Browse
Submit Data
Databases
API
Help

Dataset Information

24 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Assessing the pentose phosphate pathway using [2, 3-13 C2 ]glucose.

ABSTRACT: The pentose phosphate pathway (PPP) is essential for reductive biosynthesis, antioxidant processes and nucleotide production. Common tracers such as [1,2-13 C2 ]glucose rely on detection of 13 C in lactate and require assumptions to correct natural 13 C abundance. Here, we introduce a novel and specific tracer of the PPP, [2,3-13 C2 ]glucose. 13 C NMR analysis of the resulting isotopomers is informative because [1,2-13 C2 ]lactate arises from glycolysis and [2,3-13 C2 ]lactate arises exclusively through the PPP. A correction for natural abundance is unnecessary. In rats receiving [2,3-13 C2 ]glucose, the PPP was more active in the fed versus fasted state in the liver and the heart, consistent with increased expression of key enzymes in the PPP. Both the PPP and glycolysis were substantially increased in hepatoma compared with liver. In summary, [2,3-13 C2 ]glucose and 13 C NMR simplify assessment of the PPP.

SUBMITTER: Lee MH

PROVIDER: S-EPMC6525052 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Assessing the pentose phosphate pathway using [2, 3-13 C2 ]glucose.

Lee Min Hee MH Malloy Craig R CR Corbin Ian R IR Li Junjie J Jin Eunsook S ES

NMR in biomedicine 20190329 6

The pentose phosphate pathway (PPP) is essential for reductive biosynthesis, antioxidant processes and nucleotide production. Common tracers such as [1,2-13 C2 ]glucose rely on detection of 13 C in lactate and require assumptions to correct natural 13 C abundance. Here, we introduce a novel and specific tracer of the PPP, [2,3-13 C2 ]glucose. 13 C NMR analysis of the resulting isotopomers is informative because [1,2-<su ...[more]

PMID: 30924572

Similar Datasets

Glycolysis and the pentose phosphate pathway after human traumatic brain injury: microdialysis studies using 1,2-(13)C2 glucose.

Project description:Increased 'anaerobic' glucose metabolism is observed after traumatic brain injury (TBI) attributed to increased glycolysis. An alternative route is the pentose phosphate pathway (PPP), which generates putatively protective and reparative molecules. To compare pathways we employed microdialysis to perfuse 1,2-(13)C2 glucose into the brains of 15 TBI patients and macroscopically normal brain in six patients undergoing surgery for benign tumors, and to simultaneously collect products for nuclear magnetic resonance (NMR) analysis. (13)C enrichment for glycolytic 2,3-(13)C2 lactate was the median 5.4% (interquartile range (IQR) 4.6-7.5%) in TBI brain and 4.2% (2.4-4.4%) in 'normal' brain (P<0.01). The ratio of PPP-derived 3-(13)C lactate to glycolytic 2,3-(13)C2 lactate was median 4.9% (3.6-8.2%) in TBI brain and 6.7% (6.3-8.9%) in 'normal' brain. An inverse relationship was seen for PPP-glycolytic lactate ratio versus PbtO2 (r=-0.5, P=0.04) in TBI brain. Thus, glycolytic lactate production was significantly greater in TBI than 'normal' brain. Several TBI patients exhibited PPP-lactate elevation above the 'normal' range. There was proportionally greater PPP-derived lactate production with decreasing PbtO2. The study raises questions about the roles of the PPP and glycolysis after TBI, and whether they can be manipulated to achieve a better outcome. This study is the first direct comparison of glycolysis and PPP in human brain.

| S-EPMC4294402 | biostudies-literature

Multiple independent fusions of glucose-6-phosphate dehydrogenase with enzymes in the pentose phosphate pathway.

Project description:Fusions of the first two enzymes in the pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconolactonase (6PGL), have been previously described in two distant clades, chordates and species of the malarial parasite Plasmodium. We have analyzed genome and expressed sequence data from a variety of organisms to identify the origins of these gene fusion events. Based on the orientation of the domains and range of species in which homologs can be found, the fusions appear to have occurred independently, near the base of the metazoan and apicomplexan lineages. Only one of the two metazoan paralogs of G6PD is fused, showing that the fusion occurred after a duplication event, which we have traced back to an ancestor of choanoflagellates and metazoans. The Plasmodium genes are known to contain a functionally important insertion that is not seen in the other apicomplexan fusions, highlighting this as a unique characteristic of this group. Surprisingly, our search revealed two additional fusion events, one that combined 6PGL and G6PD in an ancestor of the protozoan parasites Trichomonas and Giardia, and another fusing G6PD with phosphogluconate dehydrogenase (6PGD) in a species of diatoms. This study extends the range of species known to contain fusions in the pentose phosphate pathway to many new medically and economically important organisms.

| S-EPMC3148214 | biostudies-literature

Glial glucose fuels the neuronal pentose phosphate pathway for long-term memory.

Project description:Brain function relies almost solely on glucose as an energy substrate. The main model of brain metabolism proposes that glucose is taken up and converted into lactate by astrocytes to fuel the energy-demanding neuronal activity underlying plasticity and memory. Whether direct neuronal glucose uptake is required for memory formation remains elusive. We uncover, in Drosophila, a mechanism of glucose shuttling to neurons from cortex glia, an exclusively perisomatic glial subtype, upon formation of olfactory long-term memory (LTM). In vivo imaging reveals that, downstream of cholinergic activation of cortex glia, autocrine insulin signaling increases glucose concentration in glia. Glucose is then transferred from glia to the neuronal somata in the olfactory memory center to fuel the pentose phosphate pathway and allow LTM formation. In contrast, our results indicate that the increase in neuronal glucose metabolism, although crucial for LTM formation, is not routed to glycolysis.

| S-EPMC8411112 | biostudies-literature

Hyperpolarized δ-[1-13 C]gluconolactone as a probe of the pentose phosphate pathway.

Project description:The pentose phosphate pathway (PPP) is thought to be upregulated in trauma (to produce excess NADPH) and in cancer (to provide ribose for nucleotide biosynthesis), but simple methods for detecting changes in flux through this pathway are not available. MRI of hyperpolarized 13 C-enriched metabolites offers considerable potential as a rapid, non-invasive tool for detecting changes in metabolic fluxes. In this study, hyperpolarized δ-[1-13 C]gluconolactone was used as a probe to detect flux through the oxidative portion of the pentose phosphate pathway (PPPox ) in isolated perfused mouse livers. The appearance of hyperpolarized (HP) H13 CO3- within seconds after exposure of livers to HP-δ-[1-13 C]gluconolactone demonstrates that this probe rapidly enters hepatocytes, becomes phosphorylated, and enters the PPPox pathway to produce HP-H13 CO3- after three enzyme catalyzed steps (6P-gluconolactonase, 6-phosphogluconate dehydrogenase, and carbonic anhydrase). Livers perfused with octanoate as their sole energy source show no change in production of H13 CO3- after exposure to low levels of H2 O2 , while livers perfused with glucose and insulin showed a twofold increase in H13 CO3- after exposure to peroxide. This indicates that flux through the PPPox is stimulated by H2 O2 in glucose perfused livers but not in livers perfused with octanoate alone. Subsequent perfusion of livers with non-polarized [1,2-13 C]glucose followed by 1 H NMR analysis of lactate in the perfusate verified that flux through the PPPox is indeed low in healthy livers and modestly higher in peroxide damaged livers. We conclude that hyperpolarized δ-[1-13 C]gluconolactone has the potential to serve as a metabolic imaging probe of this important biological pathway.

| S-EPMC5502806 | biostudies-literature

Bayesian 13C-Metabolic Flux Analysis of Parallel Tracer Experiments in Granulocytes: A Directional Shift within the Non-Oxidative Pentose Phosphate Pathway Supports Phagocytosis.

Project description:The pentose phosphate pathway (PPP) plays a key role in the cellular regulation of immune function; however, little is known about the interplay of metabolic adjustments in granulocytes, especially regarding the non-oxidative PPP. For the determination of metabolic mechanisms within glucose metabolism, we propose a novel set of measures for 13C-metabolic flux analysis based on ex vivo parallel tracer experiments ([1,2-13C]glucose, [U-13C]glucose, [4,5,6-13C]glucose) and gas chromatography-mass spectrometry labeling measurements of intracellular metabolites, such as sugar phosphates and their fragments. A detailed constraint analysis showed that the permission range for net and irreversible fluxes was limited to a three-dimensional space. The overall workflow, including its Bayesian flux estimation, resulted in precise flux distributions and pairwise confidence intervals, some of which could be represented as a line due to the strength of their correlation. The principal component analysis that was enabled by these behaviors comprised three components that explained 99.6% of the data variance. It showed that phagocytic stimulation reversed the direction of non-oxidative PPP net fluxes from ribose-5-phosphate biosynthesis toward glycolytic pathways. This process was closely associated with the up-regulation of the oxidative PPP to promote the oxidative burst.

| S-EPMC10820746 | biostudies-literature

Reduced methylation of PFKFB3 in cancer cells shunts glucose towards the pentose phosphate pathway.

Project description:Haem oxygenase (HO)-1/carbon monoxide (CO) protects cancer cells from oxidative stress, but the gas-responsive signalling mechanisms remain unknown. Here we show using metabolomics that CO-sensitive methylation of PFKFB3, an enzyme producing fructose 2,6-bisphosphate (F-2,6-BP), serves as a switch to activate phosphofructokinase-1, a rate-limiting glycolytic enzyme. In human leukaemia U937 cells, PFKFB3 is asymmetrically di-methylated at R131 and R134 through modification by protein arginine methyltransferase 1. HO-1 induction or CO results in reduced methylation of PFKFB3 in varied cancer cells to suppress F-2,6-BP, shifting glucose utilization from glycolysis toward the pentose phosphate pathway. Loss of PFKFB3 methylation depends on the inhibitory effects of CO on haem-containing cystathionine β-synthase (CBS). CBS modulates remethylation metabolism, and increases NADPH to supply reduced glutathione, protecting cells from oxidative stress and anti-cancer reagents. Once the methylation of PFKFB3 is reduced, the protein undergoes polyubiquitination and is degraded in the proteasome. These results suggest that the CO/CBS-dependent regulation of PFKFB3 methylation determines directional glucose utilization to ensure resistance against oxidative stress for cancer cell survival.

| S-EPMC3959213 | biostudies-literature

Ex Vivo 13C-Metabolic Flux Analysis of Porcine Circulating Immune Cells Reveals Cell Type-Specific Metabolic Patterns and Sex Differences in the Pentose Phosphate Pathway.

Project description:In general, females present with stronger immune responses than males, but scarce data are available on sex-specific differences in immunometabolism. In this study, we characterized porcine peripheral blood mononuclear cell (PBMC) and granulocyte energy metabolism using a Bayesian 13C-metabolic flux analysis, which allowed precise determination of the glycolytic, pentose phosphate pathway (PPP), and tricarboxylic acid cycle (TCA) fluxes, together with an assessment of the superoxide anion radical (O2•-) production and mitochondrial O2 consumption. A principal component analysis allowed for identifying the cell type-specific patterns of metabolic plasticity. PBMCs displayed higher TCA cycle activity, especially glutamine-derived aspartate biosynthesis, which was directly related to mitochondrial respiratory activity and inversely related to O2•- production. In contrast, the granulocytes mainly utilized glucose via glycolysis, which was coupled to oxidative PPP utilization and O2•- production rates. The granulocytes of the males had higher oxidative PPP fluxes compared to the females, while the PBMCs of the females displayed higher non-oxidative PPP fluxes compared to the males associated with the T helper cell (CD3+CD4+) subpopulation of PBMCs. The observed sex-specific differences were not directly attributable to sex steroid plasma levels, but we detected an inverse correlation between testosterone and aldosterone plasma levels and showed that aldosterone levels were related with non-oxidative PPP fluxes of both cell types.

| S-EPMC10813356 | biostudies-literature

Queueing theory model of pentose phosphate pathway.

Project description:Due to its role in maintaining the proper functioning of the cell, the pentose phosphate pathway (PPP) is one of the most important metabolic pathways. It is responsible for regulating the concentration of simple sugars and provides precursors for the synthesis of amino acids and nucleotides. In addition, it plays a critical role in maintaining an adequate level of NADPH, which is necessary for the cell to fight oxidative stress. These reasons prompted the authors to develop a computational model, based on queueing theory, capable of simulating changes in PPP metabolites' concentrations. The model has been validated with empirical data from tumor cells. The obtained results prove the stability and accuracy of the model. By applying queueing theory, this model can be further expanded to include successive metabolic pathways. The use of the model may accelerate research on new drugs, reduce drug costs, and reduce the reliance on laboratory animals necessary for this type of research on which new methods are tested.

| S-EPMC8930976 | biostudies-literature

Convergent synthesis of 13N-labelled Peptidic structures using aqueous [13N]NH3.

Project description:BackgroundNitrogen-13 has a 10-min half-life which places time constraints on the complexity of viable synthetic methods for its incorporation into PET imaging agents. In exploring ways to overcome this limitation, we have used the Ugi reaction to develop a rapid one-pot method for radiolabelling peptidic molecules using [13N]NH3 as a synthetic precursor.MethodsCarrier-added [13N]NH3 (50 μL) was added to a solution of carboxylic acid, aldehyde, and isocyanide in 2,2,2-TFE (200 μL). The mixture was heated in a microwave synthesiser at 120 °C for 10 min. Reactions were analysed by radio-HPLC and radio-LCMS. Isolation of the target 13N-labelled peptidic Ugi compound was achieved via semi-preparative radio-HPLC as demonstrated for Ugi1.ResultsRadio-HPLC analysis of each reaction confirmed the formation of radioactive products co-eluting with their respective reference standards with radiochemical yields of the crude products ranging from 11% to 23%. Two cyclic γ-lactam structures were also achieved via intra-molecular reactions. Additional radioactive by-products observed in the radio-chromatogram were identified as 13N-labelled di-imines formed from the reaction of [13N]NH3 with two isocyanide molecules. The desired 13N-labelled Ugi product was isolated using semi-preparative HPLC.ConclusionWe have developed a one-pot method that opens up new routes to radiolabel complex, peptidic molecules with 13N using aqueous [13N]NH3 as a synthetic precursor.

| S-EPMC5824707 | biostudies-literature

A new inhibitor of glucose-6-phosphate dehydrogenase blocks pentose phosphate pathway and suppresses malignant proliferation and metastasis in vivo.

Project description:Pentose phosphate pathway (PPP) is a major glucose metabolism pathway, which has a fundamental role in cancer growth and metastasis. Even though PPP blockade has been pointed out as a very promising strategy against cancer, effective anti-PPP agents are not still available in the clinical setting. Here we demonstrate that the natural molecule polydatin inhibits glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of PPP. Polydatin blocks G6PD causing accumulation of reactive oxygen species and strong increase of endoplasmic reticulum stress. These effects are followed by cell cycle block in S phase, an about 50% of apoptosis, and 60% inhibition of invasion in vitro. Accordingly, in an orthotopic metastatic model of tongue cancer, 100 mg/kg polydatin induced an about 30% tumor size reduction with an about 80% inhibition of lymph node metastases and 50% reduction of lymph node size (p < 0.005). Polydatin is not toxic in animals up to a dose of 200 mg/kg and a phase II clinical trial shows that it is also well tolerated in humans (40 mg twice a day for 90 days). Thus, polydatin may be used as a reliable tool to limit human cancer growth and metastatic spread.

| S-EPMC5951921 | biostudies-literature