Project description:Transcriptomic data related to 4 different subpopulations found in Mex3a Ki/+ Lgr5 Gfp in APCflfl adenomas in untreated animals. Adenomas where induced with 3%DSS and a single shot of 8mg/kg of Tamoxifen. The populations are refered as Mex3a + Lgr5, Mex3a- Lgr5+ Mex3a+ Lgr5- and Mex3a- Lgr5- according to the flow cytometry profile. Cells were isolated using FACsARIA (BD)
Project description:The intestinal epithelium is continuously regenerated by highly proliferative Lgr5+ intestinal stem cells (ISCs). The existence of a population of quiescent ISCs has been suggested yet its identity and features remain controversial. Here we describe that the expression of the RNA-binding protein Mex3a labels a subpopulation of Lgr5+ cells that divide less frequently and contribute to regenerate all intestinal lineages with slow kinetics. Single cell transcriptomic analysis revealed two classes of Lgr5-high cells, one of them defined by the Mex3a-expression program and by low levels of proliferation genes. Lineage tracing experiments show that large fraction of Mex3a+ cell population is continuously recalled into the rapidly dividing self-renewing ISC pool in homeostatic conditions. Chemotherapy and radiation target preferentially rapidly dividing Lgr5+ cells but spare the Mex3a-high/Lgr5+ population, which helps sustain the renewal of the intestinal epithelium during treatment.
Project description:Mex3a labells a subpopulation of Cancer Stem cells defined by their slow proliferative behaviour. Nevertheless, the precise function of MEX3A is unknown, although it plays a role in chemoresistance. The Mex3a KO adenomas are less chemoresistant compared to their WT controls. We used microarrays to elucidate changes in gene expression in cells with the Mex3a promoter active (tomato expressing cells)
Project description:Proximal mouse small intestine from mice bearing the Lgr5 GFP/+ and Mex3a Tom/+ alleles were used to obtain single cell preparations. Cells were selected for GFP expression and different levels of tdTomato were defined. Sorted cells were lysed and processed for transcriptomic analysis
Project description:The generation of the Lgr5_EGFP_ires_CreERT2 knock-in mouse allows marking of Lgr5 positive cells of different tissues. Here we use these mice to sort Lgr5 positive cells and their daughter cells form intestinal adenomas and describe the expression profile of these two cell populations.
Project description:The generation of the Lgr5_EGFP_ires_CreERT2 knock-in mouse allows marking of Lgr5 positive cells of different tissues. Here we use these mice to sort Lgr5 positive cells and their daughter cells form intestinal adenomas and describe the expression profile of these two cell populations. Intestinal adenomas were generated by inducing Apc deletion through tamoxifen injection in Apc_fl/fl-Lgr5_EGFP_ires_CreERT2 mice. In these mice, GFP is expressed under the control of the Lgr5 promoter, leading to highest GFP levels in Lgr5 positive cells (GFP-high). Dividing GFP-high cells pass on Gfp two their daughter cells, thereby diluting the GFP. Daughter cells can therefore be isolated based on their lower GFP positivity (GFP-low). We sorted these two cell fractions (GFP-high and GFP-low) and compared them to each other on 4X44K Agilent Whole Mouse Genome dual colour Microarrays (G4122F). Three independent sorts were performed and RNA of GFP-high cells hybridized directly against RNA of GFP-low cells in three dye swap experiments, resulting in six individual arrays.
Project description:The effort to better understand intestinal stem cell (ISC) identity and regulation remains a challenge. We have been studying the RNA-binding protein MEX3A as a putative ISC marker. In that context, we have generated the first Mex3a knockout (KO) mouse model and show MEX3A is crucial for maintenance of the Lgr5+ ISC pool. As part of a phenotypic characterization pipeline, we have performed transcriptomic profiling (RNA-sequencing) of isolated Mex3a KO small intestinal crypts and compared it against small intestinal crypts isolated from age-matched wild-type controls.
Project description:The generation of the Lgr5_EGFP_ires_CreERT2 knock-in mouse allows marking of Lgr5 positive cells of different tissues by GFP expression. Here we use these mice to sort GFP positive cells from intestinal adenomas and compare those to GFP positive cells from normal small intestine.
Project description:Sessile serrated adenomas are now recognized as precursor lesions of a substantial subset of colorectal cancers arising via a so-called “serrated pathway”. However, their biological markers remain to be defined. The aim of our study was to identify differentially expressed genes in sessile serrated adenomas, hyperplastic polyps and tubular adenomas. Gene expression analysis demonstrated molecular differences between polyp types. Further studies using QRT-PCR on Cathepsin E demonstrated a significantly (p< 0.05) higher expression in sessile serrated adenomas as compared to both other polyp types. Trefoil Factor 1, showed the same trend of expression for sessile serrated adenomas as compared to hyperplastic polyps, and was significantly higher in both polyps compared to tubular adenomas. Immunohistochemistry for both proteins demonstrated strong cytoplasmic staining of abnormal crypts in all sessile serrated adenomas while staining in tubular adenomas and hyperplastic polyps was weak and focal. BRAF and KRAS mutation analysis were employed to further validate polyp discrimination. The findings demonstrated the positive association of the BRAF mutation, V600E, with sessile serrated adenomas and KRAS mutations with tubular adenomas (P<0.05). This study demonstrates CTSE and TFF1 over-expression in sessile serrated adenomas compared to both hyperplastic polyps and tubular adenomas. Keywords: colonic polyp tissue comparison, linear modelling, SSA
Project description:Mex3a is an RNA binding protein of unknown function. To elucidate the contribution of Mex3a to tumoral heterogeneity, Mex3a KO organoids engineered by CRISPR were sequenced in three different conditions. Live organoids (DAPI negative) were sorted in Control, after 2 days of FOLFIRI and after 5 days of treatment. Two WT organoids (parental and a derived clone) and two KO (KO1 and KO2, two independent clones) were used for this experiment.