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.

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.

scholarly journals Metformin Delays Satellite Cell Activation and Maintains Quiescence

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Theodora Pavlidou ◽  
Milica Marinkovic ◽  
Marco Rosina ◽  
Claudia Fuoco ◽  
Simone Vumbaca ◽  
...  
Keyword(s):  
Satellite Cell ◽  
Muscle Tissue ◽  
Satellite Cells ◽  
Cell Activation ◽  
Myogenic Differentiation ◽  
Metabolic State ◽  
Cell Pool ◽  
Age Related ◽  
Satellite Cell Activation

The regeneration of the muscle tissue relies on the capacity of the satellite stem cell (SC) population to exit quiescence, divide asymmetrically, proliferate, and differentiate. In age-related muscle atrophy (sarcopenia) and several dystrophies, regeneration cannot compensate for the loss of muscle tissue. These disorders are associated with the depletion of the satellite cell pool or with the loss of satellite cell functionality. Recently, the establishment and maintenance of quiescence in satellite cells have been linked to their metabolic state. In this work, we aimed to modulate metabolism in order to preserve the satellite cell pool. We made use of metformin, a calorie restriction mimicking drug, to ask whether metformin has an effect on quiescence, proliferation, and differentiation of satellite cells. We report that satellite cells, when treated with metformin in vitro, ex vivo, or in vivo, delay activation, Pax7 downregulation, and terminal myogenic differentiation. We correlate the metformin-induced delay in satellite cell activation with the inhibition of the ribosome protein RPS6, one of the downstream effectors of the mTOR pathway. Moreover, in vivo administration of metformin induces a belated regeneration of cardiotoxin- (CTX-) damaged skeletal muscle. Interestingly, satellite cells treated with metformin immediately after isolation are smaller in size and exhibit reduced pyronin Y levels, which suggests that metformin-treated satellite cells are transcriptionally less active. Thus, our study suggests that metformin delays satellite cell activation and differentiation by favoring a quiescent, low metabolic state.

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 KLF4 suppresses transformation of pre-B cells by ABL oncogenes

Blood ◽  
2006 ◽  
Vol 109 (2) ◽  
pp. 747-755 ◽  
Author(s):  
Michael G. Kharas ◽  
Isharat Yusuf ◽  
Vanessa M. Scarfone ◽  
Vincent W. Yang ◽  
Julia A. Segre ◽  
...  
Keyword(s):  
Cell Cycle ◽  
B Cells ◽  
Tumor Suppressor ◽  
B Cell ◽  
Cell Activation ◽  
Cell Transformation ◽  
Cell Lineage ◽  
Cell Types ◽  
B Cell Malignancies

Abstract Genes that are strongly repressed after B-cell activation are candidates for being inactivated, mutated, or repressed in B-cell malignancies. Krüppel-like factor 4 (Klf4), a gene down-regulated in activated murine B cells, is expressed at low levels in several types of human B-cell lineage lymphomas and leukemias. The human KLF4 gene has been identified as a tumor suppressor gene in colon and gastric cancer; in concordance with this, overexpression of KLF4 can suppress proliferation in several epithelial cell types. Here we investigate the effects of KLF4 on pro/pre–B-cell transformation by v-Abl and BCR-ABL, oncogenes that cause leukemia in mice and humans. We show that overexpression of KLF4 induces arrest and apoptosis in the G1 phase of the cell cycle. KLF4-mediated death, but not cell-cycle arrest, can be rescued by Bcl-XL overexpression. Transformed pro/pre-B cells expressing KLF4 display increased expression of p21CIP and decreased expression of c-Myc and cyclin D2. Tetracycline-inducible expression of KLF4 in B-cell progenitors of transgenic mice blocks transformation by BCR-ABL and depletes leukemic pre-B cells in vivo. Collectively, our work identifies KLF4 as a putative tumor suppressor in B-cell malignancies.

scholarly journals Pro-myogenic small molecules revealed by a chemical screen on primary muscle stem cells

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sean M. Buchanan ◽  
Feodor D. Price ◽  
Alessandra Castiglioni ◽  
Amanda Wagner Gee ◽  
Joel Schneider ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Stem Cell ◽  
Small Molecules ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Muscle Repair ◽  
Muscle Stem Cells

Abstract Satellite cells are the canonical muscle stem cells that regenerate damaged skeletal muscle. Loss of function of these cells has been linked to reduced muscle repair capacity and compromised muscle health in acute muscle injury and congenital neuromuscular diseases. To identify new pathways that can prevent loss of skeletal muscle function or enhance regenerative potential, we established an imaging-based screen capable of identifying small molecules that promote the expansion of freshly isolated satellite cells. We found several classes of receptor tyrosine kinase (RTK) inhibitors that increased freshly isolated satellite cell numbers in vitro. Further exploration of one of these compounds, the RTK inhibitor CEP-701 (also known as lestaurtinib), revealed potent activity on mouse satellite cells both in vitro and in vivo. This expansion potential was not seen upon exposure of proliferating committed myoblasts or non-myogenic fibroblasts to CEP-701. When delivered subcutaneously to acutely injured animals, CEP-701 increased both the total number of satellite cells and the rate of muscle repair, as revealed by an increased cross-sectional area of regenerating fibers. Moreover, freshly isolated satellite cells expanded ex vivo in the presence of CEP-701 displayed enhanced muscle engraftment potential upon in vivo transplantation. We provide compelling evidence that certain RTKs, and in particular RET, regulate satellite cell expansion during muscle regeneration. This study demonstrates the power of small molecule screens of even rare adult stem cell populations for identifying stem cell-targeting compounds with therapeutic potential.

scholarly journals A Role for Nitric Oxide in Muscle Repair: Nitric Oxide–mediated Activation of Muscle Satellite Cells

2000 ◽  
Vol 11 (5) ◽  
pp. 1859-1874 ◽  
Author(s):  
Judy E. Anderson
Keyword(s):  
Nitric Oxide ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Knockout Mice ◽  
Cell Activation ◽  
Mdx Mice ◽  
Muscle Repair ◽  
Muscle Satellite Cells ◽  
Satellite Cell Activation

Muscle satellite cells are quiescent precursors interposed between myofibers and a sheath of external lamina. Although their activation and recruitment to cycle enable muscle repair and adaptation, the activation signal is not known. Evidence is presented that nitric oxide (NO) mediates satellite cell activation, including morphological hypertrophy and decreased adhesion in the fiber-lamina complex. Activation in vivo occurred within 1 min after injury. Cell isolation and histology showed that pharmacological inhibition of nitric oxide synthase (NOS) activity prevented the immediate injury-induced myogenic cell release and delayed the hypertrophy of satellite cells in that muscle. Transient activation of satellite cells in contralateral muscles 10 min later suggested that a circulating factor may interact with NO-mediated signaling. Interestingly, satellite cell activation in muscles of mdx dystrophic mice and NOS-I knockout mice quantitatively resembled NOS-inhibited release of normal cells, in agreement with reports of displaced and reduced NOS expression in dystrophin-deficient mdx muscle and the complete loss of NOS-I expression in knockout mice. Brief NOS inhibition in normal and mdx mice during injury produced subtle alterations in subsequent repair, including apoptosis in myotube nuclei and myotube formation inside laminar sheaths. Longer NOS inhibition delayed and restricted the extent of repair and resulted in fiber branching. A model proposes the hypothesis that NO release mediates satellite cell activation, possibly via shear-induced rapid increases in NOS activity that produce “NO transients.”

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 The p38α/β MAPK functions as a molecular switch to activate the quiescent satellite cell

2005 ◽  
Vol 169 (1) ◽  
pp. 105-116 ◽  
Author(s):  
Nathan C. Jones ◽  
Kristina J. Tyner ◽  
Lisa Nibarger ◽  
Heather M. Stanley ◽  
Dawn D.W. Cornelison ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Satellite Cell ◽  
Satellite Cells ◽  
Cell Activation ◽  
Molecular Switch ◽  
Quiescent State ◽  
Mitogen Activated Protein ◽  
Skeletal Muscle Satellite Cell ◽  
External Stimuli

Somatic stem cells cycle slowly or remain quiescent until required for tissue repair and maintenance. Upon muscle injury, stem cells that lie between the muscle fiber and basal lamina (satellite cells) are activated, proliferate, and eventually differentiate to repair the damaged muscle. Satellite cells in healthy muscle are quiescent, do not express MyoD family transcription factors or cell cycle regulatory genes and are insulated from the surrounding environment. Here, we report that the p38α/β family of mitogen-activated protein kinases (MAPKs) reversibly regulates the quiescent state of the skeletal muscle satellite cell. Inhibition of p38α/β MAPKs (a) promotes exit from the cell cycle, (b) prevents differentiation, and (c) insulates the cell from most external stimuli allowing the satellite cell to maintain a quiescent state. Activation of satellite cells and p38α/β MAPKs occurs concomitantly, providing further support that these MAPKs function as a molecular switch for satellite cell activation.

scholarly journals Semaphorin 3A mediated brain tumor stem cell proliferation and invasion in EGFRviii mutant gliomas

BMC Cancer ◽  
2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Dominique M. O. Higgins ◽  
Maisel Caliva ◽  
Mark Schroeder ◽  
Brett Carlson ◽  
Pavan S. Upadhyayula ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cell ◽  
Brain Tumor ◽  
Propidium Iodide ◽  
Tumor Stem Cell ◽  
Semaphorin 3A ◽  
Brain Tumor Stem Cell ◽  
Proliferation And Invasion ◽  
Invasion Assays

Abstract Background Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults, with a median survival of approximately 15 months. Semaphorin 3A (Sema3A), known for its axon guidance and antiangiogenic properties, has been implicated in GBM growth. We hypothesized that Sema3A directly inhibits brain tumor stem cell (BTSC) proliferation and drives invasion via Neuropilin 1 (Nrp1) and Plexin A1 (PlxnA1) receptors. Methods GBM BTSC cell lines were assayed by immunostaining and PCR for levels of Semaphorin 3A (Sema3A) and its receptors Nrp1 and PlxnA1. Quantitative BrdU, cell cycle and propidium iodide labeling assays were performed following exogenous Sema3A treatment. Quantitative functional 2-D and 3-D invasion assays along with shRNA lentiviral knockdown of Nrp1 and PlxnA1 are also shown. In vivo flank studies comparing tumor growth of knockdown versus control BTSCs were performed. Statistics were performed using GraphPad Prism v7. Results Immunostaining and PCR analysis revealed that BTSCs highly express Sema3A and its receptors Nrp1 and PlxnA1, with expression of Nrp1 in the CD133 positive BTSCs, and absence in differentiated tumor cells. Treatment with exogenous Sema3A in quantitative BrdU, cell cycle, and propidium iodide labeling assays demonstrated that Sema3A significantly inhibited BTSC proliferation without inducing cell death. Quantitative functional 2-D and 3-D invasion assays showed that treatment with Sema3A resulted in increased invasion. Using shRNA lentiviruses, knockdown of either NRP1 or PlxnA1 receptors abrogated Sema3A antiproliferative and pro-invasive effects. Interestingly, loss of the receptors mimicked Sema3A effects, inhibiting BTSC proliferation and driving invasion. Furthermore, in vivo studies comparing tumor growth of knockdown and control infected BTSCs implanted into the flanks of nude mice confirmed the decrease in proliferation with receptor KD. Conclusions These findings demonstrate the importance of Sema3A signaling in GBM BTSC proliferation and invasion, and its potential as a therapeutic target.

Mechanical load-dependent regulation of satellite cell and fiber size in rat soleus muscle

2006 ◽  
Vol 290 (4) ◽  
pp. C981-C989 ◽  
Author(s):  
X. D. Wang ◽  
F. Kawano ◽  
Y. Matsuoka ◽  
K. Fukunaga ◽  
M. Terada ◽  
...  
Keyword(s):  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Central Region ◽  
Sarcomere Length ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fiber Properties ◽  
Rat Soleus Muscle ◽  
The Mean

The effects of mechanical unloading and reloading on the properties of rat soleus muscle fibers were investigated in male Wistar Hannover rats. Satellite cells in the fibers of control rats were distributed evenly throughout the fiber length. After 16 days of hindlimb unloading, the number of satellite cells in the central, but not the proximal or distal, region of the fiber was decreased. The number of satellite cells in the central region gradually increased during the 16-day period of reloading. The mean sarcomere length in the central region of the fibers was passively shortened during unloading due to the plantarflexed position at the ankle joint: sarcomere length was maintained at <2.1 μm, which is a critical length for tension development. Myonuclear number and domain size, fiber cross-sectional area, and the total number of mitotically active and quiescent satellite cells of whole muscle fibers were lower than control fibers after 16 days of unloading. These values then returned to control values after 16 days of reloading. These results suggest that satellite cells play an important role in the regulation of muscle fiber properties. The data also indicate that the satellite cell-related regulation of muscle fiber properties is dependent on the level of mechanical loading, which, in turn, is influenced by the mean sarcomere length. However, it is still unclear why the region-specific responses, which were obvious in satellite cells, were not induced in myonuclear number and fiber cross-sectional area.

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