RANK-DEPENDENT CONTROL OF TUFT AND BEST4 CELL DEVELOPMENT IN THE INTESTINE

Specialist intestinal epithelial cells are critical for barrier integrity and immune responses at the mucosal boundary, yet the pathways that govern their development are incompletely defined. Here, we identify an essential role for TNFRSF11A/RANK in shaping intestinal epithelial specialization in zebrafish. Using lineage trajectory analysis, we identified two tuft cell subtypes, including a subtype enriched for expression of genes required to produce pro-inflammatory leukotrienes. We showed that RANK deficiency reduced the abundance of type-2 tuft cells and BEST4 cells, increased goblet cell frequency, and promoted the accumulation of pro-inflammatory leukocytes in the gut. Functionally, we demonstrated that BEST4 cell numbers expand following infection with a pandemic strain of Vibrio cholerae, implicating this lineage in host defense against enteric pathogens. Together, our findings establish RANK as a critical determinant of epithelial diversification, linking loss of RANK to impaired epithelial immune regulation and an elevated inflammatory state.