Lgr5 marks adult progenitor cells contributing to skeletal muscle regeneration and sarcoma formation

Regeneration of adult skeletal muscle is driven largely by resident satellite cells, a stem cell population increasingly considered to display a high degree of molecular heterogeneity. In this study, we find that Lgr5, a receptor for Rspo and a potent mediator of Wnt/β-catenin signaling, marks a subset of activated satellite cells that contribute to muscle regeneration. Lgr5 is found to be rapidly upregulated in purified myogenic progenitors following acute cardiotoxin-induced injury. In vivo lineage tracing using our Lgr5-2ACreERT2R26tdTomatoLSL reporter mouse model shows that Lgr5+ cells can reconstitute damaged muscle fibers following muscle injury, as well as replenish the quiescent satellite cell pool. Moreover, conditional mutation in Lgr52ACreERT2;KrasG12D;Trp53flox/flox mice drives undifferentiated pleomorphic sarcoma formation in adult mice, thereby substantiating Lgr5+ cells as a cell of origin of sarcomas. Our findings provide the groundwork for developing Rspo/Wnt-signaling-based therapeutics to potentially enhance regenerative outcomes of skeletal muscles in degenerative muscle diseases.Agency for Science, Technology and Research (A*STAR)National Research Foundation (NRF)Published versionThis research is supported by the National Research Foundation, Prime Minister’s Office, Singapore under its Investigatorship Program (award no. NRF-NRF12017-03). We thank IMB-AMP and SBIC-Nikon Imaging Centre (Biopolis, Singapore) for imaging assistance, Seri Mustafah at A*STAR SIgN for assistance with FACS sorting, and Grace Lim for proofreading the manuscript

A constant pool of Lgr5+ intestinal stem cells is required for intestinal homeostasis

Lgr5+ crypt base columnar cells, the operational intestinal stem cells (ISCs), are thought to be dispensable for small intestinal (SI) homeostasis. Using a Lgr5-2A-DTR (diphtheria toxin receptor) model, which ablates Lgr5+ cells with near-complete efficiency and retains endogenous levels of Lgr5 expression, we show that persistent depletion of Lgr5+ ISCs in fact compromises SI epithelial integrity and reduces epithelial turnover in vivo. In vitro, Lgr5-2A-DTR SI organoids are unable to establish or survive when Lgr5+ ISCs are continuously eliminated by adding DT to the media. However, transient exposure to DT at the start of culture allows organoids to form, and the rate of outgrowth reduces with the increasing length of DT presence. Our results indicate that intestinal homeostasis requires a constant pool of Lgr5+ ISCs, which is supplied by rapidly reprogrammed non-Lgr5+ crypt populations when preexisting Lgr5+ ISCs are ablated.Agency for Science, Technology and Research (A*STAR)National Research Foundation (NRF)Published versionThe authors thank IMB-IMU and the SBIC-Nikon Imaging Centre staff for imaging assistance; K. Murad for assistance with the experiments; G. Lim for manuscript assistance; and F. de Sauvage for providing the Lgr5-DTR-EGFP mice. N.B. is supported by the Agency for Science, Technology and Research (A ∗ Star) , the Japan Society for the Promotion of Science (JSPS) KAKENHI grant no. 17H01399 , and the National Research Foundation Singapore (Investigatorship Program award no. NRF-NRF12017-03 )

AQP5 enriches for stem cells and cancer origins in the distal stomach

LGR5 marks resident adult epithelial stem cells at the gland base in the mouse pyloric stomach(1), but the identity of the equivalent human stem cell population remains unknown owing to a lack of surface markers that facilitate its prospective isolation and validation. In mouse models of intestinal cancer, LGR5(+) intestinal stem cells are major sources of cancer following hyperactivation of the WNT pathway(2). However, the contribution of pyloric LGR5(+) stem cells to gastric cancer following dysregulation of the WNT pathway-a frequent event in gastric cancer in humans(3)-is unknown. Here we use comparative profiling of LGR5(+) stem cell populations along the mouse gastrointestinal tract to identify, and then functionally validate, the membrane protein AQP5 as a marker that enriches for mouse and human adult pyloric stem cells. We show that stem cells within the AQP5(+) compartment are a source of WNT-driven, invasive gastric cancer in vivo, using newly generated Aqp5-creERT2 mouse models. Additionally, tumour-resident AQP5(+) cells can selectively initiate organoid growth in vitro, which indicates that this population contains potential cancer stem cells. In humans, AQP5 is frequently expressed in primary intestinal and diffuse subtypes of gastric cancer (and in metastases of these subtypes), and often displays altered cellular localization compared with healthy tissue. These newly identified markers and mouse models will be an invaluable resource for deciphering the early formation of gastric cancer, and for isolating and characterizing human-stomach stem cells as a prerequisite for harnessing the regenerative-medicine potential of these cells in the clinic. AQP5 is identified as a marker for pyloric stem cells in humans and mice, and stem cells in the AQP5(+) compartment are shown to be a source of invasive gastric cancer in mouse models