Consequences of calorie restriction and calorie excess for the physiological parameters of the yeast Saccharomyces cerevisiae cells

Abstract

Glucose plays an important role in cell metabolism and has an impact on cellular physiology. Changes in glucose availability may strongly influence growth rate of the cell size, cell metabolism and the rate of generation of cellular by-products, such as reactive oxygen species. The positive effect of low glucose concentration conditions-calorie restriction is observed in a wide range of species, including the Saccharomyces cerevisiae yeast, yet little is known about the effect of high glucose concentrations-calorie excess. Such analysis seems to be particularly important due to recently common problem of diabetes and obesity. The effect of glucose on morphological and physiological parameters of the yeast cell was conducted using genetic alteration (disruption of genes involved in glucose signalling) and calorie restriction and calorie excess conditions. The results show a significant relationship among extracellular glucose concentration, cell size and reactive oxygen species generation in yeast cells. Furthermore, the results obtained through the use of mutant strains with disorders in glucose signalling pathways suggest that the intracellular level of glucose is more important than its extracellular concentration. These data also suggest that the calorie excess as a factor, which has a significant impact on cell physiology, requires further comprehensive analyses.

Reproductive Potential of Yeast Cells Depends on Overall Action of Interconnected Changes in Central Carbon Metabolism, Cellular Biosynthetic Capacity, and Proteostasis

“…On the one hand, high glycolytic flux will favor fermentation and production of building blocks; on the other hand, it will reduce respiration capabilities. Hence, it is observed that ATP is produced by respiration at low glucose uptake rate [ 52 , 53 ], which is consistent with our observations (this study) and [ 12 ]. It turn, high glucose uptake rate and high glycolytic flux will correspond to higher biosynthetic rate.…”

“…Consistently with previous findings [ 43 , 45 ], cells lacking HXK2 display increased reproductive potential ( Figure 1 B,C) together with increased respiration (evidenced by the high level of ATP, high value of MMP and developed mitochondrial network— Figure 2 A,B and Figure 3 A–D). However, other observations in the case of Δ hxk2 strain, such as decreased rate of glucose uptake [ 12 ]; disturbing in glucose repression even in high glucose media (this study); the MMP analysis; mitochondrial morphology; and ATP level, in used conditions and rho 0 cells ( Figure 3 A–D and Figure 2 A–D) led to the assumption that increased reproductive potential ( Figure 1 A–C) is not a direct result of increased respiratory metabolism. But it may be a consequence of changes in metabolic fluxes in central carbon metabolic pathways.…”

“…A higher ATP level can also be partly caused by changes in CCM pathways, especially given that some literature data seem to indirectly confirm such idea. First, it was shown that deletion of HXK2 results in decreased fluxes through the glycolytic/fermentative enzymes and significant reduction in fermentative capacity [ 12 , 38 , 50 ]. Secondly, flux through the tricarboxylic acid (TCA) cycle can be independent of glucose concentration of the medium, but is inversely correlated with glucose uptake rate and to a lesser extent with the growth rate [ 51 ].…”

“…Cell size and the rate of cell size increase per generation also play an important role in the regulation of reproductive potential [ 8 , 9 , 10 , 11 ]. More importantly, those parameters may be modulated, among others, by nutrient content [ 12 , 13 ].…”

Nicotinamide, Nicotinamide Riboside and Nicotinic Acid—Emerging Roles in Replicative and Chronological Aging in Yeast

“…Calorie restriction (CR) is a practice of limiting nutrient intake without malnutrition known to extend lifespan in a wide spectrum of organisms, ranging from yeast to primates [68][69][70]. In yeast, CR is generally imposed by reducing the glucose concentration in the growth medium from 2% to 0.5-0.2%: a growth condition that sustains growth as well as 2% glucose [71,72]. In this context, much work has been done on potential mechanisms by which glucose levels may affect Sir2 enzymatic activity.…”