The transcription factor MyoD can coax na?e fibroblasts or otherwise committed cells to adopt the skeletal muscle phenotype by activating the muscle gene expression program. Activation of muscle gene expression occurs in quantal steps with not all the target genes of MyoD being activated at the same time. Some genes are induced in the initial phases, others at later stages despite the fact that MyoD is present throughout the differentiation process. MyoD is post-translationally modified by phosphorylation, ubiquitination, and acetylation. Here, we have employed a model system in which MyoD and its non-acetylatable version were inducibly expressed in mouse embryonic fibroblasts derived from mice to investigate how MyoD acetylation may contribute to differential gene activation.
MyoD acetylation influences temporal patterns of skeletal muscle gene expression.
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View SamplesTemporal expression profiling was utilized to define transcriptional regulatory pathways in vivo in a mouse muscle regeneration model. Potential downstream targets of MyoD were identified by temporal expression, promoter data base mining, and gel shift assays; Slug and calpain 6 were identified as novel MyoD targets. Slug, a member of the snail/slug family of zinc finger transcriptional repressors critical for mesoderm/ectoderm development, was further shown to be a downstream target by using promoter/reporter constructs and demonstration of defective muscle regeneration in Slug null mice.
Slug is a novel downstream target of MyoD. Temporal profiling in muscle regeneration.
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View SamplesThe integration of positive and negative intra- and extra-cellular signals dictates whether a cell will proliferate or differentiate. While it is intuitive to speculate that nutrients availability may influence this alternative, a comprehensive complement of the molecular determinants involved in this process has not been elucidated yet. In this study, we will investigate how nutrients (glucose) affect skeletal myogenesis. C2C12 cells will be cultured in high glucose and low glucose conditions, and their differenciation will be studied.
Glucose restriction inhibits skeletal myoblast differentiation by activating SIRT1 through AMPK-mediated regulation of Nampt.
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View SamplesEnhancers play a central role in cell-type-specific gene expression and are marked by H3K4me1/2. Active enhancers are further marked by H3K27ac. However, the methyltransferases responsible for the deposition of H3K4me1/2 on enhancers remain elusive. Furthermore, the functions of these methyltransferases on enhancers and associated cell-type-specific gene expression are poorly understood. Here, we identify MLL4 (KMT2D) as a major H3K4 mono- and di-methyltransferase in mammalian cells. Using adipogenesis and myogenesis as model systems, we show that MLL4 exhibits cell-type- and differentiation-stage-specific genomic binding and is predominantly localized on enhancers. MLL4 co-localizes with lineage-determining transcription factors (TFs) on active enhancers during differentiation. Deletion of MLL4 dramatically decreases H3K4me1/2 and H3K27ac on enhancers and leads to severe defects in cell-type-specific gene expression and cell differentiation. Finally, we provide evidence that lineage-determining TFs recruit and require MLL4 to establish enhancers critical for cell-type-specific gene expression. Together, these results identify MLL4 as an H3K4 mono-/di-methyltransferase required for enhancer activation during cell differentiation. Overall design: RNA-Seq analysis of mRNA profiles in adenoviral GFP- or Cre-infected MLL3-/-;MLL4-flox/flox cells. Preadipocytes: brown preadipocytes before differentiation. D5 myocytes: 5 days after MyoD-induced myogenesis of brown preadipocytes.
H3K4 mono- and di-methyltransferase MLL4 is required for enhancer activation during cell differentiation.
Specimen part, Subject
View SamplesSelective genetic ablation of the SIRT1 deacetylase domain in skeletal muscle results in increased H4K16 acetylation and deregulated activation of the myogenic program in satellite cells Overall design: To establish the role of the deacetylase SIRT1 in skeletal muscle we examined the genome wide distribution of H4K16ac in quiescent (FI) and proliferating (Cul) satellite cells isolated from WT mice (C57Bl/6 background) and SIRT1mKO (generated via breeding of Pax7cre/+ knock-in mice with mice containing the floxed exon 4 SIRT1 allele). We also analyzed the distribution of SIRT1 in quiescent and proliferating FACS isolated WT satellite cells (two replicates). We generated the mRNA profiles (at least two replicate for each experiment) of FACS isolated quiescent, proliferating and differentiating (1 day in differentiation medium) satellite cells of WT mice and SIRT1mKO. The selective genetic ablation of the SIRT1 deacetylase domain in skeletal muscle results in increased H4K16 acetylation and deregulated activation of the myogenic program.
The NAD(+)-dependent SIRT1 deacetylase translates a metabolic switch into regulatory epigenetics in skeletal muscle stem cells.
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View SamplesRNA-Seq analysis was performed to define the associated changes in gene expression of skeletal muscle treated with follistatin Overall design: Skeletal muscle mRNA profiles from follistatin and control treated tibialis anterior muscles. Acute (3 day treatment, 3 control and 4 follistatin replicates) and chronic (7or 14 day treatment, 3 control and 4 follistatin replicates) timepoints were analysed.
Integrated expression analysis of muscle hypertrophy identifies <i>Asb2</i> as a negative regulator of muscle mass.
Specimen part, Cell line, Treatment, Subject
View SamplesSummary: Genetic disorders of muscle cause muscular dystrophy, and are some of the most common inborn errors of metabolism. Muscle also rapidly remodels in response to training and innervation. Muscle weakness and wasting is important in such conditions as aging, critical care medicine, space flight, and diabetes. Finally, muscle can also be used to investigate systemic defects, and the compensatory mechansisms invoked by cells to overcome biochemical and genetic abnormalities. Here, we provide a 13 group data set for comparative profiling of human skeletal muscle. Groups studied are: Normal human skeletal muscle, Acute quadriplegic myopathy (AQM; critical care myopathy), Juvenile dermatomyositis (JDM), Amyotophic lateral sclerosis (ALS), spastic paraplegia (SPG4; spastin), Fascioscapulohumeral muscular dystrophy (FSHD), Emery Dreifuss muscular dystrophy (both X linked recessive emerin form; autosomal dominant Lamin A/C form), Becker muscular dystrophy (partial loss of dystrophin), Duchenne muscular dystrophy (complete loss of dystrophin), Calpain 3 (LGMD2A), dysferlin (LGMD2B), FKRP (glycosylation defect; homozygous for a missense mutation). U133A and U133B microarrays are both available.
Nuclear envelope dystrophies show a transcriptional fingerprint suggesting disruption of Rb-MyoD pathways in muscle regeneration.
Specimen part, Disease, Disease stage
View SamplesThe role of FoxP3+ regulatory T (Treg) cells in the maintenance of immunological tolerance is well established. Recently, genome-wide association studies (GWAS) in humans have associated polymorphisms within the BACH2 locus encoding the transcription factor BTB and CNC homology 1, basic leucine zipper transcription factor 2 (Bach2) with diverse allergic and autoimmune diseases including asthma, multiple sclerosis, Crohn's disease, celiac disease, generalized vitiligo and type 1 diabetes. Common to these diseases is a failure to adequately maintain immunological tolerance. However, a role for Bach2 in this process has not been established.Here, by assessing the phenotype of mice in which the Bach2 gene is disrupted, we demonstrate a non-redundant role for Bach2 in the prevention of a spontaneous lethal inflammatory disorder predominantly affecting the lung and gut with excessive T helper 2 (Th2) responses and formation of circulating autoantibodies. Bach2 was necessary for efficient induction of FoxP3 expression both during thymopoesis and upon stimulation of nave peripheral CD4+ T cells under Treg polarizing conditions in vitro. Consequently, in bone marrow reconstitution experiments, Bach2 expression within the haematopoetic system was necessary for suppression of lethal autoimmunity in a manner that was FoxP3 dependent. These findings demonstrate a requirement for Bach2 in early lineage commitment of both thymic and induced Treg cells and point to shared mechanisms that underlie diverse allergic and autoimmune disorders that may serve as targets in the development of novel therapeutic strategies.
BACH2 represses effector programs to stabilize T(reg)-mediated immune homeostasis.
Sex, Specimen part
View SamplesTo further understand the differences occurring in MCF10A cells as they polarize and differentiate in the Transwell model, we performed gene expression profiling with Affymetrix Human Genome U133 Plus 2.0 Arrays. Four experimental time points, were sampled: conventional cultures of MCF10A cells grown on plastic (Monolayer) and MCF10A cells plated on Transwells sampled at three TEER values, 200-300 cm2 (Base), 1400-1600 cm2 (Midpoint), and 3000-3200 cm2 (Plateau).
In vitro multipotent differentiation and barrier function of a human mammary epithelium.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
Genomic binding of PAX8-PPARG fusion protein regulates cancer-related pathways and alters the immune landscape of thyroid cancer.
Specimen part, Treatment
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