A novel myogenic cell line with phenotypic properties of muscle progenitors (original) (raw)
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Sca-1 negatively regulates proliferation and differentiation of muscle cells
Developmental Biology, 2005
Satellite cells are tissue-specific stem cells critical for skeletal muscle growth and regeneration. Upon exposure to appropriate stimuli, satellite cells produce progeny myoblasts. Heterogeneity within a population of myoblasts ensures that a subset of myoblasts readily differentiate to form myotubes, whereas other myoblasts remain undifferentiated and thus available for future muscle growth. The mechanisms that contribute to this heterogeneity in myoblasts are largely unknown. We show that satellite cells are Sca-1 neg but give rise to myoblasts that are heterogeneous for sca-1 expression. The majority of myoblasts are sca-1 neg , rapidly divide, and are capable of undergoing myogenic differentiation to form myotubes. In contrast, a minority population is sca-1 pos , divides slower, and does not readily form myotubes. Sca-1 expression is not static but rather dynamically modulated by the microenvironment. Gain-of-function and loss-of-function experiments demonstrate that sca-1 has a functional role in regulating proliferation and differentiation of myoblasts. Myofiber size of sca-1 null muscles is altered in an age-dependent manner, with increased size observed in younger mice and decreased size in older mice. These studies reveal a novel system that reversibly modulates the myogenic behavior of myoblasts. These studies provide evidence that, rather than being a fixed property, myoblast heterogeneity can be modulated by the microenvironment. D
Muscle morphogenetic protein induces myogenic gene expression in Swiss-3T3 cells
Wound Repair and Regeneration, 1998
Myogenesis is thought to be regulated by the MyoD family of regulatory genes, which includes MyoD, myogenin, MRF- 4/myf-6, and myf-5. In situ hybridization studies of vertebrate skeletal muscle development have shown the colocalization of the MyoD family of regulatory genes to specific stages of muscle development. Although many studies have analyzed the regulatory role of these genes during myogenesis, there have been few reports dealing with the activation of these myogenic regulatory genes by exogenous agents. We have previously shown that muscle morphogenetic protein induces myogenesis in clonal populations of avian pluripotent stem cells. The current study was designed to examine the ability of muscle morphogenetic protein to induce myogenesis in a clonal population derived from the established fibroblastic Swiss-3T3 cell line. Swiss-3T3 cells were cloned to generate separate cell populations, tested for pluripotency, propagated through 690 cell doublings, retested for pluripotency, treated with muscle morphogenetic protein, and examined for the induction of gene expression using probes for the transcription products of MyoD and myogenin. Muscle morphogenetic protein induced the expression of mRNAs for MyoD and myogenin, suggesting a role for this compound as an exogenous activator of myogenesis.
Skeletal muscle progenitor cells in development and regeneration
In mammals, the repair of skeletal muscle damage in the adult shares many features with embryonic muscle formation. The aim of this review is to outline the cellular and molecular mechanisms that govern muscle development and regeneration. Skeletal muscle tissue is comprised of multinucleated myofibres that arise from the fusion of mononucleated myoblasts during embryonic development. In muscle precursor cells, elaborate mechanisms co-ordinate regulation of the cell cycle with the onset of tissue-specific gene expression and may protect these progenitors from precocious differentiation. Differentiated myofibres are incapable of resuming active proliferation, but damaged adult muscle can regenerate. This regenerative capacity resides in a population of undifferentiated myogenic precursor cells known as satellite cells (SC) that are associated with the myofibres. SC contribute to postnatal muscle fibre growth as well as regeneration and are believed to function as the stem cells of ad...
PLOS ONE, 2019
Human embryonic stem cell (hESC)-derived skeletal muscle progenitors (SMP)-defined as PAX7-expressing cells with myogenic potential-can provide an abundant source of donor material for muscle stem cell therapy. As in vitro myogenesis is decoupled from in vivo timing and 3D-embryo structure, it is important to characterize what stage or type of muscle is modeled in culture. Here, gene expression profiling is analyzed in hESCs over a 50 day skeletal myogenesis protocol and compared to datasets of other hESC-derived skeletal muscle and adult murine satellite cells. Furthermore, day 2 cultures differentiated with high or lower concentrations of CHIR99021, a GSK3A/GSK3B inhibitor, were contrasted. Expression profiling of the 50 day time course identified successively expressed gene subsets involved in mesoderm/paraxial mesoderm induction, somitogenesis, and skeletal muscle commitment/formation which could be regulated by a putative cascade of transcription factors. Initiating differentiation with higher CHIR99021 concentrations significantly increased expression of MSGN1 and TGFB-superfamily genes, notably NODAL, resulting in enhanced paraxial mesoderm and reduced ectoderm/neuronal gene expression. Comparison to adult satellite cells revealed that genes expressed in 50-day cultures correlated better with those expressed by quiescent or early activated satellite cells, which have the greatest therapeutic potential. Day 50 cultures were similar to other hESC-derived skeletal muscle and both expressed known and novel SMP surface proteins. Overall, a putative cascade of transcription factors has been identified which regulates four stages of myogenesis. Subsets of these factors were upregulated by high CHIR99021 or their binding sites were
Cultured myf5 null and myoD null muscle precursor cells display distinct growth defects
Biology of the Cell, 2000
Laboratoire de développement cellulaire - URA 1947, Institut Pasteur, 25, rue du D r -Roux, 75724 Paris cedex 15, France Myf-5 and MyoD are the two muscle regulatory factors expressed from the myoblast stage to maintain the identity and to promote the subsequent differentiation of muscle precursor cells. To get insight into their role we have studied the capacity to proliferate and to differentiate of myf-5 and myoD null myoblasts in primary cultures and in the subsequent passages. Our results indicate that myf-5 null myoblasts differ from wild type (wt) myoblasts in that they undergo precocious differentiation: they become myogenin-and troponin T-positive and fail to incorporate bromodeoxyuridine (BrdU) under culture conditions and at a time when wt cells are not yet differentiated and continue to proliferate. In primary cultures of myoD null cells, up to 60% of the cells were scored as myoblasts on the basis of the expression of myf-5. These myoD-deficient myoblasts, unlike myoD-expressing cells, were poorly differentiating and displayed a severe growth defect that led to their elimination from the cultures: within a few passages myoblasts were absent from myoD-deficient cultures, which mostly consisted of senescent cells. That a null mutation in either gene reduces the proliferative potential of cultured myoblasts raises the possibility that Myf-5 and MyoD serve proliferation of muscle precursor cells. © 2000 Éditions scientifiques et médicales Elsevier SAS myf-5 / myoD / muscle / regeneration / proliferation Proliferation and differentiation of myf5 and myoD null myoblasts D. Montarras et al. 566 Biology of the Cell 92 (2000) 565-572 Proliferation and differentiation of myf5 and myoD null myoblasts D. Montarras et al.
Stac3 Is Required for Myotube Formation and Myogenic Differentiation in Vertebrate Skeletal Muscle
Journal of Biological Chemistry, 2012
Background: Stac3, an uncharacterised gene, was identified by its high expression levels in vertebrate muscle. Results: Knockdown of stac3 inhibited zebrafish myofibrillar protein assembly and differentiation in C2C12 cells by perturbing Akt signaling and cell cycle exit. Conclusion: Stac3 is a novel regulator of myogenic differentiation. Significance: Identifying new genes controlling myogenic differentiation will allow greater understanding of processes leading to muscular diseases.
Experimental Cell Research, 2011
A high concentration of bone morphogenetic proteins (BMPs) stimulates myogenic progenitor cells to undergo heterotopic osteogenic differentiation. However, the physiological role of the Smad signaling pathway during terminal muscle differentiation has not been resolved. We report here that Smad1/5/8 was phosphorylated and activated in undifferentiated growing mouse myogenic progenitor Ric10 cells without exposure to any exogenous BMPs. The amount of phosphorylated Smad1/5/8 was severely reduced during precocious myogenic differentiation under the high cell density culture condition even in growth medium supplemented with a high concentration of serum. Inhibition of the Smad signaling pathway by dorsomorphin, an inhibitor of Smad activation, or noggin, a specific antagonist of BMP, induced precocious terminal differentiation of myogenic progenitor cells in a cell density-dependent fashion even in growth medium. In addition, Smad1/5/8 was transiently activated in proliferating myogenic progenitor cells during muscle regeneration in rats. The present results indicate that the Smad signaling pathway is involved in a critical switch between growth and differentiation of myogenic progenitor cells both in vitro and in vivo. Furthermore, precocious cell density-dependent myogenic differentiation suggests that a community effect triggers the terminal muscle differentiation of myogenic cells by quenching the Smad signaling.
Myogenin regulates a distinct genetic program in adult muscle stem cells
Developmental Biology, 2008
In contrast to the detailed understanding we have for the regulation of skeletal muscle gene expression in embryos, similar insights into postnatal muscle growth and regeneration are largely inferential or do not directly address gene regulatory mechanisms. Muscle stem cells (satellite cells) are chiefly responsible for providing new muscle during postnatal and adult life. The purpose of this study was to determine the role that the myogenic basic helix-loop-helix regulatory factor myogenin has in postnatal muscle growth and adult muscle stem cell gene expression. We found that myogenin is absolutely required for skeletal muscle development and survival until birth, but it is dispensable for postnatal life. However, Myog deletion after birth led to reduced body size implying a role for myogenin in regulating body homeostasis. Despite a lack of skeletal muscle defects in Myog-deleted mice during postnatal life and the efficient differentiation of cultured Myog-deleted adult muscle stem cells, the loss of myogenin profoundly altered the pattern of gene expression in cultured muscle stem cells and adult skeletal muscle. Remarkably, these changes in gene expression were distinct from those found in Myog-null embryonic skeletal muscle, indicating that myogenin has separate functions during postnatal life.
Skeletal Muscle - From Myogenesis to Clinical Relations
2012
Skeletal Muscle-From Myogenesis to Clinical Relations 32 they differentiate somites produce the dermomyotome, a 'C' shaped epithelium containing proliferative muscle precusors (myoblasts) that express the transcription factor Pax3 [22]. Somites can be divided into two major domains: epaxial, located dorso-medially, and hypaxial, located ventrolaterally. Muscles arising from these domains correspond to the adult epaxial and hypaxial muscles which are innervated by the dorsal and ventral ramus of the spinal cord respectively. Cells from the dermomytome migrate around the edges of the dermomyotome to form an underlying layer, the primary myotome [23, 24], where the MRFs are first expressed and muscles begin to differentiate. The muscles of the limb are also derived from somites but are generated when myoblasts delaminate from the hypaxial dermomyotome and migrate into the forming limb bud [17, 25]. This process is regulated by production of HGF/SF from the lateral mesoderm at limb levels which induces migration of myoblasts, to maintain them in a proliferative state and to delay MRF expression [26-28]. The expression of MyoD in these different muscle groups during embryo development is shown in figure 1. The Myogenic Regulatory Factors: Critical Determinants of Muscle Identity in Development, Growth and Regeneration 33 The Myogenic Regulatory Factors: Critical Determinants of Muscle Identity in Development, Growth and Regeneration 39 issue of what are target genes of each MRF in vivo and how do they differ in their activity in different muscle types. Understanding the answers to these questions will provide key insights which will directly influence both basic science and regenerative medicine.