Probes for INS

The biliary system plays an important role in several acquired and genetic disorders of the liver. We have previously shown that biliary duct epithelium contains cells giving rise to proliferative Lgr5+ organoids in vitro. However, it remained unknown whether all biliary cells or only a specific subset had this clonogenic activity. The cell surface protease ST14 was identified as a positive marker for the clonogenic subset of cholangiocytes and was used to separate clonogenic and non-clonogenic duct cells by fluorescence-activated cell sorting. Only ST14hi duct cells had the ability to generate organoids that could be serially passaged. The gene expression profiles of clonogenic and non-clonogenic duct cells were similar, but several hundred genes were differentially expressed. RNA fluorescence in situ hybridization showed that clonogenic duct cells are interspersed among regular biliary epithelium at a ∼1:3 ratio. We conclude that adult murine cholangiocytes can be subdivided into two populations differing in their proliferative capacity.

The oral mucosa is one of the most rapidly dividing tissues in the body and serves as a barrier to physical and chemical insults from mastication, food, and microorganisms. Breakdown of this barrier can lead to significant morbidity and potentially life-threatening infections for patients. Determining the identity and organization of oral epithelial progenitor cells (OEPCs) is therefore paramount to understanding their roles in homeostasis and disease. Using lineage tracing and label retention experiments, we show that rapidly dividing OEPCs are located broadly within the basal layer of the mucosa throughout the oral cavity. Quantitative clonal analysis demonstrated that OEPCs undergo population-asymmetrical divisions following neutral drift dynamics and that they respond to chemotherapy-induced damage by altering daughter cell fates. Finally, using single-cell RNA-seq, we establish the basal layer population structure and propose a model that defines the organization of cells within the basal layer.

The constant regeneration of stomach epithelium is driven by long-lived stem cells, but the mechanism that regulates their turnover is not well understood. We have recently found that the gastric pathogen Helicobacter pylori can activate gastric stem cells and increase epithelial turnover, while Wnt signalling is known to be important for stem cell identity and epithelial regeneration in several tissues. Here we find that antral Wnt signalling, marked by the classic Wnt target gene Axin2, is limited to the base and lower isthmus of gastric glands, where the stem cells reside. Axin2 is expressed by Lgr5+ cells, as well as adjacent, highly proliferative Lgr5- cells that are able to repopulate entire glands, including the base, upon depletion of the Lgr5+ population. Expression of both Axin2 and Lgr5 requires stroma-derived R-spondin 3 produced by gastric myofibroblasts proximal to the stem cell compartment. Exogenous R-spondin administration expands and accelerates proliferation of Axin2+/Lgr5- but not Lgr5+ cells. Consistent with these observations, H. pylori infection increases stromal R-spondin 3 expression and expands the Axin2+ cell pool to cause hyperproliferation and gland hyperplasia. The ability of stromal niche cells to control and adapt epithelial stem cell dynamics constitutes a sophisticated mechanism that orchestrates epithelial regeneration and maintenance of tissue integrity.