Muscle Satellite Cell Heterogeneity: Does Embryonic Origin Matter?

Muscle regeneration is an important homeostatic process of adult skeletal muscle that recapitulates many aspects of embryonic myogenesis. Satellite cells (SCs) are the main muscle stem cells responsible for skeletal muscle regeneration. SCs reside between the myofiber basal lamina and the sarcolemma of the muscle fiber in a quiescent state. However, in response to physiological stimuli or muscle trauma, activated SCs transiently re-enter the cell cycle to proliferate and subsequently exit the cell cycle to differentiate or self-renew. Recent evidence has stated that SCs display functional heterogeneity linked to regenerative capability with an undifferentiated subgroup that is more prone to self-renewal, as well as committed progenitor cells ready for myogenic differentiation. Several lineage tracing studies suggest that such SC heterogeneity could be associated with different embryonic origins. Although it has been established that SCs are derived from the central dermomyotome, how a small subpopulation of the SCs progeny maintain their stem cell identity while most progress through the myogenic program to construct myofibers is not well understood. In this review, we synthesize the works supporting the different developmental origins of SCs as the genesis of their functional heterogeneity.

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Tumor Necrosis Factor Alpha Regulates Skeletal Myogenesis by Inhibiting SP1 Interaction with cis-Acting Regulatory Elements within the Fbxl2 Gene Promoter

Molecular and Cellular Biology ◽

10.1128/mcb.00040-20 ◽

2020 ◽

Vol 40 (12) ◽

Author(s):

Michael E. O’Brien ◽

James Londino ◽

Marcus McGinnis ◽

Nathaniel Weathington ◽

Jessica Adair ◽

...

Keyword(s):

Cell Cycle ◽

Skeletal Muscle ◽

Muscle Regeneration ◽

Cell Cycle Progression ◽

Myogenic Differentiation ◽

Core Promoter ◽

Skeletal Muscle Regeneration ◽

Skeletal Myogenesis ◽

Necrosis Factor Alpha ◽

Tnf Α

ABSTRACT FBXL2 is an important ubiquitin E3 ligase component that modulates inflammatory signaling and cell cycle progression, but its molecular regulation is largely unknown. Here, we show that tumor necrosis factor alpha (TNF-α), a critical cytokine linked to the inflammatory response during skeletal muscle regeneration, suppressed Fbxl2 mRNA expression in C2C12 myoblasts and triggered significant alterations in cell cycle, metabolic, and protein translation processes. Gene silencing of Fbxl2 in skeletal myoblasts resulted in increased proliferative responses characterized by activation of mitogen-activated protein (MAP) kinases and nuclear factor kappa B and decreased myogenic differentiation, as reflected by reduced expression of myogenin and impaired myotube formation. TNF-α did not destabilize the Fbxl2 transcript (half-life [t1/2], ∼10 h) but inhibited SP1 transactivation of its core promoter, localized to bp −160 to +42 within the proximal 5′ flanking region of the Fbxl2 gene. Chromatin immunoprecipitation and gel shift studies indicated that SP1 interacted with the Fbxl2 promoter during cellular differentiation, an effect that was less pronounced during proliferation or after TNF-α exposure. TNF-α, via activation of JNK, mediated phosphorylation of SP1 that impaired its binding to the Fbxl2 promoter, resulting in reduced transcriptional activity. The results suggest that SP1 transcriptional activation of Fbxl2 is required for skeletal muscle differentiation, a process that is interrupted by a key proinflammatory myopathic cytokine. IMPORTANCE Skeletal muscle regeneration and repair involve the recruitment and proliferation of resident satellite cells that exit the cell cycle during the process of myogenic differentiation to form myofibers. We demonstrate that the ubiquitin E3 ligase subunit FBXL2 is essential for skeletal myogenesis through its important effects on cell cycle progression and cell proliferative signaling. Further, we characterize a new mechanism whereby sustained stimulation by a major proinflammatory cytokine, TNF-α, regulates skeletal myogenesis by inhibiting the interaction of SP1 with the Fbxl2 core promoter in proliferating myoblasts. Our findings contribute to the understanding of skeletal muscle regeneration through the identification of Fbxl2 as both a critical regulator of myogenic proliferative processes and a susceptible gene target during inflammatory stimulation by TNF-α in skeletal muscle. Modulation of Fbxl2 activity may have relevance to disorders of muscle wasting associated with sustained proinflammatory signaling.

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Pannexin 1 Regulates Skeletal Muscle Regeneration by Promoting Bleb-Based Myoblast Migration and Fusion Through a Novel Lipid Based Signaling Mechanism

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.736813 ◽

2021 ◽

Vol 9 ◽

Author(s):

Katia Suarez-Berumen ◽

Henry Collins-Hooper ◽

Anastasia Gromova ◽

Robyn Meech ◽

Alessandra Sacco ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Regeneration ◽

Muscle Development ◽

Myogenic Differentiation ◽

Skeletal Muscle Regeneration ◽

Stem Cell Population ◽

Amoeboid Movement ◽

Paracrine Signaling ◽

Signaling Mechanism ◽

Adult Skeletal Muscle

Adult skeletal muscle has robust regenerative capabilities due to the presence of a resident stem cell population called satellite cells. Muscle injury leads to these normally quiescent cells becoming molecularly and metabolically activated and embarking on a program of proliferation, migration, differentiation, and fusion culminating in the repair of damaged tissue. These processes are highly coordinated by paracrine signaling events that drive cytoskeletal rearrangement and cell-cell communication. Pannexins are a family of transmembrane channel proteins that mediate paracrine signaling by ATP release. It is known that Pannexin1 (Panx1) is expressed in skeletal muscle, however, the role of Panx1 during skeletal muscle development and regeneration remains poorly understood. Here we show that Panx1 is expressed on the surface of myoblasts and its expression is rapidly increased upon induction of differentiation and that Panx1–/– mice exhibit impaired muscle regeneration after injury. Panx1–/– myoblasts activate the myogenic differentiation program normally, but display marked deficits in migration and fusion. Mechanistically, we show that Panx1 activates P2 class purinergic receptors, which in turn mediate a lipid signaling cascade in myoblasts. This signaling induces bleb-driven amoeboid movement that in turn supports myoblast migration and fusion. Finally, we show that Panx1 is involved in the regulation of cell-matrix interaction through the induction of ADAMTS (Disintegrin-like and Metalloprotease domain with Thrombospondin-type 5) proteins that help remodel the extracellular matrix. These studies reveal a novel role for lipid-based signaling pathways activated by Panx1 in the coordination of myoblast activities essential for skeletal muscle regeneration.

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Smad4 restricts differentiation to promote expansion of satellite cell derived progenitors during skeletal muscle regeneration

eLife ◽

10.7554/elife.19484 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 16

Author(s):

Nicole D Paris ◽

Andrew Soroka ◽

Alanna Klose ◽

Wenxuan Liu ◽

Joe V Chakkalakal

Keyword(s):

Skeletal Muscle ◽

Muscle Regeneration ◽

Myogenic Differentiation ◽

Skeletal Muscle Regeneration ◽

Proliferative Potential ◽

Adult Skeletal Muscle ◽

Resident Stem Cells ◽

Elevated Activity ◽

Specific Deletion ◽

Tgfβ Superfamily

Skeletal muscle regenerative potential declines with age, in part due to deficiencies in resident stem cells (satellite cells, SCs) and derived myogenic progenitors (MPs); however, the factors responsible for this decline remain obscure. TGFβ superfamily signaling is an inhibitor of myogenic differentiation, with elevated activity in aged skeletal muscle. Surprisingly, we find reduced expression of Smad4, the downstream cofactor for canonical TGFβ superfamily signaling, and the target Id1 in aged SCs and MPs during regeneration. Specific deletion of Smad4 in adult mouse SCs led to increased propensity for terminal myogenic commitment connected to impaired proliferative potential. Furthermore, SC-specific Smad4 disruption compromised adult skeletal muscle regeneration. Finally, loss of Smad4 in aged SCs did not promote aged skeletal muscle regeneration. Therefore, SC-specific reduction of Smad4 is a feature of aged regenerating skeletal muscle and Smad4 is a critical regulator of SC and MP amplification during skeletal muscle regeneration.

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Pim1 kinase positively regulates myoblast behaviors and skeletal muscle regeneration

Cell Death and Disease ◽

10.1038/s41419-019-1993-3 ◽

2019 ◽

Vol 10 (10) ◽

Cited By ~ 1

Author(s):

Yuantong Liu ◽

Yue Shang ◽

Zihan Yan ◽

Hao Li ◽

Zhen Wang ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Regeneration ◽

Muscle Injury ◽

Myogenic Differentiation ◽

Skeletal Muscle Regeneration ◽

Myoblast Differentiation ◽

Adult Skeletal Muscle ◽

Skeletal Muscle Injury ◽

Pim1 Kinase

Abstract Adult skeletal muscle regeneration after injury depends on normal myoblast function. However, the intrinsic mechanisms for the control of myoblast behaviors are not well defined. Herein, we identified Pim1 kinase as a novel positive regulator of myoblast behaviors in vitro and muscle regeneration in vivo. Specifically, knockdown of Pim1 significantly restrains the proliferation and accelerates the apoptosis of myoblasts in vitro, indicating that Pim1 is critical for myoblast survival and amplification. Meanwhile, we found that Pim1 kinase is increased and translocated from cytoplasm into nucleus during myogenic differentiation. By using Pim1 kinase inhibitor, we proved that inhibition of Pim1 activity prevents myoblast differentiation and fusion, suggesting the necessity of Pim1 kinase activity for proper myogenesis. Mechanistic studies demonstrated that Pim1 kinase interacts with myogenic regulator MyoD and controls its transcriptional activity, inducing the expression of muscle-specific genes, which consequently promotes myogenic differentiation. Additionally, in skeletal muscle injury mouse model, deletion of Pim1 hinders the regeneration of muscle fibers and the recovery of muscle strength. Taken together, our study provides a potential target for the manipulation of myoblast behaviors in vitro and the myoblast-based therapeutics of skeletal muscle injury.

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The LIM domain protein nTRIP6 modulates the dynamics of myogenic differentiation

Scientific Reports ◽

10.1038/s41598-021-92331-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tannaz Norizadeh Abbariki ◽

Zita Gonda ◽

Denise Kemler ◽

Pavel Urbanek ◽

Tabea Wagner ◽

...

Keyword(s):

Skeletal Muscle ◽

Satellite Cells ◽

Muscle Regeneration ◽

Myogenic Differentiation ◽

Skeletal Muscle Regeneration ◽

Temporal Control ◽

Lim Domain ◽

Lim Domain Protein ◽

Domain Protein

AbstractThe process of myogenesis which operates during skeletal muscle regeneration involves the activation of muscle stem cells, the so-called satellite cells. These then give rise to proliferating progenitors, the myoblasts which subsequently exit the cell cycle and differentiate into committed precursors, the myocytes. Ultimately, the fusion of myocytes leads to myofiber formation. Here we reveal a role for the transcriptional co-regulator nTRIP6, the nuclear isoform of the LIM-domain protein TRIP6, in the temporal control of myogenesis. In an in vitro model of myogenesis, the expression of nTRIP6 is transiently up-regulated at the transition between proliferation and differentiation, whereas that of the cytosolic isoform TRIP6 is not altered. Selectively blocking nTRIP6 function results in accelerated early differentiation followed by deregulated late differentiation and fusion. Thus, the transient increase in nTRIP6 expression appears to prevent premature differentiation. Accordingly, knocking out the Trip6 gene in satellite cells leads to deregulated skeletal muscle regeneration dynamics in the mouse. Thus, dynamic changes in nTRIP6 expression contributes to the temporal control of myogenesis.

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Conditional Deletion of Dicer in Adult Mice Impairs Skeletal Muscle Regeneration

International Journal of Molecular Sciences ◽

10.3390/ijms20225686 ◽

2019 ◽

Vol 20 (22) ◽

pp. 5686 ◽

Cited By ~ 2

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.

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Tenogenic Contribution to Skeletal Muscle Regeneration: The Secretome of Scleraxis Overexpressing Mesenchymal Stem Cells Enhances Myogenic Differentiation In Vitro

International Journal of Molecular Sciences ◽

10.3390/ijms21061965 ◽

2020 ◽

Vol 21 (6) ◽

pp. 1965

Author(s):

Maximilian Strenzke ◽

Paolo Alberton ◽

Attila Aszodi ◽

Denitsa Docheva ◽

Elisabeth Haas ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Regeneration ◽

Skeletal Muscles ◽

Myogenic Differentiation ◽

Muscular Contraction ◽

Myoblast Fusion ◽

Skeletal Muscle Regeneration ◽

Potential Candidate ◽

Musculoskeletal Tissue

Integrity of the musculoskeletal system is essential for the transfer of muscular contraction force to the associated bones. Tendons and skeletal muscles intertwine, but on a cellular level, the myotendinous junctions (MTJs) display a sharp transition zone with a highly specific molecular adaption. The function of MTJs could go beyond a mere structural role and might include homeostasis of this musculoskeletal tissue compound, thus also being involved in skeletal muscle regeneration. Repair processes recapitulate several developmental mechanisms, and as myotendinous interaction does occur already during development, MTJs could likewise contribute to muscle regeneration. Recent studies identified tendon-related, scleraxis-expressing cells that reside in close proximity to the MTJs and the muscle belly. As the muscle-specific function of these scleraxis positive cells is unknown, we compared the influence of two immortalized mesenchymal stem cell (MSC) lines—differing only by the overexpression of scleraxis—on myoblasts morphology, metabolism, migration, fusion, and alignment. Our results revealed a significant increase in myoblast fusion and metabolic activity when exposed to the secretome derived from scleraxis-overexpressing MSCs. However, we found no significant changes in myoblast migration and myofiber alignment. Further analysis of differentially expressed genes between native MSCs and scleraxis-overexpressing MSCs by RNA sequencing unraveled potential candidate genes, i.e., extracellular matrix (ECM) proteins, transmembrane receptors, or proteases that might enhance myoblast fusion. Our results suggest that musculotendinous interaction is essential for the development and healing of skeletal muscles.

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Abcg2 labels multiple cell types in skeletal muscle and participates in muscle regeneration

The Journal of Cell Biology ◽

10.1083/jcb.201103159 ◽

2011 ◽

Vol 195 (1) ◽

pp. 147-163 ◽

Cited By ~ 35

Author(s):

Michelle J. Doyle ◽

Sheng Zhou ◽

Kathleen Kelly Tanaka ◽

Addolorata Pisconti ◽

Nicholas H. Farina ◽

...

Keyword(s):

Skeletal Muscle ◽

Satellite Cells ◽

Muscle Regeneration ◽

Side Population ◽

Cell Types ◽

Lineage Tracing ◽

Skeletal Muscle Regeneration ◽

Genetic Lineage ◽

Multiple Cell ◽

A Minor

Skeletal muscle contains progenitor cells (satellite cells) that maintain and repair muscle. It also contains muscle side population (SP) cells, which express Abcg2 and may participate in muscle regeneration or may represent a source of satellite cell replenishment. In Abcg2-null mice, the SP fraction is lost in skeletal muscle, although the significance of this loss was previously unknown. We show that cells expressing Abcg2 increased upon injury and that muscle regeneration was impaired in Abcg2-null mice, resulting in fewer centrally nucleated myofibers, reduced myofiber size, and fewer satellite cells. Additionally, using genetic lineage tracing, we demonstrate that the progeny of Abcg2-expressing cells contributed to multiple cell types within the muscle interstitium, primarily endothelial cells. After injury, Abcg2 progeny made a minor contribution to regenerated myofibers. Furthermore, Abcg2-labeled cells increased significantly upon injury and appeared to traffic to muscle from peripheral blood. Together, these data suggest an important role for Abcg2 in positively regulating skeletal muscle regeneration.

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Beneficial Effect of IL-4 and SDF-1 on Myogenic Potential of Mouse and Human Adipose Tissue-Derived Stromal Cells

Cells ◽

10.3390/cells9061479 ◽

2020 ◽

Vol 9 (6) ◽

pp. 1479

Author(s):

Karolina Archacka ◽

Joanna Bem ◽

Edyta Brzoska ◽

Areta M. Czerwinska ◽

Iwona Grabowska ◽

...

Keyword(s):

Skeletal Muscle ◽

Adipose Tissue ◽

Satellite Cells ◽

Stromal Cells ◽

Muscle Regeneration ◽

Myogenic Differentiation ◽

Human Adipose Tissue ◽

Skeletal Muscle Regeneration ◽

Animal Cells ◽

The Impact

Under physiological conditions skeletal muscle regeneration depends on the satellite cells. After injury these cells become activated, proliferate, and differentiate into myofibers reconstructing damaged tissue. Under pathological conditions satellite cells are not sufficient to support regeneration. For this reason, other cells are sought to be used in cell therapies, and different factors are tested as a tool to improve the regenerative potential of such cells. Many studies are conducted using animal cells, omitting the necessity to learn about human cells and compare them to animal ones. Here, we analyze and compare the impact of IL-4 and SDF-1, factors chosen by us on the basis of their ability to support myogenic differentiation and cell migration, at mouse and human adipose tissue-derived stromal cells (ADSCs). Importantly, we documented that mouse and human ADSCs differ in certain reactions to IL-4 and SDF-1. In general, the selected factors impacted transcriptome of ADSCs and improved migration and fusion ability of cells in vitro. In vivo, after transplantation into injured muscles, mouse ADSCs more eagerly participated in new myofiber formation than the human ones. However, regardless of the origin, ADSCs alleviated immune response and supported muscle reconstruction, and cytokine treatment enhanced these effects. Thus, we documented that the presence of ADSCs improves skeletal muscle regeneration and this influence could be increased by cell pretreatment with IL-4 and SDF-1.

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Klf5 regulates muscle differentiation by directly targeting muscle-specific genes in cooperation with MyoD in mice

eLife ◽

10.7554/elife.17462 ◽

2016 ◽

Vol 5 ◽

Cited By ~ 22

Author(s):

Shinichiro Hayashi ◽

Ichiro Manabe ◽

Yumi Suzuki ◽

Frédéric Relaix ◽

Yumiko Oishi

Keyword(s):

Skeletal Muscle ◽

Muscle Regeneration ◽

Myogenic Differentiation ◽

Muscle Differentiation ◽

Skeletal Muscle Regeneration ◽

Biological Processes ◽

Cell Proliferation And Differentiation ◽

Proliferation And Differentiation ◽

Acting In Concert

Krüppel-like factor 5 (Klf5) is a zinc-finger transcription factor that controls various biological processes, including cell proliferation and differentiation. We show that Klf5 is also an essential mediator of skeletal muscle regeneration and myogenic differentiation. During muscle regeneration after injury (cardiotoxin injection), Klf5 was induced in the nuclei of differentiating myoblasts and newly formed myofibers expressing myogenin in vivo. Satellite cell-specific Klf5 deletion severely impaired muscle regeneration, and myotube formation was suppressed in Klf5-deleted cultured C2C12 myoblasts and satellite cells. Klf5 knockdown suppressed induction of muscle differentiation-related genes, including myogenin. Klf5 ChIP-seq revealed that Klf5 binding overlaps that of MyoD and Mef2, and Klf5 physically associates with both MyoD and Mef2. In addition, MyoD recruitment was greatly reduced in the absence of Klf5. These results indicate that Klf5 is an essential regulator of skeletal muscle differentiation, acting in concert with myogenic transcription factors such as MyoD and Mef2.

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