Eosinophils are important in fighting parasitic infections and are implicated in the pathogenesis of asthma and allergy. Interleukin-5 (IL-5) is a critical regulator of eosinophil development, controlling proliferation, differentiation and maturation of the lineage. Mice that constitutively express IL-5 have more than 10 fold more eosinophils in the haematopoietic organs than their wild type counterparts. We have identified that much of this expansion is in a population of Siglec-F high eosinophils, which are rare in wild type mice. In this study we assessed transcription in myeloid progenitors, eosinophil precursors and Siglec-F medium and Siglec-F high eosinophils from IL-5 transgenic mice and in doing so have created a useful resource for eosinophil biologists. We have then utilised these populations to construct an eosinophil trajectory based on gene expression and to identify gene sets that are associated with eosinophil lineage progression. Cell cycle genes were significantly associated with the trajectory, and we experimentally demonstrate an increasing trend towards quiescence along the trajectory. Additionally we found gene expression changes associated with constitutive IL-5 signalling in eosinophil progenitors, many of which were not observed in eosinophils.
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Specimen part
View SamplesMicroarray analysis was used to compare the gene expression profiles of Deaf-1-transduced mouse mammary epithelial cells (MECs) relative to Deaf-1-deficient MECs.
Deaf-1 regulates epithelial cell proliferation and side-branching in the mammary gland.
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Specimen part
View SamplesTranscriptional control is dependent on a vast network of epigenetic modifications. One epigenetic mark of particular interest is tri-methylation of lysine 27 on histone H3 (H3K27me3), which is catalyzed and maintained by the Polycomb Repressor Complex (PRC2). Although this histone mark is studied widely, the precise relationship between its local pattern of enrichment and regulation of gene expression is currently unclear. We have used ChIP-seq to generate genome wide maps of H3K27me3 enrichment, and have identified three enrichment profiles with distinct regulatory consequences. First, a broad domain of H3K27me3 enrichment across the body of genes corresponds to the canonical view of H3K27me3 as inhibitory to transcription. Second, a peak of enrichment around the transcription start site is commonly associated with bivalent genes, where H3K4me3 also marks the TSS. Finally and most surprisingly, we identified an enrichment profile with a peak in the promoter of genes that is associated with active transcription. Genes with each of these three profiles were found in different proportions in each of the cell types studied. The data analysis techniques developed here will be useful for the identification of common enrichment profiles for other histone modifications that have important consequences for transcriptional regulation.
ChIP-seq analysis reveals distinct H3K27me3 profiles that correlate with transcriptional activity.
Specimen part
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Reprogramming factor expression initiates widespread targeted chromatin remodeling.
Specimen part
View SamplesDespite rapid progress in characterizing transcription factor-driven reprogramming of somatic cells to an induced pluripotent stem (iPS) cell state, many mechanistic questions still remain. To gain insight into the earliest events in the reprogramming process, we systematically analyzed the transcriptional and epigenetic changes that occur during early factor induction after discrete numbers of divisions. We observed rapid, genome-wide changes in the euchromatic histone modification, H3K4me2, at more than a thousand loci including large subsets of pluripotency or developmentally related gene promoters and enhancers. In contrast, patterns of the repressive H3K27me3 modification remained largely unchanged except for focused depletion specifically at positions where H3K4 methylation is gained. These chromatin regulatory events precede transcriptional changes within the corresponding loci. Our data provide evidence for an early, organized, and population-wide epigenetic response to ectopic reprogramming factors that clarify the temporal order through which somatic identity is reset during reprogramming.
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Specimen part
View SamplesWe report a Jak2V617F knock-in mouse myeloproliferative neoplasm (MPN) model resembling human polycythemia vera (PV). The MPN is serially transplantable and we demonstrate that the hematopoietic stem cell (HSC) compartment has the unique capacity for disease initiation but does not have a selective competitive advantage over wild type HSCs. In contrast, myeloid progenitor populations are expanded and skewed towards the erythroid lineage, but cannot transplant the disease. Treatment with a JAK2 kinase inhibitor ameliorated the MPN phenotype, but did not eliminate the disease-initiating population. These findings provide insights into the consequences of JAK2 activation on HSC differentiation and function and have the potential to inform therapeutic approaches to JAK2V617F positive MPN.
Physiological Jak2V617F expression causes a lethal myeloproliferative neoplasm with differential effects on hematopoietic stem and progenitor cells.
Specimen part
View SamplesApc, a negative regulator of the canonical Wnt signaling pathway, is a bona-fide tumor suppressor whose loss of function results in intestinal polyposis. APC is located in a commonly deleted region on human chromosome 5q, associated with myelodysplastic syndrome (MDS) suggesting that haploinsufficiency of APC contributes to the MDS phenotype. Analysis of the hematopoietic system of mice with the Apcmin allele that results in a premature stop codon and loss of function, showed no abnormality in steady state hematopoiesis. Bone marrow derived from Apcmin mice showed enhanced repopulation potential, indicating of a cell intrinsic gain of function in the long-term hematopoietic stem cell (HSC) population. However, Apcmin bone marrow was unable to repopulate secondary recipients due to loss of the quiescent HSC population. Apcmin mice developed a myelodysplastic/ myeloproliferative phenotype. Our data indicate that Wnt activation through haploinsufficiency of Apc causes insidious loss of HSC function that is only evident in serial transplantation strategies. These data provide a cautionary note for HSC expansion strategies through Wnt pathway activation, provide evidence that cell extrinsic factors can contribute to the development of myeloid disease and indicate that loss of function of APC may contribute to the phenotype observed in patients with MDS and del(5q).
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Sex, Specimen part
View SamplesWe performed gene-expression analysis of mouse Purkinje cells as a model single-type neuron. DNA microarray analysis detected at least 7,055 genes in Purkinje cells, most of which are classified into functional molecule categories.
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Sex, Specimen part
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