Enteroendocrine and tuft cells support Lgr5 stem cells on Paneth cell depletion

Cycling intestinal Lgr5(+) stem cells are intermingled with their terminally differentiated Paneth cell daughters at crypt bottoms. Paneth cells provide multiple secreted (e.g., Wnt, EGF) as well as surface-bound (Notch ligand) niche signals. Here we show that ablation of Paneth cells in mice, using a diphtheria toxin receptor gene inserted into the P-lysozyme locus, does not affect the maintenance of Lgr5(+) stem cells. Flow cytometry, single-cell sequencing, and histological analysis showed that the ablated Paneth cells are replaced by enteroendocrine and tuft cells. As these cells physically occupy Paneth cell positions between Lgr5(+) stem cells, they serve as an alternative source of Notch signals, which are essential for Lgr5(+) stem cell maintenance. Our combined in vivo results underscore the adaptive flexibility of the intestine in maintaining normal tissue homeostasis.