Recent Advances in Lgr5 Stem Cell Research.

The discovery of leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) as both a marker of adult stem cells and a critical modulator of their activity via its role as an effector of Wnt/R-spondin (Rspo) signaling has driven major advances in our understanding of stem cell biology during homeostasis, regeneration, and disease. Exciting new mouse and organoid culture models developed to study the endogenous behavior of Lgr5-expressing cells in health and disease settings have revealed the existence of facultative stem cell populations responsible for tissue regeneration, cancer stem cells (CSCs) driving metastasis in the gut, and Lgr5 niche cells in the lung. Here we review these recent advances and discuss their impact on efforts to harness the therapeutic potential of adult stem cells and their cancer counterparts in the clinic.