Inactivation Of Glyceraldehyde-3-phosphate Dehydrogenase Research Articles

Carbon dioxide/bicarbonate is required for sensitive inactivation of mammalian glyceraldehyde-3-phosphate dehydrogenase by hydrogen peroxide

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) contains an active site Cys and is one of the most sensitive cellular enzymes to oxidative inactivation and redox regulation. Here, we show that inactivation by hydrogen peroxide is strongly enhanced in the presence of carbon dioxide/bicarbonate. Inactivation of isolated mammalian GAPDH by H2O2 increased with increasing bicarbonate concentration and was sevenfold faster in 25 mM (physiological) bicarbonate compared with bicarbonate-free buffer of the same pH. H2O2 reacts reversibly with CO2 to form a more reactive oxidant, peroxymonocarbonate (HCO4-), which is most likely responsible for the enhanced inactivation. However, to account for the extent of enhancement, we propose that GAPDH must facilitate formation and/or targeting of HCO4- to promote its own inactivation. Inactivation of intracellular GAPDH was also strongly enhanced by bicarbonate: treatment of Jurkat cells with 20 µM H2O2 in 25 mM bicarbonate buffer for 5 min caused almost complete GAPDH inactivation, but no loss of activity when bicarbonate was not present. H2O2-dependent GAPDH inhibition in bicarbonate buffer was observed even in the presence of reduced peroxiredoxin 2 and there was a significant increase in cellular glyceraldehyde-3-phosphate/dihydroxyacetone phosphate. Our results identify an unrecognized role for bicarbonate in enabling H2O2 to influence inactivation of GAPDH and potentially reroute glucose metabolism from glycolysis to the pentose phosphate pathway and NAPDH production. They also demonstrate what could be wider interplay between CO2 and H2O2 in redox biology and the potential for variations in CO2 metabolism to influence oxidative responses and redox signaling.

The correlation between denaturation of glyceraldehyde-3-phosphate dehydrogenase and inactivation of Saccharomyces pastorianus cells by pressurized carbon dioxide microbubbles.

For the purpose of clarifying the relationship between pasteurization and inactivation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in Saccharomyces pastorianus cells induced by pressurized carbon dioxide microbubbles (CO2MB) treatment, a storage test of S. pastorianus cells after CO2MB treatment was conducted to ascertain their recovery, and the treatment condition in the inactivation of GAPDH in S. pastorianus cells by CO2MB was investigated. Each population of S. pastorianus for 48, 96, and 144h at 25°C was decreased significantly by CO2MB treatment at 35°C for 3min (MB35-3 and MB35-5) or at 40°C and 45°C for 1 and 3min (MB40-1, MB40-3, and MB45-1). In the storage test, recovery of treated cells was not observed after storage for 144h at 25°C. The denaturation of GAPDH in the S. pastorianus cells caused by the same treatment as the storage test was detected by using sodium dodecyl sulphate polyacrylamide gel electrophoresis. While the activities at MB35-1, MB35-3, and MB40-1 were significantly higher than those at non-treatment, and those at MB35-5, MB40-3, and MB45-1 were lower. Therefore, GAPDH denaturation, but not the activity, was associated with the inactivation of S. pastorianus cells.

The GAPDH redox switch safeguards reductive capacity and enables survival of stressed tumour cells

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is known to contain an active-site cysteine residue undergoing oxidation in response to hydrogen peroxide, leading to rapid inactivation of the enzyme. Here we show that human and mouse cells expressing a GAPDH mutant lacking this redox switch retain catalytic activity but are unable to stimulate the oxidative pentose phosphate pathway and enhance their reductive capacity. Specifically, we find that anchorage-independent growth of cells and spheroids is limited by an elevation of endogenous peroxide levels and is largely dependent on a functional GAPDH redox switch. Likewise, tumour growth in vivo is limited by peroxide stress and suppressed when the GAPDH redox switch is disabled in tumour cells. The induction of additional intratumoural oxidative stress by chemo- or radiotherapy synergized with the deactivation of the GAPDH redox switch. Mice lacking the GAPDH redox switch exhibit altered fatty acid metabolism in kidney and heart, apparently in compensation for the lack of the redox switch. Together, our findings demonstrate the physiological and pathophysiological relevance of oxidative GAPDH inactivation in mammals.

Mechanism of inactivation of glyceraldehyde-3-phosphate dehydrogenase in the presence of methylglyoxal

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is known to be one of the targets of methylglyoxal (MGO), a metabolite of glycolysis that increased in diabetes. However, the mechanism of GAPDH inactivation in the presence of MGO is unclear. The purpose of the work was to study the reaction of GAPDH with MGO and to identify the products of the reaction. It was shown that incubation of recombinant human GAPDH with MGO leads to irreversible inactivation of the enzyme, which is accompanied by a decrease in SH-group content by approximately 3.3 per tetramer GAPDH. MALDI-TOF MS analysis showed that the modification of GAPDH with MGO results in the oxidation of the catalytic cysteine residues (Cys152) to form cysteine-sulfinic acid. In addition, 2 arginine residues (R80 and R234) were identified that react with MGO to form hydroimidazolones. Incubation of SH-SY5Y neuroblastoma cells with MGO resulted in the inactivation of GAPDH and inhibition of glycolysis. The mechanism of GAPDH oxidation in the presence of MGO suggests the participation of superoxide anion, which is formed during the reaction of amino groups with methylglyoxal. The role of GAPDH in protection against the damaging effect of ROS in cells in the case of inefficiency of MGO removal by the GSH-dependent glyoxalase system is discussed.

α-Synuclein Overexpression in SH-SY5Y Human Neuroblastoma Cells Leads to the Accumulation of Thioflavin S-positive Aggregates and Impairment of Glycolysis.

Deterioration of energy metabolism in affected cells is an important feature of synucleinopathies, including Parkinson's disease. Here, we studied the association between α-synuclein accumulation and glycolysis using SH-SY5Y neuroblastoma cell lines stably expressing wild-type α-synuclein or its A53T mutant linked to the autosomal dominant form of the disease. Overexpression of both proteins led to the accumulation of thioflavin S-positive aggregates, more pronounced for α-synuclein A53T. It also caused changes in the cell energy metabolism manifested as a decrease in the lactate accumulation and glucose uptake. Impairments in glycolysis were also accompanied by a decrease in the activity of the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In vitro experiments with purified proteins indicated that GAPDH inactivation might be caused by its binding to the monomeric and oligomeric forms of α-synuclein. Therefore, a decrease in the GAPDH activity induced by its interaction with α-synuclein, might be one of the causes of glucose metabolism deterioration in synucleinopathies.

Inhibitors of Glyceraldehyde 3-Phosphate Dehydrogenase and Unexpected Effects of Its Reduced Activity.

The review describes the use of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) inhibitors to study the enzyme and to suppress its activity in various cell types. The main problem of selective GAPDH inhibition is a highly conserved nature of the enzyme active site and, especially, Cys150 environment important for the catalytic action of cysteine sulfhydryl group. Numerous attempts to find specific inhibitors of sperm GAPDH and enzymes from Trypanosoma sp. and Mycobacterium tuberculosis that would not inhibit GAPDH of somatic mammalian cells have failed, which has pushed researchers to search for new ways to solve this problem. The sections of the review are devoted to the studies of GAPDH inactivation by reactive oxygen species, glutathione, and glycating agents. The final section discusses possible effects of GAPDH inhibition and inactivation on glycolysis and related metabolic pathways (pentose phosphate pathway, uncoupling of the glycolytic oxidation and phosphorylation, etc.).

Comparison of protective properties of resveratrol and melatonin in the radiation inactivation and destruction of glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase

Purpose: This work investigates the effect of resveratrol and melatonin on structural and functional changes of two enzymes, lactate dehydrogenase (LDH) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), exposed to radiation-induced reactive oxygen species.Materials and methods: Solutions of dehydrogenases with or without antioxidants (resveratrol or melatonin) were irradiated with X-rays under the atmosphere of air and at room temperature (21 ± 2 °C). In order to determine the protective effect of melatonin and resveratrol in radiation-induced damage to GAPDH and LDH spectroscopy and HPLC methods were used. Furthermore, plausible binding sites of melatonin or resveratrol to the GAPDH or LDH molecule were analysed.Results and conclusions: Resveratrol shows better protective properties in the inactivation of GAPDH when compared to melatonin. LDH does not contain ‒SH groups in its active site, and is not inactivated by water radiolysis products other than hydroxyl radicals or the secondary radicals of the studied low-molecular-weight compounds. Resveratrol and melatonin protected the structure of LDH to a greater extent than GAPDH. This difference can be attributed to the fact that LDH potentially binds more resveratrol or melatonin molecules (27 binding sites for resveratrol and 40 for melatonin) than GAPDH (10 binding sites for resveratrol and 18 for melatonin).

Abstract CT163: A Phase Ib/II trial of high dose ascorbic acid (AA) + paclitaxel protein bound (PP) + cisplatin (C) + gemcitabine (G) in patients (pts) with metastatic pancreatic cancer (MPC)

Abstract Background Increasing evidence suggests that AA (vitamin C) can decrease the growth of aggressive tumors, including Ras-mutant tumors, by inducing oxidative stress (Chen et al. PNAS 2008; Yun et al. Science 2015; Shoenfeld et al. Cancer Cell 2017). Despite the potential to produce toxic radicals, high dose AA has generally been well tolerated in animals and humans, including in combination with chemotherapy. The reason for the cancer-specific toxicity of AA is incompletely understood. One possibility is that AA targets cancer cells due to their having larger labile iron pools. Another is that cancer cells selectively take up the oxidized form of AA, dehydroascorbate, via the GLUT1 glucose transporter, causing glutathione (GSH) depletion, intracellular ascorbate accumulation, inactivation of glyceraldehyde 3-phosphate dehydrogenase, and energetic crisis selectively in glycolytic, GLUT1-expressing cancer cells. Based on the unmet medical need in MPC, its high frequency of Ras mutations, and prior work combing PP + C + G showing promising results in 24 pts with MPC with a response rate of 70.5%, median survival 16.4 mos, [J Clin Oncol 35, 2017 (suppl 4S; abstract 341)], here we are exploring the addition of AA to PP + C + G. Methods This Phase Ib/II pilot trial utilizes a 3 + 3 design for dose escalation of AA. Primary objective(s): Phase Ib - to determine the maximum tolerated dose (MTD) of AA with PP + C + G; phase II - to determine the preliminary efficacy (disease control rate of CR+ PR+ SD x 18 weeks) of the combination with AA at MTD in pts with MPC. Exploratory objectives include analysis of tumor texture on radiologic scans as an imaging biomarker for response, biologic, pathologic and outcome measures; correlation between peak plasma levels of AA and response to treatment; potential biomarkers in the tumor including tumor immune cell infiltration, stromal activation, stem cell enumeration; changes in numbers of circulating tumor stem cells and macrophage lineage changes. #NCT03410030 Eligibility criteria include stage IV MPC, no prior treatment for MPC, ECOG 0 -1, and measurable disease. Excluded are pts with a G6PD deficiency, history of renal oxalate stones, or need of frequent capillary blood glucose monitoring as AA causes false low readings. Planned sample size is up to 24 pts in Phase Ib, up to 21 pts in Phase II. Doses are PP 125 mg/m2, G 1000 mg/m2, C 25 mg/ m2 on days 1 & 8 of a 21 day cycle. AA infusions are given on days 1, 3, 8, 10, 15, and 17 of a 21-day cycle. The AA dose for phase II will be determined in the Phase 1b study based on tolerability of AA at 25, 37.5, 56.25 or 75 gm/m2. Tumor tissue analysis will be done on pre and optional post treatment tumor biopsies. Trial opened to enrollment 4/2018. As of 1/2019, 5 pts have been treated in the AA 25 gm/m2 cohort. Supported by SU2C, Cancer Research UK, Lustgarten Foundation & Destroy Pancreatic Cancer Citation Format: Gayle S. Jameson, Erkut H. Borazanci, Joshua D. Rabinowitz, David Propper, Karen Ansaldo, Denise J. Roe, Daniel D. Von Hoff. A Phase Ib/II trial of high dose ascorbic acid (AA) + paclitaxel protein bound (PP) + cisplatin (C) + gemcitabine (G) in patients (pts) with metastatic pancreatic cancer (MPC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT163.

Glycation of α-synuclein amplifies the binding with glyceraldehyde-3-phosphate dehydrogenase.

α-Synuclein was recently found to interact with moonlighting glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) involved in neurodegenerative diseases development. In the present work, we have analyzed influence of α-synuclein glycation on this interaction, because the literature data suggest relation between diabetes and Parkinson's disease. According to zeta potential measurement, glycation can shift the charge of α-synuclein to more negative values that was pronounced in case of modification by glyceraldehyde-3-phosphate. We selected carboxymethyl lysine as a typical advanced glycation end product and performed molecular dynamics simulations. The binding was found to be electrostatically driven and was significantly amplified after α-synuclein glycation because of increase the number of acidic residues. Since the main binding site was located in the anion-binding groove, which comprises the active site of GAPDH, enhanced binding of α-synuclein can result in GAPDH inactivation. This hypothesis was proven experimentally. Glycation of α-synuclein resulted in increase of GAPDH inactivation, and this effect was more pronounced in case of modification by glyceraldehyde-3-phosphate. The obtained results can reflect the probable relations between protein glycation and neurodegenerative diseases.

Reserve Flux Capacity in the Pentose Phosphate Pathway Enables Escherichia coli's Rapid Response to Oxidative Stress.

To counteract oxidative stress and reactive oxygen species (ROS), bacteria evolved various mechanisms, primarily reducing ROS through antioxidant systems that utilize cofactor NADPH. Cells must stabilize NADPH levels by increasing flux through replenishing metabolic pathways like pentose phosphate (PP) pathway. Here, we investigate the mechanism enabling the rapid increase in NADPH supply by exposing Escherichia coli to hydrogen peroxide and quantifying the immediate metabolite dynamics. To systematically infer active regulatory interactions governing this response, we evaluated ensembles of kinetic models of glycolysis and PP pathway, each with different regulation mechanisms. Besides the known inactivation of glyceraldehyde 3-phosphate dehydrogenase by ROS, we reveal the important allosteric inhibition of the first PP pathway enzyme by NADPH. This NADPH feedback inhibition maintains a below maximum-capacity PP pathway flux under non-stress conditions. Relieving this inhibition instantly increases PP pathway flux upon oxidative stress. We demonstrate that reducing cells' capacity to rapidly reroute their flux through the PP pathway increases their oxidative stress sensitivity.

Binding of alpha-synuclein to partially oxidized glyceraldehyde-3-phosphate dehydrogenase induces subsequent inactivation of the enzyme

According to literature data, the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) co-localizes with alpha-synuclein in Lewy bodies in Parkinson's disease, which suggests the involvement of this protein in the development of synucleinopathies. The goal of the present work was to investigate the direct interaction between alpha-synuclein and GAPDH and to evaluate possible influence of this interaction on the catalytic properties of GAPDH. Molecular dynamic simulations predicted the binding of alpha-synuclein to the positively charged groove comprising NAD+-binding pocket of GAPDH. The formation of the complex between alpha-synuclein and GAPDH in vitro was confirmed by different experimental approaches. The binding of alpha-synuclein to GAPDH with partially oxidized active site cysteines resulted in the subsequent inactivation of the enzyme, decreased its thermostability and increased its propensity for aggregation. At the same time, the formation of the complex between GAPDH and monomeric alpha-synuclein prevented amyloid transformation of alpha-synuclein. This work presents the first evidence for the fact that the initial oxidation of GAPDH induces the binding of alpha-synuclein to the enzyme, leading to further inactivation of GAPDH and, as a consequence, inhibition of glycolysis. The described mechanism may contribute to the metabolic disorders that are characteristic for synucleinopathies.

Inactivation of glyceraldehyde-3-phosphate dehydrogenase by the dopamine metabolite, 3,4-dihydroxyphenylacetaldehyde

BackgroundThe aldehyde metabolite of dopamine, 3,4-dihydroxyphenylacetaldehyde (DOPAL) is an endogenous neurotoxin implicated in Parkinson's Disease. Elucidating protein targets of DOPAL is essential in understanding it's pathology. The enzyme, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a target of DOPAL. MethodsGAPDH activity was measured via reduction of NAD+ cofactor (340 nm). Protein aggregation was assessed with SDS-PAGE methods and specific modification via chemical probes. ResultsLow micromolar levels of DOPAL caused extensive GAPDH aggregation and irreversibly inhibited enzyme activity. The inactivation of GAPDH was dependent on both the catechol and aldehyde moieties of DOPAL. It is suggested that Cys are modified and oxidized by DOPAL. ConclusionsThe mechanism by which DOPAL modifies GAPDH can serve as a mechanistic explanation to the pathological events in Parkinson's Disease.

A novel moonlight function of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) for immunomodulation.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an energy metabolism-related enzyme, which generates NADH in glycolysis. Our previous study revealed a novel role of exogenous GAPDH in the amelioration of lipopolysaccharide (LPS)-induced sepsis-related, severe acute lung injury (ALI) in mice. Here, we show the effect of extracellular GAPDH on the physiological functions of macrophages, which play an important role in the onset of sepsis and ALI. GAPDH has no effect on cell viability, while it strongly suppressed cell adhesion, spreading, and phagocytic function of LPS-stimulated macrophages. GAPDH treatment significantly reduced tumor necrosis factor (TNF)-α, while it induced interleukin (IL)-10 production from LPS-stimulated macrophages in a dose-dependent manner. It is noteworthy that heat inactivation of GAPDH lost its immunomodulatory activity. Correspondingly, NADH significantly inhibited TNF-α and enhanced IL-10 production with elevation of both M1/M2 macrophage markers. These data suggest that extracellular GAPDH induces intermediate M1/M2 macrophages for termination of inflammation, partly through its enzyme activity for generation of NADH. © 2018 BioFactors, 44(6):597-608, 2018.

The glyceraldehyde-3-phosphate dehydrogenase GapDH of Corynebacterium diphtheriae is redox-controlled by protein S-mycothiolation under oxidative stress

Mycothiol (MSH) is the major low molecular weight (LMW) thiol in Actinomycetes and functions in post-translational thiol-modification by protein S-mycothiolation as emerging thiol-protection and redox-regulatory mechanism. Here, we have used shotgun-proteomics to identify 26 S-mycothiolated proteins in the pathogen Corynebacterium diphtheriae DSM43989 under hypochlorite stress that are involved in energy metabolism, amino acid and nucleotide biosynthesis, antioxidant functions and translation. The glyceraldehyde-3-phosphate dehydrogenase (GapDH) represents the most abundant S-mycothiolated protein that was modified at its active site Cys153 in vivo. Exposure of purified GapDH to H2O2 and NaOCl resulted in irreversible inactivation due to overoxidation of the active site in vitro. Treatment of GapDH with H2O2 or NaOCl in the presence of MSH resulted in S-mycothiolation and reversible GapDH inactivation in vitro which was faster compared to the overoxidation pathway. Reactivation of S-mycothiolated GapDH could be catalyzed by both, the Trx and the Mrx1 pathways in vitro, but demycothiolation by Mrx1 was faster compared to Trx. In summary, we show here that S-mycothiolation can function in redox-regulation and protection of the GapDH active site against overoxidation in C. diphtheriae which can be reversed by both, the Mrx1 and Trx pathways.

Featured Article: Pyruvate preserves antiglycation defenses in porcine brain after cardiac arrest.

Cardiac arrest (CA) and cardiocerebral resuscitation (CCR)-induced ischemia-reperfusion imposes oxidative and carbonyl stress that injures the brain. The ischemic shift to anaerobic glycolysis, combined with oxyradical inactivation of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), provokes excessive formation of the powerful glycating agent, methylglyoxal. The glyoxalase (GLO) system, comprising the enzymes glyoxalase 1 (GLO1) and GLO2, utilizes reduced glutathione (GSH) supplied by glutathione reductase (GR) to detoxify methylglyoxal resulting in reduced protein glycation. Pyruvate, a natural antioxidant that augments GSH redox status, could sustain the GLO system in the face of ischemia-reperfusion. This study assessed the impact of CA-CCR on the cerebral GLO system and pyruvate's ability to preserve this neuroprotective system following CA. Domestic swine were subjected to 10 min CA, 4 min closed-chest CCR, defibrillation and 4 h recovery, or to a non-CA sham protocol. Sodium pyruvate or NaCl control was infused (0.1 mmol/kg/min, intravenous) throughout CCR and the first 60 min recovery. Protein glycation, GLO1 content, and activities of GLO1, GR, and GAPDH were analyzed in frontal cortex biopsied at 4 h recovery. CA-CCR produced marked protein glycation which was attenuated by pyruvate treatment. GLO1, GR, and GAPDH activities fell by 86, 55, and 30%, respectively, after CA-CCR with NaCl infusion. Pyruvate prevented inactivation of all three enzymes. CA-CCR sharply lowered GLO1 monomer content with commensurate formation of higher molecular weight immunoreactivity; pyruvate preserved GLO1 monomers. Thus, ischemia-reperfusion imposed by CA-CCR disabled the brain's antiglycation defenses. Pyruvate preserved these enzyme systems that protect the brain from glycation stress. Impact statement Recent studies have demonstrated a pivotal role of protein glycation in brain injury. Methylglyoxal, a by-product of glycolysis and a powerful glycating agent in brain, is detoxified by the glutathione-catalyzed glyoxalase (GLO) system, but the impact of cardiac arrest (CA) and cardiocerebral resuscitation (CCR) on the brain's antiglycation defenses is unknown. This study in a swine model of CA and CCR demonstrated for the first time that the intense cerebral ischemia-reperfusion imposed by CA-resuscitation disabled glyoxalase-1 and glutathione reductase (GR), the source of glutathione for methylglyoxal detoxification. Moreover, intravenous administration of pyruvate, a redox-active intermediary metabolite and antioxidant in brain, prevented inactivation of glyoxalase-1 and GR and blunted protein glycation in cerebral cortex. These findings in a large mammal are first evidence of GLO inactivation and the resultant cerebral protein glycation after CA-resuscitation, and identify novel actions of pyruvate to minimize protein glycation in postischemic brain.

Molecular association of glucose-6-phosphate isomerase and pyruvate kinase M2 with glyceraldehyde-3-phosphate dehydrogenase in cancer cells.

BackgroundFor a long time cancer cells are known for increased uptake of glucose and its metabolization through glycolysis. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a key regulatory enzyme of this pathway and can produce ATP through oxidative level of phosphorylation. Previously, we reported that GAPDH purified from a variety of malignant tissues, but not from normal tissues, was strongly inactivated by a normal metabolite, methylglyoxal (MG). Molecular mechanism behind MG mediated GAPDH inhibition in cancer cells is not well understood.MethodsGAPDH was purified from Ehrlich ascites carcinoma (EAC) cells based on its enzymatic activity. GAPDH associated proteins in EAC cells and 3-methylcholanthrene (3MC) induced mouse tumor tissue were detected by mass spectrometry analysis and immunoprecipitation (IP) experiment, respectively. Interacting domains of GAPDH and its associated proteins were assessed by in silico molecular docking analysis. Mechanism of MG mediated GAPDH inactivation in cancer cells was evaluated by measuring enzyme activity, Circular dichroism (CD) spectroscopy, IP and mass spectrometry analyses.ResultHere, we report that GAPDH is associated with glucose-6-phosphate isomerase (GPI) and pyruvate kinase M2 (PKM2) in Ehrlich ascites carcinoma (EAC) cells and also in 3-methylcholanthrene (3MC) induced mouse tumor tissue. Molecular docking analyses suggest C-terminal domain preference for the interaction between GAPDH and GPI. However, both C and N termini of PKM2 might be interacting with the C terminal domain of GAPDH. Expression of both PKM2 and GPI is increased in 3MC induced tumor compared with the normal tissue. In presence of 1 mM MG, association of GAPDH with PKM2 or GPI is not perturbed, but the enzymatic activity of GAPDH is reduced to 26.8 ± 5 % in 3MC induced tumor and 57.8 ± 2.3 % in EAC cells. Treatment of MG to purified GAPDH complex leads to glycation at R399 residue of PKM2 only, and changes the secondary structure of the protein complex.ConclusionPKM2 may regulate the enzymatic activity of GAPDH. Increased enzymatic activity of GAPDH in tumor cells may be attributed to its association with PKM2 and GPI. Association of GAPDH with PKM2 and GPI could be a signature for cancer cells. Glycation at R399 of PKM2 and changes in the secondary structure of GAPDH complex could be one of the mechanisms by which GAPDH activity is inhibited in tumor cells by MG.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2172-x) contains supplementary material, which is available to authorized users.

Radicalization of Glyceraldehyde-3-Phosphate Dehydrogenase by HOCl in Living Cells

A number of post-translational oxidative modifications of the enzyme “cell-redox sensor” glyceraldehyde-3- phosphate dehydrogenase (GAPDH) have been reported. These modifications affect GAPDH structure, function, and cell fate; however no free-radical mechanisms have been reported in these processes. Herein we used the nitrone 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-based spin trapping techniques to examine a novel free radical mechanism that causes GAPDH inactivation and aggregation in RAW264.7 cells primed with lipopolysaccharide (LPS). In these primed cells, GAPDH is oxidized by myeloperoxidase (MPO)-derived hypochlorous acid (HOCl) resulting in loss of enzyme activity and aggregation, accumulation of lactate and cell death. Due to the close spatial and physical proximity between MPO and GAPDH, and the oxidizing potential of HOCl, it may be the main species that triggers radicalization of GAPDH that ultimately results in enzyme aggregation and inactivation in LPS-primed macrophages. Lysine residues are the primary radicalization sites formed upon reaction of HOCl with the enzyme. Our data highlight the important relationship between radicalization of GAPDH and fate of stressed cells, which might help teasing out the cell response to stress at sites of inflammation.

Analysis of Potential Binding Sites of 3,5,4'-Trihydroxystilbene (Resveratrol) and trans-3,3',5,5'-Tetrahydroxy-4'-methoxystilbene (THMS) to the GAPDH Molecule Using a Computational Ligand-Docking Method: Structural and Functional Changes in GAPDH Induced by the Examined Polyphenols.

The presented study analyzed potential binding sites of 3,5,4'-trihydroxystilbene (resveratrol, RSV) and its derivative, trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene (THMS) to glyceraldehyde 3-phosphate dehydrogenase (GAPDH). The effects of stilbene analogs on the structure of GAPDH were determined by fluorescence spectroscopy and ζ potential measurements. To what extent the studied compounds affect the activity of the enzyme was also assessed. A computational ligand-docking study showed that there are 11 potential binding sites of RSV and 8 such sites of THMS in the GAPDH molecule. While resveratrol does not significantly affect the activity of the dehydrogenase upon binding to it, THMS leads to approximately 10% inactivation of this enzyme. THMS has no effect on GAPDH inactivation induced by the superoxide anion radical, in contrast to resveratrol, which increases dehydrogenase inactivation.

3-bromopyruvate inhibits glycolysis, depletes cellular glutathione, and compromises the viability of cultured primary rat astrocytes.

The pyruvate analogue 3-bromopyruvate (3-BP) is an electrophilic alkylator that is considered a promising anticancer drug because it has been shown to kill cancer cells efficiently while having little toxic effect on nontumor cells. To test for potential adverse effects of 3-BP on brain cells, we exposed cultured primary rat astrocytes to 3-BP and investigated the effects of this compound on cell viability, glucose metabolism, and glutathione (GSH) content. The presence of 3-BP severely compromised cell viability and slowed cellular glucose consumption and lactate production in a time- and concentration-dependent manner, with half-maximal effects observed at about 100 µM 3-BP after 4 hr of incubation. The cellular hexokinase activity was not affected in 3-BP-treated astrocytes, whereas within 30 min after application of 3-BP the activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was inhibited, and cellular GSH content was depleted in a concentration-dependent manner, with half-maximal effects observed at about 30 µM 3-BP. The depletion of cellular GSH after exposure to 100 µM 3-BP was not prevented by the presence of 10 mM of the monocarboxylates lactate or pyruvate, suggesting that 3-BP is not taken up into astrocytes predominantly by monocarboxylate transporters. The data suggest that inhibition of glycolysis by inactivation of GAPDH and GSH depletion contributes to the toxicity that was observed for 3-BP-treated cultured astrocytes.

Steady-state hydrogen peroxide induces glycolysis in Staphylococcus aureus and Pseudomonas aeruginosa.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from human pathogens Staphylococcus aureus and Pseudomonas aeruginosa can be readily inhibited by reactive oxygen species (ROS)-mediated direct oxidation of their catalytic active cysteines. Because of the rapid degradation of H2O2 by bacterial catalase, only steady-state but not one-dose treatment with H2O2 rapidly induces glycolysis and the pentose phosphate pathway (PPP). We conducted transcriptome sequencing (RNA-seq) analyses to globally profile the bacterial transcriptomes in response to a steady level of H2O2, which revealed profound transcriptional changes, including the induced expression of glycolytic genes in both bacteria. Our results revealed that the inactivation of GAPDH by H2O2 induces metabolic levels of glycolysis and the PPP; the elevated levels of fructose 1,6-biphosphate (FBP) and 2-keto-3-deoxy-6-phosphogluconate (KDPG) lead to dissociation of their corresponding glycolytic repressors (GapR and HexR, respectively) from their cognate promoters, thus resulting in derepression of the glycolytic genes to overcome H2O2-stalled glycolysis in S. aureus and P. aeruginosa, respectively. Both GapR and HexR may directly sense oxidative stresses, such as menadione.