V-ATPase Disassembly at the Yeast Lysosome-Like Vacuole Is aPhenotypic Driver of Lysosome Dysfunction in Replicative Aging

Abstract

Declines in lysosomal acidification and function with aging are observed in organisms ranging from yeast to humans. V-ATPases play a central role in organelle acidification and V- ATPase activity is regulated by reversible disassembly in many different settings. Using the yeast Saccharomyces cerevisiae as a replicative aging model, we demonstrate that V-ATPases disassemble into their V1 and V0 subcomplexes in aging cells, with release of V1 subunit C (Vma5) from the lysosome-like vacuole into the cytosol. Disassembly is observed after >5 cell divisions and results in overall vacuole alkalinization. Caloric restriction, an established mechanism for reversing many age-related outcomes, prevents V-ATPase disassembly in older cells and preserves vacuolar pH homeostasis. Reversible disassembly is controlled in part by the activity of two opposing and conserved factors, the RAVE complex and Oxr1. The RAVE complex promotes V-ATPase assembly and a rav1{Delta} mutant shortens replicative lifespan; Oxr1 promotes disassembly and an oxr1{Delta} mutation extends lifespan. Importantly, the level of Rav2, a subunit of the RAVE complex, declines in aged cells, and Rav2 overexpression delays V-ATPase disassembly with age. These data indicate that reduced V-ATPase assembly contributes to the loss of lysosome acidification with age, which affects replicative lifespan.