BSG.S regulates ionocyte radial intercalation and function in the developing Xenopus mucociliary epithelium.

Mucociliary epithelia (MCE) line multiple vertebrate organs, including the mammalian airways, and rely on coordinated interactions among specialized cell types to clear pathogens and maintain epithelial homeostasis. Proper MCE function requires the appropriate specification and spatial organization of ionocytes, multiciliated cells, secretory cells, and basal cells. Ionocytes regulate ion transport and pH homeostasis, yet the mechanisms governing their integration and function within the developing epithelium remain incompletely understood. Basigin (BSG), also known as CD147 or EMMPRIN, is a conserved transmembrane glycoprotein implicated in cell migration, adhesion, and signaling. However, its role in mucociliary epithelial development remains unclear. Here, we show that the short isoform of BSG (BSG.S) is expressed in ionocytes of the Xenopus laevis MCE. Our findings demonstrate that BSG.S depletion impairs ionocyte radial intercalation, alters intracellular pH, and disrupts epithelial organization. Furthermore, BSG.S loss alters epithelial cell-type composition, decreasing the number of basal cells and increasing the number of multiciliated cells. These findings suggest BSG.S as a regulator of ionocyte integration, epithelial organization, and cell-type composition during mucociliary epithelial development.