Identification of Hox gene downstream genes at embryonic stages 11 and 12<br></br><br></br>Functional diversification of body parts is dependent on the formation of specialized structures along the various body axes. In animals, region-specific morphogenesis along the anterior-posterior axis is controlled by a group of conserved transcription factors encoded by the Hox genes. Although it has long been assumed that Hox proteins carry out their function by regulating distinct sets of downstream genes, only a small number of such genes have been found, with very few having direct roles in controlling cellular behavior. We have quantitatively identified hundreds of Hox downstream genes in Drosophila by microarray analysis, and validated many of them by in situ hybridizations on loss- and gain-of-function mutants. One important finding is that Hox proteins, despite their similar DNA binding properties in vitro, have highly specific effects on the transcriptome in vivo, as expression of many downstream genes responds primarily to a single Hox protein. In addition, a large fraction of downstream genes encodes realizator functions, which directly affect morphogenetic processes, such as orientation and rate of cell divisions, cell-cell adhesion and communication, cell shape and migration, or cell death. Focusing on these realizators, we provide a framework for the morphogenesis of the maxillary segment. Since the genomic organization of Hox genes and the interaction of Hox proteins with specific cofactors are conserved in vertebrates and invertebrates, and similar classes of downstream genes are regulated by Hox proteins across the metazoan phylogeny, our findings represent a first step towards a mechanistic understanding of morphological diversification within a species as well as between species.
Comparative analysis of Hox downstream genes in Drosophila.
Age, Time
View SamplesTo understand differences in the pathogenesis of synovial hyperplasia during TNF-induced arthritis, we compared the global gene expression of hTNFtg and hTNFtg;Rsk2-/y primary synovial fibroblasts.
Rsk2 controls synovial fibroblast hyperplasia and the course of arthritis.
Sex, Specimen part
View SamplesWe report the effect of TGFß vs PDGF 2h treatment in hepatic stellate cells. We also report the effect of TGFß treatment for 48h in human hepatic stellate cells. Overall design: RNA sequencing was performed after treating human hepatic stellate cells with TGFß and PDGF for 2h and also with TGFß for 48h
Enhancer of Zeste Homologue 2 Inhibition Attenuates TGF-β Dependent Hepatic Stellate Cell Activation and Liver Fibrosis.
Specimen part, Treatment, Subject
View SamplesGene expression of livers with hepatocyte-specific deletion of Hmgb1 was compared to control livers with floxed Hmgb1
High-mobility group box 1 is dispensable for autophagy, mitochondrial quality control, and organ function in vivo.
Sex, Specimen part
View SamplesBackground and aims: Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies with features of biliary tract differentiation. Incidence is increasing worldwide and these cancers collectively represent the second most common primary liver tumour. CCAs are characterized by genetic and epigenetic alterations that determine their pathogenesis. Hypermethylation of the SOX17 promoter was recently reported in human CCA tumours. SOX17 seems to be a key transcription factor for biliary embryogenesis. Here, we evaluated the role of SOX17 in cholangiocyte differentiation and in cholangiocarcinogenesis. Methods: SOX17 expression and function was evaluated during the differentiation of human induced pluripotent stem cells (iPSC) into cholangiocytes, in the dedifferentiation of normal human cholangiocytes (NHC) and in cholangiocarcinogenesis. Lentiviruses overexpressing or knocking-down SOX17 (Lent-SOX17 and Lent-shRNA-SOX17, respectively) were used. Gene expression arrays were performed. Results: SOX17 expression is highly induced in the later stages of cholangiocyte differentiation from iPSC, and mediates the acquisition of the biliary markers cytokeratin (CK) 7 and 19, as well as fibronectin. In addition, SOX17 becomes progressively downregulated in NHC over serial cell passages in vitro and this event is associated with cellular senescence; however, experimental SOX17 knocking-down in differentiated NHC decreased the expression of both CK7 and 19 without affecting cellular senescence. SOX17 expression is reduced in CCA cells compared to NHC, as well as in human CCA tissue compared to human gallbladder tissue or NHC. In a murine xenograft model, overexpression of SOX17 in CCA cells decreased their tumorigenic capacity related to increased oxidative stress and apoptosis. Interestingly, overexpression of SOX17 in NHC did not affect their survival. Moreover, SOX17 overexpression inhibited the Wnt/-catenin-dependent proliferation in CCA cells and was associated with upregulation of biliary epithelial markers and restoration of the primary cilium length. Both Wnt3a and TGF1 decreased SOX17 expression in NHC in a DNMT1-dependent manner. Inhibition of DNMT1 in CCA cells with siRNAs or pharmacological drugs upregulated SOX17 expression. Conclusion: SOX17 regulates the cholangiocyte phenotype and becomes epigenetically downregulated in CCA. SOX17 acts as a tumour suppressor in CCA, and restoration of its expression may have important therapeutic value.
SOX17 regulates cholangiocyte differentiation and acts as a tumor suppressor in cholangiocarcinoma.
Specimen part, Treatment
View SamplesThe loss of loricrin, a major component of the cornified envelope, results in a delay of epidermal barrier formation. Therefore, the living layers of the epidermis are aberrantly exposed to late-stage amniotic fluid, which may serve as the signal to upregulate genes that functionally compensate for the loss of loricrin. Consistent with this hypothesis, metabolomic studies revealed marked changes in amniotic fluid between E14.5 and E16.5 dpc. In addition, we discovered that the Nrf2/Keap1 pathway detects these compositional changes and directly upregulates the expression of genes involved in the compensatory response, thus ensuring postnatal survival. In support of this finding, we demonstrate that genetically blocking the Nrf2 pathway abolishes the compensatory response, and preemptively activating Nrf2 pharmacologically rescues the delay in barrier formation in utero. Our findings reveal that the functions of Nrf2 and the composition of amniotic fluid have co-evolved to ensure the formation of a functional barrier.
Amniotic fluid activates the nrf2/keap1 pathway to repair an epidermal barrier defect in utero.
Specimen part
View SamplesThe Nrf2 transcription factor is a key player in the cellular stress response, which regulates the expression of important antioxidant enzymes and other cytoprotective proteins. We recently generated a novel transgenic mouse model to determine the function of Nrf2 in the skin. These mice revealed interesting phenotypic abnormalities, including hyperkeratosis and acanthosis. To gain insight into the underlying molecular mechanisms, we wanted to identify genes, which are differentially expressed in the skin of wild-type and mutant mice before the onset of phenotypic abnormalities.
Nrf2 links epidermal barrier function with antioxidant defense.
Sex, Treatment
View SamplesBrief expression of pluripotency-associated factors such as Oct4, Klf4, Sox2 and c-Myc (OKSM), in combination with differentiation-inducing signals, has been reported to trigger transdifferentiation of fibroblasts into other cell types. Here we show that OKSM expression in mouse fibroblasts gives rise to both induced pluripotent stem cells (iPSCs) and induced neural stem cells (iNSCs) under conditions previously shown to induce only iNSCs. Fibroblast-derived iNSC colonies silenced retroviral transgenes and reactivated silenced X chromosomes, both hallmarks of pluripotent stem cells. Moreover, lineage tracing with an Oct4-CreER labeling system demonstrated that virtually all iNSC colonies originated from cells transiently expressing Oct4, whereas ablation of Oct4+ cells prevented iNSC formation. Lastly, an alternative transdifferentiation cocktail that lacks Oct4 and was reportedly unable to support induced pluripotency yielded iPSCs and iNSCs carrying the Oct4-CreER-derived lineage label. Together, these data suggest that iNSC generation from fibroblasts using OKSM and other pluripotency-related reprogramming factors requires passage through a transient iPSC state.
Lineage conversion induced by pluripotency factors involves transient passage through an iPSC stage.
Sex, Specimen part
View SamplesTranscriptomics analyses in these Zn-deficient rats revealed the molecular basis of ESCC abrogation by miR-31 knockout: Egln3, a negative regulator of NF-FB, was shown to be a direct miR-31 target; miR-31 inhibition/deletion resulted in suppression of miR-31-associated-EGLN3-NF-KB controlled inflammatory pathways.
Abrogation of esophageal carcinoma development in miR-31 knockout rats.
Treatment
View SamplesEmbryonic stem cells (ESCs) cells run a self-renewal gene expression program, requiring the expression of certain transcription factors accompanied by a particular chromosome organization to maintain a balance between pluripotency and the capacity for rapid differentiation. However, how transcriptional regulation is linked to chromosome organization in ESCs remains enigmatic. Here we show that Cohesin exhibits a functional role in maintaining ESC identity through association with the pluripotency transcriptional network. ChIP-seq analyses of the cohesin subunit Rad21 reveal an ESC specific cohesin binding pattern that is characterized by a CTCF independent colocalization of cohesin with pluripotency related transcription factors. Upon ESC differentiation, these binding sites disappear and instead new CTCF independent Rad21 binding sites emerge, which are enriched for binding sites of transcription factors implicated in early differentiation. Furthermore, knock-down of cohesin subunits causes expression changes that are reminiscent of the depletion of key pluripotency transcription factors, demonstrating the functional relevance of the cohesin - pluripotency transcriptional network association. Finally, we show that Nanog physically interacts with the cohesin interacting proteins Stag1 and Wapl, further substantiating this association. Based on these findings we propose that a dynamic placement of cohesin by pluripotency transcription factors contributes to a chromosome organization supporting the ESC expression program.
RAD21 cooperates with pluripotency transcription factors in the maintenance of embryonic stem cell identity.
Specimen part
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