Microtubules enable the planar cell polarity of airway cilia.

Background: Airway cilia must be physically oriented along the longitudinal tissue axis for concerted, directional motility that is essential for proper mucociliary clearance.

Results: We show that planar cell polarity (PCP) signaling specifies directionality and orients respiratory cilia. Within all airway epithelial cells, a conserved set of PCP proteins shows interdependent, asymmetric junctional localization; nonautonomous signaling coordinates polarization between cells; and a polarized microtubule (MT) network is likely required for asymmetric PCP protein localization.