Disentangling the response to lysosomal damage

The limiting membrane of lysosomes is prone to damage that can have deleterious consequences for cellular homeostasis. Cells respond to this damage with an array of molecular countermeasures, ranging from membrane repair mechanisms to elimination of terminally damaged lysosomes by selective macroautophagy. The various elements of this response therefore need to be carefully assessed in the context of the specific pathological or experimental conditions being studied. Emerging evidence has revealed further complexity within the lysosomal damage response, such as processes that contribute to initial membrane resealing as well as lysosome regeneration required to restore the lysosomal system. These mechanisms involve unusual ubiquitylation, non-canonical ATG8 lipidation, or modifications that govern lysosome tubulation or microlysophagy pathways. Therefore, caution is advised when using previously established lysosome damage reporters that might confound interpretation of the underlying events and outcomes. This Opinion article seeks to shed light on the emerging regulatory mechanisms of lysosomal regeneration and evaluate the appropriateness of various reporters and assays for studying the lysosomal damage response.