DAF-16/FOXO and HLH-30/TFEB comprise a cooperative regulatory axis controlling tubular lysosome induction in C. elegans

Although life expectancy has increased, longer lifespans do not always align with prolonged healthspans and, as a result, the occurrence of age-related degenerative diseases continues to increase. Thus, biomedical research has been shifting focus to strategies that enhance both lifespan and healthspan concurrently. Two major transcription factors that have been heavily studied in the context of aging and longevity are DAF-16/FOXO and HLH-30/TFEB; however, how these two factors coordinate to promote longevity is still not fully understood. In this study, we reveal a new facet of their cooperation that supports healthier aging in C. elegans. Namely, we demonstrate that the combinatorial effect of daf-16 and hlh-30 is required to trigger robust lysosomal tubulation, which contributes to systemic health benefits in late age by enhancing cross-tissue proteostasis mechanisms. Remarkably, this change in lysosomal morphology can be artificially induced via overexpression of SVIP, a previously characterized tubular lysosome stimulator, even when one of the key transcription factors, DAF-16, is absent. This adds to growing evidence that SVIP could be utilized to employ tubular lysosome activity in adverse conditions or disease states. Mechanistically, intestinal overexpression of SVIP leads to nuclear accumulation of HLH-30 in gut and non-gut tissues and triggers global gene expression changes that promotes systemic health benefits. Collectively, our work reveals a new cellular process that is under the control of DAF-16 and HLH-30 and provides further insight into how these two transcription factors may be exerting their pro-health effects.