Lifespan extension by calorie restriction relies on the Sty1 MAP kinase stress pathway

Either calorie restriction, loss‐of‐function of the nutrient‐dependent PKA or TOR/SCH9 pathways, or activation of stress defences improves longevity in different eukaryotes. However, the molecular links between glucose depletion, nutrient‐dependent pathways and stress responses are unknown. Here, we show that either calorie restriction or inactivation of nutrient‐dependent pathways induces lifespan extension in fission yeast, and that such effect is dependent on the activation of the stress‐dependent Sty1 mitogen‐activated protein (MAP) kinase. During transition to stationary phase in glucose‐limiting conditions, Sty1 becomes activated and triggers a transcriptional stress programme, whereas such activation does not occur under glucose‐rich conditions. Deletion of the genes coding for the SCH9‐homologue, Sck2 or the Pka1 kinases, or mutations leading to constitutive activation of the Sty1 stress pathway increase lifespan under glucose‐rich conditions, and importantly such beneficial effects depend ultimately on Sty1. Furthermore, cells lacking Pka1 display enhanced oxygen consumption and Sty1 activation under glucose‐rich conditions. We conclude that calorie restriction favours oxidative metabolism, reactive oxygen species production and Sty1 MAP kinase activation, and this stress pathway favours lifespan extension.