Dynamic regulation of histone methylation by methyltransferases and demethylases plays a central role in regulating the fate of embryonic stem (ES) cells. The histone H3K9 methyltransferase KMT1E, formerly known as ESET or Setdb1, is essential to embryonic development as the ablation of the Setdb1 gene results in peri-implantation lethality and prevents the propagation of ES cells. However, Setdb1- null blastocysts do not display global changes in H3K9 methylation or DNA methylation, arguing against a genome- wide defect. Here we show that conditional deletion of the Setdb1 gene in ES cells results in the upregulation of lineage differentiation markers, especially trophectoderm-specific factors, similar to effects observed upon loss of Oct3/4 expression in ES cells. We demonstrate that KMT1E deficiency in ES cells leads to a decrease in histone H3K9 methylation at and derepression of trophoblast-associated genes such as Cdx2. Furthermore, we find genes that are derepressed upon Setdb1 deletion to overlap with known targets of polycomb mediated repression, suggesting that KMT1E mediated H3K9 methylation acts in concert with polycomb controlled H3K27 methylation. Our studies thus demonstrate an essential role for KMT1E in the control of developmentally regulated gene expression programs in ES cells.
KMT1E mediated H3K9 methylation is required for the maintenance of embryonic stem cells by repressing trophectoderm differentiation.
Specimen part, Treatment
View SamplesEpithelial-mesenchymal transition (EMT) has been linked to cancer progression and metastatic propensity. The 4T1 tumor is a clinically relevant model of spontaneous breast cancer metastasis. Here we characterize 4T1-derived cell lines for EMT, in vitro invasiveness and in vivo metastatic ability. Contrary to expectations, the 67NR cells, which form primary tumors but fail to metastasize, express vimentin and N-cadherin, but not E-cadherin. 4T1 cells, however, express E-cadherin, are highly migratory and invasive, and metastasize to multiple sites. The 66cl4 metastatic cells display mixed epithelial and mesenchymal markers, but are less migratory and invasive than 67NR cells. These findings demonstrate that the metastatic ability of breast cancer cells does not correlate with genotypic and phenotypic properties of EMT per se, and suggest that other processes may govern metastatic capability. Gene expression analysis also has not identified differences in EMT markers, but has identified several candidate genes that may influence metastatic ability.
Epithelial-mesenchymal transition (EMT) is not sufficient for spontaneous murine breast cancer metastasis.
Sex, Specimen part
View SamplesPrions consist of aggregates of abnormal conformers of cellular prion protein (PrPC). They propagate by recruiting host-encoded PrPC although the critical interacting proteins and the reasons for the differences in susceptibility of distinct cell lines and populations are unknown. We derived a lineage of cell lines with markedly differing susceptibilities, unexplained by PrPC expression differences, to identify such factors. We examined the transcriptomes of prion-resistant revertants, isolated from highly susceptible cells, and identified a gene expression signature associated with susceptibility. Several of these genes encode proteins with a role in extracellular matrix (ECM) remodelling, a compartment in which disease-related PrP deposits. Loss-of-function of nine of these genes significantly increased susceptibility. Remarkably, inhibition of fibronectin 1 binding to integrin 8 by RGD peptide inhibited metalloproteinases (MMP)-2/9 whilst increasing prion propagation rates. This indicates that prion replication may be controlled by MMPs at the ECM in an integrin-dependent manner.
Identification of a gene regulatory network associated with prion replication.
Treatment
View SamplesPolyinosinic:polycytidylic acid (poly I:C) is a synthetic analogue of double-stranded (ds)RNA, a molecular pattern associated with viral infections, that is used to exacerbate inflammation in lung injury models. Despite its frequent use, there are no detailed studies of the responses elicited by a single topical administration of poly I:C to the lungs of mice. Our data provides the first demonstration that the molecular responses in the airways induced by poly I:C correlate to those observed in the lungs of COPD patients. These expression data also revealed three distinct phases of response to poly I:C, consistent with the changing inflammatory cell infiltrate in the airways. Poly I:C induced increased numbers of neutrophils and NK cells in the airways, which were blocked by CXCR2 and CCR5 antagonists, respectively. Using gene set variation analysis on representative data sets, gene sets defined by poly I:C-induced DEGs were enriched in the molecular profiles of chronic obstructive pulmonary disease (COPD), but not idiopathic pulmonary fibrosis patients. Collectively, these data represent a new approach for validating the clinical relevance of preclinical animal models and demonstrate that a dual CXCR2/CCR5 antagonist may be an effective treatment for COPD patients.
Double-stranded RNA induces molecular and inflammatory signatures that are directly relevant to COPD.
Sex, Specimen part, Time
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Evolutionary etiology of high-grade astrocytomas.
Sex, Time
View SamplesTo determine the regulatory pathways necessary for astrocytoma formation within complex adult brain microenvironments, we engineered mice for adult astrocyte-specific disruption of key regulators (pRb, Kras and Pten). Drivers of all astrocytoma grades were identified using CreERTM-inducible alleles. Inactivation of pRb was necessary to initiate grade II disease, and was the only lesion to do so. Additional activation of Kras progressed disease to grade III, while further Pten inactivation facilitated grade IV (glioblastoma) progression. These outcomes were elicited whether somatic events were induced broadly or focally. In vivo inactivation of pRb, which induced astrocyte proliferation and apoptosis, activated the MAPK pathway, while Kras activation and Pten loss triggered PI3K pathways.
Evolutionary etiology of high-grade astrocytomas.
Sex, Time
View SamplesFLT3-ITDs Introduce a Myeloid Differentiation and Transformation Bias in Lympho-myeloid Multipotent Progenitors
FLT3-ITDs instruct a myeloid differentiation and transformation bias in lymphomyeloid multipotent progenitors.
Sex, Specimen part
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