Age-dependent protein changes in replicatively aged budding yeast.

Using budding yeast replicative lifespan as a model for aging in actively dividing cells, we identified nuclear proteins that were increased or depleted in the earliest stages of aging. We performed a proteomic screen comparing isolated nuclei from young (~0-2 generations) versus moderately aged (~6-7 generations) yeast cells (diploid lab strain BY4743) that were isolated from mini-chemostat aging devices. We found that many age-depleted proteins were involved in ribosome biogenesis, specifically in ribosome processing, or in maintenance of chromatin stability. Many proteins that were significantly upregulated in the early stages of aging were involved in the maintenance of cellular homeostasis, including metabolic processes such as carbohydrate, glucan, NADH, and ethanol metabolism.