Abstract
After budding yeast cells cultured in a nutrient-rich liquid medium with 0.2% glucose (under caloric restriction conditions) or 2% glucose (under non-caloric restriction conditions), ferment glucose to ethanol and then consume ethanol, they enter the stationary phase. The process of their chronological aging begins. At that point, the yeast culture starts to accumulate quiescent and non-quiescent cells. Here, we purified the high- and low-density populations of quiescent and non-quiescent cells from the yeast cultures limited in calorie supply or not. We then employed mass spectrometry-based quantitative lipidomics to assess the aging-associated changes in high- and low-density cells’ lipidomes. We found that caloric restriction, a geroprotective dietary intervention, alters the concentrations of many lipid classes through most of the chronological lifespan of the high- and low-density populations of quiescent and non-quiescent cells. Specifically, caloric restriction decreased triacylglycerol, increased free fatty acid, elevated phospholipid and amplified cardiolipin concentrations. Based on these findings, we propose a hypothetical model for a caloric restriction-dependent reorganization of lipid metabolism in budding yeast’s quiescent and non-quiescent cells. We also discovered that caloric restriction creates lipidomic patterns of these cells that differ from those established by two other robust geroprotectors, namely the tor1Δ mutation and lithocholic acid.
Highlights
Culturing budding yeast Saccharomyces cerevisiae aerobically in a nutrient-rich liquid medium with 2% glucose as a single carbon source provides yeast enough calories to proliferate and survive [1]
Based on our analysis of how CR influences the properties of high- and low-density Q cells and their agerelated conversion into high- and low-density NQ cells, we proposed a hypothesis on the mechanism by which CR could decelerate the chronological aging of budding yeast because it influences the characteristic features of Q cells and their aging-associated dynamics [14, 16, 17]
We found that CR increases CER concentration in lipid droplets (LDs) cells through the chronological lifespan (Figure 5A)
Summary
Culturing budding yeast Saccharomyces cerevisiae aerobically in a nutrient-rich liquid medium with 2% glucose as a single carbon source provides yeast enough calories to proliferate and survive [1]. At some point of culturing under non-CR conditions, S. cerevisiae cells consume exogenous glucose and slow their growth [2]. These cells enter a diauxic shift period, during which they produce ethanol and catabolize it aerobically [1]. The cell cycle arrest at the “START A” checkpoint coincides with the appearance of two cell populations in the yeast culture under non-CR conditions. These populations are quiescent (Q) and nonquiescent (NQ) cells [4]. These properties are developed under the control of a nutrientsensing signaling network that integrates several signaling pathways and protein kinases [5]
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