ED 8. Hh signaling mediates both mesenchymal and epithelial quiescence during homeostasis and injury repair in the lung.
The lung epithelium actively maintains mesenchymal quiescence through paracrine Hh signaling, which also regulates a feedback loop to maintain epithelial quiescence. Epithelial injury leads to down-regulation of Hh signaling and loss of mesenchymal quiescence, which in turn stimulates epithelial regeneration to replete the airway epithelium until homeostasis is re-established.