Figure 2.

TAp73 deficiency causes profound ciliogenesis defects in airway ciliated cells in vivo. (A, left) The pseudostratified airway epithelium of wild-type (WT) bronchus shows nuclear p73 immunostaining in many suprabasal cells where MCCs reside. The tracheal and bronchial epithelium from p73 knockout mice was devoid of staining, indicating antibody specificity (data not shown). (Right) The suprabasal p73-positive cells coexpress FoxJ1, a marker of MCC cells. Immunofluorescence. Lungs were from 2-mo-old mice. (B–E) Airway epithelia of p73 knockout (p73KO) and TAp73 knockout (TAp73KO) mice exhibit severe defects in ciliogenesis. (B) The p73 knockout trachea exhibits marked loss of cilia. H&E and immunofluorescence staining for axonemal marker Ac α-Tub and BB marker Chibby (Cby). DAPI counterstain. Bar, 10 µm. (C–E) Photomicrographs of transmission electron microscopy (TEM) (C,E) and scanning electron microscopy (SEM) (D) of the trachea (C,D) and bronchus (E) from 8-wk-old p73 knockout and TAp73 knockout mice and their wild-type littermates. In contrast to the abundant, long broom-like cilia of wild-type cells, knockout MCCs have far fewer and shorter cilia (ciliary stumps; arrowhead). Interspersed microvilli are preserved (asterisk). (F,G) TAp73 depletion causes severe mucociliary clearance defects. Fluorescent microspheres were applied to tracheal explants and tracked by high-speed confocal microscopy. (F ) Bead trajectories aggregated from 2000 images over 32 sec. Particles in wild-type tracheae have long, directed trajectories along a flow field (arrow). In contrast, directional movement in the knockout trachea is strongly reduced, similar to the dead wild-type diffusion control. (G) Particle velocity histograms from all measurements. n=13,683 tracks for wild-type; n=15,951 tracks for knockout; n=19,096, tracks for control. See also Supplemental Movie S2 and Supplemental Figure S2, G and H.