scholarly journals Preservation of satellite cell number and regenerative potential with age reveals locomotory muscle bias

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robert W. Arpke ◽  
Ahmed S. Shams ◽  
Brittany C. Collins ◽  
Alexie A. Larson ◽  
Nguyen Lu ◽  
...  
Keyword(s):  
Satellite Cell ◽  
Cell Density ◽  
Satellite Cells ◽  
Tibialis Anterior ◽  
Environmental Changes ◽  
Cell Number ◽  
Self Renewal ◽  
Transplantation Assay ◽  
Muscle Groups ◽  
Old Mice

Abstract Background Although muscle regenerative capacity declines with age, the extent to which this is due to satellite cell-intrinsic changes vs. environmental changes has been controversial. The majority of aging studies have investigated hindlimb locomotory muscles, principally the tibialis anterior, in caged sedentary mice, where those muscles are abnormally under-exercised. Methods We analyze satellite cell numbers in 8 muscle groups representing locomotory and non-locomotory muscles in young and 2-year-old mice and perform transplantation assays of low numbers of hind limb satellite cells from young and old mice. Results We find that satellite cell density does not decline significantly by 2 years of age in most muscles, and one muscle, the masseter, shows a modest but statistically significant increase in satellite cell density with age. The tibialis anterior and extensor digitorum longus were clear exceptions, showing significant declines. We quantify self-renewal using a transplantation assay. Dose dilution revealed significant non-linearity in self-renewal above a very low threshold, suggestive of competition between satellite cells for space within the pool. Assaying within the linear range, i.e., transplanting fewer than 1000 cells, revealed no evidence of decline in cell-autonomous self-renewal or regenerative potential of 2-year-old murine satellite cells. Conclusion These data demonstrate the value of comparative muscle analysis as opposed to overreliance on locomotory muscles, which are not used physiologically in aging sedentary mice, and suggest that self-renewal impairment with age is precipitously acquired at the geriatric stage, rather than being gradual over time, as previously thought.

scholarly journals Myostatin negatively regulates satellite cell activation and self-renewal

2003 ◽  
Vol 162 (6) ◽  
pp. 1135-1147 ◽  
Author(s):  
Seumas McCroskery ◽  
Mark Thomas ◽  
Linda Maxwell ◽  
Mridula Sharma ◽  
Ravi Kambadur
Keyword(s):  
Satellite Cell ◽  
Satellite Cells ◽  
Cell Activation ◽  
Unit Length ◽  
Immunohistochemical Analysis ◽  
Cell Number ◽  
Negative Regulator ◽  
Self Renewal ◽  
Satellite Cell Activation

Satellite cells are quiescent muscle stem cells that promote postnatal muscle growth and repair. Here we show that myostatin, a TGF-β member, signals satellite cell quiescence and also negatively regulates satellite cell self-renewal. BrdU labeling in vivo revealed that, among the Myostatin-deficient satellite cells, higher numbers of satellite cells are activated as compared with wild type. In contrast, addition of Myostatin to myofiber explant cultures inhibits satellite cell activation. Cell cycle analysis confirms that Myostatin up-regulated p21, a Cdk inhibitor, and decreased the levels and activity of Cdk2 protein in satellite cells. Hence, Myostatin negatively regulates the G1 to S progression and thus maintains the quiescent status of satellite cells. Immunohistochemical analysis with CD34 antibodies indicates that there is an increased number of satellite cells per unit length of freshly isolated Mstn−/− muscle fibers. Determination of proliferation rate suggests that this elevation in satellite cell number could be due to increased self-renewal and delayed expression of the differentiation gene (myogenin) in Mstn−/− adult myoblasts. Taken together, these results suggest that Myostatin is a potent negative regulator of satellite cell activation and thus signals the quiescence of satellite cells.

193 Single Cell RNA-sequencing Reveals a Role of Lipid Metabolism in Muscle Satellite Cells

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 104-105
Author(s):  
Shihuan Kuang ◽  
Feng Yue ◽  
Stephanie Oprescu
Keyword(s):  
Gene Expression ◽  
Lipid Metabolism ◽  
Cell Fate ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Lipid Droplets ◽  
Self Renewal ◽  
Droplet Dynamics ◽  
Single Cell Rna Sequencing

Abstract Single Cell RNA-sequencing (scRNA-seq) is a powerful technique to deconvolute gene expression of various subset of cells intermingled within a complex tissue, such as the skeletal muscle. We first used scRNA-seq to understand dynamics of cell populations and their gene expression during muscle regeneration in murine limb muscles. This leads to the identification of a subset of satellite cells (the resident stem cells of skeletal muscles) with immune gene signatures in regenerating muscles. Next, we used scRNA-seq to examine gene expression dynamics of satellite cells at various status: quiescence, activation, proliferation, differentiation and self-renewal. This analysis uncovers stage-dependent changes in expression of genes related to lipid metabolism. Further analyses lead to the discovery of previously unappreciated dynamics of lipid droplets in satellite cells; and demonstrate that the abundance of the lipid droplets in newly divided satellite daughter cells is linked to cell fate segregation into differentiation versus self-renewal. Perturbation of lipid droplet dynamics through blocking lipolysis disrupts cell fate homeostasis and impairs muscle regeneration. Finally, we show that lipid metabolism regulates the function of satellite cells through two mechanisms. On one hand, lipid metabolism functions as an energy source through fatty acid oxidation (FAO), and blockage of FAO reduces energy production that is critical for satellite cell function. On the other hand, lipid metabolism generates bioactive molecules that influence signaling transduction and gene expression. In this scenario, lipid metabolism and FAO regulate the intracellular levels of acetyl-coA and selective acetylation of PAX7, a pivotal transcriptional factor underlying function of satellite cells. These results together reveal for the first time a critical role of lipid metabolism and lipid droplet dynamics in muscle satellite cell fate determination and regenerative function; and underscore a potential role of dietary fatty acids in satellite cell-dependent muscle development, growth and regeneration.

scholarly journals MLL1 is required for PAX7 expression and satellite cell self-renewal in mice

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Gregory C. Addicks ◽  
Caroline E. Brun ◽  
Marie-Claude Sincennes ◽  
John Saber ◽  
Christopher J. Porter ◽  
...  
Keyword(s):  
Satellite Cell ◽  
Satellite Cells ◽  
Transcriptional Activation ◽  
Cell Activation ◽  
Target Genes ◽  
Cell Function ◽  
Skeletal Muscle Regeneration ◽  
Differentiation Potential ◽  
Self Renewal

Abstract PAX7 is a paired-homeobox transcription factor that specifies the myogenic identity of muscle stem cells and acts as a nodal factor by stimulating proliferation while inhibiting differentiation. We previously found that PAX7 recruits the H3K4 methyltransferases MLL1/2 to epigenetically activate target genes. Here we report that in the absence of Mll1, myoblasts exhibit reduced H3K4me3 at both Pax7 and Myf5 promoters and reduced Pax7 and Myf5 expression. Mll1-deficient myoblasts fail to proliferate but retain their differentiation potential, while deletion of Mll2 had no discernable effect. Re-expression of PAX7 in committed Mll1 cKO myoblasts restored H3K4me3 enrichment at the Myf5 promoter and Myf5 expression. Deletion of Mll1 in satellite cells reduced satellite cell proliferation and self-renewal, and significantly impaired skeletal muscle regeneration. Pax7 expression was unaffected in quiescent satellite cells but was markedly downregulated following satellite cell activation. Therefore, MLL1 is required for PAX7 expression and satellite cell function in vivo. Furthermore, PAX7, but not MLL1, is required for Myf5 transcriptional activation in committed myoblasts.

scholarly journals Rejuvenating stem cells to restore muscle regeneration in aging

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 76 ◽  
Author(s):  
Eyal Bengal ◽  
Eusebio Perdiguero ◽  
Antonio L. Serrano ◽  
Pura Muñoz-Cánoves
Keyword(s):  
Stem Cells ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Environmental Changes ◽  
Local Environment ◽  
The Elderly ◽  
Muscle Repair ◽  
Extrinsic Factors ◽  
Repair Capacity ◽  
Cell Dysfunction

Adult muscle stem cells, originally called satellite cells, are essential for muscle repair and regeneration throughout life. Besides a gradual loss of mass and function, muscle aging is characterized by a decline in the repair capacity, which blunts muscle recovery after injury in elderly individuals. A major effort has been dedicated in recent years to deciphering the causes of satellite cell dysfunction in aging animals, with the ultimate goal of rejuvenating old satellite cells and improving muscle function in elderly people. This review focuses on the recently identified network of cell-intrinsic and -extrinsic factors and processes contributing to the decline of satellite cells in old animals. Some studies suggest that aging-related satellite-cell decay is mostly caused by age-associated extrinsic environmental changes that could be reversed by a “youthful environment”. Others propose a central role for cell-intrinsic mechanisms, some of which are not reversed by environmental changes. We believe that these proposals, far from being antagonistic, are complementary and that both extrinsic and intrinsic factors contribute to muscle stem cell dysfunction during aging-related regenerative decline. The low regenerative potential of old satellite cells may reflect the accumulation of deleterious changes during the life of the cell; some of these changes may be inherent (intrinsic) while others result from the systemic and local environment (extrinsic). The present challenge is to rejuvenate aged satellite cells that have undergone reversible changes to provide a possible approach to improving muscle repair in the elderly.

scholarly journals Heterogeneity of satellite cells implicates DELTA1/NOTCH2 signaling in self-renewal

2019 ◽  
Author(s):  
Valeria Yartseva ◽  
Leonard D. Goldstein ◽  
Julia Rodman ◽  
Lance Kates ◽  
Mark Z. Chen ◽  
...  
Keyword(s):  
Cell Fate ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Receptor Expression ◽  
Self Renewal ◽  
Cell Fate Decisions ◽  
Muscle Homeostasis ◽  
Early Regeneration ◽  
Time Point

SUMMARYHow satellite cells and their progenitors balance differentiation and self-renewal to achieve sustainable tissue regeneration is not well understood. A major roadblock to understanding satellite cell fate decisions has been the difficulty to study this process in vivo. By visualizing expression dynamics of myogenic transcription factors during early regeneration in vivo, we identified the time point at which cells undergo decisions to differentiate or self-renew. Single-cell RNA sequencing revealed heterogeneity of satellite cells during both muscle homeostasis and regeneration, including a subpopulation enriched in Notch2 receptor expression. Furthermore, we reveal that differentiating cells express the Dll1 ligand. Using antagonistic antibodies we demonstrate that the DLL1 and NOTCH2 signaling pair is required for satellite cell self-renewal. Thus, differentiating cells provide the self-renewing signal during regeneration, enabling proportional regeneration in response to injury while maintaining the satellite cell pool. These findings have implications for therapeutic control of muscle regeneration.

Inactivation of PPARβ/δ adversely affects satellite cells and reduces postnatal myogenesis

2015 ◽  
Vol 309 (2) ◽  
pp. E122-E131 ◽  
Author(s):  
Preeti Chandrashekar ◽  
Ravikumar Manickam ◽  
Xiaojia Ge ◽  
Sabeera Bonala ◽  
Craig McFarlane ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Muscle Regeneration ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Skeletal Muscle Regeneration ◽  
Muscle Weight ◽  
Cross Sectional ◽  
Postnatal Myogenesis

Peroxisome proliferator-activated receptor β/δ ( PPARβ/δ) is a ubiquitously expressed gene with higher levels observed in skeletal muscle. Recently, our laboratory showed (Bonala S, Lokireddy S, Arigela H, Teng S, Wahli W, Sharma M, McFarlane C, Kambadur R. J Biol Chem 287: 12935–12951, 2012) that PPARβ/δ modulates myostatin activity to induce myogenesis in skeletal muscle. In the present study, we show that PPARβ/δ-null mice display reduced body weight, skeletal muscle weight, and myofiber atrophy during postnatal development. In addition, a significant reduction in satellite cell number was observed in PPARβ/δ-null mice, suggesting a role for PPARβ/δ in muscle regeneration. To investigate this, tibialis anterior muscles were injured with notexin, and muscle regeneration was monitored on days 3, 5, 7, and 28 postinjury. Immunohistochemical analysis revealed an increased inflammatory response and reduced myoblast proliferation in regenerating muscle from PPARβ/δ-null mice. Histological analysis confirmed that the regenerated muscle fibers of PPARβ/δ-null mice maintained an atrophy phenotype with reduced numbers of centrally placed nuclei. Even though satellite cell numbers were reduced before injury, satellite cell self-renewal was found to be unaffected in PPARβ/δ-null mice after regeneration. Previously, our laboratory had showed (Bonala S, Lokireddy S, Arigela H, Teng S, Wahli W, Sharma M, McFarlane C, Kambadur R. J Biol Chem 287: 12935–12951, 2012) that inactivation of PPARβ/δ increases myostatin signaling and inhibits myogenesis. Our results here indeed confirm that inactivation of myostatin signaling rescues the atrophy phenotype and improves muscle fiber cross-sectional area in both uninjured and regenerated tibialis anterior muscle from PPARβ/δ-null mice. Taken together, these data suggest that absence of PPARβ/δ leads to loss of satellite cells, impaired skeletal muscle regeneration, and postnatal myogenesis. Furthermore, our results also demonstrate that functional antagonism of myostatin has utility in rescuing these effects.

scholarly journals Effects of Testosterone Supplementation on Skeletal Muscle Fiber Hypertrophy and Satellite Cells in Community-Dwelling Older Men

2006 ◽  
Vol 91 (8) ◽  
pp. 3024-3033 ◽  
Author(s):  
Indrani Sinha-Hikim ◽  
Marcia Cornford ◽  
Hilda Gaytan ◽  
Martin L. Lee ◽  
Shalender Bhasin
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Older Men ◽  
Cell Number ◽  
Community Dwelling ◽  
Testosterone Treatment ◽  
Testosterone Administration ◽  
Dose Dependent

Abstract Objective: In this study, we determined the effects of graded doses of testosterone on muscle fiber cross-sectional area (CSA) and satellite cell number and replication in older men. Participants: Healthy men, 60–75 yr old, received a long-acting GnRH agonist to suppress endogenous testosterone production and 25, 50, 125, 300, or 600 mg testosterone enanthate im weekly for 20 wk. Methods: Immunohistochemistry, light and confocal microscopy, and electron microscopy were used to perform fiber typing and quantitate myonuclear and satellite cell number in vastus lateralis biopsies, obtained before and after 20 wk of treatment. Results: Testosterone administration in older men was associated with dose-dependent increases in CSA of both types I and II fibers. Satellite cell number increased dose dependently at the three highest doses (3% at baseline vs. 6.2, 9.2, and 13.0% at 125, 300, and 600 mg doses, P < 0.05). Testosterone administration was associated with an increase in the number of proliferating cell nuclear antigen+ satellite cells (1.8% at baseline vs. 3.9, 7.5, and 13% at 125, 300, and 600 mg doses, P < 0.005). The expression of activated Notch, examined only in the 300-mg group (baseline, 2.3 vs. 9.0% after treatment, P < 0.005), increased in satellite cells after testosterone treatment. The expression of myogenin (baseline, 6.2 vs. 20.7% after treatment, P < 0.005), examined only in the 300-mg group, increased significantly in muscle fiber nuclei after testosterone treatment, but Numb expression did not change. Conclusions: Older men respond to graded doses of testosterone with a dose-dependent increase in muscle fiber CSA and satellite cell number. Testosterone-induced skeletal muscle hypertrophy in older men is associated with increased satellite cell replication and activation.

scholarly journals miR-24:Prdx6 interactions regulate oxidative stress and viability of myogenic progenitors during ageing

2021 ◽  
Author(s):  
Ana Soriano-Arroquia ◽  
John Gostage ◽  
David Bardell ◽  
Eugene McCloskey ◽  
Ilaria Bellantuono ◽  
...  
Keyword(s):  
Cell Viability ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Muscle Regeneration ◽  
Protective Mechanism ◽  
Compensatory Mechanism ◽  
Differentiation Potential ◽  
Myogenic Potential ◽  
Early Stages ◽  
Old Mice

ABSTRACTmicroRNAs regulate a myriad of physiological processes, including skeletal muscle regeneration and homeostasis. During ageing, changes in muscle fibre microenvironment contribute to the capability of satellite cells to regenerate the muscle in response to injury and loading stressors. In this study, we isolated murine satellite cells and primary myogenic progenitors from mice and humans to demonstrate that the microRNA miR-24-3p and its target peroxiredoxin 6 (Prdx6) play an important role in muscle regeneration during ageing, regulating satellite cell viability and their differentiation potential. Our results show upregulation of miR-24 during early stages of muscle regeneration in vivo in adult mice, suggesting a potential role of miR-24 at the early stages of muscle injury. On contrary, miR-24 was downregulated during regeneration of muscle of old mice. miR-24 was also downregulated, whereas its target gene Prdx6 was upregulated, in satellite cells isolated from old mice. miR-24 consistently regulated viability and myogenic potential of myogenic progenitors from both humans and old mice, suggesting that changes in miR-24 levels during ageing may contribute to defective early stages of muscle regeneration during ageing through affecting satellite cell viability and myogenic potential. This regulation likely occurs via miR-24 counteracting the generation of reactive oxygen species through Prdx6 de-repression in primary myogenic progenitors isolated from humans and old mice. We propose that downregulation of miR-24 in muscle of old mice following injury may be a protective mechanism against elevated ROS levels to maintain satellite cell viability and myogenic potential, acting through Prdx6 upregulation. However, as miR-24 is a regulator of p16 and p21, this downregulation may lead to increased satellite cell senescence, therefore representing an age-related failed compensatory mechanism.

scholarly journals Rb1 Gene Inactivation Expands Satellite Cell and Postnatal Myoblast Pools

2011 ◽  
Vol 286 (22) ◽  
pp. 19556-19564 ◽  
Author(s):  
Tohru Hosoyama ◽  
Koichi Nishijo ◽  
Suresh I. Prajapati ◽  
Guangheng Li ◽  
Charles Keller
Keyword(s):  
Cell Cycle ◽  
Stem Cell ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Cell Activation ◽  
Cell Lineage ◽  
Cell Number ◽  
Fiber Formation

Satellite cells are well known as a postnatal skeletal muscle stem cell reservoir that under injury conditions participate in repair. However, mechanisms controlling satellite cell quiescence and activation are the topic of ongoing inquiry by many laboratories. In this study, we investigated whether loss of the cell cycle regulatory factor, pRb, is associated with the re-entry of quiescent satellite cells into replication and subsequent stem cell expansion. By ablation of Rb1 using a Pax7CreER,Rb1 conditional mouse line, satellite cell number was increased 5-fold over 6 months. Furthermore, myoblasts originating from satellite cells lacking Rb1 were also increased 3-fold over 6 months, while terminal differentiation was greatly diminished. Similarly, Pax7CreER,Rb1 mice exhibited muscle fiber hypotrophy in vivo under steady state conditions as well as a delay of muscle regeneration following cardiotoxin-mediated injury. These results suggest that cell cycle re-entry of quiescent satellite cells is accelerated by lack of Rb1, resulting in the expansion of both satellite cells and their progeny in adolescent muscle. Conversely, that sustained Rb1 loss in the satellite cell lineage causes a deficit of muscle fiber formation. However, we also show that pharmacological inhibition of protein phosphatase 1 activity, which will result in pRb inactivation accelerates satellite cell activation and/or expansion in a transient manner. Together, our results raise the possibility that reversible pRb inactivation in satellite cells and inhibition of protein phosphorylation may provide a new therapeutic tool for muscle atrophy by short term expansion of the muscle stem cells and myoblast pool.

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