scholarly journals mTOR regulates skeletal muscle regeneration in vivo through kinase-dependent and kinase-independent mechanisms

2009 ◽  
Vol 297 (6) ◽  
pp. C1434-C1444 ◽  
Author(s):  
Yejing Ge ◽  
Ai-Luen Wu ◽  
Christine Warnes ◽  
Jianming Liu ◽  
Chongben Zhang ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Muscle Growth ◽  
Skeletal Muscle Regeneration ◽  
In Vivo Studies ◽  
Mrna Levels ◽  
Independent Manner ◽  
Mtor Kinase

Rapamycin-sensitive signaling is required for skeletal muscle differentiation and remodeling. In cultured myoblasts, the mammalian target of rapamycin (mTOR) has been reported to regulate differentiation at different stages through distinct mechanisms, including one that is independent of mTOR kinase activity. However, the kinase-independent function of mTOR remains controversial, and no in vivo studies have examined those mTOR myogenic mechanisms previously identified in vitro. In this study, we find that rapamycin impairs injury-induced muscle regeneration. To validate the role of mTOR with genetic evidence and to probe the mechanism of mTOR function, we have generated and characterized transgenic mice expressing two mutants of mTOR under the control of human skeletal actin (HSA) promoter: rapamycin-resistant (RR) and RR/kinase-inactive (RR/KI). Our results show that muscle regeneration in rapamycin-administered mice is restored by RR-mTOR expression. In the RR/KI-mTOR mice, nascent myofiber formation during the early phase of regeneration proceeds in the presence of rapamycin, but growth of the regenerating myofibers is blocked by rapamycin. Igf2 mRNA levels increase drastically during early regeneration, which is sensitive to rapamycin in wild-type muscles but partially resistant to rapamycin in both RR- and RR/KI-mTOR muscles, consistent with mTOR regulation of Igf2 expression in a kinase-independent manner. Furthermore, systemic ablation of S6K1, a target of mTOR kinase, results in impaired muscle growth but normal nascent myofiber formation during regeneration. Therefore, mTOR regulates muscle regeneration through kinase-independent and kinase-dependent mechanisms at the stages of nascent myofiber formation and myofiber growth, respectively.

scholarly journals PEDF-derived peptide promotes skeletal muscle regeneration through its mitogenic effect on muscle progenitor cells

2015 ◽  
Vol 309 (3) ◽  
pp. C159-C168 ◽  
Author(s):  
Tsung-Chuan Ho ◽  
Yi-Pin Chiang ◽  
Chih-Kuang Chuang ◽  
Show-Li Chen ◽  
Jui-Wen Hsieh ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cell Proliferation ◽  
Cyclin D1 ◽  
Satellite Cell ◽  
Muscle Regeneration ◽  
Muscle Fibers ◽  
Skeletal Muscle Regeneration ◽  
Satellite Cell Proliferation

In response injury, intrinsic repair mechanisms are activated in skeletal muscle to replace the damaged muscle fibers with new muscle fibers. The regeneration process starts with the proliferation of satellite cells to give rise to myoblasts, which subsequently differentiate terminally into myofibers. Here, we investigated the promotion effect of pigment epithelial-derived factor (PEDF) on muscle regeneration. We report that PEDF and a synthetic PEDF-derived short peptide (PSP; residues Ser93-Leu112) induce satellite cell proliferation in vitro and promote muscle regeneration in vivo. Extensively, soleus muscle necrosis was induced in rats by bupivacaine, and an injectable alginate gel was used to release the PSP in the injured muscle. PSP delivery was found to stimulate satellite cell proliferation in damaged muscle and enhance the growth of regenerating myofibers, with complete regeneration of normal muscle mass by 2 wk. In cell culture, PEDF/PSP stimulated C2C12 myoblast proliferation, together with a rise in cyclin D1 expression. PEDF induced the phosphorylation of ERK1/2, Akt, and STAT3 in C2C12 myoblasts. Blocking the activity of ERK, Akt, or STAT3 with pharmacological inhibitors attenuated the effects of PEDF/PSP on the induction of C2C12 cell proliferation and cyclin D1 expression. Moreover, 5-bromo-2′-deoxyuridine pulse-labeling demonstrated that PEDF/PSP stimulated primary rat satellite cell proliferation in myofibers in vitro. In summary, we report for the first time that PSP is capable of promoting the regeneration of skeletal muscle. The signaling mechanism involves the ERK, AKT, and STAT3 pathways. These results show the potential utility of this PEDF peptide for muscle regeneration.

scholarly journals Conditional Deletion of Dicer in Adult Mice Impairs Skeletal Muscle Regeneration

2019 ◽  
Vol 20 (22) ◽  
pp. 5686 ◽  
Author(s):  
Satoshi Oikawa ◽  
Minjung Lee ◽  
Takayuki Akimoto
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Myogenic Differentiation ◽  
Tibialis Anterior Muscle ◽  
Critical Factor ◽  
Skeletal Muscle Regeneration ◽  
Small Noncoding Rnas ◽  
Adult Mice

Skeletal muscle has a remarkable regenerative capacity, which is orchestrated by multiple processes, including the proliferation, fusion, and differentiation of the resident stem cells in muscle. MicroRNAs (miRNAs) are small noncoding RNAs that mediate the translational repression or degradation of mRNA to regulate diverse biological functions. Previous studies have suggested that several miRNAs play important roles in myoblast proliferation and differentiation in vitro. However, their potential roles in skeletal muscle regeneration in vivo have not been fully established. In this study, we generated a mouse in which the Dicer gene, which encodes an enzyme essential in miRNA processing, was knocked out in a tamoxifen-inducible way (iDicer KO mouse) and determined its regenerative potential after cardiotoxin-induced acute muscle injury. Dicer mRNA expression was significantly reduced in the tibialis anterior muscle of the iDicer KO mice, whereas the expression of muscle-enriched miRNAs was only slightly reduced in the Dicer-deficient muscles. After cardiotoxin injection, the iDicer KO mice showed impaired muscle regeneration. We also demonstrated that the number of PAX7+ cells, cell proliferation, and the myogenic differentiation capacity of the primary myoblasts did not differ between the wild-type and the iDicer KO mice. Taken together, these data demonstrate that Dicer is a critical factor for muscle regeneration in vivo.

scholarly journals Dietary Flaxseed Mitigates Impaired Skeletal Muscle Regeneration: in Vivo, in Vitro and in Silico Studies

2016 ◽  
Vol 13 (3) ◽  
pp. 206-219 ◽  
Author(s):  
Felicia Carotenuto ◽  
Alessandra Costa ◽  
Maria Cristina Albertini ◽  
Marco Bruno Luigi Rocchi ◽  
Alexander Rudov ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
In Silico ◽  
Skeletal Muscle Regeneration ◽  
In Silico Studies

scholarly journals IL-4 and SDF-1 Increase Adipose Tissue-Derived Stromal Cell Ability to Improve Rat Skeletal Muscle Regeneration

2020 ◽  
Vol 21 (9) ◽  
pp. 3302
Author(s):  
Małgorzata Zimowska ◽  
Karolina Archacka ◽  
Edyta Brzoska ◽  
Joanna Bem ◽  
Areta M. Czerwinska ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Muscle Regeneration ◽  
Structure And Function ◽  
Skeletal Muscle Regeneration ◽  
Stem Cell Markers ◽  
Myogenic Factors ◽  
And Function

Skeletal muscle regeneration depends on the satellite cells, which, in response to injury, activate, proliferate, and reconstruct damaged tissue. However, under certain conditions, such as large injuries or myopathies, these cells might not sufficiently support repair. Thus, other cell populations, among them adipose tissue-derived stromal cells (ADSCs), are tested as a tool to improve regeneration. Importantly, the pro-regenerative action of such cells could be improved by various factors. In the current study, we tested whether IL-4 and SDF-1 could improve the ability of ADSCs to support the regeneration of rat skeletal muscles. We compared their effect at properly regenerating fast-twitch EDL and poorly regenerating slow-twitch soleus. To this end, ADSCs subjected to IL-4 and SDF-1 were analyzed in vitro and also in vivo after their transplantation into injured muscles. We tested their proliferation rate, migration, expression of stem cell markers and myogenic factors, their ability to fuse with myoblasts, as well as their impact on the mass, structure and function of regenerating muscles. As a result, we showed that cytokine-pretreated ADSCs had a beneficial effect in the regeneration process. Their presence resulted in improved muscle structure and function, as well as decreased fibrosis development and a modulated immune response.

Plasmin activity is required for myogenesis in vitro and skeletal muscle regeneration in vivo

Blood ◽  
2002 ◽  
Vol 99 (8) ◽  
pp. 2835-2844 ◽  
Author(s):  
Mònica Suelves ◽  
Roser López-Alemany ◽  
Frederic Lluı́s ◽  
Gloria Aniorte ◽  
Erika Serrano ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Myoblast Fusion ◽  
Skeletal Muscle Regeneration ◽  
Wild Type ◽  
Plasmin Activity ◽  
Type Plasminogen Activator ◽  
Deficient Mice

Abstract Plasmin, the primary fibrinolytic enzyme, has a broad substrate spectrum and is implicated in biologic processes dependent upon proteolytic activity, such as tissue remodeling and cell migration. Active plasmin is generated from proteolytic cleavage of the zymogen plasminogen (Plg) by urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA). Here, we have investigated the role of plasmin in C2C12 myoblast fusion and differentiation in vitro, as well as in skeletal muscle regeneration in vivo, in wild-type and Plg-deficient mice. Wild-type mice completely repaired experimentally damaged skeletal muscle. In contrast, Plg−/− mice presented a severe regeneration defect with decreased recruitment of blood-derived monocytes and lymphocytes to the site of injury and persistent myotube degeneration. In addition, Plg-deficient mice accumulated fibrin in the degenerating muscle fibers; however, fibrinogen depletion of Plg-deficient mice resulted in a correction of the muscular regeneration defect. Because we found that uPA, but not tPA, was induced in skeletal muscle regeneration, and persistent fibrin deposition was also reproducible in uPA-deficient mice following injury, we propose that fibrinolysis by uPA-dependent plasmin activity plays a fundamental role in skeletal muscle regeneration. In summary, we identify plasmin as a critical component of the mammalian skeletal muscle regeneration process, possibly by preventing intramuscular fibrin accumulation and by contributing to the adequate inflammatory response after injury. Finally, we found that inhibition of plasmin activity with α2-antiplasmin resulted in decreased myoblast fusion and differentiation in vitro. Altogether, these studies demonstrate the requirement of plasmin during myogenesis in vitro and muscle regeneration in vivo.

scholarly journals In Vivo Activation of STAT3 Signaling in Satellite Cells and Myofibers in Regenerating Rat Skeletal Muscles

2002 ◽  
Vol 50 (12) ◽  
pp. 1579-1589 ◽  
Author(s):  
Katsuya Kami ◽  
Emiko Senba
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Muscle Regeneration ◽  
Intracellular Signaling ◽  
Skeletal Muscles ◽  
Early Stage ◽  
Skeletal Muscle Regeneration ◽  
Stat3 Signaling

Although growth factors and cytokines play critical roles in skeletal muscle regeneration, intracellular signaling molecules that are activated by these factors in regenerating muscles have been not elucidated. Several lines of evidence suggest that leukemia inhibitory factor (LIF) is an important cytokine for the proliferation and survival of myoblasts in vitro and acceleration of skeletal muscle regeneration. To elucidate the role of LIF signaling in regenerative responses of skeletal muscles, we examined the spatial and temporal activation patterns of an LIF-associated signaling molecule, the signal transducer and activator transcription 3 (STAT3) proteins in regenerating rat skeletal muscles induced by crush injury. At the early stage of regeneration, activated STAT3 proteins were first detected in the nuclei of activated satellite cells and then continued to be activated in proliferating myoblasts expressing both PCNA and MyoD proteins. When muscle regeneration progressed, STAT3 signaling was no longer activated in differentiated myoblasts and myotubes. In addition, activation of STAT3 was also detected in myonuclei within intact sarcolemmas of surviving myofibers that did not show signs of necrosis. These findings suggest that activation of STAT3 signaling is an important molecular event that induces the successful regeneration of injured skeletal muscles.

scholarly journals ARHGEF3 regulates skeletal muscle regeneration and strength through autophagy

2020 ◽  
Author(s):  
Jae-Sung You ◽  
Nilmani Singh ◽  
Adriana Reyes-Ordonez ◽  
Nidhi Khanna ◽  
Zehua Bao ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Mammalian Target Of Rapamycin ◽  
Akt Signaling ◽  
Skeletal Muscle Regeneration ◽  
Myoblast Differentiation ◽  
Independent Manner ◽  
And Function ◽  
Old Mice

SummarySkeletal muscle regeneration is essential for restoring muscle function upon injury and for the maintenance of muscle health with aging. ARHGEF3, a Rho-specific GEF, negatively regulates myoblast differentiation via mammalian target of rapamycin complex 2 (mTORC2)-Akt signaling in a GEF-independent manner in vitro. Here, we investigated ARHGEF3’s role in skeletal muscle regeneration by creating ARHGEF3 KO mice. These mice exhibited no discernible phenotype under normal conditions. Upon injury, however, ARHGEF3 deficiency enhanced the mass, fiber size and function of regenerating muscles in both young and aged mice. Surprisingly, these effects were not mediated by mTORC2-Akt signaling, but by the GEF activity of ARHGEF3. Furthermore, ARHGEF3 KO promoted muscle regeneration through activation of autophagy, a process that is also critical for maintaining muscle strength. Accordingly, in old mice, ARHGEF3 depletion prevented muscle weakness by restoring autophagy flux. Collectively, our findings identify an unexpected link between ARHGEF3 and autophagy-related muscle pathophysiology.

scholarly journals Collagen-VI supplementation by cell transplantation improves muscle regeneration in Ullrich congenital muscular dystrophy model mice

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nana Takenaka-Ninagawa ◽  
Jinsol Kim ◽  
Mingming Zhao ◽  
Masae Sato ◽  
Tatsuya Jonouchi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Cell Transplantation ◽  
Muscle Regeneration ◽  
Congenital Muscular Dystrophy ◽  
Induced Pluripotent Stem Cell ◽  
Skeletal Muscle Regeneration ◽  
Ullrich Congenital Muscular Dystrophy

Abstract Background Mesenchymal stromal cells (MSCs) function as supportive cells on skeletal muscle homeostasis through several secretory factors including type 6 collagen (COL6). Several mutations of COL6A1, 2, and 3 genes cause Ullrich congenital muscular dystrophy (UCMD). Skeletal muscle regeneration deficiency has been reported as a characteristic phenotype in muscle biopsy samples of human UCMD patients and UCMD model mice. However, little is known about the COL6-dependent mechanism for the occurrence and progression of the deficiency. The purpose of this study was to clarify the pathological mechanism of UCMD by supplementing COL6 through cell transplantation. Methods To test whether COL6 supplementation has a therapeutic effect for UCMD, in vivo and in vitro experiments were conducted using four types of MSCs: (1) healthy donors derived-primary MSCs (pMSCs), (2) MSCs derived from healthy donor induced pluripotent stem cell (iMSCs), (3) COL6-knockout iMSCs (COL6KO-iMSCs), and (4) UCMD patient-derived iMSCs (UCMD-iMSCs). Results All four MSC types could engraft for at least 12 weeks when transplanted into the tibialis anterior muscles of immunodeficient UCMD model (Col6a1KO) mice. COL6 protein was restored by the MSC transplantation if the MSCs were not COL6-deficient (types 1 and 2). Moreover, muscle regeneration and maturation in Col6a1KO mice were promoted with the transplantation of the COL6-producing MSCs only in the region supplemented with COL6. Skeletal muscle satellite cells derived from UCMD model mice (Col6a1KO-MuSCs) co-cultured with type 1 or 2 MSCs showed improved proliferation, differentiation, and maturation, whereas those co-cultured with type 3 or 4 MSCs did not. Conclusions These findings indicate that COL6 supplementation improves muscle regeneration and maturation in UCMD model mice.

scholarly journals S1P2 receptor promotes mouse skeletal muscle regeneration

2012 ◽  
Vol 113 (5) ◽  
pp. 707-713 ◽  
Author(s):  
Elena Germinario ◽  
Samantha Peron ◽  
Luana Toniolo ◽  
Romeo Betto ◽  
Francesca Cencetti ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Soleus Muscle ◽  
Satellite Cells ◽  
Muscle Regeneration ◽  
Muscle Growth ◽  
Skeletal Muscle Regeneration ◽  
Null Mouse ◽  
Sphingosine 1 Phosphate ◽  
Functional Inactivation

Sphingosine 1-phosphate is a bioactive lipid that modulates skeletal muscle growth through its interaction with specific receptors localized in the cell membrane of muscle fibers and satellite cells. This study analyzes the role of S1P2 receptor during in vivo regeneration of soleus muscle in two models of S1P2 deficiency: the S1P2-null mouse and wild-type mice systemically treated with the S1P2 receptor antagonist JTE-013. To stimulate regeneration, muscle degeneration was induced by injecting into soleus muscle the myotoxic drug notexin. Both ablation of S1P2 receptor and its functional inactivation delayed regeneration of soleus muscle. The exogenous supplementation of S1P or its removal, by a specific antibody, two conditions known to stimulate or inhibit, respectively, soleus muscle regeneration, were without effects when the S1P2 receptor was absent or inactive. The delayed regeneration was associated with a lower level of myogenin, a muscle differentiation marker, and reduced phosphorylation of Akt, a key marker of muscle growth. Consistently, silencing of S1P2 receptor abrogated the pro-myogenic action of S1P in satellite cells, paralleled by low levels of the myogenic transcription factor myogenin. The study indicates that S1P2 receptor plays a key role in the early phases of muscle regeneration by sustaining differentiation and growth of new-forming myofibers.

scholarly journals Circular RNA profiling of buffalo myoblasts reveals an abundant circPICALM that promotes myoblast differentiation

2020 ◽  
Author(s):  
Mingming Song ◽  
Mengjie Chen ◽  
Kongwei Huang ◽  
Dandan Zhong ◽  
Yaling Chen ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Regeneration ◽  
Muscle Development ◽  
Expression Profiles ◽  
Muscle Growth ◽  
Circular Rna ◽  
Skeletal Muscle Regeneration ◽  
Myoblast Differentiation ◽  
Circular Rnas

Abstract Background Muscle development is a precisely orchestrated and complex process, and circular RNAs (circRNAs) has been demonstrated to play important roles in skeletal muscle growth and development. However, the regulatory functions of circRNA during buffalo muscle developmental processes have not been understood.Results In this study, Ribo-Zero RNA-Seq was performed to investigate the circRNAs expression profiles of proliferated and differentiated buffalo myoblasts. A stringent set of 3,142 circRNAs was finally characterized. Comparing the expression profiles of circRNAs revealed that 110 circRNAs were expressed differentially during myoblast differentiation. We focused on the role of a candidate circRNA, which was named circPICALM based on its host gene PICALM, and was highly (but differentially) expressed in proliferated and differentiated myoblasts. Flow cytometry, EdU incorporation, and Western blotting assays demonstrate that circPICALM promoted myoblasts proliferation and inhibited cells apoptosis. Moreover, overexpression of circPICALM promoted the differentiation of primary buffalo myoblasts. Moreover, circPICALM in vivo stimulated skeletal muscle regeneration in cardiotoxin-induced muscle injury. The RNA pulldown results showed that circPICALM could capture TUBA1B protein, revealing that circPICALM might exert its biological function by binding TUBA1B protein. Conclusions These results demonstrate that the novel non-coding regulator circPICALM induces myoblast differentiation and skeletal muscle regeneration.

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