title: Identification of long-lived proteins retained in cells undergoing repeated asymmetric divisions.
abstract: Long-lived proteins have been implicated in age-associated decline in metazoa, but they have only been identified in extracellular matrices or postmitotic cells. However, the aging process also occurs in dividing cells undergoing repeated asymmetric divisions. It was not clear whether long-lived proteins exist in asymmetrically dividing cells or whether they are involved in aging. Here we identify long-lived proteins in dividing cells during aging using the budding yeast, Saccharomyces cerevisiae. Yeast mother cells undergo a limited number of asymmetric divisions that define replicative lifespan. We used stable-isotope pulse-chase and total proteome mass-spectrometry to identify proteins that were both long-lived and retained in aging mother cells after ∼ 18 cells divisions. We identified ∼ 135 proteins that we designate as long-lived asymmetrically retained proteins (LARPS). Surprisingly, the majority of LARPs appeared to be stable fragments of their original full-length protein. However, 15% of LARPs were full-length proteins and we confirmed several candidates to be long-lived and retained in mother cells by time-lapse microscopy. Some LARPs localized to the plasma membrane and remained robustly in the mother cell upon cell division. Other full-length LARPs were assembled into large cytoplasmic structures that had a strong bias to remain in mother cells. We identified age-associated changes to LARPs that include an increase in their levels during aging because of their continued synthesis, which is not balanced by turnover. Additionally, several LARPs were posttranslationally modified during aging. We suggest that LARPs contribute to age-associated phenotypes and likely exist in other organisms.
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and The Molecular and Cellular Biology Program, Fred Hutchinson Cancer Research Center and University of Washington, Seattle, WA 98109.
authors.forename: Nathaniel H
authors.initials: NH
authors.lastname: Thayer
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and.
authors.forename: Christina K
authors.initials: CK
authors.lastname: Leverich
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Fitzgibbon
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and.
authors.forename: Zara W
authors.initials: ZW
authors.lastname: Nelson
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and.
authors.forename: Kiersten A
authors.initials: KA
authors.lastname: Henderson
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and.
authors.forename: Philip R
authors.initials: PR
authors.lastname: Gafken
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and The Molecular and Cellular Biology Program, Fred Hutchinson Cancer Research Center and University of Washington, Seattle, WA 98109.
authors.forename: Jessica J
authors.initials: JJ
authors.lastname: Hsu
authors.affiliation: Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109; and dgottsch@fhcrc.org.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Gottschling
mesh_terms: D002455:Cell Division; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins
keywords: ACD; RITE; asymmetric cell division; recombination-induced tag exchange; replicative aging