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. Author manuscript; available in PMC: 2014 Nov 1.
Published in final edited form as: Prog Retin Eye Res. 2013 Aug 28;37:10.1016/j.preteyeres.2013.08.001. doi: 10.1016/j.preteyeres.2013.08.001

Figure 5. Autophagy signaling.

Figure 5

Starvation activates autophagy through inhibition of mTOR, which negatively regulates ULK1 and Class III PI3-kinase. Activation of Class III PI3-kinase in the Beclin-1-interacting complex is a key step in the formation of isolation membrane. Elongation of isolation membrane requires two ubiquitin-like conjugation systems: the Atg-5-Atg12 conjugation system and the LC3 conjugation system. Atg5-Atg12 complex and PE-conjugated LC3 (LC3-II) are recruited to isolation membrane, and facilitate the formation of autophagosome. After fusion with lysosome, the autophagosomal content is degraded in the autolysosome. Autophagy is critical for cell survival by mediating the clearance and recycling of defective proteins and organelles. Nonetheless, autophagy also induces cell death via excessive self-degradation.