Cathepsin L is required for autolysosomal clearance in Drosophila

ABSTRACT: Autophagy is a highly conserved lysosomal degrative pathway important for maintaining cellular homeostasis. Much of our current knowledge of autophagy is focused on the initiation steps with the later steps, particularly lysosomal fusion leading to autolysosome formation and the subsequent role of lysosomal enzymes in degradation and recycling become evident. Autophagy can function in both cell survival and cell death, however the mechanisms that distinguish adaptive/survival autophagy from autophagy-dependent cell death remains to be established. Here we use a proteomic analysis of larval midguts during degradation identifying a group of proteins with peptidase activity, suggesting a role in autophagy-dependent cell death. We show that Cathepsin L deficient Drosophila larval midgut cells, accumulate autophagic vesicles due to a block in autophagic flux, yet midgut degradation in not compromised. The accumulation of large aberrant autolysosomes in the absence of Cathepsin function appears to be the consequence of decreased degradative capacity as they contain undigested cytoplasmic material rather and not due to a defect in autophagosome-lysosome fusion. Finally, we find that other Cathepsins are also required for proper autolysosomal degradation in Drosophila larval midgut cells and that this is conserved in mammalian cells. Our findings suggest that Cathepsins play an important degrative role in the autolysosome to maintain autophagy flux, by balancing autophagosome production and turnover (to prevent autophagic stress).

INSTRUMENT(S): maXis

ORGANISM(S): Drosophila Melanogaster (fruit Fly)

TISSUE(S): Midgut

SUBMITTER: Jarrod Sandow  

LAB HEAD: Sharad Kumar

PROVIDER: PXD016675 | Pride | 2022-02-15

REPOSITORIES: Pride