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 Wnt target gene Lgr5 marks cycling stem cells in the small intestine, colon and hair-follicle. In the adult stomach, Lgr5 expression is confined to 3-4 proliferating cells at the gland base throughout the pylorus and limited numbers of corpus-type glands adjacent to the esophagus and squamous forestomach. In-vivo lineage tracing reveals that the pyloric Lgr5+ve cells rapidly generate all the major cell-types present in the gastric epithelium and maintain this multipotent stem cell activity over at least 20 months. In-vitro, single adult Lgr5+ve cells efficiently generate gastric units closely resembling mature pyloric glands. We conclude that Lgr5 is marking an active stem cell population at the base of the pyloric glands contributing to the long-term renewal of the adult gastric epithelium. The transcriptome of the adult Lgr5+ve stem cells harbors multiple Wnt target genes, implying a role for Wnt signaling in regulating pyloric stem cell function in-vivo. Conditional deletion of APC in these Lgr5+ve stem cells rapidly initiates tumor formation, supporting a potential role for aberrant Wnt signaling activity in gastric cancer.
Project description:This SuperSeries is composed of the following subset Series: GSE23672: COMPARATIVE TRANSCRIPTOMIC AND PROTEOMIC ANALYSIS OF LGR5+ve STEM CELLS AND THEIR DAUGHTERS (AGILENT ARRAYS) GSE33948: COMPARATIVE TRANSCRIPTOMIC AND PROTEOMIC ANALYSIS OF LGR5+ve STEM CELLS AND THEIR DAUGHTERS (AFFYMETRIX ARRAYS) Refer to individual Series
Project description:Gastric epithelial stem cells are responsible for constant epithelial self-renewal, which is accelerated by infection with the gastric pathogen Helicobacter pylori. However, the mechanism that regulates stem cell turnover in the stomach remains unknown. Here we show that signaling by R-spondin 3 and Wnt hierarchically organizes the stem cell compartment in the antrum, producing two Wnt-responsive populations, which are either Lgr5+ve or Axin2 +ve. The positional identity of the Axin2+ve population relies on R-spondin 3 produced by stromal myofibroblasts. Increased availability of R-spondin induces hyperproliferation through specific expansion of Axin2+ve but not Lgr5+ve cells. Similarly, infection with H. pylori induces an increase in stromal R-spondin 3 expression, resulting in hyperplasia as well as shedding of bacteria that have entered the gland. This identifies a role for stromal cells in environmental sensing to orchestrate epithelial homeostasis via Wnt signaling.
Project description:Multipotent stem cells and their lineage-restricted progeny drive nephron formation within the developing kidney. Validated markers of these early stem/progenitor populations are essential for deciphering their in vivo function and for evaluating their clinical potential for treating adult kidney disease. Here, we document expression of the adult stem cell marker Lgr5 in the developing kidney and assess the stem/progenitor identity of Lgr5+ve cells via in vivo lineage tracing. The appearance and localization of Lgr5+ve cells coincided with that of the S-shaped body around E14. Lgr5 expression remained restricted to cell clusters within developing nephrons in the cortex until P7, when expression was permanently silenced. In vivo lineage tracing identified Lgr5 as a marker of a novel progenitor population within nascent nephrons dedicated to generating the thick ascending limb of Henle's loop and distal convoluted tubule. The Lgr5 surface marker and experimental models described here will be invaluable for deciphering the contribution of early nephron stem cells to developmental defects and for isolating human nephron progenitors as a prerequisite to evaluating their therapeutic potential.
Project description:Introgressed variants from other species can be an important source of genetic variation because they may arise rapidly, can include multiple mutations on a single haplotype, and have often been pretested by selection in the species of origin. Although introgressed alleles are generally deleterious, several studies have reported introgression as the source of adaptive alleles-including the rodenticide-resistant variant of Vkorc1 that introgressed from Mus spretus into European populations of Mus musculus domesticus. Here, we conducted bidirectional genome scans to characterize introgressed regions into one wild population of M. spretus from Spain and three wild populations of M. m. domesticus from France, Germany, and Iran. Despite the fact that these species show considerable intrinsic postzygotic reproductive isolation, introgression was observed in all individuals, including in the M. musculus reference genome (GRCm38). Mus spretus individuals had a greater proportion of introgression compared with M. m. domesticus, and within M. m. domesticus, the proportion of introgression decreased with geographic distance from the area of sympatry. Introgression was observed on all autosomes for both species, but not on the X-chromosome in M. m. domesticus, consistent with known X-linked hybrid sterility and inviability genes that have been mapped to the M. spretus X-chromosome. Tract lengths were generally short with a few outliers of up to 2.7 Mb. Interestingly, the longest introgressed tracts were in olfactory receptor regions, and introgressed tracts were significantly enriched for olfactory receptor genes in both species, suggesting that introgression may be a source of functional novelty even between species with high barriers to gene flow.
Project description:A transcriptome study in mouse hematopoietic stem cells was performed using a sensitive SAGE method, in an attempt to detect medium and low abundant transcripts expressed in these cells. Among a total of 31,380 unique transcript, 17,326 (55%) known genes were detected, 14,054 (45%) low-copy transcripts that have no matches to currently known genes. 3,899 (23%) were alternatively spliced transcripts of the known genes and 3,754 (22%) represent anti-sense transcripts from known genes.