title: A molecular mechanism of chronological aging in yeast.
abstract: The molecular mechanisms that cause organismal aging are a topic of intense scrutiny and debate. Dietary restriction extends the life span of many organisms, including yeast, and efforts are underway to understand the biochemical and genetic pathways that regulate this life span extension in model organisms. Here we describe the mechanism by which dietary restriction extends yeast chronological life span, defined as the length of time stationary yeast cells remain viable in a quiescent state. We find that aging under standard culture conditions is the result of a cell-extrinsic component that is linked to the pH of the culture medium. We identify acetic acid as a cell-extrinsic mediator of cell death during chronological aging, and demonstrate that dietary restriction, growth in a non-fermentable carbon source, or transferring cells to water increases chronological life span by reducing or eliminating extracellular acetic acid. Other life span extending environmental and genetic interventions, such as growth in high osmolarity media, deletion of SCH9 or RAS2, increase cellular resistance to acetic acid. We conclude that acetic acid induced mortality is the primary mechanism of chronological aging in yeast under standard conditions.
authors.affiliation: Department of Biochemistry, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Burtner
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Murakami
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kennedy
authors.forename: Matt
authors.initials: M
authors.lastname: Kaeberlein
mesh_terms: D019342:Acetic Acid / Q000633:toxicity; D002021:Buffers; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D017353:Gene Deletion; D005800:Genes, Fungal; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008954:Models, Biological; D009994:Osmolar Concentration; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D013997:Time Factors
chemical_list: D002021:Buffers; D003470:Culture Media; D000431:Ethanol; D019342:Acetic Acid