Mammalian autophagy and the plasma membrane

Autophagy (literally 'self-eating') is an evolutionarily conserved degradation process where cytoplasmic components are engulfed by vesicles called autophagosomes, which are then delivered to lysosomes, where their contents are degraded. Under stress conditions, such as starvation or oxidative stress, autophagy is upregulated in order to degrade macromolecules and restore the nutrient balance. The source of membranes that participate in the initial formation of phagophores is still incompletely understood and many intracellular structures have been shown to act as lipid donors, including the endoplasmic reticulum, Golgi, nucleus, mitochondria and the plasma membrane. Here, we focus on the contributions of the plasma membrane to autophagosome biogenesis governed by ATG16L1 and ATG9A trafficking, and summarize the physiological and pathological implications of this macroautophagy route, from development and stem cell fate to neurodegeneration and cancer.