Genome-wide screen of genes required for caffeine tolerance in fission yeast.
BACKGROUND
An excess of caffeine is cytotoxic to all eukaryotic cell types. We aim to study how cells become tolerant to a toxic dose of this drug, and the relationship between caffeine and oxidative stress pathways.


RESULTS
We searched for Schizosaccharomyces pombe mutants with inhibited growth on caffeine-containing plates. We screened a collection of 2,700 haploid mutant cells, of which 98 were sensitive to caffeine. The genes mutated in these sensitive clones were involved in a number of cellular roles including the H(2)O(2)-induced Pap1 and Sty1 stress pathways, the integrity and calcineurin pathways, cell morphology and chromatin remodeling. We have investigated the role of the oxidative stress pathways in sensing and promoting survival to caffeine. The Pap1 and the Sty1 pathways are both required for normal tolerance to caffeine, but only the Sty1 pathway is activated by the drug. Cells lacking Pap1 are sensitive to caffeine due to the decreased expression of the efflux pump Hba2. Indeed, ?hba2 cells are sensitive to caffeine, and constitutive activation of the Pap1 pathway enhances resistance to caffeine in an Hba2-dependent manner.


CONCLUSIONS
With our caffeine-sensitive, genome-wide screen of an S. pombe deletion collection, we have demonstrated the importance of some oxidative stress pathway components on wild-type tolerance to the drug.
Calvo
Isabel A
IA
Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain.
Gabrielli
Natalia
N
Iglesias-Baena
Iván
I
García-Santamarina
Sarela
S
Hoe
Kwang-Lae
KL
Kim
Dong Uk
DU
Sansó
Miriam
M
Zuin
Alice
A
Pérez
Pilar
P
Ayté
José
J
Hidalgo
Elena
E
D000222:Adaptation, Physiological; D002110:Caffeine / Q000494:pharmacology*; D016681:Genome, Fungal; D006861:Hydrogen Peroxide / Q000378:metabolism; D009154:Mutation; D018384:Oxidative Stress; D000073718:Pancreatitis-Associated Proteins; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000235:genetics
D000073718:Pancreatitis-Associated Proteins; C000612141:REG3A protein, human; D002110:Caffeine; D006861:Hydrogen Peroxide