Cell fate specification relies on the action of critical transcription factors that become available at distinct stages of embryonic development. One such factor is NeuroD1, which is essential for eliciting the neuronal development program and possesses the ability to reprogram other cell types into neurons. Given this capacity, it is important to understand its targets and the mechanism underlying neuronal specification. Here, we show that NeuroD1 directly binds regulatory elements of neuronal genes that are developmentally silenced by epigenetic mechanisms. This targeting is sufficient to initiate events that confer transcriptional competence, including reprogramming of transcription factor landscape, conversion of heterochromatin to euchromatin and increased chromatin accessibility, indicating potential pioneer factor ability of NeuroD1. The transcriptional induction of neuronal fate genes is maintained via epigenetic memory despite a transient NeuroD1 induction during neurogenesis. Our study not only reveals the NeuroD1-dependent gene regulatory program driving neurogenesis but also increases our understanding of how cell-fate specification during development involves a concerted action of transcription factors and epigenetic mechanisms. Overall design: 1. Ectopic NeuroD1 was induced for 48 hours (+Dox) in ES cells for checking initiation of neuronal transcriptional program in comparison to uninduced condition (-Dox) 2. ChIP-seq was performed after 24 hours of NeuroD1 induction in ES cells.
NeuroD1 reprograms chromatin and transcription factor landscapes to induce the neuronal program.
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View SamplesSummary: Activation of the evolutionarily conserved, developmental Wnt pathway has been reported during maladaptive cardiac remodeling. Although the function of Wnt-transcriptional activation in development is well described, the consequences of Wnt pathway activation, as well as its cardiac-specific regulatory role in the adult heart, is largely unknown. We show that ß-catenin and Transcription factor 7-like 2 (TCF7L2), the main nuclear components of the Wnt-transcriptional cascade, and their transcriptional activity are increased upon pathological remodeling in both murine and human hearts. To understand the consequences of increased Wnt signaling pathway activity, we utilized an in vivo mouse model in which ß-catenin is acutely stabilized in adult cardiomyocytes (CM), leading to increased ventricular TCF7L2 expression and activation of its target genes. Mice with stabilized ß-catenin displayed cardiac hypertrophy, increased mortality, reduced cardiac function and altered calcium homeostasis, similar to experimentally induced hypertrophy. Moreover, we observed a re-activation of Wnt-dependent developmental gene programs including activation of the Wnt/ß-catenin-independent pathway, increased CM cell cycling with poly-nucleation and cytoskeletal disorganization, underscoring a central role in adult tissue remodeling. By integrating transcriptome analyses and genome-wide occupancy (ChIP-seq) of the endogenous ventricular TCF7L2, we show that upon aberrant Wnt activation, TCF7L2 induces context and Wnt-specific gene regulation in pathological remodeling. Interestingly, ß-catenin stabilized ventricles showed increased histone H3 lysine 27 acetylation (H3K27ac) and TCF7L2 recruitment to novel disease-associated gene-specific enhancers. Importantly, using integrative motif analyses and experimental evidences, our data uncovered a role for GATA4 as a cardiogenic regulator of TCF7L2/ß-catenin complex and established a paradigm for cell-specific effects of Wnt signaling. Altogether, our studies unraveled the nuclear Wnt-TCF7L2-associated chromatin landscape and its role in adult tissue remodeling leading to heart failure. Purpose: The aim of this study was to compare transcriptome profiles (RNA-seq) of normal (containing a Cre recombinase positive locus- Cre "positive" control with a WT ß-catenin locus; to eliminate effects of Cre-mediated cardiac toxicity) and ß-catenin stabilized murine adult cardiac ventricles. Methods: Adult cardiac tissue mRNA profiles for normal and Wnt-activated mice were obtained using deep sequencing, in triplicates, using Illumina HiSeq2000. The sequence reads that passed quality filters were analyzed at the transcript isoform level with TopHat followed by DESeq2. qPCR validation was performed using TaqMan and SYBR Green assays Conclusions: Our study represents the first detailed analysis of the processes triggered upon Wnt activation in the adult heart, which was so far, not investigated. We report that this Wnt activation in the adult heart maintains its developmental function; however due to the lack of adequate developmental plasticity in the adult heart, culminates in pathological remodeling. Overall design: Gene expression profiling from cardiac ventricles of 15 weeks-old mice with wild type and ß-catenin stabilized mice
A context-specific cardiac β-catenin and GATA4 interaction influences TCF7L2 occupancy and remodels chromatin driving disease progression in the adult heart.
Age, Cell line, Subject
View SamplesThe specification of hematopoietic cells in the developing embryo occurs in specific stages and is regulated by the successive establishment of specific transcriptional networks. However, the molecular mechanisms of how the different stages switch from one to another are still not well understood. Hematopoietic cells arise from endothelial cells within the dorsal aorta which transit into hematopoietic cells by a process called the endothelial-hematopoietic transition (EHT) which does not involve DNA replication. The transcription factor RUNX1 is essential for this process. Using the differentiation of mouse embryonic stem cells carrying an inducible version of RUNX1, we have previously shown that hematopoietic genes are primed prior to the EHT by the binding of transcription factors required to form both endothelial and hematopoietic cells (FLI-1 and SCL/TAL1). We demonstrated that after induction RUNX1 reshapes the transcription factor binding landscape by causing a relocation of these factors and pulling them towards its binding sites. In the study presented here, we employed the same system to globally dissect the transcriptional processes that underlay the EHT. We demonstrate that the RUNX1-mediated movement of FLI-1 involves the recruitment of the basal transcription components CDK9 and BRD4 to promoters. The looping factor LDB1 to binds to distal elements and after induction relocates towards RUNX1/FLI-1 to form a co-localizing complex in chromatin. This entire process is blocked by treatment with the BRD4 inhibitor JQ1. Our study constitutes a paradigm for transcriptional processes driving transitions in cellular shape and function which are widely observed in development and disease. Overall design: RNA-seq expreiments have been used to study RUNX1 transcription factor during Hematopoietic specification
The Co-operation of RUNX1 with LDB1, CDK9 and BRD4 Drives Transcription Factor Complex Relocation During Haematopoietic Specification.
Specimen part, Subject
View SamplesGATA6 is a transcription factor involved in the differentiation of intestinal epithelial cells into differentiated absorptive epithelial cells.
GATA factors regulate proliferation, differentiation, and gene expression in small intestine of mature mice.
Specimen part, Treatment
View SamplesWe generated three mRNA expression profiles by RNA-Seq of (i) wild-type crypts, (ii) Atoh1 knockout crypts, and (iii) purified ATOH1-positive cells. Overall design: We isolated Atoh1 knockout and littermate wild-type crypts from 6-8 week old Atoh1lox/lox;VilCreERT2 and Atoh1lox/WT;VilCreERT2 mice, respectively. In addition, ATOH1-positive cells were isolated by flow cytometry of 7AAD-negative (live), GFP-positive cells from either ileal or colonic crypts of Atoh1GFP/GFp mice (which express a functional ATOH1::GFP protein and are phenotypically normal).
Transcriptional Regulation by ATOH1 and its Target SPDEF in the Intestine.
Specimen part, Subject
View SamplesBoth a lack of biomarkers and relatively ineffective treatments constitute impediments to management of lupus nephritis (LN). Here we used gene expression microarrays to contrast the transcriptomic profiles of active SLE patients with and without LN to identify potential biomarkers for LN. RNA isolated from whole peripheral blood of active SLE patients was used for transcriptomic profiling and the data analyzed by linear modeling, with corrections for multiple testing. Results were validated in a second cohort of SLE patients, using NanoString technology. The majority of genes demonstrating altered mRNA abundance between patients with and without LN were neutrophil-related. Findings in the validation cohort confirmed this observation and showed that the levels of gene expression in renal remission were similar to active patients without LN. In secondary analyses, gene expression correlated with disease activity, hematuria and proteinuria, but not renal biopsy changes. As expression levels of the individual genes correlated strongly with each other, a composite neutrophil score was generated by summing all levels before examining additional correlations. There was a modest correlation between the neutrophil score and the blood neutrophil count, which was largely driven by the dose of steroids and not the proportion of low density and/or activated neutrophils. Analysis of longitudinal data revealed no correlation between baseline neutrophil score or changes over the first year of follow-up with subsequent renal flare or treatment outcomes, respectively. The findings argue that although the neutrophil score is associated with LN, its clinical utility as a biomarker may be limited.
Identification of a neutrophil-related gene expression signature that is enriched in adult systemic lupus erythematosus patients with active nephritis: Clinical/pathologic associations and etiologic mechanisms.
Sex, Age, Specimen part, Disease, Disease stage
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