Aging, the time-dependent accumulation of molecular damage, is the primary limiting factor of human lifespan. Slowing down damage accumulation or its prevention therefore represents a promising therapeutic paradigm to combat aging-related disease and death. While several chemical compounds extend lifespan in model organisms, their mechanism of action is often unknown, reducing their therapeutic potential. Using a systematic approach, here we show that inhibition of GMP synthesis is a novel

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... pan extension mechanism in yeast. We further discover that proteasome activation extends lifespan in part through GMP insufficiency. GMP synthesis inhibition exerts its lifespan extension effect independently of the canonical nutrient-sensing and sirtuin pathways regulating lifespan. Exposing longitudinally aging yeast cells to GMP synthesis inhibition in an age-dependent manner, we demonstrate that the lifespan extension by GMP insufficiency is facilitated by slowing, rather than reversing, the aging process in cells. While GMP and its downstream metabolites are involved in many cellular processes in cells, our results rule out the combined effect of global transcription and translation on cellular lifespan. These findings elucidate the involvement of nucleotide metabolism in the aging process. The existence of clinically-approved GMP synthesis inhibitors elicits the potential of a new class of therapeutics for aging-related disorders.