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.

Restricting bioenergetic efficiency enhances longevity and mitochondrial redox capacity in Drosophila melanogaster.

Mitochondria are essential for survival and as such, impairments in organelle homeostasis significantly accelerate age-related morbidity and mortality. Here, we determined the contribution of bioenergetic efficiency to life span and health span in Drosophila melanogaster utilizing the mitochondrial uncoupler BAM15. Life span was determined in flies fed a normal diet (ND) or high fat diet (HFD) supplemented with vehicle or BAM15. Locomotor function was determined by negative geotaxis assay in middle-aged flies fed vehicle or BAM15 under ND or HFD conditions. Redox capacity (high-resolution respirometry/fluorometry), citrate synthase (enzyme activity), mtDNA content (qPCR), gene expression (qPCR), and protein expression (western blot) were assessed in flight muscle homogenates of middle-aged flies fed vehicle or BAM15 ND. The molar ratio of H2O2 and O2 (H2O2:O2) in a defined respiratory state was calculated as a measure of redox balance. BAM15 extended life span by 9% on ND and 25% on HFD and improved locomotor activity by 125% on ND and 53% on HFD. Additionally, BAM15 enhanced oxidative phosphorylation capacity supported by pyruvate + malate, proline, and glycerol 3-phosphate. Concurrently, BAM15 enhanced the mitochondrial H2O2 production rate, reverse electron flow from mitochondrial glycerol-3-phosphate dehydrogenase (mGPDH) to Complex I, mGPDH, and Complex I without altering the H2O2:O2 ratio. BAM15 upregulated transcriptional signatures associated with mitochondrial function and fitness as well as antioxidant defense. BAM15-mediated restriction of bioenergetic efficiency prolongs life span and health span in Drosophila fed a ND or HFD. Improvements in life span and health span in ND were supported by synergistic enhancement of muscular redox capacity.