Project description:The study is intended to generate the profile of central metabolism, including glycolysis, pentose-phosphate shunt, TCA cycle and nucleotide pools.
Project description:Cancer cells display an altered metabolism with increased glycolysis and glucose uptake. Anti-cancer strategies targeting glycolysis through metabolic inhibitors have been considered. The glucose analog 2-deoxyglucose (2DG) is imported into cells and after phosphorylation becomes 2DG-6-phosphate, a toxic by-product that inhibits glycolysis. 2DG has other cellular effects and can induce resistance. Using yeast as a model, we performed an unbiased, mass-spectrometry-based approach to probe the cellular effects of 2DG on the proteome and study resistance mechanisms. We found that two 2DG-6-phosphate phosphatases, Dog1 and Dog2, were induced upon exposure to 2DG and participated in 2DG detoxication. 2DG induced Dog2 by activating several signaling pathways, such as the MAPK (the p38 ortholog Hog1)-based stress-responsive pathway, the unfolded protein response (UPR) triggered by 2DG-induced ER stress, and the MAPK (Slt2)-based cell wall integrity (CWI) pathway. Thus, 2DG-induced interference with cellular signaling rewired the expression of these endogenous phosphatases to promote 2DG resistance. Consequently, loss of the UPR or CWI pathways led to 2DG hypersensitivity. In contrast, DOG2 was transcriptionally repressed by glucose availability through the inhibition of the Snf1/AMPK pathway, and glucose-repression mutants were 2DG-resistant. The characterization and genome resequencing of spontaneous 2DG-resistant mutants revealed that DOG2 overexpression was a common strategy to achieve 2DG resistance. A human Dog2 homolog, HDHD1, also displays 2DG-6-phosphate phosphatase activity in vitro, and its overexpression conferred 2DG resistance in HeLa cells, suggesting potential interference with chemotherapies involving 2DG.
Project description:Metabolic efficiency profoundly influences organismal fitness. Heterotrophs, from yeast to mammals, derive usable energy primarily through glycolysis and respiration. While respiration is more energy-efficient, some cells favor glycolysis even when oxygen is available (aerobic glycolysis, Warburg effect). A leading explanation is that glycolysis is more efficient in terms of ATP production per unit mass of protein (i.e. faster). Through quantitative flux analysis and proteomics, we find however that mitochondrial respiration is actually more proteome-efficient than aerobic glycolysis. This is shown across yeasts, T cells, cancer cells, and tissues and tumors in vivo. Instead of aerobic glycolysis being valuable for fast ATP production, it correlates with high glycolytic protein expression, which is valuable for hypoxic growth. Aerobic glycolytic yeasts do not excel at aerobic growth, but outgrow respiratory cells in oxygen limitation. Thus, aerobic glycolysis emerges from cells maintaining a proteome conducive to both aerobic and hypoxic growth.
Project description:Metabolic efficiency profoundly influences organismal fitness. Heterotrophs, from yeast to mammals, derive usable energy primarily through glycolysis and respiration. While respiration is more energy-efficient, some cells favor glycolysis even when oxygen is available (aerobic glycolysis, Warburg effect). A leading explanation is that glycolysis is more efficient in terms of ATP production per unit mass of protein (i.e. faster). Through quantitative flux analysis and proteomics, we find however that mitochondrial respiration is actually more proteome-efficient than aerobic glycolysis. This is shown across yeasts, T cells, cancer cells, and tissues and tumors in vivo. Instead of aerobic glycolysis being valuable for fast ATP production, it correlates with high glycolytic protein expression, which is valuable for hypoxic growth. Aerobic glycolytic yeasts do not excel at aerobic growth, but outgrow respiratory cells in oxygen limitation. Thus, aerobic glycolysis emerges from cells maintaining a proteome conducive to both aerobic and hypoxic growth.
Project description:Metabolic efficiency profoundly influences organismal fitness. Heterotrophs, from yeast to mammals, derive usable energy primarily through glycolysis and respiration. While respiration is more energy-efficient, some cells favor glycolysis even when oxygen is available (aerobic glycolysis, Warburg effect). A leading explanation is that glycolysis is more efficient in terms of ATP production per unit mass of protein (i.e. faster). Through quantitative flux analysis and proteomics, we find however that mitochondrial respiration is actually more proteome-efficient than aerobic glycolysis. This is shown across yeasts, T cells, cancer cells, and tissues and tumors in vivo. Instead of aerobic glycolysis being valuable for fast ATP production, it correlates with high glycolytic protein expression, which is valuable for hypoxic growth. Aerobic glycolytic yeasts do not excel at aerobic growth, but outgrow respiratory cells in oxygen limitation. Thus, aerobic glycolysis emerges from cells maintaining a proteome conducive to both aerobic and hypoxic growth.
Project description:This is corresponding to the model of yeast glycolysis "glucose upshift" condition described in the paper "Testing Biochemistry Revisited: How In Vivo Metabolism Can Be Understood from In Vitro Enzyme Kinetics" by van Eunen et al published in Plos Comput Biol, 2012.
Project description:The Warburg effect, consisting of increased glucose uptake and glycolysis, provides metabolic energy as well as cellular building blocks for tumor growth. Inhibition of the Warburg effect with 2-deoxyglucose (2DG) has been explored in clinical trials with limited efficacy. Blockage of glycolysis can induce autopahgy resulting in alternative energy generation through oxidative phosphorylation providing a potential bypass of the effects of inhibition of glycolysis. Here in we demonstrate that activation of AMPK, as a consequence of energetic stress, induces mitochondrial energy production potentially bypassing the effects of glycolysis inhibition. We thus combined blockage of glycolysis by 2DG with inhibition of the electron transfer complex I (ETC1) in the mitochondria with the clinically applicable antidiabetic drug metformin. The combination resulted in activation of AMPK and autopahgy that however rendered eventual depletion of ATP and cell death. Furthermore, combined inhibition of glycolysis and mitochondrial respiration inhibited tumor growth and markedly decreased metastatic capacity in vivo. In order to understand the mechanism of these metabolic inhibitors, we performed whole genome transcriptional analysis. Human SK-4 esophageal cancer cell lines were treated with 5 different treatment groups [2 deoxy glucose (4mM), Metformin (5mM), AICAR (2mM), 2 deoxy glucose (4mM) plus Metformin (5mM) and 2 deoxy glucose (4mM) plus AICAR (2mM)] with non treated control groups for 12 hrs. Each groups was quadruplicated. Microarray experiments and data analysis were done at Dept. of Systems Biology, MDACC (Houston, USA)
Project description:The overall aim of the present work was to identify MTG16 functions in leukemia cells. Alterations in quantity of the MTG16 co-repressor might affect gene regulation and cell metabolism in malignant cells. Differentiated cells secure energy for cellular homeostasis largely by mitochondrial oxidation. Whereas, mature cells, proliferating tumour cells including leukemia cells depend on glycolysis and mitochondrial respiration may be low even in oxygen–rich environments.The same signal transduction pathways that govern cell proliferation give instructions for nutrient uptake and co-regulate metabolic processes. In this manner, the metabolism of tumor cells, and other highly proliferating cells, is adapted to stimulate anabolic glycolysis–driven processes for incorporation of nutrients into nucleotides, amino acids and lipids to synthesize macromolecules required for growth and proliferation. We used a doxycycline–regulated Tet-On gene expression system to achieve controlled expression of MTG16. A noticeable finding was that the expression of genes for key glycolytic regulators involved in aerobic tumor cell glycolysis was diminished by MTG16. Total cellular RNA was extracted from Raji/MTG16 Tet-On 3G cells after 8 hours of incubation with 1 mg/ml doxycycline. Cells were collected in triplicates as biological replicates. Total RNA was isolated using the RNeasy mini kit. The quality of RNA was examined by Bioanalyzer.RevertAidTM was used for synthesis of first strand cDNA from 1mg RNA using random primers.Microarray analysis was performed using Affymetrix expression system at SCIBLU Genomics.
Project description:Time course of exponentially growing yeast cells Fermenting glucose in the presence of enough oxygen to support respiration, known as aerobic glycolysis, is believed to maximize growth rate. We observed increasing aerobic glycolysis during exponential growth, suggesting additional physiological roles for aerobic glycolysis. We investigated such roles in yeast batch cultures by quantifying O2 consumption, CO2 production, amino acids, mRNAs, proteins, posttranslational modifications, and stress sensitivity in the course of nine doublings at constant rate. During this course, the cells support a constant biomass-production rate with decreasing rates of respiration and ATP production but also decrease their stress resistance. As the respiration rate decreases, so do the levels of enzymes catalyzing rate-determining reactions of the tricarboxylic-acid cycle (providing NADH for respiration) and of mitochondrial folate-mediated NADPH production (required for oxidative defense). The findings demonstrate that exponential growth can represent not a single metabolic/physiological state but a continuum of changing states and that aerobic glycolysis can reduce the energy demands associated with respiratory metabolism and stress survival.