCL12 on C2C12 cell migration, which either require CXCR3/CXCR7 or CXCR4, respectively. Our findings provide new insights into the chemokine network controlling skeletal muscle development and function and, thus, might provide a base for future therapies of muscular diseases.

scholarly journals Androgen receptor polyglutamine repeat length (AR-CAGn) modulates the effect of testosterone on androgen-associated somatic traits in Filipino young adult men

2017 ◽  
Vol 163 (2) ◽  
pp. 317-327 ◽  
Author(s):  
Calen P. Ryan ◽  
Alexander V. Georgiev ◽  
Thomas W. McDade ◽  
Lee T. Gettler ◽  
Dan T. A. Eisenberg ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Young Adult ◽  
Repeat Length ◽  
Adult Men ◽  
Polyglutamine Repeat ◽  
Somatic Traits

scholarly journals Identification of FHL1 as a regulator of skeletal muscle mass: implications for human myopathy

2008 ◽  
Vol 183 (6) ◽  
pp. 1033-1048 ◽  
Author(s):  
Belinda S. Cowling ◽  
Meagan J. McGrath ◽  
Mai-Anh Nguyen ◽  
Denny L. Cottle ◽  
Anthony J. Kee ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Skeletal Muscle Mass ◽  
Transcriptional Activity ◽  
Nuclear Translocation ◽  
Fiber Type ◽  
Normal Function ◽  
C2c12 Cells ◽  
Whole Body ◽  
Activated T Cells

Regulators of skeletal muscle mass are of interest, given the morbidity and mortality of muscle atrophy and myopathy. Four-and-a-half LIM protein 1 (FHL1) is mutated in several human myopathies, including reducing-body myopathy (RBM). The normal function of FHL1 in muscle and how it causes myopathy remains unknown. We find that FHL1 transgenic expression in mouse skeletal muscle promotes hypertrophy and an oxidative fiber-type switch, leading to increased whole-body strength and fatigue resistance. Additionally, FHL1 overexpression enhances myoblast fusion, resulting in hypertrophic myotubes in C2C12 cells, (a phenotype rescued by calcineurin inhibition). In FHL1-RBM C2C12 cells, there are no hypertrophic myotubes. FHL1 binds with the calcineurin-regulated transcription factor NFATc1 (nuclear factor of activated T cells, cytoplasmic, calcineurin-dependent 1), enhancing NFATc1 transcriptional activity. Mutant RBM-FHL1 forms aggregate bodies in C2C12 cells, sequestering NFATc1 and resulting in reduced NFAT nuclear translocation and transcriptional activity. NFATc1 also colocalizes with mutant FHL1 to reducing bodies in RBM-afflicted skeletal muscle. Therefore, via NFATc1 signaling regulation, FHL1 appears to modulate muscle mass and strength enhancement.

Polyglutamine repeat length influences human androgen receptor/c-Jun mediated transcription

1999 ◽  
Vol 277 (1) ◽  
pp. 9-12 ◽  
Author(s):  
Andrew J Grierson ◽  
Roy C Mootoosamy ◽  
Christopher C.J Miller
Keyword(s):  
Androgen Receptor ◽  
Repeat Length ◽  
Polyglutamine Repeat ◽  
Human Androgen Receptor

scholarly journals Phytochemicals in Chinese chive (Allium tuberosum) Induce the Skeletal Muscle Cell Proliferation via PI3K/Akt/mTOR and Smad Pathways in C2C12 Cells

2021 ◽  
Vol 22 (5) ◽  
pp. 2296
Author(s):  
Mira Oh ◽  
Seo-Young Kim ◽  
SeonJu Park ◽  
Kil-Nam Kim ◽  
Seung Hyun Kim
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Muscle Cell ◽  
Muscle Growth ◽  
Skeletal Muscle Cell ◽  
Water Soluble ◽  
C2c12 Cells ◽  
Allium Tuberosum ◽  
Skeletal Muscle Growth ◽  
Chinese Chive

Chinese chive (Allium tuberosum) is a medicinal food that is cultivated and consumed mainly in Asian countries. Its various phytochemicals and physiological effects have been reported, but only a few phytochemicals are available for skeletal muscle cell proliferation. Herein, we isolated a new compound, kaempferol-3-O-(6″-feruloyl)-sophoroside (1), along with one known flavonoid glycoside (2) and six amino acid (3–8) compounds from the water-soluble fraction of the shoot of the Chinese chive. The isolated compounds were identified using extensive spectroscopic methods, including 1D and 2D NMR, and evaluated for their proliferation activity on skeletal muscle cells. Among the tested compounds, newly isolated flavonoid (1) and 5-aminouridine (7) up-regulated PI3K/Akt/mTOR pathways, which implies a positive effect on skeletal muscle growth and differentiation. In particular, compound 1 down-regulated the Smad pathways, which are negative regulators of skeletal muscle growth. Collectively, we suggest that major constituents of Chinese chive, flavonoids and amino acids, might be used in dietary supplements that aid skeletal muscle growth.

scholarly journals Inositide-Dependent Phospholipase C Signaling Mimics Insulin in Skeletal Muscle Differentiation by Affecting Specific Regions of the Cyclin D3 Promoter

Endocrinology ◽  
2007 ◽  
Vol 148 (3) ◽  
pp. 1108-1117 ◽  
Author(s):  
Irene Faenza ◽  
Giulia Ramazzotti ◽  
Alberto Bavelloni ◽  
Roberta Fiume ◽  
Gian Carlo Gaboardi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Phospholipase C ◽  
Myogenic Differentiation ◽  
Muscle Differentiation ◽  
C2c12 Cells ◽  
Cyclin D3 ◽  
Expression Vectors ◽  
Skeletal Muscle Differentiation ◽  
Small Interfering Rnas

Our main goal in this study was to investigate the role of phospholipase C (PLC) β1 and PLCγ1 in skeletal muscle differentiation and the existence of potential downstream targets of their signaling activity. To examine whether PLC signaling can modulate the expression of cyclin D3, a target of PLCβ1 in erythroleukemia cells, we transfected C2C12 cells with expression vectors containing PLCβ1 or PLCγ1 cDNA and with small interfering RNAs from regions of the PLCβ1 or PLCγ1 gene and followed myogenic differentiation in this well-established cell system. Intriguingly, overexpressed PLCβ1 and PLCγ1 were able to mimic insulin induction of both cyclin D3 and muscle differentiation. By knocking down PLCβ1 or PLCγ1 expression, C2C12 cells almost completely lost the increase in cyclin D3, and the differentiation program was down-regulated. To explore the induction of the cyclin D3 gene promoter during this process, we used a series of 5′-deletions of the 1.68-kb promoter linked to a reporter gene and noted a 5-fold augmentation of promoter activity upon insulin stimulation. These constructs were also cotransfected with PLCβ1 or PLCγ1 cDNAs and small interfering RNAs, respectively. Our data indicate that PLCβ1 or PLCγ1 signaling is capable of acting like insulin in regard to both the myogenic differentiation program and cyclin D3 up-regulation. Taken together, this is the first study that hints at cyclin D3 as a target of PLCβ1 and PLCγ1 during myogenic differentiation in vitro and implies that up-regulation of these enzymes is sufficient to mimic the actions of insulin in this process.

scholarly journals Syncytin-1 Expression is Increased in Skeletal Muscle of Humans with Obesity and is Inversely Correlated to Muscle Protein Synthesis

2021 ◽  
Author(s):  
Jayachandran Ravichandran ◽  
Lori R Roust ◽  
Christos Katsanos
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
C2c12 Cell ◽  
C2c12 Cells ◽  
Anabolic Hormone ◽  
Lower Protein ◽  
Potential Link

Abstract Background: Various pathophysiological conditions alter protein metabolism in skeletal muscle, with obesity being one of them. Obesity impairs regeneration of skeletal muscle, and the same biological mechanism(s) may adversely affect protein metabolism in the muscle of these individuals. Methods: We used C2C12 cell line to evaluate the effects of the anabolic hormone insulin on the expression of protein syncytin-1, which regulates regeneration of muscle, and in the presence of fatty acids whose metabolism is altered in obesity. We used muscle biopsy samples from obese humans with lower muscle protein synthesis and lean controls to evaluate expression of syncytin-1 in obesity and its correlation with protein synthesis in muscle. Results: Insulin upregulated syncytin-1 expression in C2C12 cells and this response was impaired in the presence of the fatty acid palmitate, but not oleate. Expression of the protein 4E-BP1, which signals increase in protein synthesis in muscle, showed response similar to that of syncytin-1. Humans with obesity characterized by lower muscle protein synthesis had higher expression of syncytin-1 in muscle compared to lean humans (P < 0.01). The rate of synthesis of protein in skeletal muscle across humans subjects correlated inversely (r = -0.51; P = 0.03) with the expression of syncytin-1 in muscle. Conclusions: Our studies provide novel insights in the regulation of syncytin-1 in skeletal muscle, and describe potential link between syncytin-1 expression and protein metabolism in skeletal muscle of humans. Altered syncytin-1 expression in muscle may mediate lower protein turnover in muscle of humans with obesity.

scholarly journals MYOC Promotes the Differentiation of C2C12 Cells by Regulation of the TGF-β Signaling Pathways via CAV1

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 686
Author(s):  
Yuhan Zhang ◽  
Shuang Li ◽  
Xin Wen ◽  
Huili Tong ◽  
Shufeng Li ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Confocal Microscopy ◽  
Gastrocnemius Muscle ◽  
C2c12 Cell ◽  
C2c12 Cells ◽  
Laser Confocal Microscopy ◽  
Caveolin 1 ◽  
The Common ◽  
Sites Of Action ◽  
Cav1 Expression

Myocilin (MYOC) is a glycoprotein encoded by a gene associated with glaucoma pathology. In addition to the eyes, it also expresses at high transcription levels in the heart and skeletal muscle. MYOC affects the formation of the murine gastrocnemius muscle and is associated with the differentiation of mouse osteoblasts, but its role in the differentiation of C2C12 cells has not yet been reported. Here, MYOC expression was found to increase gradually during the differentiation of C2C12 cells. Overexpression of MYOC resulted in enhanced differentiation of C2C12 cells while its inhibition caused reduced differentiation. Furthermore, immunoprecipitation indicated that MYOC binds to Caveolin-1 (CAV1), a protein that influences the TGF-β pathway. Laser confocal microscopy also revealed the common sites of action of the two during the differentiation of C2C12 cells. Additionally, CAV1 was upregulated significantly as C2C12 cells differentiated, with CAV1 able to influence the differentiation of the cells. Furthermore, the Western blotting analysis demonstrated that the expression of MYOC affected the TGF-β pathway. Finally, MYOC was overexpressed while CAV1 was inhibited. The results indicate that reduced CAV1 expression blocked the promotion of C2C12 cell differentiation by MYOC. In conclusion, the results demonstrated that MYOC regulates TGF-β by influencing CAV1 to promote the differentiation of C2C12 cells.

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