Saccharomyces cerevisiae adapted to grow in the presence of low-dose rapamycin exhibit altered amino acid metabolism

Abstract

BackgroundRapamycin is a potent inhibitor of the highly conserved TOR kinase, the nutrient-sensitive controller of growth and aging. It has been utilised as a chemotherapeutic agent due to its anti-proliferative properties and as an immunosuppressive drug, and is also known to extend lifespan in a range of eukaryotes from yeast to mammals. However, the mechanisms through which eukaryotic cells adapt to sustained exposure to rapamycin have not yet been thoroughly investigated.MethodsHere, S. cerevisiae response to long-term rapamycin exposure was investigated by identifying the physiological, transcriptomic and metabolic differences observed for yeast populations inoculated into low-dose rapamycin-containing environment. The effect of oxygen availability and acidity of extracellular environment on this response was further deliberated by controlling or monitoring the dissolved oxygen level and pH of the culture.ResultsYeast populations grown in the presence of rapamycin reached higher cell densities complemented by an increase in their chronological lifespan, and these physiological adaptations were associated with a rewiring of the amino acid metabolism, particularly that of arginine. The ability to synthesise amino acids emerges as the key factor leading to the major mechanistic differences between mammalian and microbial TOR signalling pathways in relation to nutrient recognition.ConclusionOxygen levels and extracellular acidity of the culture were observed to conjointly affect yeast populations, virtually acting as coupled physiological effectors; cells were best adapted when maximal oxygenation of the culture was maintained in slightly acidic pH, any deviation necessitated more extensive readjustment to additional stress factors.Electronic supplementary materialThe online version of this article (10.1186/s12964-018-0298-y) contains supplementary material, which is available to authorized users.

Mmi1, the Yeast Ortholog of Mammalian Translationally Controlled Tumor Protein (TCTP), Negatively Affects Rapamycin-Induced Autophagy in Post-Diauxic Growth Phase

“…Rapamycin has been thought to fully deactivate the budding yeast TORC1 and driving cells into a quiescent/G0 state [33]. However, this dogma has changed since many groups reported only slowed proliferation upon rapamycin treatment [47,[53][54][55] and only partial inhibition of yeast TORC1 [54]. In fact, rapamycin also partially inactivates mammalian mTORC1 [57,58].…”

“…Rapamycin treatment is believed to mimic nutrient deprivation, including greatly reduced cell growth [33] and autophagy induction [32]. However, it has been demonstrated independently by several groups that even at high concentration of rapamycin, yeast cells maintain their proliferative ability [47,[53][54][55][56]. We used batch cultivation, and cells were grown in rich YPD media to OD 600 ≈ 0.8 before rapamycin was added to a final concentration 200 nM, or cells were washed and shifted to nitrogen starvation media.…”

Saccharomyces cerevisiae and Caffeine Implications on the Eukaryotic Cell

“…The macrolide drug rapamycin is a macrocyclic lactone used as immunosuppressive and anti-proliferative antibiotic which inhibits TORC1 [ 81 ]. In the presence of rapamycin, the downstream processes regulated by TORC1 (e.g., stress responses, control of gene expression, protein and ribosome synthesis, amino acid biosynthesis, nitrogen assimilation pathways, protein trafficking and stability, starvation and quiescence, autophagy) are consequently inhibited [ 82 ]. While TORC1 is involved in activities related to cell growth, TORC2 is required for polarized cell growth and cytoskeleton organization [ 73 , 79 ].…”

The Discovery of Druggable Anti-aging Agents

“…106) Rapamycin was also shown to have a distinct impact on energy metabolism compared to CR, 107) which was followed by a report that it induces a shift in amino acid metabolism. 108) The life-extending characteristic of rapamycin is promising. Rapamycin treatment increased the median lifespan in mice in a dose-and sex-dependent manner, where higher doses and female sex showed a higher-percentage increase in longevity.…”

“… 106 ) Rapamycin was also shown to have a distinct impact on energy metabolism compared to CR, 107 ) which was followed by a report that it induces a shift in amino acid metabolism. 108 )…”