Levels Of Glycolytic Intermediates Research Articles

Abstract A039: Metabolic evolution in breast cancer predicts organ-specific metastasis

Abstract The metastatic cascade is a critical component of cancer evolution. Understanding the rewired metabolism in organ-specific metastasis in breast cancer could help identify strategies to improve the treatment and prevention of metastatic disease. Here, we used a systems biology approach to assess the evolution of metabolic fluxes from parental breast cancer cells to their brain- and lung-homing metastatic derivatives. We found that divergent lineages had distinct, heritable metabolic fluxes. Lung-homing cells maintained adaptations for high glycolytic flux despite low levels of glycolytic intermediates, constitutively activating a pathway sink into lactate. This exacerbated Warburg effect –– stronger than the Warburg effect in the primary tumor –– was associated with a high ratio of lactate dehydrogenase (LDH) to pyruvate dehydrogenase (PDH) expression, a signature which correlated with lung metastasis in patients with breast cancer. While feature classification models trained on clinical characteristics alone were unable to predict tropism, the LDH/PDH ratio was a significant predictor of a patient's future metastasis to the lung but not to other organs, independent of other transcriptomic signatures. Lung- and brain-homing lineages had differential selection patterns in acidic metabolic microenvironments. High lactate efflux was also a trait in lung-homing metastatic pancreatic cancer cells, suggesting that lactate production may be a convergent phenotype in lung metastasis. Together, these analyses highlight the essential role that metabolic evolution plays in organ-specific cancer metastasis and identify a putative biomarker for predicting lung metastasis in breast cancer patients. Citation Format: Deepti Mathur, Chen Liao, Wendy Lin, Alessandro La Ferlita, Salvatore Alaimo, Samuel Taylor, Yi Zhong, Christine Iacobuzio-Donahue, Alfredo Ferro, Joao Xavier. Metabolic evolution in breast cancer predicts organ-specific metastasis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr A039.

Hexokinase-linked glycolytic overload and unscheduled glycolysis in hyperglycemia-induced pathogenesis of insulin resistance, beta-cell glucotoxicity, and diabetic vascular complications.

Hyperglycemia is a risk factor for the development of insulin resistance, beta-cell glucotoxicity, and vascular complications of diabetes. We propose the hypothesis, hexokinase-linked glycolytic overload and unscheduled glycolysis, in explanation. Hexokinases (HKs) catalyze the first step of glucose metabolism. Increased flux of glucose metabolism through glycolysis gated by HKs, when occurring without concomitant increased activity of glycolytic enzymes-unscheduled glycolysis-produces increased levels of glycolytic intermediates with overspill into effector pathways of cell dysfunction and pathogenesis. HK1 is saturated with glucose in euglycemia and, where it is the major HK, provides for basal glycolytic flux without glycolytic overload. HK2 has similar saturation characteristics, except that, in persistent hyperglycemia, it is stabilized to proteolysis by high intracellular glucose concentration, increasing HK activity and initiating glycolytic overload and unscheduled glycolysis. This drives the development of vascular complications of diabetes. Similar HK2-linked unscheduled glycolysis in skeletal muscle and adipose tissue in impaired fasting glucose drives the development of peripheral insulin resistance. Glucokinase (GCK or HK4)-linked glycolytic overload and unscheduled glycolysis occurs in persistent hyperglycemia in hepatocytes and beta-cells, contributing to hepatic insulin resistance and beta-cell glucotoxicity, leading to the development of type 2 diabetes. Downstream effector pathways of HK-linked unscheduled glycolysis are mitochondrial dysfunction and increased reactive oxygen species (ROS) formation; activation of hexosamine, protein kinase c, and dicarbonyl stress pathways; and increased Mlx/Mondo A signaling. Mitochondrial dysfunction and increased ROS was proposed as the initiator of metabolic dysfunction in hyperglycemia, but it is rather one of the multiple downstream effector pathways. Correction of HK2 dysregulation is proposed as a novel therapeutic target. Pharmacotherapy addressing it corrected insulin resistance in overweight and obese subjects in clinical trial. Overall, the damaging effects of hyperglycemia are a consequence of HK-gated increased flux of glucose metabolism without increased glycolytic enzyme activities to accommodate it.

Platelet Metabolic Profiling Reveals Glycolytic and 1-Carbon Metabolites Are Essential for GP VI-Stimulated Human Platelets-Brief Report.

Evolving evidence suggests that besides signaling pathways, platelet activation involves a complex interplay between metabolic pathways to support thrombus growth. Selective targeting of metabolic checkpoints may inhibit platelet activation and provide a novel antiplatelet strategy. We, therefore, examined global metabolic changes that occur during the transition of human platelets from resting to an activated state to identify metabolites and associated pathways that contribute to platelet activation. We performed metabolic profiling of resting and convulxin-stimulated human platelet samples. The differential levels, pathway analysis, and PCA (principal component analysis) were performed using Metaboanalyst. Metascape was used for metabolite network construction. Of the 401 metabolites identified, 202 metabolites were significantly upregulated, and 2 metabolites were downregulated in activated platelets. Of all the metabolites, lipids scored highly and constituted ≈50% of the identification. During activation, aerobic glycolysis supports energy demand and provides glycolytic intermediates required by metabolic pathways. Consistent with this, an important category of metabolites was carbohydrates, particularly the glycolysis intermediates that were significantly upregulated compared with resting platelets. We found that lysophospholipids such as 1-palmitoyl-GPA (glycero-3-phosphatidic acid), 1-stearoyl-GPS (glycero-3-phosphoserine), 1-palmitoyl-GPI (glycerophosphoinositol), 1-stearoyl-GPI, and 1-oleoyl-GPI were upregulated in activated platelets. We speculated that platelet activation could be linked to 1-carbon metabolism, a set of biochemical pathways that involve the transfer and use of 1-carbon units from amino acids, for cellular processes, including nucleotide and lysophospholipid synthesis. In alignment, based on pathway enrichment and network-based prioritization, the metabolites from amino acid metabolism, including serine, glutamate, and branched-chain amino acid pathway were upregulated in activated platelets, which might be supplemented by the high levels of glycolytic intermediates. Metabolic analysis of resting and activated platelets revealed that glycolysis and 1-carbon metabolism are necessary to support platelet activation.

Abstract 19037: Metabolomics Reveals Aerobic Glycolysis and 1-Carbon Metabolism as Major Metabolic Signature During Human Platelet Activation

Introduction: Evolving evidence suggests that besides signaling pathways, platelet activation involve a complex interplay between metabolic pathways to support thrombus growth. Selective targeting of metabolic checkpoints may inhibit platelet activation and provide a novel antiplatelet strategy. We examined global metabolic changes that occur during the transition of human platelets from resting to an activated state to identify metabolites and associated pathways that contribute to platelet activation. Methods: We performed metabolic profiling (through Metabolon Inc.) of resting and stimulated human platelet samples. The differential levels analysis, pathway analysis, and PCA were performed using Metaboanalyst. Metascape was used for metabolite network construction. Results: Of the 401 metabolites identified, 202 metabolites were significantly upregulated, and two metabolites were downregulated in activated platelets. Of all the metabolites, lipids scored highly and constituted ~50% of the identification. During activation, aerobic glycolysis supports energy demand and provides glycolytic intermediates required by metabolic pathways. Consistent with this, an important category of metabolites was carbohydrates, particularly the glycolysis intermediates that were significantly upregulated compared to resting platelets. We found that lysophospholipids such as 1-palmitoyl-GPA, 1-stearoyl-GPS, 1-palmitoyl-GPI, 1-stearoyl-GPI, 1-oleoyl-GPI were upregulated in activated platelets. We speculated that platelet activation could be linked to One-carbon (1C) metabolism, a set of biochemical pathways that involve transfer and use of 1C units from amino acids, for cellular processes, including nucleotide and lysophospholipid synthesis. In alignment, based on pathway enrichment and network-based prioritization, the metabolites from amino acid metabolism, including serine, glutamate, and branched-chain amino acids pathway were upregulated in activated platelets, which might be supplemented by the high levels of glycolytic intermediates. Conclusions: Metabolic analysis of resting and activated platelets revealed that aerobic glycolysis and 1-C carbon metabolism are vital to support platelet activation.

Abstract 4254: The ratio of key metabolic transcripts is a predictive biomarker of breast cancer metastasis to the lung

Abstract Understanding the rewired metabolism of organ-specific metastasis in breast cancer is an under-appreciated problem, with implications for the treatment and prevention of metastatic disease. Here, we used a systems biology approach and the MDA-MB 231 model to compare metabolic fluxes used by parental breast cancer cells and their brain- and lung-homing derivatives. We combined metabolomic profiling, flux measurements, spatial tissue mimetic systems, and mathematical modeling to dissect the cells’ metabolic rewiring, and identified changes specific for lung metastatic selection. We validated our results in other cell lines as well as patient data from project GENIE and the MBCP. Our results produced five biological insights: First, levels of mRNA and metabolic intermediates may anticorrelate with flux. Second, different lineages evolved from the same line can have distinct heritable metabolic fluxes. Metastatic lineages in our model display higher glycolytic flux and bioenergetics than parental cells, with lung-homing cells exhibiting by far the greatest glucose uptake and lactate production. Importantly, this occurs despite low levels of glycolytic intermediates in lung-homing cells. Third, this apparent paradox can be reconciled if feedback inhibition of the glycolysis pathway is prevented, a finding we modeled with flux-balance analysis and confirmed by 13C glucose tracing and measuring glycolytic enzymatic activities directly. Fourth, this distinct metabolic behavior in lung-homing cells is maintained by a high ratio of lactate dehydrogenase (LDH) to pyruvate dehydrogenase (PDH) gene expression, which also correlates with lung metastases in patients with breast cancer. Feature classification models trained on clinical characteristics alone were unable to predict tropism; however, the LDH/PDH ratio was a significant predictor for lung but not brain metastases, independent of other transcriptomic signatures, suggesting that this feature is a potential biomarker for lung metastasis. Fifth, this metabolic effect did not increase cellular growth rate, suggesting that lactate secretion may itself be a trait under selection in breast cancer lung metastasis. Follow up experiments and game theory-based models in a spatially structured tissue-mimetic system showed that lung-homing cells grow more favorably than brain-homing cells in nutrient-deprived gradients, demonstrating how divergent metabolisms of the lineages could lead to selection in different environments. Notably, lung metastases in a mouse model of pancreatic cancer had higher lactate production than other metastases, suggesting that this metabolic trait could be important for other cancer types. Together, our in vitro, in silico, and clinical data analyses highlight that metabolism—currency of all physiological processes—plays an essential role in the connection from gene to phenotype in metastatic disease. Citation Format: Deepti Mathur, Chen Liao, Wendy Lin, Alessandro La Ferlita, Salvatore Alaimo, Alfredo Ferro, Yi Zhong, Christine Iacobuzio-Donahue, Joao Xavier. The ratio of key metabolic transcripts is a predictive biomarker of breast cancer metastasis to the lung. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4254.

The multiple effects of REG1 deletion and SNF1 overexpression improved the production of S-adenosyl-l-methionine in Saccharomyces cerevisiae

BackgroundSaccharomyces cerevisiae is often used as a cell factory for the production of S-adenosyl-l-methionine (SAM) for diverse pharmaceutical applications. However, SAM production by S. cerevisiae is negatively influenced by glucose repression, which is regulated by a serine/threonine kinase SNF1 complex. Here, a strategy of alleviating glucose repression by deleting REG1 (encodes the regulatory subunit of protein phosphatase 1) and overexpressing SNF1 (encodes the catalytic subunit of the SNF1 complex) was applied to improve SAM production in S. cerevisiae. SAM production, growth conditions, glucose consumption, ethanol accumulation, lifespan, glycolysis and amino acid metabolism were analyzed in the mutant strains.ResultsThe results showed that the multiple effects of REG1 deletion and/or SNF1 overexpression exhibited a great potential for improving the SAM production in yeast. Enhanced the expression levels of genes involved in glucose transport and glycolysis, which improved the glucose utilization and then elevated the levels of glycolytic intermediates. The expression levels of ACS1 (encoding acetyl-CoA synthase I) and ALD6 (encoding aldehyde dehydrogenase), and the activity of alcohol dehydrogenase II (ADH2) were enhanced especially in the presence of excessive glucose levels, which probably promoted the conversion of ethanol in fermentation broth into acetyl-CoA. The gene expressions involved in sulfur-containing amino acids were also enhanced for the precursor amino acid biosynthesis. In addition, the lifespan of yeast was extended by REG1 deletion and/or SNF1 overexpression. As expected, the final SAM yield of the mutant YREG1ΔPSNF1 reached 8.28 g/L in a 10-L fermenter, which was 51.6% higher than the yield of the parent strain S. cerevisiae CGMCC 2842.ConclusionThis study showed that the multiple effects of REG1 deletion and SNF1 overexpression improved SAM production in S. cerevisiae, providing new insight into the application of the SNF1 complex to abolish glucose repression and redirect carbon flux to nonethanol products in S. cerevisiae.

Pathophysiological Changes in Erythrocytes Contributing to Complications of Inflammation and Coagulation in COVID-19.

Higher thrombotic burden in the acute phase of COVID-19 relies on a complex interplay between pro-inflammatory cytokine/chemokine release, increased endothelial dysfunction/damage, and potential sepsis-induced coagulopathy development in severe cases, all promoting coagulation activation. Plasma levels of cytokines and chemokines are known to be increased in COVID-19 however, are much higher in severe infections. Increased levels of IL-1β, IL-6, and IL-8 are known to play an important role in both acute and chronic inflammation, resulting in pathological clotting. However, little has been published on the effects of these interleukins on red blood cells (RBCs). Evidence shows that cytokines have a negative effect on the RBCs ultrastructure and introduce signs of eryptosis. Eryptosis can be described as a form of suicidal death of RBCs characterized by distinct findings of cell shrinkage, membrane blebbing, activation of proteases, and phosphatidylserine exposure at the outer membrane leaflet. Red blood cells from COVID-19 patients had increased levels of glycolytic intermediates, accompanied by oxidation and fragmentation of ankyrin, spectrin beta, and the N-terminal cytosolic domain of band 3 (AE1). Significantly altered lipid metabolism was also observed, in particular, short- and medium-chain saturated fatty acids, acyl-carnitines, and sphingolipids. Emerging research suggests that RBCs may contribute to a precision medicine approach to sepsis and have diagnostic value in monitoring complement dysregulation in COVID-19-sepsis and non-COVID sepsis as research indicates that complement activation products and viral antigens are present on RBCs in patients with COVID-19.

Metabolic Changes Induced by Cerebral Ischemia, the Effect of Ischemic Preconditioning, and Hyperhomocysteinemia.

1H Nuclear Magnetic Resonance (NMR) metabolomics is one of the fundamental tools in the fast-developing metabolomics field. It identifies and quantifies the most abundant metabolites, alterations of which can describe energy metabolism, activated immune response, protein synthesis and catabolism, neurotransmission, and many other factors. This paper summarizes our results of the 1H NMR metabolomics approach to characterize the distribution of relevant metabolites and their alterations induced by cerebral ischemic injury or its combination with hyperhomocysteinemia in the affected tissue and blood plasma in rodents. A decrease in the neurotransmitter pool in the brain tissue likely follows the disordered feasibility of post-ischemic neurotransmission. This decline is balanced by the increased tissue glutamine level with the detected impact on neuronal health. The ischemic injury was also manifested in the metabolomic alterations in blood plasma with the decreased levels of glycolytic intermediates, as well as a post-ischemically induced ketosis-like state with increased plasma ketone bodies. As the 3-hydroxybutyrate can act as a likely neuroprotectant, its post-ischemic increase can suggest its supporting role in balancing ischemic metabolic dysregulation. Furthermore, the 1H NMR approach revealed post-ischemically increased 3-hydroxybutyrate in the remote organs, such as the liver and heart, as well as decreased myocardial glutamate. Ischemic preconditioning, as a proposed protective strategy, was manifested in a lower extent of metabolomic changes and/or their faster recovery in a longitudinal study. The paper also summarizes the pre- and post-ischemic metabolomic changes in the rat hyperhomocysteinemic models. Animals are challenged with hyperglycemia and ketosis-like state. A decrease in several amino acids in plasma follows the onset and progression of hippocampal neuropathology when combined with ischemic injury. The 1H NMR metabolomics approach also offers a high potential for metabolites in discriminatory analysis in the search for potential biomarkers of ischemic injury. Based on our results and the literature data, this paper presents valuable findings applicable in clinical studies and suggests the precaution of a high protein diet, especially foods which are high in Met content and low in B vitamins, in the possible risk of human cerebrovascular neuropathology.

Mutations in the Hemoglobin Binding Domain of Band 3 Perturb Cellular Metabolism and Alter the Sickling of SS Erythrocytes

▪Under oxygenated conditions, 4 glycolytic enzymes that perform the terminal steps of glycolysis (phospho-fructoKinase [PFK], lactate dehydrogenase [LDH], aldolase [ALD] and glygeraldehyde 3 phosphate dehydrogenase [GAPDH]) bind to the cytoplasmic domain of band 3. Under deoxy conditions deoxy hemoglobin (Hb) is bound to band 3 and PFK, LDH, ALD and GAPDH are displaced (Campanella et al. PNAS 102, 2005; Blood 112, 2008). We generated transgenic mice in which the sequence encoding the first 35 amino acids of the wild type human band 3 cytoplasmic domain replaced the endogenous mouse band 3 sequences in the Slc4a1 gene, a mutant line in which human amino acids 12-21 were deleted removing the deoxy Hb binding site (-Hb) and a third line in which amino acids 1-11 were deleted creating a high affinity binding site for deoxyHb (++Hb). Erythrocytes from the mutant lines were insensitive to Oxygen concentration resulting in changes in oxygen dependent deformability and other physical properties compared to the wild type line (Chu et al. Blood 128, 2016, Zheng et al. JBC 294, 2019, Zhou et al. Sci. Adv. 5, 2019).We crossed our humanized band 3 mouse strains to the Townes Sickle Cell Disease (SCD) mouse model, maintaining both the human βA and βS alleles to generate human AA, AS and SS mice homozygous for each of the human band 3 cytoplasmic domain sequences. Using an assay in which SS red cells in phosphate buffer are deoxygenated to 6% oxygen over time (Dunkelberger et al., J. Phys. Chem. B 122, 2018), we observed that -Hb band 3/SS mice showed an accelerated rate of sickle cell formation and a higher percent of sickled cells than wild type band 3/SS mice (p<0.01). Conversely, ++Hb band 3/SS mice showed an inhibition of both the rate of sickling and the precent of sickled cells compared to wild type band 3/SS mice (p<0.05).We hypothesized that the inability of the glycolytic enzymes to reversibly bind to band 3 in the mutant mice were responsible for the differences in sickling. To test this hypothesis, we analyzed a panel of 28 cellular metabolites in 12 mice (6 female, 6 male) of each genotype: wild type band 3/AA, -AS and -SS, -Hb band 3/AA, -AS, -SS and ++Hb/AA, -AS, -SS. The metabolites were quantified by LC-MS/MS using an API 4500 triple quadrupole mass spectrometer (AB Sciex), with chromatographic resolution enabled on a polymeric amino column (apHera by Supelco) under alkaline mobile phase conditions (pH ~9.3). Stable isotope dilution and 8pt calibration curves allowed the absolute quantification of each metabolite.Consistent with the constitutive binding of the terminal glycolytic enzymes to band 3 in -Hb erythrocytes, glycolysis was inhibited after the phosphoenol pyruvate step, as evidenced by significant accumulation of the intermediates at top of the glycolysis pathway, including fructose 1,6 biphosphate (FBP; p<0.01), dihydroxyacetone phosphate/ glyceraldehyde-3-phosphate (G3P; p<0.01), and 3-phosphoglycerate/2-phosphoglycerate (PG; p<0.01). In the ++Hb mutant where the terminal glycolytic enzymes are constitutively displaced from band 3, significantly lower levels of FBP, G3P and PG were observed (p<0.01). The levels of these metabolites in wild type band 3/SS erythrocytes were intermediate between the two mutant strains.We hypothesized that the accumulation of FBP, G3P and PG contributed to the increased rate of sickling in the -Hb band 3/SS mice. To test this, we incubated wild type band 3/SS cells with either FBP or PG. Both intermediates increased the rate of sickle cell formation and percentage of sickled cells in a dose dependent fashion with no alteration in any RBC indices including MCV and osmotic fragility. We next hypothesized that reduction of the levels of glycolytic intermediates would have an antisickling effect. To test this, we incubated wild type band 3/SS cells with 2,3 diphosphoglycerol (DPG), which is a potent inhibitor of glycolysis. We found that DPG treatment led to a dose dependent decrease in the rate of sickle cell formation and percentage of sickled cells, again with no alteration in any RBC indices including MCV and osmotic fragility.We conclude that the accumulation of glycolytic intermediates leads to increased sickle cell formation. We propose that reduction in the levels of glycolytic intermediates either by accelerating the terminal stages of glycolysis or by redirection to the pentose phosphate pathway may offer a means to treat SCD. DisclosuresNo relevant conflicts of interest to declare.

Two transition states of the glycogen shunt and two steady states of gene expression support metabolic flexibility and the Warburg effect in cancer.

Previously we suggested that the early Warburg effect can be explained by the use by cancer cells the glycogen shunt during a rapid increase in glucose concentration. In analogy to the Crabtree effect in yeast, the shunt plays a critical role in maintaining homeostasis of glycolytic intermediate levels during these transitions. We extend this analysis here, and propose that the recently appreciated flexibility of cancer cell glucose and glycogen metabolism involves 4 metabolic states that we recently identified in metabolic control analysis studies of yeast. Under stable conditions of low glucose and normal O2 yeast, and by analogy cancer, cells are in the Respiration State in which through gene expression for oxidizing non glucose substrates. When their environment changes to high glucose with reduced O2 levels, such as occur in tumors, they transition to the Glycolysis State due to gene expression of new glycolytic enzyme isoforms such as PKM2. These isoforms optimize metabolism to sustain the Warburg effect. When the changes in glucose and O2 levels are rapid there may be insufficient time for gene expression to adapt. The metabolic flexibility conferred by 2 states of the glycogen shunt allow the cells to survive these transitions. The model explains experimental observations in cancer such as the function of the glycogen shunt and the frequent expression of PKM2 in cells undergoing the Warburg Effect. A surprising conclusion is that the function of PKM2 is to maintain glycolytic intermediate homeostasis rather than controlling the glycolytic flux. The glycogen shunt may also have an important role in cancer metabolic reprogramming by allowing cancer cells to survive large glucose and oxygen changes during the selection of mutations that lead to the Warburg phenotype

The Emerging Role of Pyruvate Kinase M2 in Regulating Glutaminolysis via c-Myc

The dimer form Pyruvate kinase M2 (PKM2) possesses lower glycolytic ability compared to its terameter form. This is of great importance for cancer cells since dimer PKM2 increases the levels of glycolytic intermediates for cell proliferation and growth.

Increasing glycolysis by deletion of kcs1 and arg82 improved S-adenosyl-l-methionine production in Saccharomyces cerevisiae

Reprogramming glycolysis for directing glycolytic metabolites to a specific metabolic pathway is expected to be useful for increasing microbial production of certain metabolites, such as amino acids, lipids or considerable secondary metabolites. In this report, a strategy of increasing glycolysis by altering the metabolism of inositol pyrophosphates (IPs) for improving the production of S-adenosyl-l-methionine (SAM) for diverse pharmaceutical applications in yeast is presented. The genes associated with the metabolism of IPs, arg82, ipk1 and kcs1, were deleted, respectively, in the yeast strain Saccharomyces cerevisiae CGMCC 2842. It was observed that the deletions of kcs1 and arg82 increased SAM by 83.3 % and 31.8 %, respectively, compared to that of the control. In addition to the improved transcription levels of various glycolytic genes and activities of the relative enzymes, the levels of glycolytic intermediates and ATP were also enhanced. To further confirm the feasibility, the kcs1 was deleted in the high SAM-producing strain Ymls1ΔGAPmK which was deleted malate synthase gene mls1 and co-expressed the Acetyl-CoA synthase gene acs2 and the SAM synthase gene metK1 from Leishmania infantum, to obtain the recombinant strain Ymls1Δkcs1ΔGAPmK. The level of SAM in Ymls1Δkcs1ΔGAPmK reached 2.89 g L−1 in a 250-mL flask and 8.86 g L−1 in a 10-L fermentation tank, increasing 30.2 % and 46.2 %, respectively, compared to those levels in Ymls1ΔGAPmK. The strategy of increasing glycolysis by deletion of kcs1 and arg82 improved SAM production in yeast.

Acrylamide inhibits autophagy, induces apoptosis and alters cellular metabolic profiles

Acrylamide (ACR) is generated during thermal processing of carbohydrate-rich foods at high temperature and can directly enter the body through ingestion, inhalation and skin contact. The toxicity of ACR has been widely studied. The main results of these studies show that exposure to ACR can cause neurotoxicity in both animals and humans, and show reproductive toxicity and carcinogenicity in rodent animal models. However, the mechanism of toxicity of ACR has not been studied by metabolomics approaches, and the effect of ACR on autophagy remains unknown. Here, U2OS cell were treated with ACR 6 and 24 h and collected for further study. We have demonstrated that ACR inhibited autophagic flux, and increased ROS content. Accumulation of ROS resulted in increase of apoptosis rates and secretion of inflammatory factors. In addition, significant differences in metabolic profiles were observed between ACR treated and control cells according to multiple analysis models. A total of 73 key differential metabolites were identified. They were involved in multiple metabolic pathways. Among them, exposure to ACR caused glycolysis/gluconeogenesis attenuation by decreasing levels of glycolytic intermediates, reduced the rate of the TCA cycle, while elevating levels of several amino acid metabolites and lipid metabolites. In summary, our study provides useful evidence of cytotoxicity caused by ACR via metabolomics and multiple bioanalytic methods.

Evidence of Structural Protein Damage and Membrane Lipid Remodeling in Red Blood Cells from COVID-19 Patients.

The SARS-CoV-2 beta coronavirus is the etiological driver of COVID-19 disease, which is primarily characterized by shortness of breath, persistent dry cough, and fever. Because they transport oxygen, red blood cells (RBCs) may play a role in the severity of hypoxemia in COVID-19 patients. The present study combines state-of-the-art metabolomics, proteomics, and lipidomics approaches to investigate the impact of COVID-19 on RBCs from 23 healthy subjects and 29 molecularly diagnosed COVID-19 patients. RBCs from COVID-19 patients had increased levels of glycolytic intermediates, accompanied by oxidation and fragmentation of ankyrin, spectrin beta, and the N-terminal cytosolic domain of band 3 (AE1). Significantly altered lipid metabolism was also observed, in particular, short- and medium-chain saturated fatty acids, acyl-carnitines, and sphingolipids. Nonetheless, there were no alterations of clinical hematological parameters, such as RBC count, hematocrit, or mean corpuscular hemoglobin concentration, with only minor increases in mean corpuscular volume. Taken together, these results suggest a significant impact of SARS-CoV-2 infection on RBC structural membrane homeostasis at the protein and lipid levels. Increases in RBC glycolytic metabolites are consistent with a theoretically improved capacity of hemoglobin to off-load oxygen as a function of allosteric modulation by high-energy phosphate compounds, perhaps to counteract COVID-19-induced hypoxia. Conversely, because the N-terminus of AE1 stabilizes deoxyhemoglobin and finely tunes oxygen off-loading and metabolic rewiring toward the hexose monophosphate shunt, RBCs from COVID-19 patients may be less capable of responding to environmental variations in hemoglobin oxygen saturation/oxidant stress when traveling from the lungs to peripheral capillaries and vice versa.

Valproate inhibits mitochondrial bioenergetics and increases glycolysis in Saccharomyces cerevisiae

The widely used mood stabilizer valproate (VPA) causes perturbation of energy metabolism, which is implicated in both the therapeutic mechanism of action of the drug as well as drug toxicity. To gain insight into these mechanisms, we determined the effects of VPA on energy metabolism in yeast. VPA treatment increased levels of glycolytic intermediates, increased expression of glycolysis genes, and increased ethanol production. Increased glycolysis was likely a response to perturbation of mitochondrial function, as reflected in decreased membrane potential and oxygen consumption. Interestingly, yeast, mouse liver, and isolated bovine cytochrome c oxidase were directly inhibited by the drug, while activities of other oxidative phosphorylation complexes (III and V) were not affected. These findings have implications for mechanisms of therapeutic action and toxicity.

Drosophila TRIM32 cooperates with glycolytic enzymes to promote cell growth

Cell growth and/or proliferation may require the reprogramming of metabolic pathways, whereby a switch from oxidative to glycolytic metabolism diverts glycolytic intermediates towards anabolic pathways. Herein, we identify a novel role for TRIM32 in the maintenance of glycolytic flux mediated by biochemical interactions with the glycolytic enzymes Aldolase and Phosphoglycerate mutase. Loss of Drosophila TRIM32, encoded by thin (tn), shows reduced levels of glycolytic intermediates and amino acids. This altered metabolic profile correlates with a reduction in the size of glycolytic larval muscle and brain tissue. Consistent with a role for metabolic intermediates in glycolysis-driven biomass production, dietary amino acid supplementation in tn mutants improves muscle mass. Remarkably, TRIM32 is also required for ectopic growth - loss of TRIM32 in a wing disc-associated tumor model reduces glycolytic metabolism and restricts growth. Overall, our results reveal a novel role for TRIM32 for controlling glycolysis in the context of both normal development and tumor growth.

Nutritional ketosis improves exercise metabolism in patients with very long-chain acyl-CoA dehydrogenase deficiency.

A maladaptive shift from fat to carbohydrate (CHO) oxidation during exercise is thought to underlie myopathy and exercise‐induced rhabdomyolysis in patients with fatty acid oxidation (FAO) disorders. We hypothesised that ingestion of a ketone ester (KE) drink prior to exercise could serve as an alternative oxidative substrate supply to boost muscular ATP homeostasis. To establish a rational basis for therapeutic use of KE supplementation in FAO, we tested this hypothesis in patients deficient in Very Long‐Chain acyl‐CoA Dehydrogenase (VLCAD). Five patients (range 17‐45 y; 4 M/1F) patients were included in an investigator‐initiated, randomised, blinded, placebo‐controlled, 2‐way cross‐over study. Patients drank either a KE + CHO mix or an isocaloric CHO equivalent and performed 35 minutes upright cycling followed by 10 minutes supine cycling inside a Magnetic Resonance scanner at individual maximal FAO work rate (fatmax; approximately 40% VO2max). The protocol was repeated after a 1‐week interval with the alternate drink. Primary outcome measures were quadriceps phosphocreatine (PCr), Pi and pH dynamics during exercise and recovery assayed by in vivo 31P‐MR spectroscopy. Secondary outcomes included plasma and muscle metabolites and respiratory gas exchange recordings. Ingestion of KE rapidly induced mild ketosis and increased muscle BHB content. During exercise at FATMAX, VLCADD‐specific plasma acylcarnitine levels, quadriceps glycolytic intermediate levels and in vivo Pi/PCr ratio were all lower in KE + CHO than CHO. These results provide a rational basis for future clinical trials of synthetic ketone ester supplementation therapy in patients with FAO disorders.Trial registration: ClinicalTrials.gov. Protocol ID: NCT03531554; METC2014.492; ABR51222.042.14.

Oxygen Regulates Human Pluripotent Stem Cell Metabolic Flux.

Metabolism has been shown to alter cell fate in human pluripotent stem cells (hPSC). However, current understanding is almost exclusively based on work performed at 20% oxygen (air), with very few studies reporting on hPSC at physiological oxygen (5%). In this study, we integrated metabolic, transcriptomic, and epigenetic data to elucidate the impact of oxygen on hPSC. Using 13C-glucose labeling, we show that 5% oxygen increased the intracellular levels of glycolytic intermediates, glycogen, and the antioxidant response in hPSC. In contrast, 20% oxygen increased metabolite flux through the TCA cycle, activity of mitochondria, and ATP production. Acetylation of H3K9 and H3K27 was elevated at 5% oxygen while H3K27 trimethylation was decreased, conforming to a more open chromatin structure. RNA-seq analysis of 5% oxygen hPSC also indicated increases in glycolysis, lysine demethylases, and glucose-derived carbon metabolism, while increased methyltransferase and cell cycle activity was indicated at 20% oxygen. Our findings show that oxygen drives metabolite flux and specifies carbon fate in hPSC and, although the mechanism remains to be elucidated, oxygen was shown to alter methyltransferase and demethylase activity and the global epigenetic landscape.

Effects of Acute Cold Stress on Liver O-GlcNAcylation and Glycometabolism in Mice.

Protein O-linked β-N-acetylglucosamine glycosylation (O-GlcNAcylation) regulates many biological processes. Studies have shown that O-GlcNAc modification levels can increase during acute stress and suggested that this may contribute to the survival of the cell. This study investigated the possible effects of O-GlcNAcylation that regulate glucose metabolism, apoptosis, and autophagy in the liver after acute cold stress. Male C57BL/6 mice were exposed to cold conditions (4 °C) for 0, 2, 4, and 6 h, then their livers were extracted and the expression of proteins involved in glucose metabolism, apoptosis, and autophagy was determined. It was found that acute cold stress increased global O-GlcNAcylation and protein kinase B (AKT) phosphorylation levels. This was accompanied by significantly increased activation levels of the glucose metabolism regulators 160 kDa AKT substrate (AS160), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 (PFKFB2), and glycogen synthase kinase-3β (GSK3β). The levels of glycolytic intermediates, fructose-1,6-diphosphate (FDP) and pyruvic acid (PA), were found to show a brief increase followed by a sharp decrease. Additionally, adenosine triphosphate (ATP), as the main cellular energy source, had a sharp increase. Furthermore, the B-cell lymphoma 2(Bcl-2)/Bcl-2-associated X (Bax) ratio was found to increase, whereas cysteine-aspartic acid protease 3 (caspase-3) and light chain 3-II (LC3-II) levels were reduced after acute cold stress. Therefore, acute cold stress was found to increase O-GlcNAc modification levels, which may have resulted in the decrease of the essential processes of apoptosis and autophagy, promoting cell survival, while altering glycose transport, glycogen synthesis, and glycolysis in the liver.

Identifying metabolic elements that contribute to productivity of 1-propanol bioproduction using metabolomic analysis.

Previously constructed Escherichia coli strains that produce 1-propanol use the native threonine pathway, or a heterologous citramalate pathway. However, based on the energy and cofactor requirements of each pathway, a combination of the two pathways produces synergistic effects that increase the theoretical maximum yield with a simultaneous unexplained increase in productivity. Identification of key factors that contribute to synergistic effect leading to 1-propanol yield and productivity improvement in E. coli with native threonine pathway and heterologous citramalate pathway. A combination of snapshot metabolomic profiling and dynamic metabolic turnover analysis were used to identify system-wide perturbations that contribute to the productivity improvement. In the presence of both pathways, increased glucose consumption and elevated levels of glycolytic intermediates are attributed to an elevated phosphoenolpyruvate (PEP)/pyruvate ratio that is known to increase the function of the native phosphotransferase. Turnover analysis of nitrogen containing byproducts reveals that ammonia assimilation, required for the threonine pathway, is streamlined when provided with an NAD(P)H surplus in the presence of the citramalate pathway. Our study illustrates the application of metabolomics in identification of factors that alter cellular physiology for improvement of 1-propanol bioproduction.