ABSTRACT: The impact of Mll1 removal on intestinal stem cells expressing an oncogenic form of beta-catenin (beta-cateninGOF) was analysed in 4 pairs of sorted intestinal stem cells of Lgr5-CreERT2; beta-cateninGOF;Mll1+/- (control) and Lgr5-CreERT2; beta-cateninGOF;Mll1-/- (knockout) at 10 days after tamoxifen-induced mutagenesis. Using 75-base-pair reads, around 30 million reads per sample with comparable unique mapped reads (73-78%) were obtained. To analyze differentially expressed genes, we applied DESeq2 analysis to the RNA-seq dataset. Differentially expressed genes in beta-cateninGOF; Mll1-/- versus beta-cateninGOF; Mll1+/- stem cells showed both up- and downregulation of genes at a false discovery rate (FDR) of 10%. This included a global increase in the expression of goblet cell-specific genes. Downregulated genes included specific markers of Paneth cells, indicating that ablation of Mll1 shifted the Paneth-like identity of beta-cateninGOF stem cells towards a goblet cell fate. The stem cell transcriptome further revealed that beta-cateninGOF; Mll1-/- stem cells exhibited a decreased expression of several transcription factors and stem cell genes.
Project description:The impact of removal of Mll1 in intestinal Paneth cells expressing an constitutively active form of beta-catenin (beta-cateninGOF) was analysed in 4 pairs of sorted Paneth cells of Lgr5-CreERT2; beta-cateninGOF;Mll1+/- (control) and Lgr5-CreERT2; beta-cateninGOF;Mll1-/- (knockout) mice at 10 days after tamoxifen-induced mutagenesis. Using 75-base-pair reads, around 30 million reads per sample with comparable unique mapped reads (52-93%) were obtained. To analyze differentially expressed genes, we applied DESeq2 analysis to the RNA-seq dataset. Differentially expressed genes in beta-cateninGOF; Mll1-/- versus beta-cateninGOF; Mll1+/- Paneth cells showed both up- and downregulation of genes at a false discovery rate (FDR) of 10%. This included a global increase in the expression of goblet cell-specific genes. Downregulated genes included specific markers of Paneth cells, indicating that ablation of Mll1 in Paneth cells shifted their identity towards a mixed Paneth-goblet cell fate.
Project description:The impact of Mll1 removal on the intestinal stem cells and its direct effect on neighbouring Paneth cells was evaluated in sorted intestinal stem and Paneth cells from Mll1FC/+; Lgr5-eGFP-CreERT2/+ (control) and Mll1FC/FC; Lgr5-eGFP-CreERT2/+ (knockout) mice, 4 and 10 days after tamoxifen-induced mutagenesis. Using 75-base-pair reads, 30 million reads per sample with comparable unique mapped reads for stem (70-77%) and Paneth (60-76%) cells were obtained. To analyze differentially expressed genes, we applied DESeq2 analysis to the RNA-seq dataset. Analysis by DAVID and GSEA at a false discovery rate (FDR) of 5% was conducted.The stem cell transcriptome revealed that Mll1 knockout stem cells exhibited a decreased expression of several transcription factors and stem cell genes. Additionally, Mll1 ablation in stem cells had an impact on Paneth cells. Downregulation of Paneth cell specific markers indicated a loss of Paneth cell identity.
Project description:Homeostasis of self-renewing small intestinal crypts results from neutral competition between Lgr5 stem cells, small cycling cells located at crypt bottoms1, 2. Lgr5 stem cells are interspersed between terminally differentiated Paneth cells, that are known to produce bactericidal products such as lysozyme and cryptdins/defensins3. Single Lgr5-expressing stem cells can be cultured to form long-lived, self-organizing crypt-villus organoids in the absence of non-epithelial niche cells4. Here, we note a close physical association of Lgr5 stem cells with Paneth cells in vivo and in vitro. CD24+ Paneth cells express EGF, TGF?, Wnt3 and the Notch-ligand Dll4, all essential signals for stem cell maintenance in culture. Co-culturing of sorted stem cells with Paneth cells dramatically improves organoid formation. This Paneth cell requirement can be substituted by a pulse of exogenous Wnt. Genetic removal of Paneth cells in vivo results in the concomitant loss of Lgr5 stem cells. In colon crypts, CD24+ cells residing between Lgr5 stem cells may represent the Paneth cell equivalents. We conclude that Lgr5 stem cells compete for essential niche signals provided by a specialized daughter cell, the Paneth cell. We used intestinal cell fractions from Lgr5-EGFP-ires-CreERT2 mice, expressing GFP under the control of the Lgr5 promoter. RNA was isolated from two FACS sorted cell populations: stem cells were sorted based on high level of GFP expression (GFPhi) and Paneth cells were sorted based on high level of CD24 expression (CD24hi) and high side-scatter (SSChi). Differentially labelled cRNA from GFPhi and CD24hi/SSChi cells from two different sorts (each combining ten individual mice) were hybridized on 4X44K Agilent Whole Mouse Genome dual colour Microarrays (G4122F) in two dye swap experiments, resulting in four individual arrays.
Project description:Paneth cells (PCs) are long-lived secretory cells that reside at the bottoms of small intestinal crypts. Besides serving as niche cells for the neighboring Lgr5-positive stem cells, PCs secrete granules containing a broad spectrum of antimicrobial proteins, including lysozymes and defensins1. Here, we have used single-cell RNA sequencing to explore PC differentiation. We found a maturation gradient from early secretory progenitors to mature PCs, capturing the full maturation path of PCs. Moreover, differential expression of a subset of defensin genes in lysozyme-high PCs, e.g. Defa20, reveals at least two distinct stages of maturation. We traced Lgr5+ stem cells from Lgr5-CreERT2 C57Bl6/J mice bred to a Rosa26LSL-YFP reporter mice and sorted YFP+ cells 5 days, 3 weeks and 8 weeks after tamoxifen injection.
Project description:Homeostasis of self-renewing small intestinal crypts results from neutral competition between Lgr5 stem cells, small cycling cells located at crypt bottoms1, 2. Lgr5 stem cells are interspersed between terminally differentiated Paneth cells, that are known to produce bactericidal products such as lysozyme and cryptdins/defensins3. Single Lgr5-expressing stem cells can be cultured to form long-lived, self-organizing crypt-villus organoids in the absence of non-epithelial niche cells4. Here, we note a close physical association of Lgr5 stem cells with Paneth cells in vivo and in vitro. CD24+ Paneth cells express EGF, TGFα, Wnt3 and the Notch-ligand Dll4, all essential signals for stem cell maintenance in culture. Co-culturing of sorted stem cells with Paneth cells dramatically improves organoid formation. This Paneth cell requirement can be substituted by a pulse of exogenous Wnt. Genetic removal of Paneth cells in vivo results in the concomitant loss of Lgr5 stem cells. In colon crypts, CD24+ cells residing between Lgr5 stem cells may represent the Paneth cell equivalents. We conclude that Lgr5 stem cells compete for essential niche signals provided by a specialized daughter cell, the Paneth cell.
Project description:The molecular mechanisms controlling stem cell renewal and lineage commitment are still poorly understood due to lack of reliable markers. In the adult small intestine, an example of high rate self-renewing tissue, four different epithelial cell lineages (enterocytes, Goblet, enteroendocrine and Paneth cells) are generated from a pool of stem cells localised at the bottom of the crypts of Lieberkühn. Recently, the orphan Leucine-rich repeat G protein-coupled receptor 5 (GPR49), a target of Wnt signalling, has been proposed as a marker for such cells. We investigated the role of LGR5 during intestinal development by using LGR5 null/LacZ-NeoR knock-in mice. We show that LGR5 deficiency leads to premature Paneth cell differentiation. X-gal staining on E18.5 intestine revealed that LGR5 expression is restricted to a few cells clustered within the intervillus region known to contain progenitor cells. In LGR5-null mice, expression from the LGR5 promoter was found upregulated, suggesting a loss of negative feedback control. However, neither epithelial cell proliferation nor cell migration appeared significantly impaired by LGR5 deficiency. Finally, transcriptional profiling of ileal mutant mice suggests that LGR5 plays a role in regulating the Wnt and Notch signalling pathways controlling progenitor renewal and differentiation.
Project description:Intestinal epithelium are generated by intestinal stem cells, which are recognized morphologically as slender columnar cells at the base of the crypt. Stem cells produce transit-amplifying (TA) cells, which divide a number of times and the daughter cells differentiate into absorptive enterocytes as well as secretory-lineages. Intestinal stem cells highly express Lgr5 which is decreased in TA cells. Here, we show that the zinc transported SLC39A7/ZIP7 is essential for the proliferation of TA cells and maintenance of intestinal stem cells. Lgr5Med TA cells derived from Zip7-deficient mice upregulated the expression of unfold protein responses-related genes including pro-apoptotic genes, indicating of induction of ER stress in these cells. The same effect was seen in Lgr5Hi stem cells derived from Zip7-deficient mice. We conclude that ZIP7 is fundamental to the maintenance of crypt homeostasis by resolving ER stress. Small intestinal crypts were isolated form tamoxifen-treated control (Zip7flox/+, Villin-CreERT2, Lgr5-EGFP-ires-CreERT2) and tamoxifen-treated Zip7â??IEC (Zip7flox/flox, Villin-CreERT2, Lgr5-EGFP-ires-CreERT2) mice. We FACS purified intestinal crypt cells according to their Lgr5 expression levels. RNA was isolated from four FACS sorted cell populations: Lgr5Hi cells and Lgr5Med cells derived from control mice, Lgr5Hi cells and Lgr5Med cells derived from Zip7â??IEC mice. Isolated RNA was analyzed using the Affymetrix platform.
Project description:Background & Aims: Hierarchical organization of intestine relies on their stem cells by self-renew and producing committed progenitors. Although signals like Wnt are known to animate the continued renewal by maintaining intestinal stem cells (ISCs) activity, molecular mechanisms especially E3 ubiquitin ligases that modulate ISCs ‘stemness’ and supportive niche have not been well understood. Here, we investigated the role of Cullin 4B (Cul4b) in regulating ISC functions. Methods: We generated mice with intestinal epithelial-specific disruption of Cul4b (pVillin-cre; Cul4bfn/Y), inducible disruption of Cul4b (Lgr5-creERT2; Cul4bfn/Y, CAG-creERT2; Cul4bfn/Y) and their control (Cul4bfn/Y). Intestinal tissues were analyzed by histology, immunofluorescence, RNA sequencing and mass spectrum. Intestinal organoids deprived from mice with pVillin-Cre; Cul4bfn/Y, Lgr5-Cre; Cul4bfn/Y, Tg-Cul4b and their controls were used in assays to measure intestinal self-renewal, proliferation and differentiation. Wnt signaling and intestinal markers were analyzed by immunofluorescence and immunoblot assays. Differential proteins upon Cul4b ablation or Cul4b-interacting proteins were identified by mass spectrometry. Results: Cul4b specifically located at ISCs zone. Block of Cul4b impaired intestinal homeostasis maintenance by reduced self-renewal and proliferation. Transcriptome analysis revealed that Cul4b-null intestine lose ISC characterization and showed disturbed ISC niche. Mechanistically, reactivated Wnt pathway could recover intestinal dysfunction of Cul4b knockout mice. Analysis of differential total and ubiquitylated proteins uncovered the novel targeting substrate of Cullin-Ring ubiquitin ligase 4b (CRL4b), immunity-related GTPase family M member 1 (Irgm1) in intestine. Decreased Irgm1 rescued abnormally interferon signaling, overemphasized autophagy and downstream phosphate proteins in Cul4b knockout mice. Conclusion: We conclude that Cul4b is essential for ISC self-renewal and Paneth cell function by targeting Irgm1 and modulating Wnt signaling. Our results demonstrate that Cul4b is a novel ISC stemness and niche regulator.
Project description:At the base of the intestinal crypt, long-lived Lgr5+ stem cells are intercalated by Paneth cells that provide essential niche signals for stem-cell maintenance. This unique epithelial anatomy makes the intestinal crypt one of the most accessible models for the study of adult stem cell biology. The glycosylation patterns of this compartment are poorly characterized and the impact of glycans on stem cell differentiation remains largely unexplored. We found that Paneth cells, but not Lgr5+ stem cells, express abundant terminal N-acetyllactosamine (LacNAc). Employing an enzymatic method to edit glycans in cultured crypt organoids, we assessed the functional role of LacNAc in the intestinal crypt. We show that blocking access to LacNAc on Paneth cells leads to hyperproliferation of the neighbouring Lgr5+ stem cells, which is accompanied by the down-regulation of genes that are known as negative regulators of proliferation
Project description:Lgr5+ stem cells reside at crypt bottoms of the small and large intestine. Small intestinal Paneth cells supply Wnt3, EGF and Notch signals to neighboring Lgr5+ stem cells. While the colon lacks Paneth cells, Deep Crypt Secretory (DCS) cells are intermingled with Lgr5+ stem cells at crypt bottoms. Here, we report Reg4 as a marker of DCS cells. To investigate a niche function, we eliminated DCS cells using the diphtheria-toxin receptor gene knocked into the murine Reg4 locus. Ablation of DCS cells results in loss of stem cells from colonic crypts and disrupts gut homeostasis and colon mini-gut formation. In agreement, sorted Reg4+ DCS cells promote organoid formation of single Lgr5+ colon stem cells. Stem cells are forced to generate DCS cells in vitro by combined Notch inhibition and Wnt activation. We conclude that Reg4+ DCS cells serve as Paneth cell equivalents in the colon crypt niche.