-
ELife Oct 2021Non-centrosomal microtubule-organizing centers (MTOCs) are pivotal for the function of multiple cell types, but the processes initiating their formation are unknown....
Non-centrosomal microtubule-organizing centers (MTOCs) are pivotal for the function of multiple cell types, but the processes initiating their formation are unknown. Here, we find that the transcription factor myogenin is required in murine myoblasts for the localization of MTOC proteins to the nuclear envelope. Moreover, myogenin is sufficient in fibroblasts for nuclear envelope MTOC (NE-MTOC) formation and centrosome attenuation. Bioinformatics combined with loss- and gain-of-function experiments identified induction of AKAP6 expression as one central mechanism for myogenin-mediated NE-MTOC formation. Promoter studies indicate that myogenin preferentially induces the transcription of muscle- and NE-MTOC-specific isoforms of and , which encodes nesprin-1α, the NE-MTOC anchor protein in muscle cells. Overexpression of AKAP6β and nesprin-1α was sufficient to recruit endogenous MTOC proteins to the nuclear envelope of myoblasts in the absence of myogenin. Taken together, our results illuminate how mammals transcriptionally control the switch from a centrosomal MTOC to an NE-MTOC and identify AKAP6 as a novel NE-MTOC component in muscle cells.
Topics: 3T3 Cells; A Kinase Anchor Proteins; Animals; Cell Line; HEK293 Cells; Humans; Mice; Microtubule-Organizing Center; Muscle Cells; Myogenin; Nuclear Envelope
PubMed: 34605406
DOI: 10.7554/eLife.65672 -
Journal of Clinical Pathology Jun 2003The diagnosis of paediatric solid tumours is often based on small tissue needle biopsies in which many different entities demonstrate a "small round cell tumour"... (Review)
Review
The diagnosis of paediatric solid tumours is often based on small tissue needle biopsies in which many different entities demonstrate a "small round cell tumour" phenotype and in which there may be insufficient tissue to allow the interpretation of diagnostic architectural features, which may be present in larger specimens. Therefore, the extensive use of a panel of immunohistochemical markers is part of the routine handling and investigation of such biopsies to reach a definite diagnosis. However, in some cases the morphological and routine immunohistochemical findings may be insufficient for a precise diagnosis or they may be difficult to interpret in the given clinical context. Although many paediatric tumours exhibit characteristic chromosomal translocations with resultant specific fusion transcripts, these require molecular methods for their detection, usually on fresh tissue samples, which may not always be available. As more immunohistochemical markers become available, more precise diagnosis on such small biopsies may be possible. This review examines the use of the immunohistochemical markers, MyoD1 and myogenin, in the diagnosis of paediatric rhabdomyosarcoma, including its subtypes.
Topics: Biomarkers, Tumor; Child; Diagnosis, Differential; Humans; MyoD Protein; Myogenin; Neoplasm Proteins; Prognosis; Rhabdomyosarcoma, Alveolar; Rhabdomyosarcoma, Embryonal
PubMed: 12783965
DOI: 10.1136/jcp.56.6.412 -
Development (Cambridge, England) Feb 2021SMAD2 is a transcription factor, the activity of which is regulated by members of the transforming growth factor β (TGFβ) superfamily. Although activation of SMAD2 and...
SMAD2 is a transcription factor, the activity of which is regulated by members of the transforming growth factor β (TGFβ) superfamily. Although activation of SMAD2 and SMAD3 downstream of TGFβ or myostatin signaling is known to inhibit myogenesis, we found that SMAD2 in the absence of TGFβ signaling promotes terminal myogenic differentiation. We found that, during myogenic differentiation, SMAD2 expression is induced. Knockout of SMAD2 expression in primary myoblasts did not affect the efficiency of myogenic differentiation but produced smaller myotubes with reduced expression of the terminal differentiation marker myogenin. Conversely, overexpression of SMAD2 stimulated myogenin expression, and enhanced both differentiation and fusion, and these effects were independent of classical activation by the TGFβ receptor complex. Loss of in muscle satellite cells resulted in decreased muscle fiber caliber and impaired regeneration after acute injury. Taken together, we demonstrate that SMAD2 is an important positive regulator of myogenic differentiation, in part through the regulation of .
Topics: Animals; Cell Differentiation; Gene Expression Regulation, Developmental; Gene Knockdown Techniques; Gene Knockout Techniques; Mice; Mice, Knockout; Muscle Development; Muscle Fibers, Skeletal; Myoblasts; Myogenin; Myostatin; Signal Transduction; Smad2 Protein; Smad3 Protein; Transforming Growth Factor beta
PubMed: 33462116
DOI: 10.1242/dev.195495 -
Communications Biology Jun 2020Deciphering the molecular mechanisms underpinning myoblast differentiation is a critical step in developing the best strategy to promote muscle regeneration in patients...
Deciphering the molecular mechanisms underpinning myoblast differentiation is a critical step in developing the best strategy to promote muscle regeneration in patients suffering from muscle-related diseases. We have previously established that a rexinoid x receptor (RXR)-selective agonist, bexarotene, enhances the differentiation and fusion of myoblasts through a direct regulation of MyoD expression, coupled with an augmentation of myogenin protein. Here, we found that RXR signaling associates with the distribution of myogenin at poised enhancers and a distinct E-box motif. We also found an association of myogenin with rexinoid-responsive gene expression and identified an epigenetic signature related to histone acetyltransferase p300. Moreover, RXR signaling augments residue-specific histone acetylation at enhancers co-occupied by p300 and myogenin. Thus, genomic distribution of transcriptional regulators is an important designate for identifying novel targets as well as developing therapeutics that modulate epigenetic landscape in a selective manner to promote muscle regeneration.
Topics: Acetylation; Animals; Bexarotene; Cell Differentiation; Cell Line; Chromatin Immunoprecipitation; E1A-Associated p300 Protein; Enhancer Elements, Genetic; Epigenesis, Genetic; Histones; Mice; Myoblasts; Myogenin; Retinoid X Receptors; Signal Transduction
PubMed: 32555436
DOI: 10.1038/s42003-020-1043-9 -
Nature Communications Oct 2018Each skeletal muscle acquires its unique size before birth, when terminally differentiating myocytes fuse to form a defined number of multinucleated myofibres. Although...
Each skeletal muscle acquires its unique size before birth, when terminally differentiating myocytes fuse to form a defined number of multinucleated myofibres. Although mice in which the transcription factor Myogenin is mutated lack most myogenesis and die perinatally, a specific cell biological role for Myogenin has remained elusive. Here we report that loss of function of zebrafish myog prevents formation of almost all multinucleated muscle fibres. A second, Myogenin-independent, fusion pathway in the deep myotome requires Hedgehog signalling. Lack of Myogenin does not prevent terminal differentiation; the smaller myotome has a normal number of myocytes forming more mononuclear, thin, albeit functional, fast muscle fibres. Mechanistically, Myogenin binds to the myomaker promoter and is required for expression of myomaker and other genes essential for myocyte fusion. Adult myog mutants display reduced muscle mass, decreased fibre size and nucleation. Adult-derived myog mutant myocytes show persistent defective fusion ex vivo. Myogenin is therefore essential for muscle homeostasis, regulating myocyte fusion to determine both muscle fibre number and size.
Topics: Animals; Cells, Cultured; Chromatin Immunoprecipitation; Embryo, Nonmammalian; Female; Male; Muscle Cells; Myogenin; NADH Tetrazolium Reductase; RNA, Messenger; Reverse Transcriptase Polymerase Chain Reaction; Zebrafish
PubMed: 30315160
DOI: 10.1038/s41467-018-06583-6 -
Advances in Anatomic Pathology May 2002The MyoD1 family of myogenic nuclear regulatory proteins includes MyoD1/myf3 and myogenin/myf4. These genes and their proteins are critical for skeletal muscle... (Review)
Review
The MyoD1 family of myogenic nuclear regulatory proteins includes MyoD1/myf3 and myogenin/myf4. These genes and their proteins are critical for skeletal muscle development. Antibodies to MyoD1 and myogenin are relatively recent additions to the armamentarium of the surgical pathologist. This article reviews the biology of the myogenic nuclear regulatory proteins and their use in the diagnosis of rhabdomyosarcoma. Special attention is given to technical and interpretative issues critical to the use of these antibodies in diagnostic pathology.
Topics: Biomarkers; Humans; Immunohistochemistry; MyoD Protein; Myogenin; Rhabdomyosarcoma
PubMed: 11981115
DOI: 10.1097/00125480-200205000-00003 -
Pathology Oncology Research : POR Sep 2008Myogenin immunostaining has been described as a useful marker of the alveolar subtype of rhabdomyosarcoma and as a tool for distinguishing it from the more common... (Review)
Review
Myogenin immunostaining has been described as a useful marker of the alveolar subtype of rhabdomyosarcoma and as a tool for distinguishing it from the more common embryonal subtype. To add to the growing body of literature describing this phenomenon we analysed myogenin immunohistochemical staining in 152 tumors using a rhabdomyosarcoma tissue array. Results were analysed blinded to histological type by two independent investigators. Samples were excluded if any samples failed to stain with desmin and/or myogenin. Mean percentage of myogenin positive cells was significantly greater for ARMS (n = 31; mean percentage positivity 59% (95% confidence intervals +/- 7%) than ERMS (n = 41, mean percentage positivity 16%, 95% confidence intervals +/- 4; P < 0.0001). This data is consistent with previously published studies identifying strong nuclear myogenin staining in a high proportion of cells as a marker of alveolar histology.
Topics: Biomarkers, Tumor; Diagnosis, Differential; Humans; Myogenin; Prognosis; Rhabdomyosarcoma, Alveolar; Rhabdomyosarcoma, Embryonal; Sensitivity and Specificity; Tissue Array Analysis
PubMed: 18493875
DOI: 10.1007/s12253-008-9012-5 -
Biochemical and Biophysical Research... May 2021Angiotensin II (Ang II), an important component of the renin-angiotensin system (RAS), plays a critical role in the pathogenesis of cardiovascular disorders. In...
BACKGROUND
Angiotensin II (Ang II), an important component of the renin-angiotensin system (RAS), plays a critical role in the pathogenesis of cardiovascular disorders. In addition, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been considered as a promising platform for studying personalized medicine for heart diseases. However, whether Ang II can induce the apoptosis of hiPSC-CMs is not known.
METHODS
In this study, we treated hiPSC-CMs with different concentrations of Ang II [0 nM (vehicle as a control), 1 nM, 10 nM, 100 nM, 1 μM, 10 μM, 100 μM, and 1 mM] for various time periods (24 h, 48 h, 6 days, and 10 days) and analyzed the viability and apoptosis of hiPSC-CMs.
RESULTS
We found that treatment with 1 mM Ang II for 10 days reduced the viability of hiPSC-CMs by 41% (p = 2.073E-08) and increased apoptosis by 2.74-fold, compared to the control group (p = 6.248E-12). MYOG, which encodes the muscle-specific transcription factor myogenin, was also identified as an apoptosis-suppressor gene in Ang II-treated hiPSC-CMs. Ectopic MYOG expression decreased the apoptosis and increased the viability of Ang II-treated hiPSC-CMs. Further analysis of the RNA sequencing (RNA-seq) data illustrated that myogenin ameliorated Ang II-induced apoptosis of hiPSC-CMs by downregulating the expression of proinflammatory genes.
CONCLUSION
Our findings suggest that Ang II induces the apoptosis of hiPSC-CMs and that myogenin attenuates Ang II-induced apoptosis.
Topics: Angiotensin II; Apoptosis; Cells, Cultured; Gene Expression Profiling; Gene Expression Regulation; Humans; Induced Pluripotent Stem Cells; Myocytes, Cardiac; Myogenin; Time Factors
PubMed: 33743352
DOI: 10.1016/j.bbrc.2021.03.031 -
Frontiers in Bioscience (Landmark... Feb 2024Myogenin is well known as a crucial transcription factor in skeletal muscle development, yet its other biological functions remain unexplored. Previous research showed...
BACKGROUND
Myogenin is well known as a crucial transcription factor in skeletal muscle development, yet its other biological functions remain unexplored. Previous research showed that myogenin suppresses apoptosis induced by angiotensin II in human induced pluripotent stem cell-derived cardiomyocytes, and offered a new perspective on myogenin's role in cardioprotection. However, the detailed mechanism of this cardioprotection, especially under oxidative stress, is still unclear.
METHODS
In this study, hydrogen peroxide (H2O2) was used to generate reactive oxygen species in myogenin-overexpressing cardiomyocytes. The apoptosis was examined by flow cytometry. Transcriptome sequencing (RNA-seq) was performed to identify genes regulated by myogenin. Western blotting was used to detect the protein level of and the phosphorylation level of p38 mitogen-activated protein kinase (MAPK). The dual-luciferase reporter assay and ChIP assay were used to confirm the binding of myogenin to the promoter region of . overexpression and knockdown assays were performed to study its anti-apoptotic role.
RESULTS
Flow cytometry analysis of apoptosis showed that overexpressing myogenin for 24 and 48 hours decreased the apoptotic ratio by 47.9% and 63.5%, respectively, compared with untreated controls. Transcriptome sequencing performed on cardiomyocytes that expressed myogenin for different amounts of time (6, 12, 24, and 48 hours) identified as being up-regulated by myogenin. Western blotting showed that overexpression of myogenin increased the expression of and decreased the phosphorylation level of p38 MAPK. A dual-luciferase reporter assay proved that myogenin bound directly to the promoter region of and led to strong relative luciferase activity. Direct expression of and significantly reduced the rates of apoptosis and necrosis in cells treated with H2O2. Knockdown of significantly increased the rate of apoptosis in cells treated with H2O2.
CONCLUSIONS
The present findings suggest that myogenin might attenuate apoptosis induced by reactive oxygen species by up-regulating and inactivating the p38 MAPK pathway.
Topics: Humans; Reactive Oxygen Species; Hydrogen Peroxide; Myogenin; Induced Pluripotent Stem Cells; Apoptosis; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Luciferases
PubMed: 38420814
DOI: 10.31083/j.fbl2902049 -
ELife Oct 2020Growth and maintenance of skeletal muscle fibres depend on coordinated activation and return to quiescence of resident muscle stem cells (MuSCs). The transcription...
Growth and maintenance of skeletal muscle fibres depend on coordinated activation and return to quiescence of resident muscle stem cells (MuSCs). The transcription factor Myogenin (Myog) regulates myocyte fusion during development, but its role in adult myogenesis remains unclear. In contrast to mice, zebrafish are viable, but have hypotrophic muscles. By isolating adult myofibres with associated MuSCs, we found that myofibres have severely reduced nuclear number, but increased myonuclear domain size. Expression of fusogenic genes is decreased, Pax7 upregulated, MuSCs are fivefold more numerous and mis-positioned throughout the length of myofibres instead of localising at myofibre ends as in wild-type. Loss of Myog dysregulates mTORC1 signalling, resulting in an 'alerted' state of MuSCs, which display precocious activation and faster cell cycle entry ex vivo, concomitant with upregulation. Thus, beyond controlling myocyte fusion, Myog influences the MuSC:niche relationship, demonstrating a multi-level contribution to muscle homeostasis throughout life.
Topics: Animals; Gene Knockout Techniques; Homeostasis; Muscle, Skeletal; Myofibrils; Myogenin; Stem Cells; Zebrafish; Zebrafish Proteins
PubMed: 33001028
DOI: 10.7554/eLife.60445