Autophagy receptor optineurin promotes autophagosome formation by potentiating LC3-II production and phagophore maturation.

Autophagy is an essential physiological process that maintains cellular homeostasis by eliminating harmful protein aggregates, damaged organelles and certain pathogens through lysosomal degradation. During autophagy specialized structures, known as autophagosomes are formed that recruit the cargo through autophagy receptors, and deliver it to lysosomes. Optineurin (Optn) is an autophagy receptor that mediates cargo selective autophagy. Recently, we have identified a novel function of Optn that promotes autophagosome formation during non-selective autophagy. Optn-deficient cells show reduced formation of autophagosomal protein LC3-II and lower number of autophagosomes as well as autolysosomes. Interestingly, formation of phagophores is increased in Optn-deficient cells. This suggests that Optn promotes autophagosome formation by potentiating LC3-II production and phagophore maturation. Phosphorylation of Optn at Ser-177 is required for promoting autophagosome formation. Here, we discuss various aspects of the role of Optn in the formation of autophagosomes and Atg16L1-positive vesicles. We also discuss the potential role of Rab1a-Optn interaction.