Lysosome docking to Omegasomes and ER-connected Phagophores Occurs During DNAJB12 and GABARAP-Dependent Selective Autophagy of Misfolded P23H-Rhodopsin

Abstract

AbstractWe report on how the ER-associated-autophagy pathway (ERAA) delivers P23H-rhodopsin (P23H-R) to the lysosome. P23H-R accumulates in an ERAD-resistant conformation that is stabilized by DNAJB12 and Hsp70. P23H-R, DNAJB12, and FIP200 co-localize in discrete foci that punctuate the rim of omegasome rings coated by WIPI1. P23H-R tubules thread through the wall of WIPI1 rings into their central cavity. Transfer of P23H-R from ER-connected phagophores to lysosomes requires GABARAP, and is associated with the transient docking of lysosomes to WIPI1 rings. Instances of lysosomes docking to WIPI1 foci are constitutive, and increase 250% upon P23H-R expression. After departure from WIPI1 rings, new patches of P23H-R are seen in the membranes of lysosomes. The absence of GABARAP prevents transfer of P23H-R from phagophores to lysosomes without interfering with docking. These data identify lysosome docking to omegasomes as an important step in the DNAJB12 and GABARAP-dependent autophagic disposal of dominantly toxic P23H-R.