Cancer cells have abnormal gene expression profiles, however, the transcription factors and the architecture of the regulatory network that drive cancer specific gene expression is often not known. Here we studied a model of Ras-driven invasive tumorigenesis in Drosophila epithelial tissues and combined in vivo genetics with high-throughput sequencing and computational modeling to decipher the regulatory logic of tumor cells. Surprisingly, we discovered that the bulk of the tumor specific gene expression is driven by an ectopic network of a few transcription factors that are overexpressed and/or hyperactivated in tumor cells. These factors are Stat, AP-1, the bHLH proteins Myc and AP-4, the nuclear hormone receptor Ftz-f1, the nuclear receptor coactivator Taiman/AIB1, and Mef2. Notably, many of these transcription factors are also hyperactivated in human tumors. Bioinformatics analysis predicted that these factors directly regulate the majority of the tumor specific gene expression, that they are interconnected by extensive cross-regulation, and that they show a high degree of co-regulation of target genes. Indeed, the factors of this network were required in multiple epithelia for tumor growth and invasiveness and knock-down of individual factors caused a reversion of the tumor specific expression profile, but had no observable effect on normal tissues. We further found that the Hippo pathway effector Yki/Sd was strongly activated in tumor cells and initiated cellular reprogramming by activating several transcription factors of this network. Thus, modeling regulatory networks identified an ectopic yet highly ordered network of master regulators that control tumor cell specific gene expression. Overall design: RNA-seq gene expression profiling across Drosophila 3rd instar larval wild type wing discs and genetic perturbations of wts.
An Ectopic Network of Transcription Factors Regulated by Hippo Signaling Drives Growth and Invasion of a Malignant Tumor Model.
Subject, Time
View SamplesWe identified the Hippo pathway and its effector YAP as a key pathway that controls stellate cell activation. YAP is a transcriptional co-activator and we found that it drives the earliest changes in gene expression during stellate cell activation.
The Hippo pathway effector YAP controls mouse hepatic stellate cell activation.
Specimen part, Treatment
View SamplesThe homeodomain transcription factor, Pdx-1, has important roles in pancreatic development and -cell function and survival. In the present study, we demonstrate that adenovirus-mediated overexpression of Pdx-1 in rat or human islets also stimulates cell replication. Moreover, co-overexpression of Pdx-1 with another homeodomain transcription factor, Nkx6.1, has an additive effect on proliferation compared to either factor alone, implying discrete activating mechanisms. Consistent with this, Nkx6.1 stimulates mainly -cell proliferation, whereas Pdx-1 stimulates both - and -cell proliferation. Furthermore, cyclins D1/D2 are upregulated by Pdx-1 but not by Nkx6.1, and inhibition of cdk4 blocks Pdx-1- but not Nkx6.1-stimulated islet cell proliferation. Genes regulated by Pdx-1 and not Nkx6.1 were identified by microarray analysis. Two members of the transient receptor potential cation (TRPC) channel family, TRPC3 and TRPC6, are upregulated by Pdx-1 overexpression, and siRNA-mediated knockdown of TRPC3/6 or TRPC6 alone inhibits Pdx-1-induced but not Nkx6.1-induced islet cell proliferation. Pdx-1 also stimulates ERK1/2 phosphorylation, an effect partially blocked by knockdown of TRPC3/6, and blockade of ERK1/2 activation with a MEK1/2 inhibitor partially impairs Pdx-1-stimulated proliferation. These studies define a pathway by which overexpression of Pdx-1 activates islet cell proliferation that is distinct from and additive to a pathway activated by Nkx6.1.
Pdx-1 activates islet α- and β-cell proliferation via a mechanism regulated by transient receptor potential cation channels 3 and 6 and extracellular signal-regulated kinases 1 and 2.
Sex, Age, Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Promoter-proximal transcription factor binding is transcriptionally active when coupled with nucleosome repositioning in immediate vicinity.
Specimen part, Disease, Cell line
View SamplesNon-metastatic 2 (NME2) is an established metastases suppressor in multiple human cancer types. However, the molecular mechanisms of NME2 action remain insufficiently resolved. We recently validated the transcription regulatory activity of NME2 with respect to control of proto-oncogene c-MYC expression. We hypothesized that large scale transcriptional potential of NME2 may be at the core of metastases suppression by NME2. Using a combination of high throughput genomic assays such as chromatin immunoprecipitation coupled to promoter array hybridization (ChIP-chip) and gene expression profiling, we characterized the transcriptional roles of NME2. Specifically, we found a set of NME2 target genes which changed expression upon selective depletion of NME2 in a lung cancer cell line, A549. The analysis of gene expression suggested control of various biological pathways esp. cell adhesion and apoptosis by NME2 target genes which could be important in regulation of metastases.
Promoter-proximal transcription factor binding is transcriptionally active when coupled with nucleosome repositioning in immediate vicinity.
Specimen part, Cell line
View SamplesIt is widely believed that reorganization of nucleosomes result in availability of binding sites that engage transcription factors during eukaryotic gene regulation. Recent findings, on the other hand, suggest that transcription factors induced as a result of physiological perturbations directly (or in association with chromatin modifiers) may alter nucleosome occupancy to facilitate DNA binding. Although, together these suggest a close relationship between transcription factor binding and nucleosome reorganization, the nature of the inter-dependency, or to what extent it influences regulatory transcription is not clear. Moreover, since most studies used physiolgical pertubations that induced multiple transcription factor chromatin modifiers, the relatively local (or direct) effect of transcription factor binding on nucleosome occupancy remains unclear. With these in mind, we used a single transcription factor to induce physiological changes, representing metastatic (aggressive cancer) and the corresponding non-metastatic state, in human cancer cells. Following characterization of the two states (before and after induction of the transcription factor) we determined: (a) genome wide binding sites of the transcription factor, (b) promoter nucleosome occupancy and (c) transcriptome profiles, independently in both conditions. Interestingly, we find only ~20% of TF binding results from nucleosome reorganization - however, almost all corresponding genes were transcriptionally altered. Whereas, in cases where TF-occupancy was independent of nucleosome repositioning (in close vicinity), or co-occurred with nucleosomes, only a small fraction of the corresponding genes were expressed/repressed. Together, these indicate a model where TF occupancy only when coupled with nucleosome repositioning in close proximity is transcriptionally active. This, to our knowledge, for the first time also helps explain why genome wide TF occupancy (e.g., from ChIP-seq) is typically associated with only a small fraction of genes that change expression.
Promoter-proximal transcription factor binding is transcriptionally active when coupled with nucleosome repositioning in immediate vicinity.
Specimen part, Cell line
View SamplesThe plasma protein FHR1 induces release of inflammatory cytokines IL-1ß, IL-6, IL-18 or TNFa from blood-derived human monocytes. RNA sequencing was performed from RNA of BSA- or FHR1-treated monocytes from 4 different donors. In response to FHR1, 522 monocytic genes were upregulated (gene ontology enrichment analysis), including 35 inflammation related genes, e.g. TNF. Also, G protein-coupled receptors such as EMR2/ADGRE2 were upregulated in response to FHR1. Overall design: Blood-derived monocytes were treated with BSA or FHR1, after 4h RNA was isolated. RNA of 4 donors were combined and sequenced.
Serum FHR1 binding to necrotic-type cells activates monocytic inflammasome and marks necrotic sites in vasculopathies.
Specimen part, Treatment, Subject
View SamplesThis includes bulk RNA-seq samples for sorted LT-HSCs, ST-HSCs, and MPPs stimulated (or not) with LPS+PAM. Samples taken at various time points. Overall design: sorted LT-HSCs, ST-HSCs, and MPPs stimulated (or not) with LPS+PAM at various time points
Heterogeneous Responses of Hematopoietic Stem Cells to Inflammatory Stimuli Are Altered with Age.
Specimen part, Treatment, Subject
View SamplesAging and increased amyloid burden are major risk factors for cognitive diseases such as Alzheimer''s Disease (AD). An effective therapy does not yet exist. Here we use mouse models for age-associated memory impairment and amyloid deposition to study transcriptome and cell type-specific epigenome plasticity at the systems level in the brain and in peripheral organs. We show that at the level of epigenetic gene-expression aging and amyloid pathology are associated with inflammation and impaired synaptic function in the hippocampal CA1 region. While inflammation is associated with increased gene-expression that is linked to a subset of transcription factors, de-regulation of plasticity genes is mediated via different mechanisms in the amyloid and the aging model. Amyloid pathology impairs histone-acetylation and decreases expression of plasticity genes while aging affects differential splicing that is linked to altered H4K12 acetylation at the intron-exon junction in neurons but not in non-neuronal cells. We furthermore show that oral administration of the clinically approved histone deacetylase inhibitor Vorinostat not only restores spatial memory, but also exhibits an anti-inflammatory action and reinstates epigenetic balance and transcriptional homeostasis at the level of gene expression and exon usage. This is the first systems-level investigation of transcriptome plasticity in the hippocampal CA1 region in aging and AD models and of the effects of an orally dosed histone deacetylase inhibitor. Our data has important implications for the development of minimally invasive and cost-effective therapeutic strategies against age-associated cognitive decline. In fact, our data strongly suggest to test Vorinostat in patients suffering from AD. Overall design: mRNA profile from aged (CA1 and liver) and APP/PS1 (CA1) animals treated with oral vehicle or SAHA for 4 weeks
HDAC inhibitor-dependent transcriptome and memory reinstatement in cognitive decline models.
No sample metadata fields
View SamplesAdult neurogenesis occurs in mammals and provides a mechanism for continuous neural plasticity in the brain.However, little is known about the molecular mechanisms regulating hippocampal neural progenitor cells (NPCs) and whether their fate can be pharmacologically modulated to improve neural plasticity and regeneration. Here, we report the characterization of a unique small molecule (KHS101) that selectively induces a neuronal differentiation phenotype. Mechanism of action studies revealed a link of KHS101 to cell cycle exit and specific binding to the TACC3 protein, whose knockdown in NPCs recapitulates the KHS101-induced phenotype. Upon systemic administration, KHS101 distributed to the brainandresulted in a significant increase in neuronal differentiation in vivo. Our findings indicate that KHS101 accelerates neuronal differentiation by interaction with TACC3 and may provide a basis for pharmacological intervention.directed at endogenous NPCs.
A small molecule accelerates neuronal differentiation in the adult rat.
Specimen part, Treatment
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