Atg8ylation coordinates stress granule formation and mTOR inactivation in response to lysosomal damage

ABSTRACT: Stress granule formation is a part of cellular homeostatic responses, with prototypical inducers being viral infections, heat shock and oxidative damage. Here we show that lysosomal damage is a previously unappreciated robust inducer of stress granule formation interlinked with mTOR inactivation during lysosomal damage. We find the two processes to be coordinated by a non-autophagy function of mammalian Atg8 proteins (mAtg8s). Stress granules were induced in response to biochemical damage and diverse lysosome damaging biological agents including SARS-CoV-2 ORF3a, Mycobacterium tuberculosis and protopathic tau. Proteomic analyses of purified lysosomes subjected to biochemical damage revealed recruitment to lysosomes of a network of stress granule proteins, including G3BP1 and NUFIP2. G3BP1 and NUFIP2 contributed to inactivation of mTOR during lysosomal damage via the Ragulator-RagA/B system. Lysosomal damage recruited a subset of mAtg8s commonly related to autophagy but also known to associate with other stressed or remodeling membranes. The GABARAP subset of mAtg8s interacted with G3BP1 and NUFIP2 and were required for NUFIP2 and G3BP1 recruitment to the damaged lysosomes. GABARAPs acted as a switch between the utilization of G3BP1 and NUFIP2 in stress granule formation vs. their role in mTOR inactivation. We furthermore found that mAtg8s lipidation, referred herein as Atg8ylation to distinguish it from its conventional implication in autophagy, but not the canonical autophagy factors ATG13, FIP200, and ATG9A, favored mTOR inactivation during lysosomal damage vs. the stress granule formation. Thus, cells utilize Atg8ylation as a response to membrane stress for specific outcomes beyond the process of autophagy, which include the coordinated stress granule formation and mTOR inactivation during lysosomal damage

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Homo Sapiens (ncbitaxon:9606)

SUBMITTER: Vojo Deretic  

PROVIDER: MSV000088152 | MassIVE |

SECONDARY ACCESSION(S): PXD028745

REPOSITORIES: MassIVE