scholarly journals Sequestration of pRb by Cyclin D3 Causes Intranuclear Reorganization of Lamin A/C during Muscle Cell Differentiation

2005 ◽  
Vol 16 (4) ◽  
pp. 1948-1960 ◽  
Author(s):  
Indumathi Mariappan ◽  
Veena K. Parnaik
Keyword(s):  
Muscle Cells ◽  
Cell Types ◽  
Cyclin D3 ◽  
Myoblast Differentiation ◽  
Regulatory Factor ◽  
C2c12 Myoblasts ◽  
Muscle Cell Differentiation ◽  
Adenovirus E1a ◽  
Nuclear Domains ◽  
Myogenic Program

The A-type lamins that localize in nuclear domains termed lamin speckles are reorganized and antigenically masked specifically during myoblast differentiation. This rearrangement was observed to be linked to the myogenic program as lamin speckles, stained with monoclonal antibody (mAb) LA-2H10, were reorganized in MyoD-transfected fibroblasts induced to transdifferentiate to muscle cells. In C2C12 myoblasts, speckles were reorganized early during differentiation in cyclin D3–expressing cells. Ectopic cyclin D3 induced lamin reorganization in C2C12 myoblasts but not in other cell types. Experiments with adenovirus E1A protein that can bind to and segregate the retinoblastoma protein (pRb) indicated that pRb was essential for the cyclin D3–mediated reorganization of lamin speckles. Cyclin D3–expressing myoblasts displayed site-specific reduction of pRb phosphorylation. Furthermore, disruption of lamin structures by overexpression of lamins inhibited expression of the muscle regulatory factor myogenin. Our results suggest that the reorganization of internal lamins in muscle cells is mediated by key regulators of the muscle differentiation program.

Distinct changes in intranuclear lamin A/C organization during myoblast differentiation

2001 ◽  
Vol 114 (22) ◽  
pp. 4001-4011 ◽  
Author(s):  
Bh. Muralikrishna ◽  
Jyotsna Dhawan ◽  
Nandini Rangaraj ◽  
Veena K. Parnaik
Keyword(s):  
Cell Cycle ◽  
Rna Splicing ◽  
Cell Types ◽  
Immunoblot Analysis ◽  
Splicing Factor ◽  
Myoblast Differentiation ◽  
Structural Reorganization ◽  
C2c12 Myoblasts ◽  
Muscle Cell Differentiation ◽  
And Migration

Intranuclear lamin foci or speckles have been observed in various cell types. In order to explore the possibility of changes in internal lamin organization during muscle differentiation, we have examined the appearance of A-type lamin speckles that associate with RNA splicing factor speckles in C2C12 myoblasts and myotubes. Lamin speckles were observed in dividing myoblasts but disappeared early during the course of differentiation in postmitotic myocytes, and were absent in myotubes and muscle fibers. However, no changes were seen in the typical peripheral organization of lamins A/C or B1 or in RNA splicing factor speckles. Lamin speckles were also absent in quiescent myoblasts but reappeared as cells were reactivated to enter the cell cycle. These changes were not observed in other quiescent cell types. Immunoblot analysis indicated that the abundance and migration of lamins A and C was not altered in differentiated myoblasts. When myotube or quiescent myoblast nuclei were extracted with nucleases and detergent, a uniformly stained internal lamina was revealed, indicating that lamins A/C were antigenically masked in these cells, probably owing to structural reorganization of the lamina during differentiation or quiescence. Our results suggest that muscle cell differentiation is accompanied by regulated rearrangements in the organization of the A-type lamins.

Hormonal stimulation of myoblast differentiation in the absence of DNA synthesis

1982 ◽  
Vol 243 (5) ◽  
pp. C278-C284 ◽  
Author(s):  
K. A. Turo ◽  
J. R. Florini
Keyword(s):  
Creatine Kinase ◽  
Cell Differentiation ◽  
Dna Synthesis ◽  
Muscle Cell ◽  
Fold Increase ◽  
Cell Types ◽  
Myoblast Differentiation ◽  
Hormonal Stimulation ◽  
Muscle Cell Differentiation ◽  
Stimulation Of

The role of DNA synthesis in the final stages of muscle cell differentiation has been a subject of controversy for more than a decade. In an attempt to resolve disagreements over the necessity for a unique (or "quantal") mitosis just prior to the conversion of proliferating myoblasts to form postmitotic myotubes, we have studied the effects of insulin and somatomedin on the stimulation of myoblast differentiation with or without DNA synthesis. Under conditions in which at least 95% of [3H]thymidine incorporation was blocked by cytosine arabinoside, there was a 5- to 10-fold increase in the extent of differentiation (determined as fusion or creatine kinase elevation) on addition of insulin or multiplication-stimulating activity. The effect of the hormones was on myoblast differentiation, not enzyme induction; insulin did not cause any increase in creatine kinase when it was added to performed myotubes. These studies were done using two different cell types, Yaffe's L6 cell line and Japanese quail myoblasts in serum-free media; we obtained similar results in both. Our results are not compatible with the view that a quantal mitosis is required at a late stage of muscle cell differentiation.

scholarly journals Critical Role Played by Cyclin D3 in the MyoD-Mediated Arrest of Cell Cycle during Myoblast Differentiation

1999 ◽  
Vol 19 (7) ◽  
pp. 5203-5217 ◽  
Author(s):  
Carlo Cenciarelli ◽  
Francesca De Santa ◽  
Pier Lorenzo Puri ◽  
Elisabetta Mattei ◽  
Letizia Ricci ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Critical Role ◽  
Cyclin D3 ◽  
Myoblast Differentiation ◽  
Specific Gene ◽  
Gene Expressions ◽  
Adenovirus E1a ◽  
Skeletal Myoblasts ◽  
Myogenic Factors ◽  
Cell Cycle Inhibitors

ABSTRACT During the terminal differentiation of skeletal myoblasts, the activities of myogenic factors regulate not only tissue-specific gene expressions but also the exit from the cell cycle. The induction of cell cycle inhibitors such as p21 and pRb has been shown to play a prominent role in the growth arrest of differentiating myoblasts. Here we report that, at the onset of differentiation, activation by MyoD of the Rb, p21, and cyclin D3 genes occurs in the absence of new protein synthesis and with the requirement of the p300 transcriptional coactivator. In differentiated myocytes, cyclin D3 also becomes stabilized and is found nearly totally complexed with unphosphorylated pRb. The detection of complexes containing cyclin D3, cdk4, p21, and PCNA suggests that cdk4, along with PCNA, may get sequestered into high-order structures held together by pRb and cyclin D3. Cyclin D3 up-regulation and stabilization is inhibited by adenovirus E1A, and this correlates with the ability of E1A to promote pRb phosphorylation; conversely, the overexpression of cyclin D3 in differentiated myotubes counteracts the E1A-mediated reactivation of DNA synthesis. These results indicate that cyclin D3 critically contributes to the irreversible exit of differentiating myoblasts from the cell cycle.

scholarly journals Annexins and Membrane Repair Dysfunctions in Muscular Dystrophies

2021 ◽  
Vol 22 (10) ◽  
pp. 5276
Author(s):  
Coralie Croissant ◽  
Romain Carmeille ◽  
Charlotte Brévart ◽  
Anthony Bouter
Keyword(s):  
Skeletal Muscle ◽  
Muscular Dystrophy ◽  
Genetic Disorders ◽  
Muscle Cells ◽  
Cell Types ◽  
Clinical Severity ◽  
Skeletal Muscle Cells ◽  
Muscular Dystrophies ◽  
Membrane Repair ◽  
Human Skeletal Muscle Cells

Muscular dystrophies constitute a group of genetic disorders that cause weakness and progressive loss of skeletal muscle mass. Among them, Miyoshi muscular dystrophy 1 (MMD1), limb girdle muscular dystrophy type R2 (LGMDR2/2B), and LGMDR12 (2L) are characterized by mutation in gene encoding key membrane-repair protein, which leads to severe dysfunctions in sarcolemma repair. Cell membrane disruption is a physiological event induced by mechanical stress, such as muscle contraction and stretching. Like many eukaryotic cells, muscle fibers possess a protein machinery ensuring fast resealing of damaged plasma membrane. Members of the annexins A (ANXA) family belong to this protein machinery. ANXA are small soluble proteins, twelve in number in humans, which share the property of binding to membranes exposing negatively-charged phospholipids in the presence of calcium (Ca2+). Many ANXA have been reported to participate in membrane repair of varied cell types and species, including human skeletal muscle cells in which they may play a collective role in protection and repair of the sarcolemma. Here, we discuss the participation of ANXA in membrane repair of healthy skeletal muscle cells and how dysregulation of ANXA expression may impact the clinical severity of muscular dystrophies.

scholarly journals A Chalcone from Ashitaba (Angelica keiskei) Stimulates Myoblast Differentiation and Inhibits Dexamethasone-Induced Muscle Atrophy

Nutrients ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2419 ◽  
Author(s):  
Minson Kweon ◽  
Hyejin Lee ◽  
Cheol Park ◽  
Yung Hyun Choi ◽  
Jae-Ha Ryu
Keyword(s):  
Muscle Atrophy ◽  
Muscle Protein ◽  
Ethanol Extract ◽  
Mitogen Activated Protein Kinase ◽  
Myoblast Differentiation ◽  
Active Principle ◽  
Mrna Levels ◽  
C2c12 Myoblasts ◽  
E3 Ligases ◽  
Angelica Keiskei

Ashitaba, Angelica keiskei Koidzumi (AK), as a traditional medicine in Korea, Japan, and China, has been known as an elixir of life having therapeutic potential. However, there is no scientific evidence to support that Ashitaba can enhance or maintain muscle strength. To find a new therapeutic agent from the medicinal plant, we evaluated the anti-myopathy effect of chalcones from ethanol extract of AK (EAK) in cellular and animal models of muscle atrophy. To examine anti-myopathy activity, EAK was treated into dexamethasone injected rats and muscle thickness and histopathological images were analyzed. Oral administration of EAK (250 or 500 mg/kg) alleviated muscle atrophic damages and down-regulated the mRNA levels of muscle-specific ubiquitin-E3 ligases. Among ten compounds isolated from EAK, 4-hydroxyderricin was the most effective principle in stimulating myogenesis of C2C12 myoblasts via activation of p38 mitogen-activated protein kinase (MAPK). In three cellular muscle atrophy models with C2C12 myoblasts damaged by dexamethasone or cancer cell-conditioned medium, 4-hydroxyderricin protected the myosin heavy chain (MHC) degradation through suppressing expressions of MAFbx, MuRF-1 and myostatin. These results suggest that the ethanol extract and its active principle, 4-hydroxyderricin from AK, can overcome the muscle atrophy through double mechanisms of decreasing muscle protein degradation and activating myoblast differentiation.

Metabolic modulation of hexokinase association with mitochondria in living smooth muscle cells

1996 ◽  
Vol 270 (2) ◽  
pp. C488-C499 ◽  
Author(s):  
R. M. Lynch ◽  
W. Carrington ◽  
K. E. Fogarty ◽  
F. S. Fay
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Energy State ◽  
Single Cells ◽  
Inverse Correlation ◽  
Muscle Cells ◽  
Cell Types ◽  
Differential Sensitivity ◽  
Similar Distribution ◽  
Apparent Difference

Hexokinase isoform I binds to mitochondria of many cell types. It has been hypothesized that this association is regulated by changes in the concentrations of specific cellular metabolites. To study the distribution of hexokinase in living cells, fluorophore-labeled functional hexokinase I was prepared. After microinjection into A7r5 smooth muscle cells, hexokinase localized to distinct structures identified as mitochondria. The endogenous hexokinase demonstrated a similar distribution with the use of immunocytochemistry. 2-Deoxyglucose elicited an increase in glucose 6-phosphate (G-6-P) and a decrease in ATP levels and diminished hexokinase binding to mitochondria in single cells. 3-O-methylglucose elicited slowly developing decreases in all three parameters. In contrast, cyanide elicited a rapid decrease in both ATP and hexokinase binding. Analyses of changes in metabolite levels and hexokinase binding indicate a positive correlation between binding and cell energy state as monitored by ATP. On the other hand, only in the presence of 2-deoxyglucose was the predicted inverse correlation between binding and G-6-P observed. Unlike the relatively large changes in distribution observed with the fluorescent-injected hexokinase, cyanide caused only a small decrease in the localization of endogenous hexokinase with mitochondria. These findings suggest that changes in the concentrations of specific metabolites can alter the binding of hexokinase I to specific sites on mitochondria. Moreover, the apparent difference in sensitivity of injected and endogenous hexokinase to changes in metabolites may reflect the presence of at least two classes of binding mechanisms for hexokinase, with differential sensitivity to metabolites.

Interleukin-6 promotes myogenic differentiation of mouse skeletal muscle cells: role of the STAT3 pathway

2013 ◽  
Vol 304 (2) ◽  
pp. C128-C136 ◽  
Author(s):  
Miriam Hoene ◽  
Heike Runge ◽  
Hans Ulrich Häring ◽  
Erwin D. Schleicher ◽  
Cora Weigert
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Myogenic Differentiation ◽  
Muscle Cells ◽  
C2c12 Cells ◽  
Skeletal Muscle Cells ◽  
Wild Type ◽  
C2c12 Myoblasts ◽  
Sequence Of Events ◽  
Primary Mouse

Myogenic differentiation of skeletal muscle cells is characterized by a sequence of events that include activation of signal transducer and activator of transcription 3 (STAT3) and enhanced expression of its target gene Socs3. Autocrine effects of IL-6 may contribute to the activation of the STAT3-Socs3 cascade and thus to myogenic differentiation. The importance of IL-6 and STAT3 for the differentiation process was studied in C2C12 cells and in primary mouse wild-type and IL-6−/− skeletal muscle cells. In differentiating C2C12 myoblasts, the upregulation of IL-6 mRNA expression and protein secretion started after increased phosphorylation of STAT3 on tyrosine 705 and increased mRNA expression of Socs3 was observed. Knockdown of STAT3 and IL-6 mRNA in differentiating C2C12 myoblasts impaired the expression of the myogenic markers myogenin and MyHC IIb and subsequently myotube fusion. However, the knockdown of IL-6 did not prevent the induction of STAT3 tyrosine phosphorylation. The IL-6-independent activation of STAT3 was verified in differentiating primary IL-6−/− myoblasts. The phosphorylation of STAT3 and the expression levels of STAT3, Socs3, and myogenin during differentiation were comparable in the primary myoblasts independent of the genotype. However, IL-6−/− cells failed to induce MyHC IIb expression to the same level as in wild-type cells and showed reduced myotube formation. Supplementation of IL-6 could partially restore the fusion of IL-6−/− cells. These data demonstrate that IL-6 depletion during myogenic differentiation does not reduce the activation of the STAT3-Socs3 cascade, while IL-6 and STAT3 are both necessary to promote myotube fusion.

scholarly journals Learning the human chromatin network from all ENCODE ChIP-seq data

2015 ◽  
Author(s):  
Scott M. Lundberg ◽  
William B. Tu ◽  
Brian Raught ◽  
Linda Z. Penn ◽  
Michael M. Hoffman ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Protein Interactions ◽  
Graphical Model ◽  
Cell Types ◽  
Statistical Technique ◽  
Regulatory Factor ◽  
Genomic Context ◽  
Regulatory Factors ◽  
Conditional Dependence ◽  
Factor Interactions

Introduction: A cell's epigenome arises from interactions among regulatory factors --- transcription factors, histone modifications, and other DNA-associated proteins --- co-localized at particular genomic regions. Identifying the network of interactions among regulatory factors, the chromatin network, is of paramount importance in understanding epigenome regulation. Methods: We developed a novel computational approach, ChromNet, to infer the chromatin network from a set of ChIP-seq datasets. ChromNet has four key features that enable its use on large collections of ChIP-seq data. First, rather than using pairwise co-localization of factors along the genome, ChromNet identifies conditional dependence relationships that better discriminate direct and indirect interactions. Second, our novel statistical technique, the group graphical model, improves inference of conditional dependence on highly correlated datasets. Such datasets are common because some transcription factors form a complex and the same transcription factor is often assayed in different laboratories or cell types. Third, ChromNet's computationally efficient method and the group graphical model enable the learning of a joint network across all cell types, which greatly increases the scope of possible interactions. We have shown that this results in a significantly higher fold enrichment for validated protein interactions. Fourth, ChromNet provides an efficient way to identify the genomic context that drives a particular network edge, which provides a more comprehensive understanding of regulatory factor interactions. Results: We applied ChromNet to all available ChIP-seq data from the ENCODE Project, consisting of 1451 ChIP-seq datasets, which revealed previously known physical interactions better than alternative approaches. ChromNet also identified previously unreported regulatory factor interactions. We experimentally validated one of these interactions, between the MYC and HCFC1 transcription factors. Discussion: ChromNet provides a useful tool for understanding the interactions among regulatory factors and identifying novel interactions. We have provided an interactive web-based visualization of the full ENCODE chromatin network and the ability to incorporate custom datasets at http://chromnet.cs.washington.edu.

scholarly journals E1a induces the expression of epithelial characteristics.

1994 ◽  
Vol 127 (4) ◽  
pp. 1085-1096 ◽  
Author(s):  
S M Frisch
Keyword(s):  
Tumor Cells ◽  
Present Report ◽  
Human Tumor ◽  
Cell Types ◽  
Suppressor Gene ◽  
Specific Cell ◽  
Human Tumor Cells ◽  
Mammalian Embryo ◽  
Adenovirus E1a ◽  
Mesenchymal Differentiation

Cells closely resembling epithelia constitute the first specific cell type in a mammalian embryo. Many other cell types emerge via epithelial-mesenchymal differentiation. The transcription factors and signal transduction pathways involved in this differentiation are being elucidated. I have previously reported (Frisch, 1991) that adenovirus E1a is a tumor suppressor gene in certain human cell lines. In the present report, I demonstrate that E1a expression caused diverse human tumor cells (rhabdomyosarcoma, fibrosarcoma, melanoma, osteosarcoma) and fibroblasts to assume at least two of the following epithelial characteristics: (a) epithelioid morphology; (b) epithelial-type intercellular adhesion proteins localized to newly formed junctional complexes; (c) keratin-containing intermediate filaments; and (d) down-regulation of non-epithelial genes. E1a thus appeared to partially convert diverse human tumor cells into an epithelial phenotype. This provides a new system for molecular analysis of epithelial-mesenchymal interconversions. This effect may also contribute to E1a's tumor suppression activity, possibly through sensitization to anoikis (Frisch, S.M., and H. Francis, 1994. J. Cell Biol. 124:619-626).

scholarly journals Comprehensive Analytics of Actovegin® and Its Effect on Muscle Cells

2017 ◽  
Vol 38 (11) ◽  
pp. 809-818 ◽  
Author(s):  
Franz-Xaver Reichl ◽  
Lesca Holdt ◽  
Daniel Teupser ◽  
Gregor Schütze ◽  
Alan Metcalfe ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Muscle Cell ◽  
Muscle Cells ◽  
Primary Antibody ◽  
Myosin Heavy Chains ◽  
C2c12 Myoblasts ◽  
Heavy Chains ◽  
Human Adult ◽  
Differentiation Medium ◽  
The Mean

AbstractThe ingredients of Actovegin® were analyzed and its effects on the muscle cell proliferation were investigated. C2C12 myoblasts were cultured in medium. Actovegin® was added in five different concentrations (1, 5, 25, 125, and 250 µg) to the differentiation medium. The formations of proliferation factor Ki67 and myosin heavy chains were measured by immunofluorescence. The first primary antibody was anti-Ki67 and anti-Mf20. Cells were washed and treated with the second fluorochrome. Thirty-one Actovegin® ingredients were found to contain significantly higher concentrations and twenty-nine ingredients were found to contain significantly lower concentrations, compared to the mean ranges as described in the literature for the normal physiological concentrations in human adult serum/plasma. A significant increase in the formation of Ki67 was observed in Actovegin® groups, compared to controls. The mean area of myotubes was significantly increased in Actovegin® groups. A significant decrease in the number of myotubes was observed. An increased myotube size (fusion) was observed. The intensity of Mf20 was significantly increased in Actovegin® groups. It could be demonstrated that Actovegin® contains many physiological substances in significantly higher and some in lower concentrations compared to human adult serum. Furthermore, it could be shown that Actovegin® improves muscle cell proliferation.

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