scholarly journals Human myotube formation is determined by MyoD–Myomixer/Myomaker axis

2020 ◽  
Vol 6 (51) ◽  
pp. eabc4062
Author(s):  
Haifeng Zhang ◽  
Junfei Wen ◽  
Anne Bigot ◽  
Jiacheng Chen ◽  
Renjie Shang ◽  
...  
Keyword(s):  
Transcriptional Control ◽  
Myoblast Fusion ◽  
Low Grade ◽  
Fusion Model ◽  
Genetic Studies ◽  
Biochemical Assays ◽  
E Box ◽  
Human Muscles ◽  
Human Muscle Cells ◽  
Human Myoblast

Myoblast fusion is essential for formations of myofibers, the basic cellular and functional units of skeletal muscles. Recent genetic studies in mice identified two long-sought membrane proteins, Myomaker and Myomixer, which cooperatively drive myoblast fusion. It is unknown whether and how human muscles, with myofibers of tremendously larger size, use this mechanism to achieve multinucleations. Here, we report an interesting fusion model of human myoblasts where Myomaker is sufficient to induce low-grade fusion, while Myomixer boosts its efficiency to generate giant myotubes. By CRISPR mutagenesis and biochemical assays, we identified MyoD as the key molecular switch of fusion that is required and sufficient to initiate Myomixer and Myomaker expression. Mechanistically, we defined the E-box motifs on promoters of Myomixer and Myomaker by which MyoD induces their expression for multinucleations of human muscle cells. Together, our study uncovered the key molecular apparatus and the transcriptional control mechanism underlying human myoblast fusion.

scholarly journals TFG/TAF30/ANC1, a component of the yeast SWI/SNF complex that is similar to the leukemogenic proteins ENL and AF-9.

1996 ◽  
Vol 16 (7) ◽  
pp. 3308-3316 ◽  
Author(s):  
B R Cairns ◽  
N L Henry ◽  
R D Kornberg
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acute Leukemia ◽  
Rna Polymerase Ii ◽  
Protein Interaction ◽  
Transcriptional Control ◽  
Gene Products ◽  
Yeast Saccharomyces Cerevisiae ◽  
Genetic Studies ◽  
Biochemical Studies ◽  
Transcription Complexes

The SWI1/ADR6, SWI2/SNF2, SWI3, SNF5, and SNF6 gene products are all required for proper transcriptional control of many genes in the yeast Saccharomyces cerevisiae. Genetic studies indicated that these gene products might form a multiprotein SWI/SNF complex important for chromatin transitions preceding transcription from RNA polymerase II promoters. Biochemical studies identified a SWI/SNF complex containing these and at least six additional polypeptides. Here we show that the 29-kDa component of the SWI/SNF complex is identical to TFG3/TAF30/ANC1. Thus, a component of the SWI/SNF complex is also a member of the TFIIF and TFIID transcription complexes. TFG3 interacted with the SNF5 component of the SWI/SNF complex in protein interaction blots. TFG3 is significantly similar to ENL and AF-9, two proteins implicated in human acute leukemia. These results suggest that ENL and AF-9 proteins interact with the SNF5 component of the human SWI/SNF complex and raise the possibility that the SWI/SNF complex is involved in acute leukemia.

scholarly journals Human Myoblast Fusion Requires Expression of Functional Inward Rectifier Kir2.1 Channels

2001 ◽  
Vol 153 (4) ◽  
pp. 677-686 ◽  
Author(s):  
Jacqueline Fischer-Lougheed ◽  
Jian-Hui Liu ◽  
Estelle Espinos ◽  
David Mordasini ◽  
Charles R. Bader ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Muscle Development ◽  
Myoblast Fusion ◽  
Inward Rectifier ◽  
Resting Membrane Potential ◽  
Skeletal Muscle Development ◽  
K Channels ◽  
Window Current ◽  
Human Myoblast

Myoblast fusion is essential to skeletal muscle development and repair. We have demonstrated previously that human myoblasts hyperpolarize, before fusion, through the sequential expression of two K+ channels: an ether-à-go-go and an inward rectifier. This hyperpolarization is a prerequisite for fusion, as it sets the resting membrane potential in a range at which Ca2+ can enter myoblasts and thereby trigger fusion via a window current through α1H T channels.

scholarly journals A conserved role for AMP-activated protein kinase in NGLY1 deficiency

PLoS Genetics ◽  
2020 ◽  
Vol 16 (12) ◽  
pp. e1009258
Author(s):  
Seung Yeop Han ◽  
Ashutosh Pandey ◽  
Tereza Moore ◽  
Antonio Galeone ◽  
Lita Duraine ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Protein Kinase ◽  
Global Developmental Delay ◽  
Genetic Studies ◽  
Ampk Signaling ◽  
Biochemical Assays ◽  
Severe Reduction ◽  
Amp Activated Protein Kinase ◽  
Impaired Energy Metabolism

Mutations in human N-glycanase 1 (NGLY1) cause the first known congenital disorder of deglycosylation (CDDG). Patients with this rare disease, which is also known as NGLY1 deficiency, exhibit global developmental delay and other phenotypes including neuropathy, movement disorder, and constipation. NGLY1 is known to regulate proteasomal and mitophagy gene expression through activation of a transcription factor called "nuclear factor erythroid 2-like 1" (NFE2L1). Loss of NGLY1 has also been shown to impair energy metabolism, but the molecular basis for this phenotype and its in vivo consequences are not well understood. Using a combination of genetic studies, imaging, and biochemical assays, here we report that loss of NGLY1 in the visceral muscle of the Drosophila larval intestine results in a severe reduction in the level of AMP-activated protein kinase α (AMPKα), leading to energy metabolism defects, impaired gut peristalsis, failure to empty the gut, and animal lethality. Ngly1–/– mouse embryonic fibroblasts and NGLY1 deficiency patient fibroblasts also show reduced AMPKα levels. Moreover, pharmacological activation of AMPK signaling significantly suppressed the energy metabolism defects in these cells. Importantly, the reduced AMPKα level and impaired energy metabolism observed in NGLY1 deficiency models are not caused by the loss of NFE2L1 activity. Taken together, these observations identify reduced AMPK signaling as a conserved mediator of energy metabolism defects in NGLY1 deficiency and suggest AMPK signaling as a therapeutic target in this disease.

scholarly journals Role of an inward rectifier K+current and of hyperpolarization in human myoblast fusion

1998 ◽  
Vol 510 (2) ◽  
pp. 467-476 ◽  
Author(s):  
J.-H. Liu ◽  
P. Bijlenga ◽  
J. Fischer-Lougheed ◽  
T. Occhiodoro ◽  
A. Kaelin ◽  
...  
Keyword(s):  
Myoblast Fusion ◽  
Inward Rectifier ◽  
K Current ◽  
Human Myoblast

scholarly journals How I Diagnose Low-Grade Myelodysplastic Syndromes

2020 ◽  
Vol 154 (1) ◽  
pp. 5-14
Author(s):  
Alexa J Siddon ◽  
Robert P Hasserjian
Keyword(s):  
Myelodysplastic Syndromes ◽  
Peripheral Blood ◽  
Diagnostic Algorithm ◽  
Low Grade ◽  
Multiple Sources ◽  
Genetic Studies ◽  
Genetic Abnormalities ◽  
Ancillary Studies ◽  
Diagnostic Setting

Abstract Objectives Myelodysplastic syndromes (MDS) are a group of myeloid neoplasms that are often difficult to diagnose due to their pathologic and clinical heterogeneity. The key features of MDS are peripheral blood cytopenias, ineffective hematopoiesis manifesting as morphologic dysplasia, and clonal genetic abnormalities. The most difficult diagnostic dilemmas often arise in low-grade MDS cases (lacking excess blasts), which can be difficult to distinguish from other causes of cytopenia. This distinction requires the integration of information from the peripheral blood (both CBC parameters and morphology), bone marrow morphology, genetic studies, and interrogation of the clinical record to exclude secondary causes. Methods We discuss the approach to the diagnosis of low-grade MDS (cases lacking increased blasts), including a diagnostic algorithm and two illustrative cases. Results The appropriate use of ancillary studies is important to support or dispute the likelihood of low-grade MDS in conjunction with the findings of morphologic dysplasia. Interpreting the results of cytogenetics and next-generation sequencing can be challenging and must incorporate the emerging knowledge of clonal hematopoiesis of indeterminate potential. Conclusions The role of pathologists in integrating data from multiple sources in the diagnosis of low-grade MDS is evolving and becoming increasingly complex; in this challenging diagnostic setting, it is important to feel comfortable with uncertainty and maintain a conservative approach.

Mitochondrial Dysfunction and Migraine

Cephalalgia ◽  
2006 ◽  
Vol 26 (4) ◽  
pp. 361-372 ◽  
Author(s):  
M Sparaco ◽  
M Feleppa ◽  
RB Lipton ◽  
AM Rapoport ◽  
ME Bigal
Keyword(s):  
Mitochondrial Dysfunction ◽  
Molecular Genetic ◽  
Resonance Spectroscopy ◽  
Genetic Studies ◽  
Mtdna Mutations ◽  
Oxidative Energy Metabolism ◽  
Biochemical Assays ◽  
Biochemical Imaging ◽  
Muscle Biopsies ◽  
The Brain

The molecular basis of migraine is still not completely understood. An impairment of mitochondrial oxidative metabolism might play a role in the pathophysiology of this disease, by influencing neuronal information processing. Biochemical assays of platelets and muscle biopsies performed in migraine sufferers have shown a decreased activity of the respiratory chain enzymes. Studies with phosphorus magnetic resonance spectroscopy (31P-MRS) have demonstrated an impairment of the brain oxidative energy metabolism both during and between migraine attacks. However, molecular genetic studies have not detected specific mitochondrial DNA (mtDNA) mutations in patients with migraine, although other studies suggest that particular genetic markers (i.e. neutral polymorphisms or secondary mtDNA mutations) might be present in some migraine sufferers. Further studies are still needed to clarify if migraine is associated with unidentified mutations on the mtDNA or on nuclear genes that code mitochondrial proteins. In this paper, we review morphological, biochemical, imaging and genetic studies which bear on the hypothesis that migraine may be related to mitochondrial dysfunction at least in some individuals.

scholarly journals Interplay of the E box, the cyclic AMP response element, and HTF4/HEB in transcriptional regulation of the neurospecific, neurotrophin-inducible vgf gene.

1997 ◽  
Vol 17 (3) ◽  
pp. 1244-1253 ◽  
Author(s):  
G Di Rocco ◽  
M Pennuto ◽  
B Illi ◽  
N Canu ◽  
G Filocamo ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cyclic Amp ◽  
Transcriptional Control ◽  
Specific Expression ◽  
Response Element ◽  
Expression Screening ◽  
E Protein ◽  
E Box ◽  
Cyclic Amp Response Element

vgf is a neurotrophin response-specific, developmentally regulated gene that codes for a neurosecretory polypeptide. Its transcription in neuronal cells is selectively activated by the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor, and neurotrophin 3, which induce survival and differentiation, and not by epidermal growth factor. We studied a short region of the rat vgf promoter which is essential for its regulated expression. A cyclic AMP response element (CRE) within this region is necessary for NGF induction of vgf transcription. Two sites upstream of CRE, an E box and a CCAAT sequence, bind nuclear protein complexes and are involved in transcriptional control. The E box has a dual role. It acts as an inhibitor in NIH 3T3 fibroblasts, together with a second E box located downstream, and as a stimulator in the NGF-responsive cell line PC12. By expression screening, we have isolated the cDNA for a basic helix-loop-helix transcription factor, a homolog of the HTF4/HEB E protein, that specifically binds the vgf promoter E box. The E protein was present in various cell lines, including PC12 cells, and was a component of a multiprotein nuclear complex that binds the promoter in vitro. The E box and CRE cooperate in binding to this complex, which may be an important determinant for neural cell-specific expression.

scholarly journals The Role of the Rad55–Rad57 Complex in DNA Repair

Genes ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1390
Author(s):  
Upasana Roy ◽  
Eric C. Greene
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Homologous Recombination ◽  
Single Molecule ◽  
Genome Integrity ◽  
Genetic Studies ◽  
Biochemical Assays ◽  
Rad51 Paralogs ◽  
Higher Eukaryotes

Homologous recombination (HR) is a mechanism conserved from bacteria to humans essential for the accurate repair of DNA double-stranded breaks, and maintenance of genome integrity. In eukaryotes, the key DNA transactions in HR are catalyzed by the Rad51 recombinase, assisted by a host of regulatory factors including mediators such as Rad52 and Rad51 paralogs. Rad51 paralogs play a crucial role in regulating proper levels of HR, and mutations in the human counterparts have been associated with diseases such as cancer and Fanconi Anemia. In this review, we focus on the Saccharomyces cerevisiae Rad51 paralog complex Rad55–Rad57, which has served as a model for understanding the conserved role of Rad51 paralogs in higher eukaryotes. Here, we discuss the results from early genetic studies, biochemical assays, and new single-molecule observations that have together contributed to our current understanding of the molecular role of Rad55–Rad57 in HR.

scholarly journals Ectopic Methylation of a Single Persistently Unmethylated CpG in the Promoter of the Vitellogenin Gene Abolishes Its Inducibility by Estrogen through Attenuation of Upstream Stimulating Factor Binding

2019 ◽  
Vol 39 (23) ◽  
Author(s):  
Lia Kallenberger ◽  
Rachel Erb ◽  
Lucie Kralickova ◽  
Andrea Patrignani ◽  
Esther Stöckli ◽  
...  
Keyword(s):  
Dna Methyltransferase ◽  
Transcriptional Control ◽  
Dna Demethylation ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Reporter System ◽  
E Box ◽  
Stimulating Factor

ABSTRACT The enhancer/promoter of the vitellogenin II gene (VTG) has been extensively studied as a model system of vertebrate transcriptional control. While deletion mutagenesis and in vivo footprinting identified the transcription factor (TF) binding sites governing its tissue specificity, DNase hypersensitivity and DNA methylation studies revealed the epigenetic changes accompanying its hormone-dependent activation. Moreover, upon induction with estrogen (E2), the region flanking the estrogen-responsive element (ERE) was reported to undergo active DNA demethylation. We now show that although the VTG ERE is methylated in embryonic chicken liver and in LMH/2A hepatocytes, its induction by E2 was not accompanied by extensive demethylation. In contrast, E2 failed to activate a VTG enhancer/promoter-controlled luciferase reporter gene methylated by SssI. Surprisingly, this inducibility difference could be traced not to the ERE but rather to a single CpG in an E-box (CACGTG) sequence upstream of the VTG TATA box, which is unmethylated in vivo but methylated by SssI. We demonstrate that this E-box binds the upstream stimulating factor USF1/2. Selective methylation of the CpG within this binding site with an E-box-specific DNA methyltransferase, Eco72IM, was sufficient to attenuate USF1/2 binding in vitro and abolish the hormone-induced transcription of the VTG gene in the reporter system.

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