PROJECT SUMMARY: Aging is an evolutionarily conserved process of physical and mental decline in the later years of life. The aging of multicellular animals from fruit flies to humans share many similarities. For both flies and mammals, aging leads to loss of circadian rhythms or 24-hour oscillations in function and behavior, including sleep, feeding, metabolism, and other tissue-specific functions. The core circadian "clock" is a negative transcriptional feedback loop: a heterodimeric transcriptional activating complex that drives the expression of hundreds of genes, including their own inhibitors, driving circadian oscillation of gene expression. In both flies and mammals, these clocks exist in nearly every tissue tested. The brain clock (also called the central clock) coordinates many other tissue-specific clocks in the body (also called "peripheral clocks"). These peripheral clocks drive circadian oscillations in tissue-specific gene expression, which in turn drive tissue-specific circadian oscillations in function. Thus, age-related loss of circadian gene expression is thought to affect multiple tissues and have pathologic effects on health. Unfortunately, there are currently few central or peripheral clock therapeutic interventions that enhance circadian regulation in the elderly. In preliminary data, my lab developed two time-restricted feeding, or TRF, regimens that robustly extend lifespan (15-20%), improve circadian function, and increase lipid metabolism in Drosophila. TRF is a dietary regimen in which eating is restricted to a specific daily time window. We found that TRF enhanced circadian-regulated transcription and that TRF-mediated lifespan extension required both circadian regulation and autophagy, a conserved longevity pathway. We also found that, independent of autophagy, TRF increases lipid metabolism, the most common health benefit sought by people who undertake TRF. Here we propose to test the hypothesis that TRF enhances circadian clocks in multiple tissues that promote anti-aging health benefits. Specifically, we will 1) investigate the impact of TRF on different circadian clocks (both peripheral and central), as well as examining clock-to-clock communication; 2) investigate TRF health benefits for the immune system and brain and identify tissue-specific clock(s) required for diverse TRF health benefits; 3) investigate the molecular mechanism(s) underlying autophagy-independent TRF-induced changes in lipid metabolism (storage and usage). These results will help to characterize the anti-aging effects of TRF and identify potential therapeutic targets. Drosophila have provided crucial information about circadian regulation and aging and the fly is a powerful genetic model system. Circadian regulation, metabolism, and aging are highly evolutionarily conserved processes. Thus, we expect that the results of the proposed experiments will have relevance for human health and aging-related therapeutic intervention.