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 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: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 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: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:Atoh1 is the master transcription factor of intestinal secretory cells. Lineage-tracing model of Atoh1+ve cells showed that the progeny of Atoh1+ve cells can develop into either LGR5+ve or LGR5-ve cells. Present analysis compared the gene expression profile of Atoh1+ve cell-derived LGR5+ve cells and LGR5-ve cells, compared to the resident LGR5+ve cell population of the mouse small intestine.
Project description:The epithelial lining of the small intestine is continuously renewed from a small number of stem cells including Lgr5 expressing crypt base cells that have been shown to be a rapidly cycling stem cell population in homeostasis. Alternative markers of intestinal stem cells have variously identified populations as rapidly cycling or quiescent with proposed roles for the latter as a parallel or reserve stem cell population. However, the exact nature of quiescent crypt cells remains unknown. Here by applying novel mouse models that permit their isolation and characterisation as label-retaining cells (LRCs), and for the first time performing lineage tracing from them, we show quiescent cells to be committed secretory precursors that are capable of recall to the stem cell state. We reveal LRCs to be a small subset of the rapidly cycling Lgr5 expressing population committed along the Paneth-enteroendocrine lineage. Significantly, after injury and subsequent regeneration they are clonogenic, as shown by both lineage tracing and organoid growth demonstrating that they can be recalled to the stem cell pool. These findings in establishing quiescent cells as an effective clonogenic reserve during injury provides a motivation for investigating their role in the maintenance of cancer growth following adjuvant treatment. Six age and sex (female) matched Cyp1a1-H2B-YFP mice ten days post βNF induction were used comparing three cell populations from each. Following epithelial isolation, single cell preparation and staining with anti-CD24 anitbody and UEA-1 lectin, 30,000 cells were flow sorted for each population: Paneth cells (Paneth) were defined as CD24+/UEA+, YFP-LRCs (YFPpos) as CD24+/UEA-/YFP+ and LCCs (YFPneg) as CD24+/UEA-/YFP-. Microarray expression comparison was then performed to identify unique markers of each population. RNA amplification and hybridisation was performed at the Paterson Institute, Manchester, UK, Microarray Facility using Nugen Ovation Pico WTA System for amplification and then hybridisation to a Mouse Exon 1.0 ST Array. Arrays were scanned using an Affymetrix GeneChip scanner 3000 running GCOS software.
Project description:The epithelial lining of the small intestine is continuously renewed from a small number of stem cells including Lgr5 expressing crypt base cells that have been shown to be a rapidly cycling stem cell population in homeostasis. Alternative markers of intestinal stem cells have variously identified populations as rapidly cycling or quiescent with proposed roles for the latter as a parallel or reserve stem cell population. However, the exact nature of quiescent crypt cells remains unknown. Here by applying novel mouse models that permit their isolation and characterisation as label-retaining cells (LRCs), and for the first time performing lineage tracing from them, we show quiescent cells to be committed secretory precursors that are capable of recall to the stem cell state. We reveal LRCs to be a small subset of the rapidly cycling Lgr5 expressing population committed along the Paneth-enteroendocrine lineage. Significantly, after injury and subsequent regeneration they are clonogenic, as shown by both lineage tracing and organoid growth demonstrating that they can be recalled to the stem cell pool. These findings in establishing quiescent cells as an effective clonogenic reserve during injury provides a motivation for investigating their role in the maintenance of cancer growth following adjuvant treatment.
Project description:Genome wide expression profiling to determine the overlap of Affymetrix-signals with SOLID sequencing RNA was extracted using the Qiagen RNeasy kit following the manufacturers guidelines, arrays were prepared and hybridized following the Affymetrix protocol. Mus musculus samples from small intestine and colon, to be compared to transcript data aquired with other techniques
Project description:The small intestine has a robust regenerative capacity, and various cell types serve as “cells-of-origin” in the epithelial regeneration process after injury. However, how much each population contributes to regeneration remains unclear. Using lineage tracing, we found that Lgr5-expressing cells’ derivatives contained radioresistant ISCs crucial for epithelial regeneration in the damaged intestine after radiation. Single-cell RNA sequencing analysis of Lgr5-derivatives identified primary source of epithelial regeneration in the irradiation damaged intetsine.