Macroautophagy is a catabolic process critical for the degradation of intracellular material, but its physiological functions in vertebrates are not fully understood. Here, we discuss our recent finding that macroautophagy plays a role in lamellar body maturation. The lamellar body is a lysosome-related organelle and stores phospholipid-containing surfactant complexes that reduce the surface tension of the air-water interface in order to inflate the airspace in lungs and swim bladders. In the epithelial cells of these organs, autophagosomes fuse with immature lamellar bodies to increase their size and lipid contents. This function is essential for respiration after birth in mice and for maintaining buoyancy in zebrafish. These findings unveil a novel function of macroautophagy in the maturation of surfactant-containing lamellar bodies.
Keywords: Autophagy; lamellar body; lung; lysosome-related organelle; swim bladder; zebrafish.