The MYC transcription factor is an unstable protein and its turnover is controlled by the ubiquitin system. Ubiquitination enhances MYC-dependent transactivation, but the underlying mechanism remains unresolved. Here we show that proteasomal turnover of MYC is dispensable for recruitment of RNA polymerase II (RNAPII), but is required to promote transcriptional elongation at MYC target genes. Degradation of MYC stimulates histone acetylation and recruitment of BRD4 and P-TEFb to target promoters, leading to phosphorylation of RNAPII CTD and the release of elongating RNAPII. In the absence of degradation, the RNA polymerase II-associated factor (PAF) complex associates with MYC via interaction of its CDC73 subunit with a conserved domain in the amino-terminus of MYC ("MYC box I"), suggesting that a MYC/PAF complex is an intermediate in transcriptional activation. Since histone acetylation depends on a second highly conserved domain in MYCs amino-terminus ("MYC box II"), we propose that both domains co-operate to transfer elongation factors onto paused RNAPII. Overall design: RNA-Seq Experiments were performed in a primary breast epithelial cell line (IMEC).The cell line expressed doxycycline-inducible versions of MYC (WT;Kless,Swap=WTN-KC). Where indicated cells were transfected with siRNAs (siCtrl;siSKP2). Where indicated cells were treaed with the proteasome inhibitor MG132 or EtOH as solvent control. DGE was performed by comparing Dox-treated populations expressing either Dox-inducible MYC or a vector control or comparing Dox-induced cells with EtOH (solvent control) treated cells.
Ubiquitin-Dependent Turnover of MYC Antagonizes MYC/PAF1C Complex Accumulation to Drive Transcriptional Elongation.
No sample metadata fields
View SamplesIn several developmental lineages, an increase in expression of the MYC proto-oncogene drives the transition from quiescent stem cells to transit amplifying cells. The mechanism by which MYC restricts self-renewal of adult stem cells is unknown. Here, we show that MYC activates a stereotypic transcriptional program of genes involved in protein translation and mitochondrial biogenesis in mammary epithelial cells and indirectly inhibits the YAP/TAZ co-activators that are essential for mammary stem cell self-renewal. We identify a phospholipase of the mitochondrial outer membrane, PLD6, as the mediator of MYC activity. PLD6 mediates a change in the mitochondrial fusion/fission balance that promotes nuclear export of YAP/TAZ in a LATS- and RHO-independent manner. Mouse models and human pathological data confirm that MYC suppresses YAP/TAZ activity in mammary tumors. PLD6 is also required for glutaminolysis, arguing that MYC-dependent changes in mitochondrial dynamics balance cellular energy metabolism with the self-renewal potential of adult stem cells. Overall design: RNA-Seq Experiments in 2 different primary breast epithelial cell lines (HMLE, which were sorted according to CD44/CD24 surface markers & unsorted IMEC). Both cell lines expressed a doxycycline-inducible version of MYC. For the HMLE cell line DGE analysis was performed for the uninduced (EtOH) situation, comparing CD44high vs CD44 low and for the induced situation Dox vs. EtOH for the CD44high population. For the IMEC cell line DGE was performed by comparing Dox-treated populations expressing either Dox-inducible MYC or a vector control which allows to filter out potential effects due to doxycycline treatment.
A MYC-Driven Change in Mitochondrial Dynamics Limits YAP/TAZ Function in Mammary Epithelial Cells and Breast Cancer.
No sample metadata fields
View SamplesA mouse embryonic stem cell line was generated which stably expressed the ngn3 transcription factor under the control of the Tet-On inducible system using knock-ins in the ROSA26 and the HPRT loci. The undifferentiated mouse embryonic stem cells were then differentiated into Embryoid Bodies in suspension culture and were either treated with Doxycycline to induce NGN3 expression or left untreated as a contol. Cells were harvested at 12 hours, 24 hours and 48 hours.
A shift from reversible to irreversible X inactivation is triggered during ES cell differentiation.
Sex, Specimen part, Cell line, Treatment, Time
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Chromatin structure and gene expression programs of human embryonic and induced pluripotent stem cells.
Cell line
View SamplesKnowledge of both the global chromatin structure and the gene expression programs of human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells should provide a robust means to assess whether the genomes of these cells have similar pluripotent states. Recent studies have suggested that ES and iPS cells represent different pluripotent states with substantially different gene expression profiles. We describe here a comparison of global chromatin structure and gene expression data for a panel of human ES and iPS cells. Genome-wide maps of nucleosomes with histone H3K4me3 and H3K27me3 modifications indicate that there is little difference between ES and iPS cells with respect to these marks. Gene expression profiles confirm that the transcriptional programs of ES and iPS cells show very few consistent differences. Although some variation in chromatin structure and gene expression was observed in these cell lines, these variations did not serve to distinguish ES from iPS cells.
Chromatin structure and gene expression programs of human embryonic and induced pluripotent stem cells.
Cell line
View SamplesGene expression heterogeneity in the pluripotent state of mouse embryonic stem cells (mESCs) has been increasingly well-characterized. In contrast, exit from pluripotency and lineage commitment have not been studied systematically at the single-cell level. Here we measured the gene expression dynamics of retinoic acid driven mESC differentiation using an unbiased single-cell transcriptomics approach. We found that the exit from pluripotency marks the start of a lineage bifurcation as well as a transient phase of susceptibility to lineage specifying signals. Our study revealed several transcriptional signatures of this phase, including a sharp increase of gene expression variability and a handover between two classes of transcription factors. In summary, we provide a comprehensive analysis of lineage commitment at the single cell level, a potential stepping stone to improved lineage control through timing of differentiation cues. Overall design: Bulk and single-cell RNA-seq (SCRB-seq and SMART-seq) of mouse embryonic stem cells after different periods of continuous exposure to retinoic acid. Bulk RNA-seq of cell lines derived after retinoic exposure and after differentiation with retinoic acid and MEK inhibitor combined.
Dynamics of lineage commitment revealed by single-cell transcriptomics of differentiating embryonic stem cells.
Cell line, Subject
View SamplesESCs and NPCs are two setm cell types which rely on expression of the transcription factor Sox2. We profilled gene expression in ESCs and NPCs to correlate genome-wide Sox2 ChIP-Seq data in these cells with expression of putative targets
SOX2 co-occupies distal enhancer elements with distinct POU factors in ESCs and NPCs to specify cell state.
No sample metadata fields
View SamplesMicroRNAs (miRNAs) post-transcriptionally regulate the expression of thousands of distinct mRNAs. While some regulatory interactions help to maintain basal cellular functions, others are likely relevant in more specific settings, such as response to stress. Here we describe such a role for the mir-290-295 cluster, the dominant miRNA cluster in mouse embryonic stem cells (mESCs). Examination of a target list generated from bioinformatic prediction, as well as expression data following miRNA loss, revealed strong enrichment for apoptotic regulators, two of which we validated directly: Caspase 2, the most highly conserved mammalian caspase, and Ei24, a p53 transcriptional target. Consistent with these predictions, mESCs lacking miRNAs were more likely to initiate apoptosis following genotoxic exposure to gamma irradiation or doxorubicin. Knockdown of either candidate partially rescued this pro-apoptotic phenotype, as did transfection of members of the mir-290-295 cluster. These findings were recapitulated in a specific mir-290-295 deletion line, confirming that they reflect miRNA functions at physiological levels. In contrast to the basal regulatory roles previously identified, the pro-survival phenotype shown here may be most relevant to stressful gestations, where pro-oxidant metabolic states induce DNA damage. Similarly, this cluster may mediate chemotherapeutic resistance in a neoplastic context, making it a useful clinical target.
A latent pro-survival function for the mir-290-295 cluster in mouse embryonic stem cells.
Specimen part
View SamplesHuman and mouse embryonic stem cells (ESCs) are derived from blastocyst stage embryos but have very different biological properties, and molecular analyses suggest that the pluripotent state of human ESCs isolated so far corresponds to that of mouse derived epiblast stem cells (EpiSCs). Here we rewire the identity of conventional human ESCs into a more immature state that extensively shares defining features with pluripotent mouse ESCs. This was achieved by exogenous induction of Oct4, Klf4 and Klf2 factors combined with LIF and inhibitors of glycogen synthase kinase 3 (GSK3) and mitogen-activated protein kinase (ERK) pathway. Forskolin, a protein kinase A pathway agonist that induces Klf4 and Klf2 expression, can transiently substitute for the requirement for ectopib transgene expression. In contrast to conventional human ESCs, these epigenetically converted cells have growth properties, an X chromosome activation state (XaXa), a gene expression profile, and signaling pathway dependence that are highly similar to that of mouse ESCs. Finally, the same growth conditions allow the derivation of human induced pluripotent stem (iPS) cells with similar properties as mouse iPS cells. The generation of nave human ESCs will allow the molecular dissection of a previously undefined pluripotent state in humans, and may open up new opportunities for patient-specific, disease-relevant research.
Human embryonic stem cells with biological and epigenetic characteristics similar to those of mouse ESCs.
Specimen part
View SamplesMicroglia-like cells and neural cells were generated from several hES and hIPS lines. As subset was characterized by RNA seq and compared to expression profiles of published primary and induced samples. ABSTRACT: Microglia, the only lifelong resident immune cells of the central nervous system (CNS), are highly specialized macrophages which have been recognized to play a crucial role in neurodegenerative diseases such as Alzheimer's, Parkinson's and Adrenoleukodystrophy (ALD). However, in contrast to other cell types of the human CNS, bona fide microglia have not yet been derived from cultured human pluripotent stem cells. Here we establish a robust and efficient protocol for the rapid production of microglia-like cells from human embryonic stem (ES) and induced pluripotent stem (iPS) cells that uses defined serum-free culture conditions. These in vitro pluripotent stem cell-derived microglia-like cells (termed pMGLs) faithfully recapitulate the expected ontogeny and characteristics of their in vivo counterparts and resemble primary fetal human and mouse microglia. We generated these cells from multiple disease-specific cell lines, and find that pMGLs derived from MeCP2 mutant hES cells are smaller than their isogenic controls. We further describe a culture platform to study integration and live behavior of pMGLs in organotypic 3D-cultures. This modular differentiation system allows the study of microglia in highly defined conditions, as they mature in response to developmentally relevant cues, and provides a framework to study the long-term interaction of microglia residing in a tissue-like environment. Overall design: Individual donors/genetic backgrounds. Dataset inlcudes 4 differentiated neural progenitor biological replicates (NPC1-4), 2 primary fetal microglia samples as reference, 5 induced microglia samples grown in basal medium (pMGL1-5), 3 induced microglia samples grown in neural conditioned medium (pMGL1-3+NCM)
Efficient derivation of microglia-like cells from human pluripotent stem cells.
Subject
View Samples