FIGURE 1.

Macroautophagy signaling in the mammalian brain. It consists in three main phases: formation-elongation of a round structure, maturation then its content degradation-recycling. The first step of autophagy starts in the cytoplasm with the “phagophore,” a peculiar double membrane structure derived from ER, Golgi complex or plasmalemma that subsequently elongates, and closes on itself to produce an “autophagosome,” filled with proteins or lipidic material and damaged organelles. Then the “autophagosome” progressively matures and merges with lysosomes becoming an “autolysosome” or “amphisome”to complete clearing. In the last final step, all cargo is dismantled by acidic lysosomal hydrolases and eventually a new phagophore is reformed. Major regulators of different phases are class III PI3-K complex and Beclin 1 protein, Atg proteins cascade resulting in Atg3/Atg7 mediated LC3I into LC3II conversion as indicated and discussed in the text. Extensive details on macroautophagy machinery are reported by Feng et al. (2014).