Oct4, Sox2, Klf4, and cMyc (OSKM) reprogram somatic cells to pluripotency. To gain a mechanistic understanding of their function, we mapped OSKM-binding, stage-specific transcription-factors (TFs), and chromatin-states in discrete reprogramming stages and performed loss- and gain-of-function experiments. We found that early in reprogramming OSK extensively bind somatic-enhancers and initiate their decommissioning by recruiting Hdac1. Concurrently, OSK engage other sites, including specific pluripotency-enhancers, and induce the relocation of somatic TFs to these sites and away from somatic-enhancers, extending somatic-enhancer decommissioning genome-wide. Pluripotency-enhancer selection early in reprogramming occurs predominantly at sites with high OSK-motif densities and requires collaborative binding by OSK. Most pluripotency-enhancers are selected later and occupied by OS and stage-specific-TFs like Esrrb. Overexpression of stage-specific-TFs influences reprogramming efficiency by changing OSK-occupancy, somatic-enhancer decommissioning, and pluripotency-enhancer selection. We propose that collaborative interactions among OSK and with stage-specific-TFs direct both somatic-enhancer decommissioning and pluripotency-enhancer selection, which drives the enhancer reorganization underlying reprogramming Overall design: RNA-seq
Cooperative Binding of Transcription Factors Orchestrates Reprogramming.
Specimen part, Cell line, Subject
View SamplesNaïve human embryonic stem cells (hESCs) can be derived from primed hESCs or directly from blastocysts, but their X-chromosome state has remained unresolved. We found that the inactive X-chromosome (Xi) of primed hESCs was reactivated in naïve culture conditions. Similar to cells of the blastocyst, resulting naive cells exhibited two active X-chromosomes with XIST expression and chromosome-wide transcriptional dampening, and initiated XIST-mediated X-inactivation upon differentiation. Both establishment and exit from the naïve state (differentiation) happened via an XIST-negative XaXa intermediate. Together, these findings identify a cell culture system for functionally exploring the two X-chromosome dosage compensation processes in early human development: X-dampening and X-inactivation. Furthermore, the naïve state reset Xi abnormalities of primed hESCs, providing cells better suited for downstream applications. However, naïve hESCs displayed differences to the embryo because XIST expression was predominantly mono-allelic instead of bi-allelic, and X-inactivation was non-random, indicating the need for further culture improvement. Overall design: Differentiated naïve human embryonic stem cells and naïve human embryonic stem cells at different passages (Exp1 for late passage, Exp2 for early passage) were subjected to single cell RNA sequencing by the Fluidigm C1 Single-Cell Auto Prep System.
Human Naive Pluripotent Stem Cells Model X Chromosome Dampening and X Inactivation.
Specimen part, Subject
View SamplesMouse ES cells were stably transduced with a lentivirus expressing either wild-type KBP or the stable mutant KBP(KK/RR) and maintained in self-renewing growth conditions. RNA-seq was performed to assess mRNA expression differences caused by the stabilization of KBP. Overall design: 6 samples [a triplicate set for ES cells expressing wild-type KBP and a triplicate set expressing KBP(KK/RR)] were analyzed.
The TDH-GCN5L1-Fbxo15-KBP axis limits mitochondrial biogenesis in mouse embryonic stem cells.
Specimen part, Subject
View SamplesTransition from a partially reprogrammed pre-iPSC state to iPSC state can be achieved by modulating levels of histone modifying enzymes or proteins that can bind to histone modifications
Proteomic and genomic approaches reveal critical functions of H3K9 methylation and heterochromatin protein-1γ in reprogramming to pluripotency.
Specimen part
View SamplesFemale human ESC-lines can carry active X-chromosomes (Xa) or an XIST-RNA-coated inactive X-chromosome (XiXIST+). Additionally, many ESC lines have abnormal X-chromosomeinactivation (XCI)-states where the Xi no longer expresses XIST-RNA and has transcriptionally active regions (eroded Xi=Xe). The fate of each XCI-state upon differentiation is unclear because individual lines often contain a mixture of XCI-states. Here, we established homogeneous XiXa, XeXa, and XaXa ESC-lines. Employing RNA-FISH, RNA-sequencing and DNA methylation analyses, we found that these lines were unable to initiate XIST-expression and X-chromosome-wide silencing upon differentiation indicating that the ESC XCI-state is maintained in differentiated cells. Consequently, differentiated XeXa and XaXa cells displayed higher levels of X-linked gene-expression than XiXa cells. Although global transcriptional compensation between X-chromosomes and autosomes is not required for female ESC-differentiation, the degree of X-chromosome-silencing influences differentiation efficiencies. Our data suggest that the XiXIST+Xa state is inherent to human ESCs and that all other XCI-states, including XaXa, are abnormal and arise during ESC-derivation or maintenance. Overall design: RNA-seq was used to measure the expression state of X-linked and autosomal genes in undifferentiated human embryonic stem cells with different X-chromosome states and their differentiated cells.
Human Embryonic Stem Cells Do Not Change Their X Inactivation Status during Differentiation.
Specimen part, Subject
View SamplesWe have undertaken a screen of mouse limb tendon cells in order to identify molecular pathways involved in tendon development. Mouse limb tendon cells were isolated based on Scleraxis (Scx) expression at different stages of development: E11.5, E12.5 and E14.5
Transcriptomic analysis of mouse limb tendon cells during development.
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View SamplesCellular dedifferentiation signifies the withdrawal of cells from a specific differentiated state into a stem cell-like undifferentiated state. However, the mechanism of dedifferentiation remains obscure. We showed that mature adipocytes (MA) and follicular granulosa cells (GC), which have distinct functions in vivo, can dedifferentiate during culture in vitro and acquire multipotency.
Gene expression profiling in multipotent DFAT cells derived from mature adipocytes.
Specimen part
View SamplesTissue morphogenesis relies on proper differentiation of morphogenetic domains, adopting specific cell behaviours. Yet, how signalling pathways interact to determine and coordinate these domains remains poorly understood. Dorsal closure (DC) of the Drosophila embryo represents a powerful model to study epithelial cell sheet sealing. In this process, JNK (JUN N-terminal Kinase) signalling controls leading edge (LE) differentiation generating local forces and cell shape changes essential for DC. The LE represents a key morphogenetic domain in which, in addition to JNK, a number of signalling pathways converges and interacts (anterior/posterior -AP- determination; segmentation genes, such as Wnt/Wingless; TGF/Decapentaplegic). To better characterize properties of the LE morphogenetic domain, we used microarrays to identify genes whose expression is regulated by the JNK pathway during dorsal closure of the Drosophila embryo.
The Drosophila serine protease homologue Scarface regulates JNK signalling in a negative-feedback loop during epithelial morphogenesis.
Specimen part
View SamplesPerivascular adipose tissue (PVAT) is thought to play a role in vascular homeostasis and in the pathogenesis of diseases of large vessels, including abdominal aortic aneurysm (AAA). We tested the hypothesis that locally restricted transcriptional profiles characterize PVAT surrounding AAA. Using a genome-wide approach, we investigated the PVAT transcriptome of AAA in 30 patients with either large (55 mm) or small (<55 mm) aneurysm diameter. We performed a data adjustment step using the DaMiRseq R/Bioconductor package, to remove the effect of confounders as produced by high-throughput gene expression techniques. We compared PVAT of AAA with PVAT of not-dilated abdominal aorta of each patient to limit the effect of inter-individual variability, using the limma R/Bioconductor package. We found highly consistent differences in PVAT gene expression clearly distinguishing PVAT of AAA from PVAT of not-dilated aorta, which increased in number and magnitude with increasing AAA diameter. These changes did not systemically affect other abdominal adipose depots (omental or subcutaneous fat). We dissected putative mechanisms associated with PVAT involvement in AAA through a functional enrichment network analysis: both innate and adaptive immune-response genes along with genes related to cell-death pathways, metabolic processes of collagen, sphingolipids, aminoglycans and extracellular matrix degradation were strongly overrepresented in PVAT of AAA compared with PVAT of not-dilated aorta. Our results provide support to a possible role of PVAT in AAA pathogenesis and suggest that AAA is an immunologic disease with an underlying autoimmune component. These disease-specific expression signatures could help identifying pharmacological targets for preventing AAA progression.
Genome-Wide Expression Profiling Unveils Autoimmune Response Signatures in the Perivascular Adipose Tissue of Abdominal Aortic Aneurysm.
Sex, Age, Specimen part, Subject
View SamplesThe apical junctional complex (AJC), composed of tight junctions and adherens junctions, is essential for maintaining epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are both associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating AJC integrity in the small airway epithelium (SAE), the primary site of pathological changes in COPD. Transcriptome analysis revealed a global down-regulation of physiological AJC gene expression in the SAE of healthy smokers (n=53) compared to healthy nonsmokers (n=59), an observation associated with changes in molecular pathways regulating epithelial differentiation such as PTEN signaling and accompanied by induction of cancer-related AJC genes. Genome-wide co-expression analysis identified a smoking-sensitive AJC transcriptional network. The overall expression of AJC-associated genes was further decreased in COPD smokers (n=23). Exposure of human airway epithelial cells to cigarette smoke extract in vitro resulted in down-regulation of several AJC-related genes, accompanied by decreased transepithelial resistance. Thus, cigarette smoking alters the AJC gene expression architecture in the human airway epithelium, providing a molecular basis for the dysregulation of airway epithelial barrier function during the development of smoking-induced lung disease.
Cigarette smoking reprograms apical junctional complex molecular architecture in the human airway epithelium in vivo.
Sex, Age
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