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. 2020 Mar 31;13:42. doi: 10.3389/fnmol.2020.00042

FIGURE 1.

FIGURE 1

Roles of VMP1 in autophagy. Under starvation, MTORC1 dissociates from the ULK1/2 complex consisting of ULK1/2-ATG13-ATG101-FIP200; then ATG13 and ULK1/2 are partially dephosphorylated by as yet unidentified phosphatases, allowing the induction of macroautophagy. Nucleation and elongation of the IMs are aided by the class III PtdIns3K complex and ATG12-ATG5-ATG16L1 complex. Eventually, the expanding membrane closes around its cargo and separates from the ER to form a mature autophagosome. LC3-II is cleaved from the outer membrane of the autophagosome. The outer membrane of the autophagosome will then fuse with the lysosomal membrane to form an autolysosome. The contents of the autolysosome are then degraded and exported back into the cytoplasm for recycling. However, VMP1 depletion will lead to tight contacts of IMs with ER, inhibiting the departure of IMs from ER, thus resulting in the failed fusion of autophagosome with lysosome. Eventually, the autophagic flux is disrupted. This figure was modified from Figure 2 in Parzych and Klionsky (2014).