The 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 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 SamplesAcute myeloid leukemia (AML) is characterized by molecular heterogeneity. As commonly altered genomic regions point to candidate genes involved in leukemogenesis, we used microarray-based comparative genomic hybridization and single nucleotide polymorphism profiling data of 391 AML cases to further narrow down genomic regions of interest. Targeted-resequencing of 1000 genes located in the critical regions was performed in a representative cohort of 50 AML samples comprising all major cytogenetic subgroups. We identified 120 missense/nonsense mutations as well as 60 insertions/deletions affecting 73 different genes (~3.6 tumor-specific aberrations/AML). While most of the newly identified alterations were non-recurrent, we observed a number of mutations affecting genes involved in epigenetic regulation including known candidates like TET2, TET1, DNMT3A and DNMT1, as well as mutations in the histone methyltransferases NSD1, EZH2 and MLL3. Furthermore, we found mutations in the splicing factor SFPQ and in the non-classical regulators of mRNA-processing CTCF and RAD21. These splicing-related mutations affected 10% of AML patients in a mutually exclusive manner. In conclusion, we could identify a significant enrichment of alterations in genes involved in aberrant splicing and epigenetic regulation in genomic regions commonly altered in AML, highlighting their important role in the molecular pathogenesis of AML.
Commonly altered genomic regions in acute myeloid leukemia are enriched for somatic mutations involved in chromatin remodeling and splicing.
Specimen part, Disease
View SamplesCancer 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 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 SamplesGlobal, genomic responses of erythrocytes to infectious agents have been difficult to measure, because these cells are e-nucleated. We have previously demonstrated that in vitro matured, nucleated erythroblast cells at the orthochromatic stage can be efficiently infected by the human malaria parasite Plasmodium falciparum. We now show that infection of orthochromatic cells induces change in 609 host genes. 592 of these transcripts are up-regulated and associated with metabolic and chaperone pathways unique to P. falciparum infection, as well as a wide range of signaling pathways that are also induced in related apicomplexan infections of mouse hepatocytes or human fibroblast cells. Our data additionally show that polychromatophilic cells, which precede the orthochromatic stage and are not infected when co-cultured with P. falciparum, up-regulate a small set of 35 genes, 9 of which are associated with pathways of hematopoiesis and/or erythroid cell development. These data unexpectedly predict that blood stage P. falciparum may induce host responses common to infections of other pathogens. Further P. falciparum may modulate gene expression in bystander erythroblasts and thus influence pathways of erythrocyte development.
P. falciparum modulates erythroblast cell gene expression in signaling and erythrocyte production pathways.
Specimen part
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