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 ◽  
...  

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.

Author(s):  
Hyunju Liu ◽  
Su-Mi Lee ◽  
Hosouk Joung

AbstractSUMOylation is one of the post-translational modifications that involves the covalent attachment of the small ubiquitin-like modifier (SUMO) to the substrate. SUMOylation regulates multiple biological processes, including myoblast proliferation, differentiation, and apoptosis. 2-D08 is a synthetically available flavone, which acts as a potent cell-permeable SUMOylation inhibitor. Its mechanism of action involves preventing the transfer of SUMO from the E2 thioester to the substrate without influencing SUMO-activating enzyme E1 (SAE-1/2) or E2 Ubc9-SUMO thioester formation. However, both the effects and mechanisms of 2-D08 on C2C12 myoblast cells remain unclear. In the present study, we found that treatment with 2-D08 inhibits C2C12 cell proliferation and differentiation. We confirmed that 2-D08 significantly hampers the viability of C2C12 cells. Additionally, it inhibited myogenic differentiation, decreasing myosin heavy chain (MHC), MyoD, and myogenin expression. Furthermore, we confirmed that 2-D08-mediated anti-myogenic effects impair myoblast differentiation and myotube formation, reducing the number of MHC-positive C2C12 cells. In addition, we found that 2-D08 induces the activation of ErK1/2 and the degradation of MyoD and myogenin in C2C12 cells. Taken together, these results indicated that 2-D08 treatment results in the deregulated proliferation and differentiation of myoblasts. However, further research is needed to investigate the long-term effects of 2-D08 on skeletal muscles.


2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Hristina Obradović ◽  
Jelena Krstić ◽  
Tamara Kukolj ◽  
Drenka Trivanović ◽  
Ivana Okić Đorđević ◽  
...  

Interleukin 17 (IL-17) is a cytokine with pleiotropic effects associated with several inflammatory diseases. Although elevated levels of IL-17 have been described in inflammatory myopathies, its role in muscle remodeling and regeneration is still unknown. Excessive extracellular matrix degradation in skeletal muscle is an important pathological consequence of many diseases involving muscle wasting. In this study, the role of IL-17 on the expression of matrix metalloproteinase- (MMP-) 9 in myoblast cells was investigated. The expression of MMP-9 after IL-17 treatment was analyzed in mouse myoblasts C2C12 cell line. The increase in MMP-9 production by IL-17 was concomitant with its capacity to inhibit myogenic differentiation of C2C12 cells. Doxycycline (Doxy) treatment protected the myogenic capacity of myoblasts from IL-17 inhibition and, moreover, increased myotubes hypertrophy. Doxy blocked the capacity of IL-17 to stimulate MMP-9 production by regulating IL-17-induced ERK1/2 MAPK activation. Our results imply that MMP-9 mediates IL-17’s capacity to inhibit myoblast differentiation during inflammatory diseases and indicate that Doxy can modulate myoblast response to inflammatory induction by IL-17.


PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244791
Author(s):  
Wan-Huai Teo ◽  
Jeng-Fan Lo ◽  
Yu-Ning Fan ◽  
Chih-Yang Huang ◽  
Tung-Fu Huang

Ageing and chronic diseases lead to muscle loss and impair the regeneration of skeletal muscle. Thus, it’s crucial to seek for effective intervention to improve the muscle regeneration. Tid1, a mitochondrial co-chaperone, is important to maintain mitochondrial membrane potential and ATP synthesis. Previously, we demonstrated that mice with skeletal muscular specific Tid1 deficiency displayed muscular dystrophy and postnatal lethality. Tid1 can interact with STAT3 protein, which also plays an important role during myogenesis. In this study, we used GMI, immunomodulatory protein of Ganoderma microsporum, as an inducer in C2C12 myoblast differentiation. We observed that GMI pretreatment promoted the myogenic differentiation of C2C12 myoblasts. We also showed that the upregulation of mitochondria protein Tid1 with the GMI pre-treatment promoted myogenic differentiation ability of C2C12 cells. Strikingly, we observed the concomitant elevation of STAT3 acetylation (Ac-STAT3) during C2C12 myogenesis. Our study suggests that GMI promotes the myogenic differentiation through the activation of Tid1 and Ac-STAT3.


2015 ◽  
Vol 93 (1) ◽  
pp. 8-15 ◽  
Author(s):  
Lin Mi ◽  
Youlei Li ◽  
Qiangling Zhang ◽  
Chen Zhao ◽  
Ying Peng ◽  
...  

MicroRNAs (miRNAs) are novel and potent regulators in myogenesis. However, the molecular mechanisms that many miRNAs regulate myoblast proliferation and differentiation which are largely unknown. Here, we found that miR-139-5p increased during C2C12 myoblast proliferation, while presenting an inverse trend during C2C12 myoblast differentiation. Flow cytometry and EdU incorporation assay showed that miR-139-5p slowed down the growth of C2C12 cells. Additional study demonstrated that ectopic introduction of miR-139-5p into C2C12 cells blocked myoblast differentiation. Importantly, we demonstrated for the first time that Wnt1, which is associated with the Wnt/β-catenin signaling pathway, was a direct target of miR-139-5p. Moreover, we found that the expression level of Wnt1 was suppressed significantly (p < 0.01) by miR-139-5p, which triggered inhibition of Wnt/β-catenin signaling through upregulation of glycogen synthase kinase 3 beta (GSK-3β; p < 0.05) and downregulation of p-GSK-3β (p < 0.01), β-catenin (p < 0.05), and nuclear β-catenin (p < 0.01). Taken together, these results suggest that miR-139-5p is an important negative regulator in myogenesis through blocking the Wnt1-mediated Wnt/β-catenin signaling pathway.


2020 ◽  
Vol 74 (1) ◽  
pp. 18-33
Author(s):  
Irina Maslovaric ◽  
Vesna Ilic ◽  
Ana Stancic ◽  
Juan Santibanez ◽  
Drenka Trivanovic ◽  
...  

Introduction. Blood products, i.e. platelet rich plasma (PRP), leukocyte-poor plasma (PRP) and platelet poor plasma (PPP), have previously been used to improve muscle regeneration. In this study, six months? frozen-stored PPP of individuals who practiced different types of physical exercise was analysed; it could steer mouse C2C12 myoblast cells towards proliferation, migration and myogenic differentiation, and it could affect the morphology/shape of myotubes. Materials and Methods. PPP of male Olympic weightlifters, football players and professional folk dancers, aged 15-19, was collected 12 h post-training and stored for 6 months at -20?C. C2C12 cell proliferation was assessed by MTT test, motility by scratch assay, myogenic differentiation by myotube formation and gelatinase activity by gel-zymography. Results and Conclusions. PPP induced proliferation and migration of C2C12 cells. Proliferative capacity was as follows: weightlifters > dancers > football players; mean migratory capacity was: weightlifters = dancers > football players. PPP induced formation of myotubes; significant inter-individual variations were detected: PPP from weightlifters induced formation of round myotubes, and PPP from football players and dancers induced formation of elongated myotubes. The mean myotube area was as follows: football players > dancers > weightlifters. PPP gelatinolytic activity was observed; it was negatively correlated with C2C12 myoblast proliferation. These results provide general but distinct evidence that PPP of individuals practicing certain types of exercise can specifically modify myoblast morphology/function. This is significant for explaining physiological responses and adaptations to exercise. In conclusion, long-term, frozen-stored PPP preserves its potential to modify myoblast morphology and function.


2014 ◽  
Vol 9 (11) ◽  
pp. 1030-1036 ◽  
Author(s):  
Yaqiu Lin ◽  
Yanying Zhao ◽  
Ruiwen Li ◽  
Jiaqi Gong ◽  
Yucai Zheng ◽  
...  

AbstractPGC-1α has been implicated as an important mediator of functional capacity of skeletal muscle. However, the role of PGC-1α in myoblast differentiation remains unexplored. In the present study, we observed a significant up-regulation of PGC-1α expression during the differentiation of murine C2C12 myoblast. To understand the biological significance of PGC-1α up-regulation in myoblast differentiation, C2C12 cells were transfected with murine PGC-1α cDNA and siRNA targeting PGC-1α, respectively. PGC-1α over-expressing clones fused to form typical myotubes with higher mRNA level of myosin heavy chain isoform I (MyHCI) and lower MyHCIIX. No obvious differentiation was observed in PGC-1α-targeted siRNA-transfected cells with marked decrement of mRNA levels of MyHCI and MyHCIIX. Furthermore, PGC-1α increased the expression of MyoD and MyoG in C2C12 cells, which controlled the commitment of precursor cells to myotubes. These results indicate that PGC-1α is associated with myoblast differentiation and elevates MyoD and MyoG expression levels in C2C12 cells.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kristen K. Bjorkman ◽  
Massimo Buvoli ◽  
Emily K. Pugach ◽  
Michael M. Polmear ◽  
Leslie A. Leinwand

Abstract Background Myogenesis is driven by specific changes in the transcriptome that occur during the different stages of muscle differentiation. In addition to controlled transcriptional transitions, several other post-transcriptional mechanisms direct muscle differentiation. Both alternative splicing and miRNA activity regulate gene expression and production of specialized protein isoforms. Importantly, disruption of either process often results in severe phenotypes as reported for several muscle diseases. Thus, broadening our understanding of the post-transcriptional pathways that operate in muscles will lay the foundation for future therapeutic interventions. Methods We employed bioinformatics analysis in concert with the well-established C2C12 cell system for predicting and validating novel miR-1 and miR-206 targets engaged in muscle differentiation. We used reporter gene assays to test direct miRNA targeting and studied C2C12 cells stably expressing one of the cDNA candidates fused to a heterologous, miRNA-resistant 3′ UTR. We monitored effects on differentiation by measuring fusion index, myotube area, and myogenic gene expression during time course differentiation experiments. Results Gene ontology analysis revealed a strongly enriched set of putative miR-1 and miR-206 targets associated with RNA metabolism. Notably, the expression levels of several candidates decreased during C2C12 differentiation. We discovered that the splicing factor Srsf9 is a direct target of both miRNAs during myogenesis. Persistent Srsf9 expression during differentiation impaired myotube formation and blunted induction of the early pro-differentiation factor myogenin as well as the late differentiation marker sarcomeric myosin, Myh8. Conclusions Our data uncover novel miR-1 and miR-206 cellular targets and establish a functional link between the splicing factor Srsf9 and myoblast differentiation. The finding that miRNA-mediated clearance of Srsf9 is a key myogenic event illustrates the coordinated and sophisticated interplay between the diverse components of the gene regulatory network.


2020 ◽  
Author(s):  
Ruo-nan Zhang ◽  
Yan Wang ◽  
Yun Liu ◽  
Xin Bao ◽  
Wei Xu ◽  
...  

Abstract Backgorund:Neuromuscular diseases are a kind of nervous system diseases that have a high disability rate.Ezrin’ role in skeletal muscle has not been identified. This study aims to confirm the effect and mechanism of Ezrin on myoblast differentiation and fusion, myotube size, and myofiber type.Method:By using immunoassaying and western blot analyses, Ezrin, MyHC,MEF2c, MyoG, PKAα/β/γ, PKA reg Iα, PKA reg IIβand NFATc1-c4 were detected in myoblast cells treated with Ad-Ezrin or Ad-shEzrin. Real-time PCR were used to evaluate MyoD, Myf5, MyHC-I , MyHC-IIa/b and MyHC-IIx in myoblast cells. PKA inhibitor H-89 or PKAreg I activator N6-Bz-cAMP were added into medium to confirm their relationship between Ezrin and PKA during myoblast differentiation/fusion. In vitro, Ad-NFATc1/c2 or Ad-shNFATc3/c4 were respectively transfected into C2C12 cells, myoblast differentiation/fusion, myotube size and myofiber type were assessed by using immunostaining of MyHC, MEF2c and MyoG. In vivo, transfection of Ad-Ezrin into gastrocnemius and soleus muscles for 7 days, the numbers of MyHC-1 postivemyofibers were analyzed after immunostaining of MyHC-1.Results: Ezrin expression were time-dependently increased during myoblast differentiation/fusion. Knockdown of Ezrin by shRNA delayed myoblast differentiation and fusion in a time dose-dependent pattern, as shown by immunostaining of MyHC. Conversely, over-expression of Ezrin by adenovirus time- and dosage-dependently promoted myoblastdifferentiation/fusion, and muscle fiber specialization characterized by increased MyHC I and MyHCIIa/b. Forced expression of Ezrin did not alter PKA, and PKAreg II α levels, but altered the levels of PKAreg I α/β, Myf5 and MyoD, and leading to the accumulation of MyoG+/MEF2c+ nuclei. By contrast, Ezrin knockdown significantly decreased the PKA reg I/II ratio and MyoG+/MEF2c+ nuclei. The PKA inhibitor H-89 remarkably abolished the beneficial effect of over-expressingEzrin on the numbers of MyHC+ myotubes and MyoG+/MEF2c nuclei. These opposite changes mediated by knocking down Ezrin were almost eliminated by PKAreg I activator N6-Bz-cAMP. Furthermore, over-expression of NFATc2 or knockdown of NFATc4reversed the inhibitory effect of Ezrin knockdown on myoblast differentiation/fusion, resulting in the recovery of the numbers ofMyoG+/MEF2c+ nucleiin3-nuclei+myotubes. Meanwhile, overexpression of Ezrin specifically induced type I muscle fiber specialization, which was associated with increased levels of NFATc1/c2. Furthermore, in vivo transfection ofAd-Ezrin into gastrocnemius and soleus muscles increased the numbers of MyHC-1 postivemyofibers. By contrast, knockdown of NFATc4resulted in the recovery to normal levels of MyHC-2b in Ezrin-knockdown myoblast cells, attributingtoregainingMyoDand MEF2c expression. Conclusions: Ezrin trigger myoblast differentiation and fusion, myotube size, and alters muscle fiber specialization through PKA-NFAT-MyoD/MEF2C signalling pathway.


2020 ◽  
Author(s):  
H M Arif Ullah ◽  
A. K. Elfadl ◽  
SunYoung Park ◽  
Yong Deuk Kim ◽  
Myung-Jin Chung ◽  
...  

Abstract Background: Nogo-A (Rtn 4A), a member of the reticulon 4 (Rtn4) protein family, is a neurite outgrowth inhibitor protein that is primarily expressed in the central nervous system (CNS). However, the role of Nogo-A in inflammatory mechanisms remains unclear. Therefore, in this study, we used Nogo-knockout (KO) mice to explore its potential role in the inflammatory process. Here, we investigated whether Nogo-A affects the inflammatory process through transcription factor C/EBP homologous protein (CHOP). Results: Our results demonstrated that Nogo-A, CHOP, and pro-inflammatory factors were activated in the following: notexin-induced muscle injury, in human Duchenne muscular dystrophy (DMD) patients, in dystrophin-deficient (mdx) mice, in differentiated C2C12 myoblast cells, and in lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages (BMDM). Moreover, we found that Nogo-KO BMDM exhibited lower migratory ability compared with wild type (WT) BMDM after LPS treatment. Conclusion: Our data demonstrated that the Nogo-A-CHOP signaling pathway regulated the inflammatory process in notexin-induced injured muscle, in mdx mice, in DMD patients, in differentiated C2C12 cells, and in LPS-stimulated BMDM. Taken together, these results suggest that Nogo-A plays a vital role in inflammatory processes, which resembles the pathological mechanisms observed in the CNS.


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