Motile airway cilia that propel contaminants out of the lung are oriented in a common direction by planar cell polarity (PCP) signaling, which localizes PCP protein complexes to opposite cell sides throughout the epithelium to orient cytoskeletal remodeling. In airway epithelia, PCP is determined in a 2-phase process. First, cell-cell communication via PCP complexes polarizes all cells with respect to the proximal-distal tissue axis. Second, during ciliogenesis, multiciliated cells (MCCs) undergo cytoskeletal remodeling to orient their cilia in the proximal direction. The second phase not only directs cilium polarization, but also consolidates polarization across the epithelium. Here, we demonstrate that in airway epithelia, PCP depends on MCC differentiation. PCP mutant epithelia have misaligned cilia, and also display defective barrier function and regeneration, indicating that PCP regulates multiple aspects of airway epithelial homeostasis. In humans, MCCs are often sparse in chronic inflammatory diseases, and these airways exhibit PCP dysfunction. The presence of insufficient MCCs impairs mucociliary clearance in part by disrupting PCP-driven polarization of the epithelium. Consistent with defective PCP, barrier function and regeneration are also disrupted. Pharmacological stimulation of MCC differentiation restores PCP and reverses these defects, suggesting its potential for broad therapeutic benefit in chronic inflammatory disease.
Eszter K. Vladar, Jayakar V. Nayak, Carlos E. Milla, Jeffrey D. Axelrod
Vangl1 expression and localization evolves during airway epithelial differentiation.
Mouse tracheal epithelial cells (MTECs) undergoing differentiation labeled with Vangl1 (green), acetylated α-tubulin (cilia, red) and Ecad (blue) antibodies show that before ciliogenesis (air-liquid interface [ALI]+0 days, left) Vangl1 signal is low and localization is weakly asymmetric in all cells. As multiciliated cells (MCCs) appear (ALI+4 days, middle) Vangl1 signal increases in nascent MCCs and becomes more asymmetric, and finally in mature, fully ciliated MTECs (ALI+14 days, right) Vangl1 crescents are robust and fully asymmetric in MCCs and weak in other cells. Manders’ overlap coefficient ± standard error indicated on merged images. Images representative of