Xist is indispensable for X chromosome inactivation (XCI) in female mammalian cells. However, how Xist RNA directs chromosome-wide transcriptional inactivation of the X chromosome is largely unknown. Here, to study chromosome inactivation by Xist, we generated a system where ectopic Xist expression can be induced from several genomic contexts in aneuploid mouse ES cells. We found that ectopic Xist expression from any location on the X chromosome faithfully recapitulated endogenous XCI, showing the potency of Xist to initiate XCI. Genes that escape XCI remain consistently transcriptionally active upon ectopic XCI, regardless of their position relative to Xist transgenes, and the enrichment of CTCF at their promoters is implicated in directing XCI escape. Xist expression from autosomes facilitates their transcriptional silencing to different degrees, and gene density in proximity of the Xist transcription locus plays a central role in determining the efficiency of gene inactivation. We also show that the enrichment of LINE elements together with a specific chromatin environment facilitates Xist-mediated silencing of both X-linked and autosomal genes. These findings provide new insights into the epigenetic mechanisms that mediate XCI and identify genomic features that promote Xist-mediated chromosome-wide gene inactivation Overall design: 60 RNA-seq from mouse embryonic stem cells and fully differentiated neurons in which ectopic Xist epression is either triggered (plus samples) or not (minus samples) upon doxycycline treatment.
Genetic and epigenetic features direct differential efficiency of Xist-mediated silencing at X-chromosomal and autosomal locations.
Sex, Specimen part, Cell line, Subject
View SamplesBackground: During early embryonic development, one of the two X chromosomes in mammalian female cells is inactivated to compensate for a potential imbalance in transcript levels with male cells containing a single X chromosome. We use mouse female Embryonic Stem Cells (ESCs) with nonrandom XCI and polymorphic X chromosomes to study the dynamics of gene silencing over the inactive X chromosome (Xi) by high-resolution allele-specific RNA-Seq. Results: Induction of XCI by differentiation of female ESCs shows that genes proximal to the X-inactivation center (XIC) are silenced earlier than distal genes, while lowly expressed genes show faster XCI dynamics than highly expressed genes. The active X chromosome shows a minor but significant increase in gene activity during differentiation, resulting in complete dosage compensation in differentiated cell types. Genes escaping XCI show little or no silencing during early propagation of XCI. Using allele-specific RNA-Seq of Neural Progenitor Cells (NPCs) generated from the female ESCs, we identify three regions distal to the XIC that stably escape XCI during differentiation of the female ESCs, as well as during propagation of the NPCs. These regions coincide with Topologically Associated Domains (TADs) as determined in the undifferentiated female ESCs. Also the previously characterized human gene clusters escaping XCI correlate with TADs. Conclusions: Together, the dynamics of gene silencing observed over the Xi during XCI provide further insight in the formation and maintenance of the repressive Xi complex. The association of regions of escape with TADs, in mouse and human, suggests a regulatory role for TADs during propagation of XCI. Overall design: 19 RNA-Seq profiles of mouse ESCs, EpiSCs and NPCs, mostly from distant crosses to allow allele specific mapping. 1 HiC profile of an undifferentiated mouse female ESC line containing a Tsix mutation. Mainly focusing on X inactivation.
Dynamics of gene silencing during X inactivation using allele-specific RNA-seq.
No sample metadata fields
View SamplesTo examine the impact of tumors on the immune system, we compared global gene expression profiles of peripheral blood T cells from previously untreated patients with B cell chronic lymphocytic leukemia (CLL) with those from age-matched healthy donors. Although the cells analyzed were not part of the malignant clone, analysis revealed differentially expressed genes, mainly involved in cell differentiation in CD4 cells and defects in cytoskeleton formation, vesicle trafficking, and cytotoxicity in CD8 cells of the CLL patients. In coculture experiments using CLL cells and T cells from healthy allogeneic donors, similar defects developed in both CD4 and CD8 cells. These changes were induced only with direct contact and were not cytokine mediated. Identification of the specific pathways perturbed in the T cells of cancer-bearing patients will allow us to assess steps to repair these defects, which will likely be required to enhance antitumor immunity.
Chronic lymphocytic leukemia cells induce changes in gene expression of CD4 and CD8 T cells.
No sample metadata fields
View SamplesPrevious studies in our laboratory demonstrated that the azurophil granule protease neutrophil elastase (NE) cleaves PML-RARA (PR), the fusion protein that initiates acute promyelocytic leukemia (APL). Further, NE deficiency reduces the penetrance of APL in a murine model of this disease. We therefore predicted that NE-mediated PR cleavage might be important for its ability to initiate APL. To test this hypothesis, we generated a mouse expressing NE-resistant PR. These mice developed APL indistinguishable from wild type PR, but with significantly reduced latency (median leukemia-free survival of 274 days versus 473 days for wild type PR, p<0.001). Resistance to proteolysis may increase the abundance of full length PR protein in early myeloid cells, and our previous data suggested that non-cleaved PR may be less toxic to early myeloid cells. Together, these effects appear to increase the leukemogenicity of NE-resistant PR, contrary to our previous prediction. We conclude that NE deficiency may reduce APL penetrance via indirect mechanisms that are still NE dependent.
A protease-resistant PML-RAR{alpha} has increased leukemogenic potential in a murine model of acute promyelocytic leukemia.
Cell line
View SamplesMurine pancreatic beta cell line MIN6 was growth at two different concentrations of glucose (22,2 and 5,5 mM of glucose), 37C, 5% CO2 and was treated at four different concentrations of human amylin (0, 1, 10 and 20 uM) during three different times (2, 12 and 24 hours)
Impairment of the ubiquitin-proteasome pathway is a downstream endoplasmic reticulum stress response induced by extracellular human islet amyloid polypeptide and contributes to pancreatic beta-cell apoptosis.
No sample metadata fields
View SamplesThis analysis represents the first comprehensive sampling of germ cells in the developing testis over time, at high-resolution, single-cell depth. From these analyses, we have not only revealed novel genetic regulatory signatures of murine germ cells over time, but have also demonstrated that cell types positive for a single marker gene have the capacity to change dramatically during testis maturation, and therefore cells of a particular “identity” may differ significantly from postnatal to adult life. Overall design: Single-cell suspensions of mammalian testes ranging from PND6 to adult were processed for single-cell RNAseq (10x Genomics Chromium) and libraries were sequenced on a NextSeq500 (Illumina).
Dynamic transcriptome profiles within spermatogonial and spermatocyte populations during postnatal testis maturation revealed by single-cell sequencing.
Age, Disease, Cell line, Subject
View SamplesIntra-islet crosstalk between islet cells is critical in orchestrating the body’s response to changes in blood glucose levels, but is incompletely understood. In this study, we used transgenic mouse lines that allowed the purification and transcriptomic characterisation of alpha, beta, and delta cells, yielding an RNA-sequencing database that can be searched for regulatory proteins which are differentially expressed between cell types. As an illustrative example, we examined the expression of g-protein coupled receptors, and found that the ghrelin receptor, Ghsr, was highly expressed in delta cells compared to alpha and beta cells. GHSR excitation elicited increases in cytosolic calcium levels in primary delta cells. In the perfused pancreas, the application of ghrelin stimulated somatostatin secretion, correlating with a decrease in insulin and glucagon release, which was sensitive to somatostatin receptor antagonism. These results show that ghrelin acts specifically on delta cells within pancreatic islets to affect blood glucose regulation. Overall design: Examination of transcriptomic profiles obtained from pancreatic alpha, beta and delta cells
Transcriptomic profiling of pancreatic alpha, beta and delta cell populations identifies delta cells as a principal target for ghrelin in mouse islets.
Specimen part, Cell line, Subject
View SamplesEnteroendocrine L-cells release hormones that control metabolism and appetite and are targets under investigation for the treatment of diabetes and obesity. Understanding L-cell diversity and expression profiles is critical for identifying target receptors that will translate into altered hormone secretion. We performed single cell RNA sequencing of mouse L-cells from the upper small intestine to distinguish cellular populations, revealing that L-cells form 3 major clusters: a group with typical characteristics of classical L-cells, including high expression of Gcg and Pyy; a cell type overlapping with Gip-expressing K-cells; and a unique cluster expressing Tph1 and Pzp that was predominantly located in duodenal villi and co-produced 5HT. Expression of G-protein coupled receptors differed between clusters, suggesting the cell types are differentially regulated, and would be differentially targetable. Our findings support the emerging concept that many enteroendocrine cell populations are highly overlapping, with individual cells producing a range of peptides previously assigned to distinct cell types. Overall design: Single cell RNA sequencing of mouse duodenal L-cells cells
Single-cell RNA-sequencing reveals a distinct population of proglucagon-expressing cells specific to the mouse upper small intestine.
Specimen part, Subject
View SamplesThe characteristics of immune cells infiltrating pediatric brain tumors is largely unexplored. A better understanding of these characteristics will provide a foundation for development of immunotherapy for pediatric brain tumors.
Characterization of distinct immunophenotypes across pediatric brain tumor types.
Specimen part, Disease, Disease stage
View SamplesTo better understand the pathogenesis of acute promyelocytic leukemia (APL, FAB M3 AML), we identified genes that are expressed differently in APL cells compared to other acute myeloid leukemia subtypes, and to normal promyelocytes. Comparative gene expression analysis of 14 M3, 62 other AML (M0, M1, M2 and M4) and 5 enriched normal promyelocyte samples revealed a signature of 1,121 genes that are specifically dysregulated in M3 samples relative to other AML, and that do not simply represent normal promyelocyte expression (M3-specific signature). We used a novel, high throughput digital platform (Nanostring's nCounter system) to evaluate a subset of the most significantly dysregulated genes in 30 AML samples; 33 of 37 evaluable gene expression patterns were validated. In an additional analysis, we selected only genes that are dysregulated in M3 both compared to other AML subtypes, and to purified normal CD34+ cells, promyelocytes, and/or neutrophils, thereby isolating a 478 gene "composite M3 dysregulome". Surprisingly, the expression of only a few of these genes was significantly altered in PR-9 cells after PML-RARA induction, suggesting that most of these genes are not direct targets of PML-RARA. Comparison of the M3-specific signature to our previously described murine APL dysregulome revealed 33 commonly dysregulated genes, including JUN, EGR1, and TNF. Collectively, these results suggest that PML-RARA initiates a transcriptional cascade which generates a unique downstream expression signature in both primary human and mouse APL cells.
High throughput digital quantification of mRNA abundance in primary human acute myeloid leukemia samples.
Sex, Race
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