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Response of Saccharomyces cerevisiae to the stimulation of lipopolysaccharide.

Shen L, Li Y, Jiang L, Wang X - PLoS ONE (2014)

Bottom Line: In this study, we found that lipopolysaccharide-treated S. cerevisiae cells could be stained by methylene blue, but did not die.Significantly regulated genes (460 up-regulated genes and 135 down-regulated genes) in lipopolysaccharide-treated S. cerevisiae cells were analyzed on Gene Ontology, and used to establish physical protein-protein interaction network and protein phosphorylation network.Based on these analyses, most of the regulated genes in lipopolysaccharide-treated S. cerevisiae cells were related to cell wall, membrane, peroxisome and mitochondrion.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; School of Biotechnology, Jiangnan University, Wuxi, China.

ABSTRACT
Lipopolysaccharide, known as endotoxin, can stimulate potent host immune responses through the complex of Toll-like-receptor 4 and myeloid differentiation protein 2; but its influence on Saccharomyces cerevisiae, a model organism for studying eukaryotes, is not clear. In this study, we found that lipopolysaccharide-treated S. cerevisiae cells could be stained by methylene blue, but did not die. Transcriptional profiling of the lipopolysaccharide-treated S. cerevisiae cells showed that 5745 genes were modulated: 2491 genes up-regulated and 3254 genes down-regulated. Significantly regulated genes (460 up-regulated genes and 135 down-regulated genes) in lipopolysaccharide-treated S. cerevisiae cells were analyzed on Gene Ontology, and used to establish physical protein-protein interaction network and protein phosphorylation network. Based on these analyses, most of the regulated genes in lipopolysaccharide-treated S. cerevisiae cells were related to cell wall, membrane, peroxisome and mitochondrion. Further experiments demonstrated that lipopolysaccharide stimulation caused the exposure of phosphatidylserine and the increase of mitochondrial membrane potential in S. cerevisiae cells, but levels of intracellular reactive oxygen species and metacaspase activation were not increased. This study demonstrated that lipopolysaccharide stimulation causes significant changes in S. cerevisiae cells, and the results would contribute to understand the response of eukaryotic cells to lipopolysaccharide stimulation.

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Flow cytometry analysis of LPS-treated S. cerevisiae BY4742 cells stained by Annexin-V-FITC and PI.Untreated cells were used as blank control (Control) and 50% heat-treated dead cells were used as positive control (Heated). The cross gate, in order to show the stained proportions, was set by both blank control and positive control.
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pone-0104428-g007: Flow cytometry analysis of LPS-treated S. cerevisiae BY4742 cells stained by Annexin-V-FITC and PI.Untreated cells were used as blank control (Control) and 50% heat-treated dead cells were used as positive control (Heated). The cross gate, in order to show the stained proportions, was set by both blank control and positive control.

Mentions: All cells are separated from the extracellular environment by the membrane, a phospholipid bilayer. In eukaryotic cells, the lipid composition of the outer and inner leaflets of the membrane is not symmetrical. Phosphatidylserine is restricted to the inner leaflet of the membrane, and the exposure of phosphatidylserine to the outer leaflet of the membrane is a classic feature of apoptotic cells and acts as an “eat me” signal allowing phagocytosis [3], [30]. Since the transcriptome analysis showed that many modulated genes in S. cerevisiae BY4742 cells treated with LPS were related to cell response (Table S4), FITC-labeled Annexin V was used to detect the exposure of phosphatidylserine in the cells [30], using 50% heat-treated dead cells as positive control [38]. About 57.0% population of LPS-treated S. cerevisiae BY4742 cells showed similar pattern to the major population of untreated cells (89.0%), but 36.8% population of LPS-treated cells showed different patterns either from the untreated cells or the heat-treated dead cells (Fig. 7), suggesting that this 36.8% population of LPS-treated S. cerevisiae BY4742 cells were injured but not dead. The membrane integrity was tested by staining with propidium iodide [30]. Propidium iodide could be taken up by 43.7% of the heat-treated cells, but only by 5.8% of the LPS-treated cells and 0.3% of the untreated S. cerevisiae BY4742 cells, respectively (Fig. 7). This suggests that after LPS stimulation the cell membranes of S. cerevisiae BY4742 might be slightly injured for signal transduction but not damaged as that of the heat-treated cells, and also explains the methylene blue staining and the viability of S. cerevisiae BY4742 cells after exposure to LPS.


Response of Saccharomyces cerevisiae to the stimulation of lipopolysaccharide.

Shen L, Li Y, Jiang L, Wang X - PLoS ONE (2014)

Flow cytometry analysis of LPS-treated S. cerevisiae BY4742 cells stained by Annexin-V-FITC and PI.Untreated cells were used as blank control (Control) and 50% heat-treated dead cells were used as positive control (Heated). The cross gate, in order to show the stained proportions, was set by both blank control and positive control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126697&req=5

pone-0104428-g007: Flow cytometry analysis of LPS-treated S. cerevisiae BY4742 cells stained by Annexin-V-FITC and PI.Untreated cells were used as blank control (Control) and 50% heat-treated dead cells were used as positive control (Heated). The cross gate, in order to show the stained proportions, was set by both blank control and positive control.
Mentions: All cells are separated from the extracellular environment by the membrane, a phospholipid bilayer. In eukaryotic cells, the lipid composition of the outer and inner leaflets of the membrane is not symmetrical. Phosphatidylserine is restricted to the inner leaflet of the membrane, and the exposure of phosphatidylserine to the outer leaflet of the membrane is a classic feature of apoptotic cells and acts as an “eat me” signal allowing phagocytosis [3], [30]. Since the transcriptome analysis showed that many modulated genes in S. cerevisiae BY4742 cells treated with LPS were related to cell response (Table S4), FITC-labeled Annexin V was used to detect the exposure of phosphatidylserine in the cells [30], using 50% heat-treated dead cells as positive control [38]. About 57.0% population of LPS-treated S. cerevisiae BY4742 cells showed similar pattern to the major population of untreated cells (89.0%), but 36.8% population of LPS-treated cells showed different patterns either from the untreated cells or the heat-treated dead cells (Fig. 7), suggesting that this 36.8% population of LPS-treated S. cerevisiae BY4742 cells were injured but not dead. The membrane integrity was tested by staining with propidium iodide [30]. Propidium iodide could be taken up by 43.7% of the heat-treated cells, but only by 5.8% of the LPS-treated cells and 0.3% of the untreated S. cerevisiae BY4742 cells, respectively (Fig. 7). This suggests that after LPS stimulation the cell membranes of S. cerevisiae BY4742 might be slightly injured for signal transduction but not damaged as that of the heat-treated cells, and also explains the methylene blue staining and the viability of S. cerevisiae BY4742 cells after exposure to LPS.

Bottom Line: In this study, we found that lipopolysaccharide-treated S. cerevisiae cells could be stained by methylene blue, but did not die.Significantly regulated genes (460 up-regulated genes and 135 down-regulated genes) in lipopolysaccharide-treated S. cerevisiae cells were analyzed on Gene Ontology, and used to establish physical protein-protein interaction network and protein phosphorylation network.Based on these analyses, most of the regulated genes in lipopolysaccharide-treated S. cerevisiae cells were related to cell wall, membrane, peroxisome and mitochondrion.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, China; School of Biotechnology, Jiangnan University, Wuxi, China.

ABSTRACT
Lipopolysaccharide, known as endotoxin, can stimulate potent host immune responses through the complex of Toll-like-receptor 4 and myeloid differentiation protein 2; but its influence on Saccharomyces cerevisiae, a model organism for studying eukaryotes, is not clear. In this study, we found that lipopolysaccharide-treated S. cerevisiae cells could be stained by methylene blue, but did not die. Transcriptional profiling of the lipopolysaccharide-treated S. cerevisiae cells showed that 5745 genes were modulated: 2491 genes up-regulated and 3254 genes down-regulated. Significantly regulated genes (460 up-regulated genes and 135 down-regulated genes) in lipopolysaccharide-treated S. cerevisiae cells were analyzed on Gene Ontology, and used to establish physical protein-protein interaction network and protein phosphorylation network. Based on these analyses, most of the regulated genes in lipopolysaccharide-treated S. cerevisiae cells were related to cell wall, membrane, peroxisome and mitochondrion. Further experiments demonstrated that lipopolysaccharide stimulation caused the exposure of phosphatidylserine and the increase of mitochondrial membrane potential in S. cerevisiae cells, but levels of intracellular reactive oxygen species and metacaspase activation were not increased. This study demonstrated that lipopolysaccharide stimulation causes significant changes in S. cerevisiae cells, and the results would contribute to understand the response of eukaryotic cells to lipopolysaccharide stimulation.

Show MeSH
Related in: MedlinePlus