Systematic screen for mutants resistant to TORC1 inhibition in fission yeast reveals genes involved in cellular ageing and growth.
Target of rapamycin complex 1 (TORC1), which controls growth in response to nutrients, promotes ageing in multiple organisms. The fission yeast Schizosaccharomyces pombe emerges as a valuable genetic model system to study TORC1 function and cellular ageing. Here we exploited the combinatorial action of rapamycin and caffeine, which inhibit fission yeast growth in a TORC1-dependent manner. We screened a deletion library, comprising ∼84% of all non-essential fission yeast genes, for drug-resistant mutants. This screen identified 33 genes encoding functions such as transcription, kinases, mitochondrial respiration, biosynthesis, intra-cellular trafficking, and stress response. Among the corresponding mutants, 5 showed shortened and 21 showed increased maximal chronological lifespans; 15 of the latter mutants showed no further lifespan increase with rapamycin and might thus represent key targets downstream of TORC1. We pursued the long-lived sck2 mutant with additional functional analyses, revealing that the Sck2p kinase functions within the TORC1 network and is required for normal cell growth, global protein translation, and ribosomal S6 protein phosphorylation in a nutrient-dependent manner. Notably, slow cell growth was associated with all long-lived mutants while oxidative-stress resistance was not.
Department of Genetics, Evolution and Environment, and Institute of Healthy Ageing, Darwin Building, University College London, Gower Street, London WC1E 6BT, UK.
Charalampos
C
Rallis
Luis
L
López-Maury
Teodora
T
Georgescu
Vera
V
Pancaldi
Jürg
J
Bähler
Cell growth; Chronological lifespan; Oxidative stress; Protein translation; S. pombe; S6 kinase Sck2; TOR