FIGURE 7.

Proposed schematic models for ATG4B regulation of autophagy. We propose a model whereby the rate of autophagic flux is impacted by the activity of ATG4B, and where ATG4B activity is impacted by post-translational modifications that include phosphorylation (positive) and oxidation (negative). Previous studies proposed a model whereby ROS is induced under starvation, thereby attenuating ATG4B activity and causing reduced LC3 delipidation (22). The data reported here reveal that starvation increases phosphorylation of ATG4B, thereby augmenting ATG4B activity, promoting LC3 delipidation. Thus, a well-balanced activation of ATG4B, that maintains the proper level of LC3 lipidation becomes a critical factor for autophagosome maturation.