NEUROEPITHELIAL BODIES AND TERMINAL BRONCHIOLES ARE NICHES FOR DISTINCTIVE CLUB CELLS THAT CAN REPAIR AIRWAYS FOLLOWING ACUTE NOTCH INHIBITION

Abstract

Airway club cells (CCs) have the dual role of a secretory cell and a progenitor cell. Using pharmacological, genetic, and cell-ablation approaches we probe the role of canonical Notch signalling in the regulation of the regenerative capacity of CCs. We report that in response to its perturbation, different subpopulations of CCs adopt distinct fates. Upon acute inhibition of Notch, the majority transdifferentiate into multiciliated cells. However, a "variant" subpopulation (v-CCs), juxtaposed with Neuroepithelial Bodies (5-10%) and neighbouring bronchioalveolar duct junctions (>80%), does not. Instead, v-CCs transition into partially differentiated/lineage ambiguous states but can revert to a CC fate upon restoration of Notch signalling and repopulate the airways with CCs and multiciliated cells. Analysis of a v-CC lineage marker (Uroplakin3a), coupled with sequential Notch inhibition, reveals that differential responses of v-CCs to Notch inhibition are regulated by their cellular microenvironment. We propose that perturbations to Notch signalling may be a common consequence of airway injury and that microenvironmental signals diversify CCs to create a robust pool that can repair airways upon acute Notch inhibition.