The SIT4 gene, which encodes protein phosphatase 2A, is required for telomere function in Saccharomyces cerevisiae.
Life span and number of cell divisions in eukaryotes are limited. The accumulation of stress-associated damage due to ageing may cause irreversible cell cycle arrest, so-called "cellular senescence". Although many genes have been implicated in determining life span, regulatory systems that counteract age-related stress have not yet been clarified. We examined senescence during a stress of Saccharomyces cerevisiae strains carrying disruptions in protein phosphatase (PPase)-encoding genes in order to identify the system counteracting senescence. Among these strains, short telomeres were found in the sit4 disruptant that lacks one form of protein phosphatase 2A (PP2A). Silencing ability in the subtelomeric region was impaired and hyperphosphorylation of Sir3 was also observed in this mutant. The sit4 mutant was found to have altered nucleoli and a life span as short as an sgs1 mutant. These observations suggest that the PP2A pathway regulates life span in yeast.
Hayashi
Naoyuki
N
Department of Molecular Oncology, Cancer Research Institute, Kanazawa University, 13-1 Takara-machi, Kanazawa, Ishikawa, 920-0934, Japan. naoyuki@kenroku.kanazawa-u.ac.jp
Nomura
Takahiro
T
Sakumoto
Naoko
N
Mukai
Yukio
Y
Kaneko
Yoshinobu
Y
Harashima
Satoshi
S
Murakami
Seishi
S
D002453:Cell Cycle; D002455:Cell Division; D020868:Gene Silencing; D018384:Oxidative Stress; D010749:Phosphoprotein Phosphatases / Q000378:metabolism* / Q000502:physiology; D054648:Protein Phosphatase 2; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D016615:Telomere / Q000502:physiology*; D013997:Time Factors
D029701:Saccharomyces cerevisiae Proteins; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; C104343:SIT4 protein, S cerevisiae