Active Lgr5 Positive Stem Cells Drive Self-Renewal in the Pyloric Stomach and Efficiently Build Pyloric Units In-vitro. Mus musculus

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. Overall design: The pyloric region of 20 stomachs was isolated from 20 Lgr5-EGFP-ires-CreERT2 knock-in mice, tissue trypsinized to single cells and FACS sorted. Two populations were isolated, one expressing GFP at high levels and one expressing GFP at low levels. RNA from these cell populations was isolated, differentially labeled and hybridized on two microarrays in a colourswitch experiment.