Project description:Immortal spheroids were generated from fetal mouse intestine using the culture system developed to culture organoids from adult intestinal epithelium. Spheroids are made of a monostratified polarized epithelium displaying a poorly differentiated intestinal phenotype. The proportion of spheroids generated from intestinal explants progressively decreases from fetal to postnatal period, with a corresponding increase in production of organoids. Spheroid cells show indefinite self-renewing properties but exhibit a transcriptome strikingly different from that of adult intestinal stem cells reminiscent of incompletely caudalized progenitors. The receptor Lgr4, but not Lgr5, is essential for their growth. Trop2/Tacstd2 and Cnx43/Gja1, two markers highly enriched in spheroids, are expressed throughout the E14 intestinal epithelium. Comparison of in utero and neonatal lineage tracing using Cnx43-CreER and Lgr5-CreERT2 mice identified spheroid-generating cells as developmental progenitors involved in generation of the prenatal intestinal epithelium. Ex vivo, spheroid cells have the potential to differentiate into organoids, thus qualifying them as a new type of intestinal stem-like cells. Two-channel microarray experiments were performed from spheroid/organoid pairs isolated each from a given embryo. Following initial seeding of small intestine from a given embryo/mouse (at E16, E18 or P0), spheroids and organoids were selectively picked up for each animal and replated for 3 passages to reach sample homogeneity. Hybridization was performed on the 4 independent pairs with dye-swap.
Project description:Immortal spheroids were generated from fetal mouse intestine using the culture system developed to culture organoids from adult intestinal epithelium. Spheroids are made of a monostratified polarized epithelium displaying a poorly differentiated intestinal phenotype. The proportion of spheroids generated from intestinal explants progressively decreases from fetal to postnatal period, with a corresponding increase in production of organoids. Spheroid cells show indefinite self-renewing properties but exhibit a transcriptome strikingly different from that of adult intestinal stem cells reminiscent of incompletely caudalized progenitors. The receptor Lgr4, but not Lgr5, is essential for their growth. Trop2/Tacstd2 and Cnx43/Gja1, two markers highly enriched in spheroids, are expressed throughout the E14 intestinal epithelium. Comparison of in utero and neonatal lineage tracing using Cnx43-CreER and Lgr5-CreERT2 mice identified spheroid-generating cells as developmental progenitors involved in generation of the prenatal intestinal epithelium. Ex vivo, spheroid cells have the potential to differentiate into organoids, thus qualifying them as a new type of intestinal stem-like cells.
Project description:In adult stomach, Lgr5 is a marker of epithelial glandular stem cells that grow in the three dimensional ex vivo culture system as organoids. However, little is known about the markers that characterize fetal progenitors before cytodifferentiation and their potential involvement in regenerative processes in adults. Using the ex vivo culture system, we isolated epithelial progenitors from the fetal stomach. These cells generated stable undifferentiated immortal spheroids showing lower growth factor requirements as compared to the adult-type gastric Lgr5-expressing organoids. Although very similar in their gene expression profiles, cultured fetal gastric and intestinal spheroids differentially expressed Sox2/Cdx2 genes involved in regional pre-patterning. Accordingly, gastric but not intestinal spheroids, spontaneously converted into the cell lineages of the adult glandular stomach ex vivo. In vivo, the Trop2 marker enriched in the fetal gastric spheroids was transiently expressed in the gastric epithelium before cytodifferentiation while it remained barely detectable under glandular homeostasis in adults. However, upon specific ablation of the Lgr5 stem cell pool, highly proliferative Trop2-expressing cells rapidly emerged in the adult epithelium, qualifying Trop2 as a marker of Lgr5-independent gastric stem cells. Together, these data indicate that the Trop2 receptor identifies gastric fetal progenitors and adult stem/progenitor cells involved in regeneration of glandular stomach.
Project description:To follow the changes in the transcriptional programs accompanying the specification of the embryonic Lgr5+ cells we sequenced whole transcriptomes of embryonic intestinal epithelium progenitors (at E13.5 and E15.5). EpCAM positive embryonic gut epithelium was isolated from dissected small intestines using fluorescence activated cell sorting (FACS). Lgr5+ progenitors were purified on the basis of GFP fluorescence from Lgr5GFP-Cre-ERT mice (Barker et al. 2007). Double positive embryonic progenitors were isolated by FACS based on GFP and tdTomato fluorescence.
Project description:Perturbed intestinal epithelial homeostasis demonstrated as decreased Lgr5+ intestinal stem cells (Lgr5 ISCs) and increased secretory lineages were observed in our study where Lkb1 was specfically deleted in Lgr5 ISCs using Lgr5-EGFP-creERT2 (Tamoxifen) deletor. To gain mechanistic insight how Lkb1 maintains intestinal epithelial stem cell homeostasis, Lkb1 deficient ISCs (Lgr5-high cells) and progenitors (Lgr5-low cells) are isolated by flow cytometry and profiled by RNA sequencing to compare with controls (Lkb1 wild type ISCs and progenitors).
Project description:The small intestine is a rapidly proliferating organ that is maintained by a small population of Lgr5-expressing intestinal stem cells (ISCs). However, several Lgr5-negative ISC populations have been identified, and this remarkable plasticity allows the intestine to rapidly respond to both the local environment and to damage. The mediators of such plasticity are still largely unknown. Using intestinal organoids and mouse models, we show that upon ribosome impairment (driven by Rptor deletion, amino acid starvation, or low dose cyclohexamide treatment) ISCs gain an Lgr5-negative, fetal-like identity. This is accompanied by a rewiring of metabolism. Our findings suggest that the ribosome can act as a sensor of nutrient availability, allowing ISCs to respond to the local nutrient environment. Mechanistically, we show that this phenotype requires the activation of ZAKɑ, which in turn activates YAP, via SRC. Together, our data reveals a central role for ribosome dynamics in intestinal stem cells, and identify the activation of ZAKɑ as a critical mediator of stem cell identity.
Project description:The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. We have recently demonstrated the presence of approximately six cycling Lgr5+ stem cells at the bottoms of small intestinal crypts1. We have now established long-term culture conditions under which single crypts undergo multiple crypt fission events, whilst simultanously generating villus-like epithelial domains in which all differentiated cell types are present. Single sorted Lgr5+ stem cells can also initiate these crypt-villus organoids. Tracing experiments indicate that the Lgr5+ stem cell hierarchy is maintained in organoids. We conclude that intestinal crypt-villus units are self-organizing structures, which can be built from a single stem cell in the absence of a non-epithelial cellular niche. Keywords: expression profiling Freshly isolated small intestinal crypts from two mice were divided into two parts. RNA was directly isolated from one part (RNeasy Mini Kit, Qiagen), the other part was cultured for one week according to the conditions described in the associated paper, followed by RNA isolation. We prepared labeled cRNA following the manufacturer’s instruction (Agilent Technologies). Differentially labelled cRNA from small intestinal crypts and organoids were hybridised separately for the two mice on a 4X44k Agilent Whole Mouse Genome dual colour Microarrays (G4122F) in two dye swap experiments, resulting in four individual arrays.
Project description:The intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. We have recently demonstrated the presence of approximately six cycling Lgr5+ stem cells at the bottoms of small intestinal crypts1. We have now established long-term culture conditions under which single crypts undergo multiple crypt fission events, whilst simultanously generating villus-like epithelial domains in which all differentiated cell types are present. Single sorted Lgr5+ stem cells can also initiate these crypt-villus organoids. Tracing experiments indicate that the Lgr5+ stem cell hierarchy is maintained in organoids. We conclude that intestinal crypt-villus units are self-organizing structures, which can be built from a single stem cell in the absence of a non-epithelial cellular niche. Keywords: expression profiling
Project description:The currently accepted intestinal epithelial cell organization model equates crypt base columnar (CBC) cells, marked by high levels of Lgr5 expression, with the intestinal stem cell (ISC). However, recent intestinal regeneration studies have uncovered limitations of the ‘Lgr5-CBC’ model, leading to two major views: one favoring the presence of a quiescent reserve stem cell population, the other calling for differentiated cell plasticity. To test if an alternative model may help reconcile these perspectives, we studied the hierarchical organization of crypt epithelial cells in an unbiased fashion, by combining high-resolution, single-cell profiling and lineage tracing in multiple transgenic mouse models. These show that Lgr5 is not a specific ISC marker; rather, cells located in the crypt isthmus, which include Lgr5low cells, comprise the ISCs that sustain tissue homeostasis. Following irradiation or intestinal injury, surviving ISCs and progenitors, but not differentiated cells, participate in intestinal regeneration, suggesting that neither de-differentiation nor reserve stem cell populations are drivers of intestinal regeneration. Our results provide a novel viewpoint for the intestinal crypt epithelium, in which ISCs localize to the crypt isthmus, and ISC potential is restricted to stem and progenitor cells.