XB130 deficiency affects tracheal epithelial differentiation during airway repair

The repair and regeneration of airway epithelium is important for maintaining homeostasis of the respiratory system. XB130 is an adaptor protein involved in the regulation of cell proliferation, survival and migration. In the human trachea, XB130 is expressed on the apical site of ciliated epithelial cells. We hypothesize that XB130 may play a role in epithelial repair and regeneration after injury. Xb130 knockout (KO) mice were generated, and a mouse isogenic tracheal transplantation model was used. Adult Xb130 KO mice did not show any significant anatomical and physiological phenotypes in comparison with their wild type (WT) littermates. The tracheal epithelium in Xb130 KO mice, however, was significantly thicker than that in WT mice. Severe ischemic epithelial injury was observed immediately after the tracheal transplantation, which was followed by epithelial cell flattening, proliferation and differentiation. No significant differences were observed in terms of initial airway injury and apoptosis. However, at Day 10 after transplantation, the epithelial layer was significantly thicker in Xb130 KO mice, and associated with greater proliferative (Ki67+) and basal (CK5+) cells, as well as thickening of the connective tissue and fibroblast layer between the epithelium and tracheal cartilages. These results suggest that XB130 is involved in the regulation of airway epithelial differentiation, especially during airway repair after injury.