Genome-wide profiles of chromatin interaction in mouse nephron progenitor cells [HiC]
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ABSTRACT: During embryonic kidney development, nephron progenitor cells (NPCs) self-renew and differentiate into all cells in mature nephrons. The Wnt signaling components Wnt9b and β-catenin are required for both NPC self-renewal and differentiation. A low level of Wnt/β-catenin are associated with NPC self-renewal while a high level with differentiation. To investigate the transcriptional mechanisms behind Wnt/β-catenin-driven regulation of NPCs states, we modeled NPC self-renewal and differentiation in vitro with NPEM (Brown et al., 2015) supplemented with low (1.25 μM) or high (5 μM) concentration of CHIR22091 (CHIR), a small molecule GSK3β inhibitor that stabilizes β-catenin. To investigate change of higher-order chromatin structure of NPC under influence of CHIR treatment, here we generated HiC data from primary NPC, as well as NPC cultured in low and high CHIR concentration.
Project description:During embryonic kidney development, nephron progenitor cells (NPCs) self-renew and differentiate into all cells in mature nephrons. The Wnt signaling components Wnt9b and β-catenin are required for both NPC self-renewal and differentiation. A low level of Wnt/β-catenin are associated with NPC self-renewal while a high level with differentiation. To investigate the transcriptional mechanisms behind Wnt/β-catenin-driven regulation of NPCs states, we modeled NPC self-renewal and differentiation in vitro with NPEM (Brown et al., 2015) supplemented with low (1.25 μM) or high (5 μM) concentration of CHIR22091 (CHIR), a small molecule GSK3β inhibitor that stabilizes β-catenin. To investigate change of NPC chromatin landscape under influence of CHIR treatment, here we generated ATAC-Seq data from primary NPC, as well as NPC cultured in low and high CHIR concentration.
Project description:During embryonic kidney development, nephron progenitor cells (NPCs) self-renew and differentiate into all cells in mature nephrons. The Wnt signaling components Wnt9b and β-catenin are required for both NPC self-renewal and differentiation. A low level of Wnt/β-catenin are associated with NPC self-renewal while a high level with differentiation. To investigate the transcriptional mechanisms behind Wnt/β-catenin-driven regulation of NPCs states, we modeled NPC self-renewal and differentiation in vitro with NPEM (Brown et al., 2015) supplemented with low (1.25 μM) or high (5 μM) concentration of CHIR22091 (CHIR), a small molecule GSK3β inhibitor that stabilizes β-catenin. To investigate change of NPC chromatin landscape under influence of CHIR treatment, here we generated ATAC-Seq data from primary NPC, as well as NPC cultured in low and high CHIR concentration.
Project description:During embryonic kidney development, nephron progenitor cells (NPCs) self-renew and differentiate into all cells in mature nephrons. The Wnt signaling components Wnt9b and β-catenin are required for both NPC self-renewal and differentiation. A low level of Wnt/β-catenin are associated with NPC self-renewal while a high level with differentiation. To investigate the transcriptional mechanisms behind Wnt/β-catenin-driven regulation of NPCs states, we modeled NPC self-renewal and differentiation in vitro with NPEM (Brown et al., 2015) supplemented with low (1.25 μM) or high (5 μM) concentration of CHIR22091 (CHIR), a small molecule GSK3β inhibitor that stabilizes β-catenin. We have found the Tcf/Lef family repressors Tcf7l1 and Tcf7l2 are enriched in low CHIR condition, while the activators Tcf7 and Lef1 in high CHIR condition, correlating with the NPC differentiation program transiting from being repressed to activated. To identify direct transcriptional targets of Tcf/Lef factors and β-catenin, here we generated ChIP-Seq data from primary NPC, as well as NPC cultured in low and high CHIR concentration.
Project description:The aggregation of nephron progenitor cells (NPC) is required to form the nephron precursor renal vesicle (RV) as they undergo the mesenchymal-to-epithelial transition (MET). Canonical Wnt signaling regulates the MET of NPCs via the effector molecule β-catenin. β-catenin acts as a transcriptional co-activator during the differentiation of NPCs, however, if it has any role as an adhesion regulating molecule via the cadherin-catenin complex is currently unknown. Using in vitro NPC culture system with gene editing and modulated Wnt signaling input, we investigated the morphological transition of NPCs and its underlying mechanism modeling the initial step of the MET in vivo. Increasing Wnt signaling input with the small molecule agonist CHIR resulted in the aggregation of NPCs similar to the generation of the nephron anlagen. By removing β- and α-catenin from the NPCs, NPCs are sorted out from these aggregates, demonstrating the key role of the cadherin-catenin complex in the aggregation. β-catenin was essential for the induction, however, the removal of α-catenin did not affect the transcriptional profile of NPCs. Removal of extracellular Ca2+ resulted in the transient loss of cell-cell contacts suggesting the role of cadherins in the aggregation process. The analysis of in vitro bulk RNA-seq cadherin expression profile matched the in vivo cadherin expression profile determined by single-cell RNA-seq. The combined removal of pre-existing and inducible cadherins phenocopied the results of β- and α-catenin KO experiments highlighting the crucial role of the cadherin-catenin complex by multiple lines of evidence. Notably, the induction of NPCs is independent of their aggregation. The in vitro modeling of nephron development provides a mechanistic understanding how cell adhesion is regulated via the cadherin-catenin complex during nephrogenesis.
Project description:Wnt/β-catenin signaling is a highly conserved molecular pathway that plays a crucial role in stem/progenitor systems and cancer. β-catenin, the main Wnt pathway effector, has two pools within a cell: one for cell-cell adhesion at the membrane and the other for transcriptional functions in the nucleus. However, the mechanism by which β-catenin mediates both roles remain unclear. The tightly controlled, well characterized system of nephrogenesis is an ideal model to decouple the roles of β-catenin at the membrane and in the nucleus. In kidney development, a delicate balance of nephron progenitor cell self-renewal and differentiation is required for the mesenchymal to epithelial transition (MET) in nephrogenesis and is driven by Wnt/β-catenin signaling. Given an ability to isolate and manipulate large numbers of NPCs in tissue culture, we can dissect the dual nature of β-catenin as a transcriptional activator and component of a cell membrane complex in adhesion. We pioneered a method using CRISPR/Cas9 gene editing to rapidly remove β-catenin, Tcf/Lef factors and simultaneous cadherin genes in primary NPCs. We have characterized the effects of modulating β-catenin and integrated RNA-seq results from β-catenin’s removal with mouse ChIP-seq and mouse single cell RNA -seq data. Functional analysis of β-catenin removal provides strong evidence for β-catenin regulation of NPC proliferation, independent of a direct Lef/Tcf associated transcriptional program. Together these data suggest β-catenin mediates aggregation, the first step in MET, through β-catenin mediated cell adhesion complexes while simultaneous transcriptional activation within these structures initiates the nephrogenic program. The studies provide new insight into the direct transcriptional role of Lef/Tcf/β-catenin complexes associated with the initiation of a nephron forming program. Overall, this study enhances an understanding of the molecular mechanisms underlying kidney development and the dual nature of β-catenin stem/progenitor systems at large.
Project description:Canonical Wnt and Nodal signaling are both required for induction of the primitive streak (PS), which guides organization of the early embryo. The Wnt effector β-catenin is thought to function in these early lineage specification decisions via transcriptional activation of Nodal signaling. Here, we demonstrate a broader role for β-catenin in PS formation by analyzing its genome-wide binding in a human embryonic stem cell model of PS induction. β-catenin occupies regulatory regions in numerous PS and neural crest genes, and direct interactions between β-catenin and the Nodal effectors SMAD2/3 are required at these regions for PS gene activation. Furthermore, OCT4 binding in proximity to these sites is likewise required for PS induction, suggesting a collaborative interaction between β-catenin and OCT4. Induction of neural crest genes by β-catenin is repressed by SMAD2/3, ensuring proper lineage specification. This study provides mechanistic insight into how Wnt signaling controls early cell lineage decisions. Examination of β-catenin binding in hESC incubated in media control (RPMI), media containing CHIR or CHIR+SB for 6h and analyzed by ChIP-sequencing
Project description:The Wnt/β-catenin signalling pathway is a key regulator of embryonic stem cell self-renewal and differentiation. Constitutive activation of this pathway has been shown to significantly increase mouse embryonic stem cell (mESC) self-renewal and pluripotency marker expression. In this study, we generated a novel β-catenin knock-out model in mESCs by using CRISPR/Cas9 technology to delete putatively functional N-terminally truncated isoforms observed in previous knock-out models. While we showed that aberrant N-terminally truncated isoforms are not functional in mESCS, we observed that canonical Wnt signalling is not active in mESCs, as β-catenin ablation does not alter mESC transcriptional profile in LIF-enriched culture conditions; on the other hand, Wnt signalling activation represses mESC spontaneous differentiation. We also showed that transcriptionally silent β-catenin (ΔC) isoforms can rescue β-catenin knock-out self-renewal defects in mESCs, cooperating with TCF1 and LEF1 in the inhibition of mESC spontaneous differentiation in a Gsk3 dependent manner.
Project description:The Wnt pathway is a key regulator of embryonic development, cell growth, differentiation, polarity formation, neural development, carcinogenesis, and stem cell self-renewal, and deregulation of the Wnt signalling is associated with many human disease. The central player in the Wnt pathway is β-catenin, A recent study has shown that β-catenin/Tcf/Lef signaling pathway is an essential growth-regulatory pathway in cardiomyocytes. We used DNA microarrays to detail the global trends in gene expression underlying β-catenin-overexpressed cardiomyocytes and identified distinct classes of up- or down-regulated genes during this process. Our findings suggest that β-catenin plays a critical role in regulating cardiac dysfunction at transcriptional level and may provide novel insight into how β-catenin modulates heart diseases. Cardiomyocytes were infected with GFP control or β-catenin adenoviruses for RNA extraction and hybridization on Affymetrix microarrays. We sought to define the effects of β-catenin on the global programme of gene expression in primary cardiomyocytes. To that end, neonatal rat cardiomyocytes were infected with GFP control (G) or β-catenin adenovirus (B) for 24 hours.
Project description:The homeostasis of the gut epithelium relies upon continuous renewal and proliferation of crypt-resident intestinal epithelial stem cells (IESCs). Wnt/β-catenin signaling is required for IESC maintenance, however, it remains unclear how this pathway selectively governs the identity and proliferative decisions of IESCs. Here, we demonstrate that C-terminally-recruited transcriptional co-factors of β-catenin act as all-or-nothing regulators of Wnt-target gene expression. Blocking their interactions with β-catenin rapidly induces loss of IESCs and intestinal homeostasis. Conversely, N-terminally recruited co-factors fine-tune β-catenin’s transcriptional output to ensure proper self-renewal and proliferative behaviour of IESCs. Impairment of N-terminal interactions triggers transient hyperproliferation of IESCs, resulting in exhaustion of the self-renewing stem cell pool. IESC mis-differentiation, accompanied by intrinsic and extrinsic stress signalling results in a process resembling aberrant "villisation" of intestinal crypts. Our data suggest that IESC-specific Wnt/β-catenin output requires discrete regulation of transcription by transcriptional co-factors.
Project description:The homeostasis of the gut epithelium relies upon continuous renewal and proliferation of crypt-resident intestinal epithelial stem cells (IESCs). Wnt/β-catenin signaling is required for IESC maintenance, however, it remains unclear how this pathway selectively governs the identity and proliferative decisions of IESCs. Here, we demonstrate that C-terminally-recruited transcriptional co-factors of β-catenin act as all-or-nothing regulators of Wnt-target gene expression. Blocking their interactions with β-catenin rapidly induces loss of IESCs and intestinal homeostasis. Conversely, N-terminally recruited co-factors fine-tune β-catenin’s transcriptional output to ensure proper self-renewal and proliferative behaviour of IESCs. Impairment of N-terminal interactions triggers transient hyperproliferation of IESCs, resulting in exhaustion of the self-renewing stem cell pool. IESC mis-differentiation, accompanied by intrinsic and extrinsic stress signalling results in a process resembling aberrant "villisation" of intestinal crypts. Our data suggest that IESC-specific Wnt/β-catenin output requires discrete regulation of transcription by transcriptional co-factors.