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. Author manuscript; available in PMC: 2013 Jul 3.
Published in final edited form as: Cell Metab. 2012 Jul 3;16(1):18–31. doi: 10.1016/j.cmet.2012.06.002

Figure 3.

Figure 3

Yeast Chronological Life Span Major Regulatory Pathways. The nutrient-sensing pathways controlled by Sch9, Tor, and Ras converge on the protein kinase Rim15. A major portion of the effect of CR on longevity appears to be mediated by the down-regulation of the Ras/AC/PKA and Tor/Sch9 pathways and consequent activation of the Rim15-controlled Msn2/4 and Gis1 stress-responsive transcription factors. Reduced Tor/Sch9 signaling (genetic mutations or rapamycin) also increases coupled mitochondrial respiration and membrane potential (Δψ m) during growth phase, which leads to an adaptive mitochondrial ROS signal. During stationary phase (i.e. chronological aging), Tor and Sch9 deficiencies and adaptive mitochondrial ROS signaling decrease ROS production and enhance cellular stress responses, culminating in life span extension.