Differential response of embryonic and fetal myoblasts to TGF beta: a possible regulatory mechanism of skeletal muscle histogenesis

Development ◽  
1994 ◽  
Vol 120 (4) ◽  
pp. 925-933 ◽  
Author(s):  
M.G. Cusella-De Angelis ◽  
S. Molinari ◽  
A. Le Donne ◽  
M. Coletta ◽  
E. Vivarelli ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Proximal Region ◽  
S Phase ◽  
Fiber Formation ◽  
Limb Bud ◽  
Tgf Beta ◽  
Heavy Chains ◽  
Skeletal Myoblasts ◽  
Brdu Labeling

Embryonic and fetal skeletal myoblasts were grown in culture in the presence of TGF beta. Under the conditions employed, TGF beta inhibited differentiation of fetal but not of embryonic myoblasts. To investigate the possible relevance of these data to skeletal muscle histogenesis in vivo, we studied the proliferation/differentiation state of mesodermal cells in the proximal region of the limb bud at the time of primary fiber formation. BrdU labeling and immunostaining for myosin heavy chains revealed that very few mesodermal cells enter the S phase of the cycle when differentiated primary fibers first appear. However, a few hours later, many cells in S phase surround newly formed muscle fibers, suggesting that the latter may be a source of mitogens for undifferentiated myoblasts. Co-culture experiments supported this hypothesis, showing that medium conditioned by fiber-containing explants can stimulate myoblast proliferation. Taken together these data suggested a possible mechanism for the regulation of muscle fiber formation. The model assumes that fibers form in the proximal region of the limb bud, where TGF beta is known to be present, and BrdU labeling experiments did not reveal cells in S phase. It is conceivable that non-dividing embryonic myoblasts (which do not respond to TGF beta) can undergo differentiation, while fetal myoblasts are inhibited by TGF beta. Once formed, primary fibers may stimulate a new wave of proliferation in fetal myoblasts, in order to expand the pool of cells needed to form secondary fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Cell kinetics of human tumors by in vitro bromodeoxyuridine labeling.

1989 ◽  
Vol 37 (9) ◽  
pp. 1449-1454 ◽  
Author(s):  
J S Meyer ◽  
J Nauert ◽  
S Koehm ◽  
J Hughes
Keyword(s):  
Tritiated Thymidine ◽  
S Phase ◽  
Dna Flow Cytometry ◽  
Breast Carcinomas ◽  
Brdu Labeling ◽  
The Central Nervous System ◽  
Labeling Method ◽  
Kinetics Of

We labeled active S-phase cells in primary breast carcinomas with a modified 5-bromo-2'-deoxyuridine (BrdU) procedure using a silver-enhanced colloidal gold visualization step. Separate samples of 29 tumors were labeled with BrdU or tritiated thymidine ([3H]-dThd), and the labeling indices (LI) from the two methods were equivalent (Spearman's correlation coefficient = 0.96). Three breast carcinomas were incubated in various mixes of both BrdU and [3H]-dThd and developed sequentially for each. Paired photomicrographs showed that the same nuclei were labeled by either precursor. The in vitro method yielded LIs similar to those reported after in vivo pulse BrdU labeling for tumors of the central nervous system. The BrdU LI correlated significantly (r = 0.76, p less than 0.001) with % S-phase by DNA flow cytometry in 33 breast carcinomas. The BrdU labeling method is simpler and more rapid than the [3H]-dThd procedure (1-2 days for completion for the former, 7-10 days for the latter), and it provides an equivalent measurement of proliferative index.

Embryonic Stem Cells Differentiated in Vitro as a Novel Source of Cells for Transplantation

1996 ◽  
Vol 5 (2) ◽  
pp. 131-143 ◽  
Author(s):  
Jonathan Dinsmore ◽  
Judson Ratliff ◽  
Terry Deacon ◽  
Peyman Pakzaba ◽  
Douglas Jacoby ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Es Cells ◽  
Embryonic Stem ◽  
Muscle Cells ◽  
Cell Types ◽  
Cell Type ◽  
Skeletal Myoblasts ◽  
Muscle Cell Type

The controlled differentiation of mouse embryonic stem (ES) cells into near homogeneous populations of both neurons and skeletal muscle cells that can survive and function in vivo after transplantation is reported. We show that treatment of pluripotent ES cells with retinoic acid (RA) and dimethylsulfoxide (DMSO) induce differentiation of these cells into highly enriched populations of γ-aminobutyric acid (GABA) expressing neurons and skeletal myoblasts, respectively. For neuronal differentiation, RA alone is sufficient to induce ES cells to differentiate into neuronal cells that show properties of postmitotic neurons both in vitro and in vivo. In vivo function of RA-induced neuronal cells was demonstrated by transplantation into the quinolinic acid lesioned striatum of rats (a rat model for Huntington's disease), where cells integrated and survived for up to 6 wk. The response of embryonic stem cells to DMSO to form muscle was less dramatic than that observed for RA. DMSO-induced ES cells formed mixed populations of muscle cells composed of cardiac, smooth, and skeletal muscle instead of homogeneous populations of a single muscle cell type. To determine whether the response of ES cells to DMSO induction could be further controlled, ES cells were stably transfected with a gene coding for the muscle-specific regulatory factor, MyoD. When induced with DMSO, ES cells constitutively expressing high levels of MyoD differentiated exclusively into skeletal myoblasts (no cardiac or smooth muscle cells) that fused to form myotubes capable of spontaneous contraction. Thus, the specific muscle cell type formed was controlled by the expression of MyoD. These results provided evidence that the specific cell type formed (whether it be muscle, neuronal, or other cell types) can be controlled in vitro. Further, these results demonstrated that ES cells can provide a source of multiple differentiated cell types that can be used for transplantation.

scholarly journals MyoD, myogenin independent differentiation of primordial myoblasts in mouse somites.

1992 ◽  
Vol 116 (5) ◽  
pp. 1243-1255 ◽  
Author(s):  
M G Cusella-De Angelis ◽  
G Lyons ◽  
C Sonnino ◽  
L De Angelis ◽  
E Vivarelli ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Posttranscriptional Regulation ◽  
Proximal Region ◽  
Limb Bud ◽  
Northern Analysis ◽  
Myogenic Cells

The accumulation of two myogenic regulatory proteins, MyoD and myogenin, was investigated by double-immunocytochemistry and correlated with myosin heavy chain expression in different classes of myoblasts in culture and during early myogenesis in vivo. During in vitro differentiation of fetal myoblasts, MyoD-positive cells were detected first, followed by the appearance of cells positive for both MyoD and myogenin and finally by the appearance of differentiated myocytes and myotubes expressing myosin heavy chain (MHC). A similar pattern of expression was observed in cultures of embryonic and satellite cells. In contrast, most myogenic cells isolated from newly formed somites, expressed MHC in the absence of detectable levels of myogenin or MyoD. In vivo, the appearance of both myogenin and MyoD proteins was only detected at 10.5 d postcoitum (d.p.c.), when terminally differentiated muscle cells could already be identified in the myotome. Parasagittal sections of the caudal myotomes of 10.5-d-old embryos showed that expression of contractile proteins preceded the expression of myogenin or MyoD and, when coexpressed, MHC and myogenin did not co-localize within all the cells of the myotome. In the limb bud, however, many myogenin (or MyoD) positive/MHC negative cells could be observed in the proximal region at day 11. During further embryonic development the expression of these proteins remained constant in all the muscle anlagens examined, decreasing to a low level during the late fetal period. Western and Northern analysis confirmed that the myogenin protein could only be detected after 10.5 d.p.c. while the corresponding message was clearly present at 9.5 d.p.c., strongly suggesting a posttranscriptional regulation of myogenin during this stage of embryonic development. These data show that the first myogenic cells which appear in the mouse myotome, and can be cultured from it, accumulate muscle structural proteins in their cytoplasm without expressing detectable levels of myogenin protein (although the message is clearly accumulated). Neither MyoD message or protein are detectable in these cells, which may represent a distinct myogenic population whose role in development remains to be established.

scholarly journals The expression of slow myosin during mammalian somitogenesis and limb bud differentiation.

1988 ◽  
Vol 107 (6) ◽  
pp. 2191-2197 ◽  
Author(s):  
E Vivarelli ◽  
W E Brown ◽  
R G Whalen ◽  
G Cossu
Keyword(s):  
Monoclonal Antibodies ◽  
Developmental Stages ◽  
Mouse Embryos ◽  
Fiber Formation ◽  
Limb Bud ◽  
Slow Myosin ◽  
Fast Myosin ◽  
The Relationship ◽  
Cells Cultured

The developmental pattern of slow myosin expression has been studied in mouse embryos from the somitic stage to the period of secondary fiber formation and in myogenic cells, cultured from the same developmental stages. The results obtained, using a combination of different polyclonal and monoclonal antibodies, indicate that slow myosin is coexpressed in virtually all the cells that express embryonic (fast) myosin in somites and limb buds in vivo as well as in culture. On the contrary fetal or late myoblasts (from 15-d-old embryos) express in culture only embryonic (fast) myosin. At this stage, muscle cells in vivo, as already shown (Crow, M.T., and F.A. Stockdale. 1986. Dev. Biol. 113:238-254; Dhoot, G.K. 1986. Muscle & Nerve. 9:155-164; Draeger, A., A.G. Weeds, and R.B. Fitzsimons. 1987. J. Neurol. Sci. 81:19-43; Miller, J.B., and F.A. Stockdale. 1986. J. Cell Biol. 103:2197-2208), consist of primary myotubes, which express both myosins, and secondary myotubes, which express preferentially embryonic (fast) myosin. Under no circumstance neonatal or adult fast myosins were detected. Western blot analysis confirmed the immunocytochemical data. These results suggest that embryonic myoblasts in mammals are all committed to the mixed embryonic-(fast) slow lineage and, accordingly, all primary fibers express both myosins, whereas fetal myoblasts mostly belong to the embryonic (fast) lineage and likely generate fibers containing only embryonic (fast) myosin. The relationship with current models of avian myogenesis are discussed.

scholarly journals Testosterone Promotes the Proliferation of Chicken Embryonic Myoblasts Via Androgen Receptor Mediated PI3K/Akt Signaling Pathway

2020 ◽  
Vol 21 (3) ◽  
pp. 1152 ◽  
Author(s):  
Dongfeng Li ◽  
Qin Wang ◽  
Kai Shi ◽  
Yinglin Lu ◽  
Debing Yu ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Androgen Receptor ◽  
Muscle Development ◽  
Fiber Formation ◽  
Cross Sectional ◽  
Protein Levels ◽  
Proliferative Effect ◽  
Phosphoinositide 3 Kinase

Testosterone (T) is essential for muscle fiber formation and growth. However, the specific mechanism by which T regulates skeletal muscle development in chicken embryos remains unclear. In this study, the role of T in myoblast proliferation both in vivo and in vitro was investigated. Results showed that the T administration significantly increased the ratio of breast muscle and leg muscle. T induced a significant increase in the cross-sectional area (CSA) and density of myofiber and the ratio of PAX7-positive cells in the skeletal muscle. Exogenous T also induced the upregulation of myogenic regulatory factors (MRFs) and cyclin-dependent kinases (CDK2)/Cyclin D1 (CCND1) and protein levels of androgen receptor (AR), p-Akt and PAX7. Furthermore, T treatment significantly promoted myoblasts cultured in vitro entering a new cell cycle and increased PAX7-positive cells. The mRNA and protein expression of AR and PAX7 were upregulated when treated with T compared to that of the control. The addition of T induced proliferation accompanied by increasing AR level as well as PI3K (Phosphoinositide 3-kinase)/Akt activation. However, T-induced proliferation was attenuated by AR, PI3K, and Akt-specific inhibitors. These data indicated that the pro-proliferative effect of T was regulated though AR in response to the activation of PI3K/Akt signalling pathway.

scholarly journals MyoD-positive myoblasts are present in mature fetal organs lacking skeletal muscle

2001 ◽  
Vol 155 (3) ◽  
pp. 381-392 ◽  
Author(s):  
Jacquelyn Gerhart ◽  
Brian Bast ◽  
Christine Neely ◽  
Stephanie Iem ◽  
Paula Amegbe ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Rt Pcr ◽  
Skeletal Myoblasts ◽  
In Situ Hybridizations ◽  
Fetal Organs ◽  
The Brain

The epiblast of the chick embryo gives rise to the ectoderm, mesoderm, and endoderm during gastrulation. Previous studies revealed that MyoD-positive cells were present throughout the epiblast, suggesting that skeletal muscle precursors would become incorporated into all three germ layers. The focus of the present study was to examine a variety of organs from the chicken fetus for the presence of myogenic cells. RT-PCR and in situ hybridizations demonstrated that MyoD-positive cells were present in the brain, lung, intestine, kidney, spleen, heart, and liver. When these organs were dissociated and placed in culture, a subpopulation of cells differentiated into skeletal muscle. The G8 antibody was used to label those cells that expressed MyoD in vivo and to follow their fate in vitro. Most, if not all, of the muscle that formed in culture arose from cells that expressed MyoD and G8 in vivo. Practically all of the G8-positive cells from the intestine differentiated after purification by FACS®. This population of ectopically located cells appears to be distinct from multipotential stem cells and myofibroblasts. They closely resemble quiescent, stably programmed skeletal myoblasts with the capacity to differentiate when placed in a permissive environment.

scholarly journals Electromechanical Coupling between Skeletal and Cardiac Muscle

2000 ◽  
Vol 149 (3) ◽  
pp. 731-740 ◽  
Author(s):  
Hans Reinecke ◽  
Glen H. MacDonald ◽  
Stephen D. Hauschka ◽  
Charles E. Murry
Keyword(s):  
Skeletal Muscle ◽  
Gap Junctions ◽  
Cardiac Muscle ◽  
Gap Junction ◽  
Electromechanical Coupling ◽  
Skeletal Myoblasts ◽  
Adult Cardiomyocytes ◽  
Synchronous Contraction ◽  
Skeletal Myotubes

Skeletal myoblasts form grafts of mature muscle in injured hearts, and these grafts contract when exogenously stimulated. It is not known, however, whether cardiac muscle can form electromechanical junctions with skeletal muscle and induce its synchronous contraction. Here, we report that undifferentiated rat skeletal myoblasts expressed N-cadherin and connexin43, major adhesion and gap junction proteins of the intercalated disk, yet both proteins were markedly downregulated after differentiation into myo-tubes. Similarly, differentiated skeletal muscle grafts in injured hearts had no detectable N-cadherin or connexin43; hence, electromechanical coupling did not occur after in vivo grafting. In contrast, when neonatal or adult cardiomyocytes were cocultured with skeletal muscle, ∼10% of the skeletal myotubes contracted in synchrony with adjacent cardiomyocytes. Isoproterenol increased myotube contraction rates by 25% in coculture without affecting myotubes in monoculture, indicating the cardiomyocytes were the pacemakers. The gap junction inhibitor heptanol aborted myotube contractions but left spontaneous contractions of individual cardiomyocytes intact, suggesting myotubes were activated via gap junctions. Confocal microscopy revealed the expression of cadherin and connexin43 at junctions between myotubes and neonatal or adult cardiomyocytes in vitro. After microinjection, myotubes transferred dye to neonatal cardiomyocytes via gap junctions. Calcium imaging revealed synchronous calcium transients in cardiomyocytes and myotubes. Thus, cardiomyocytes can form electromechanical junctions with some skeletal myotubes in coculture and induce their synchronous contraction via gap junctions. Although the mechanism remains to be determined, if similar junctions could be induced in vivo, they might be sufficient to make skeletal muscle grafts beat synchronously with host myocardium.

Protease-activated receptor-2 mediates proliferative responses in skeletal myoblasts

2000 ◽  
Vol 113 (24) ◽  
pp. 4427-4433
Author(s):  
C. Chinni ◽  
M.R. de Niese ◽  
A.L. Jenkins ◽  
R.N. Pike ◽  
S.P. Bottomley ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Neonatal Rat ◽  
Skeletal Myoblast ◽  
Skeletal Myoblasts ◽  
Tethered Ligand ◽  
Polymerase Chain ◽  
Protease Activated Receptor 2 ◽  
G Protein Coupled ◽  
Dose Dependent

Protease-activated receptor-2 (PAR-2) is a G protein-coupled receptor that is cleaved by proteases within the N terminus, exposing a new tethered ligand that binds and activates the receptor. Activators of PAR-2 include trypsin and mast cell tryptase. Skeletal myoblasts are known to express PAR-1, a thrombin receptor. The current study was undertaken to determine whether myoblasts express PAR-2. Primary neonatal rat and mouse skeletal myoblast cultures were shown to express PAR-2 in polymerase chain reaction and immunocytochemical studies. Expression of PAR-2 was also demonstrated by immunohistochemistry in developing mouse skeletal muscle in vivo. Trypsin or a synthetic peptide corresponding to the rat PAR-2 tethered ligand caused a dose-dependent elevation in intracellular calcium in cultured rat myoblasts, with an EC(50) of 13 nM or 56 microM, respectively. Studies aimed at identifying the function of PAR-2 in myoblasts demonstrated no effect of the receptor-activating peptide on survival or fusion in serum-deprived myoblasts. The PAR-2-activating peptide did, however, stimulate proliferation of serum-deprived myoblasts. These results demonstrate that skeletal muscle cells express PAR-2, activation of which leads to stimulation of myoblast proliferation.

scholarly journals Transdifferentiation of Human Fibroblasts into Skeletal Muscle Cells: Optimization and Assembly into Engineered Tissue Constructs through Biological Ligands

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 539
Author(s):  
Khaled M. A. Abdel-Raouf ◽  
Rachid Rezgui ◽  
Cesare Stefanini ◽  
Jeremy C. M. Teo ◽  
Nicolas Christoforou
Keyword(s):  
Skeletal Muscle ◽  
Human Fibroblasts ◽  
Direct Reprogramming ◽  
Efficient System ◽  
Tissue Constructs ◽  
Skeletal Myoblasts ◽  
Tnf Α ◽  
Engineered Tissue ◽  
Muscle Models

The development of robust skeletal muscle models has been challenging due to the partial recapitulation of human physiology and architecture. Reliable and innovative 3D skeletal muscle models recently described offer an alternative that more accurately captures the in vivo environment but require an abundant cell source. Direct reprogramming or transdifferentiation has been considered as an alternative. Recent reports have provided evidence for significant improvements in the efficiency of derivation of human skeletal myotubes from human fibroblasts. Herein we aimed at improving the transdifferentiation process of human fibroblasts (tHFs), in addition to the differentiation of murine skeletal myoblasts (C2C12), and the differentiation of primary human skeletal myoblasts (HSkM). Differentiating or transdifferentiating cells were exposed to single or combinations of biological ligands, including Follistatin, GDF8, FGF2, GDF11, GDF15, hGH, TMSB4X, BMP4, BMP7, IL6, and TNF-α. These were selected for their critical roles in myogenesis and regeneration. C2C12 and tHFs displayed significant differentiation deficits when exposed to FGF2, BMP4, BMP7, and TNF-α, while proliferation was significantly enhanced by FGF2. When exposed to combinations of ligands, we observed consistent deficit differentiation when TNF-α was included. Finally, our direct reprogramming technique allowed for the assembly of elongated, cross-striated, and aligned tHFs within tissue-engineered 3D skeletal muscle constructs. In conclusion, we describe an efficient system to transdifferentiate human fibroblasts into myogenic cells and a platform for the generation of tissue-engineered constructs. Future directions will involve the evaluation of the functional characteristics of these engineered tissues.

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