Prom1 and Notch regulate ciliary length and dynamics in multiciliated cells of the airway epithelium

Abstract

Differences in ciliary morphology and dynamics among multiciliated cells of the respiratory tract have been well reported and known to contribute to efficient mucociliary clearance. Nevertheless, little is known about how phenotypic differences among multiciliated cells are established in the mammalian lung. Here we show that Prominin-1 (Prom1), a transmembrane protein widely used as stem cell and tumor-initiating marker, is crucial to this process. During airway differentiation, Prom1 becomes restricted to multiciliated cells, where it is expressed at distinct levels along the proximal-distal axis of the airways and in the adult airway epithelium in vitro. We found that Prom1 is induced by Notch in post-specified multiciliated cells and that Notch inactivation abolishes the gradients of Prom1 in the developing airways and in differentiating organotypic cultures. Prom1 was not required for multicilia formation and when inactivated resulted in longer cilia, which remained functional but beating at a lower frequency. Disruption of Notch resulted in opposite effects and suggested that Notch fine-tunes Prom1 levels to regulate the multiciliated cell phenotype and generate diversity among these cells in the respiratory tract. By controlling these features, this mechanism contributes to the innate defense of the lung against environmental agents and prevent pulmonary disease. Significance StatementMulticiliated cells are integral components of the epithelia from a variety of organs. In the respiratory tract they are crucial for mucociliary clearance, a first line of defense against environmental agents and microorganisms. Regional differences in ciliary morphology and dynamics of multiciliated cells have been well described. However, little is known about the events generating phenotypical and functional differences among these cells in airways. Here we provide evidence of a novel mechanism in post-specified multiciliated progenitors whereby local Notch and Prom1 regulate ciliary length and ciliary beating to generate morphological and functional diversity among the multiciliated cells. The findings provide insights into the impact of these signals in maintaining the integrity and function of the airway epithelium, preventing pulmonary disease.