Figure 5.

Partial inhibition of TORC1 activity causes precocious nuclear localization of Msn2. (A) Eight hours after strains were inoculated into SC media, an Msn2-GFP fusion protein accumulates in the nucleus of gln3Δ cells and cells treated with 600 pg/mL rapamycin or 200 μM MSX, but not in untreated parental cells. The frequency of Msn2-GFP nuclear localization is 56% of gln3Δ cells, 52% of rapamycin-treated cells, and 57% of MSX-treated cells, but only 12% of untreated parental control cells. Approximately 100 cells were examined per group. (B) Msn2 and Msn4 are required for the full life span extension of the gln3Δ strain. We measured viability 4 wk post-inoculation and observed that transcriptional activity of Msn2 and Msn4 is crucial for maximal CLS. However, the gln3Δ mutation activates an Msn2- and Msn4-independent pathway that can extend life span relative to wild type cells. (C) An integrated model linking long-lived deletion strains, reduced amino acid levels, and rapamycin treatment to increased stress response and longevity.