Alveolar epithelial cell integrity: A venerable target in the lung.

Eukaryotic cells have developed a litany of conserved mechanisms to deal with membrane injuries. The first line of defense consists of homeostatic regulation of membrane tension as a preventative measure against the occurrence of injury. When these measures fail, cells can engage in elaborate signaling mechanisms aimed at quickly restoring integrity. Based on the overall direction of membrane lipid trafficking, these repair mechanisms can be divided into three broad categories: exocytosis, endocytosis, and ectocytosis. For alveolar epithelial cells (AECs), repair of endogenous cell populations is especially important for the prevention of severe lung pathologies. We provide a focus on the pulmonary setting within this chapter while incorporating relevant findings from other cell types. We emphasize the signals and molecular moieties that have demonstrated critical involvement in the repair process within AECs and other cell types that constantly encounter threats to their membrane integrity.