Fig. 2

Some examples of the signaling mechanisms involved in AT2 to AT1 transition. Endothelial cells, fibroblasts and immune cells compose the niche that release signals to activate AT2s. These signaling molecules activate their respective receptors expressed on the surface of AT2s. Downstream factors such as YAP, and β-Catenin/TCF are activated to promote the AT2 to become AT2/AT1 transitional cells and finally convert to AT1s. A dynamically regulated Notch by Dlk1 is also needed for AT2/AT1 transition