Showing papers on "Methylglyoxal published in 2019"

Oxidative Damage and Antioxidant Defense in Sesamum indicum after Different Waterlogging Durations

Abstract: The present study was designed to investigate the duration-dependent changes in the biochemical attributes of sesame in response to waterlogging stress. Sesame plants (Sesamum indicum L. cv. BARI Til-4) were subjected to waterlogging for 2, 4, 6, and 8 days during the vegetative stage and data were measured following waterlogging treatment. The present study proves that waterlogging causes severe damage to different attributes of the sesame plant. The plants showed an increasing trend in lipid peroxidation as well as hydrogen peroxide (H2O2) and methylglyoxal contents that corresponded to increased stress duration. A prolonged period of waterlogging decreased leaf relative water content and proline content. Photosynthetic pigments, like chlorophyll (chl) a, b, and chl (a+b) and carotenoid contents, also decreased over time in stressed plants. Glutathione (GSH) and oxidized glutathione (GSSG) contents increased under waterlogging, while the GSH/GSSG ratio and ascorbate content decreased, indicating the disruption of redox balance in the cell. Ascorbate peroxidase, monodehydroascorbate reductase, and glutathione peroxidase activity increased under waterlogging, while dehydroascorbate reductase, glutathione reductase, and catalase activity mostly decreased. Waterlogging modulated the glyoxalase system mostly by enhancing glyoxalase II activity, with a slight increase in glyoxalase I activity. The present study also demonstrates the induction of oxidative stress via waterlogging in sesame plants and that stress levels increase with increased waterlogging duration.

Activation of the unfolded protein response in high glucose treated endothelial cells is mediated by methylglyoxal

Abstract: Metabolic dysfunction of endothelial cells in hyperglycemia contributes to the development of vascular complications of diabetes where increased reactive glycating agent, methylglyoxal (MG), is involved. We assessed if increased MG glycation induced proteotoxic stress, identifying related metabolic drivers and protein targets. Human aortal endothelial cells (HAECs) were incubated in high glucose concentration (20 mM versus 5 mM control) in vitro for 3–6 days. Flux of glucose metabolism, MG formation and glycation and changes in cytosolic protein abundances, MG modification and proteotoxic responses were assessed. Similar studies were performed with human microvascular endothelial HMEC-1 cells where similar outcomes were observed. HAECs exposed to high glucose concentration showed increased cellular concentration of MG (2.27 ± 0.21 versus 1.28 ± 0.03 pmol/106 cells, P < 0.01) and formation of MG-modified proteins (24.0 ± 3.7 versus 14.1 ± 3.2 pmol/106 cells/day; P < 0.001). In proteomics analysis, high glucose concentration increased proteins of the heat shock response – indicating activation of the unfolded protein response (UPR) with downstream inflammatory and pro-thrombotic responses. Proteins susceptible to MG modification were enriched in protein folding, protein synthesis, serine/threonine kinase signalling, glycolysis and gluconeogenesis. MG was increased in high glucose by increased flux of MG formation linked to increased glucose metabolism mediated by proteolytic stabilisation and increase of hexokinase-2 (HK-2); later potentiated by proteolytic down regulation of glyoxalase 1 (Glo1) - the major enzyme of MG metabolism. Silencing of Glo1, selectively increasing MG, activated the UPR similarly. Silencing of HK-2 prevented increased glucose metabolism and MG formation. trans-Resveratrol and hesperetin combination (tRES-HESP) corrected increased MG and glucose metabolism by increasing expression of Glo1 and decreasing expression of HK-2. Increased MG glycation activates the UPR in endothelial cells and thereby may contribute to endothelial cell dysfunction in diabetic vascular disease where tRES-HESP may provide effective therapy.

Exogenous Nitric Oxide Mitigates Nickel-Induced Oxidative Damage in Eggplant by Upregulating Antioxidants, Osmolyte Metabolism, and Glyoxalase Systems

Abstract: Nitric oxide (NO) at optimal levels is considered beneficial to plant functioning. The present study was carried out to investigate the role of exogenously applied NO (100 and 150 µM sodium nitropurusside, SNP) in amelioration of nickel (Ni)-mediated oxidative effects in eggplant. Ni stress declined growth and biomass production, relative water content (RWC), and chlorophyll pigment synthesis, thereby affecting the photosynthetic efficiency. Exogenously applied SNP proved beneficial in mitigating the Ni-mediated growth restrictions. NO-treated seedlings exhibited improved photosynthesis, stomatal conductance, and chlorophyll content with the effect of being apparent at lower concentration (100 µM SNP). SNP upregulated the antioxidant system mitigating the oxidative damage on membranes due to Ni stress. The activity of superoxide dismutase, catalase, glutathione S-transferase, ascorbate peroxidase, and glutathione reductase was upregulated due to SNP which also increased the ascorbate and reduced glutathione content. SNP-supplied seedlings also showed higher proline and glycine betaine accumulation, thereby improving RWC and antioxidant system. Glyoxalase I activity was induced due to SNP application declining the accumulation of methylglyoxal. NO-mediated mitigation of Ni toxicity was confirmed using NO scavenger (PTIO, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), which reversed the influence of SNP almost entirely on the parameters studied. Uptake of nitrogen (N), potassium (K), and calcium (Ca) was increased due to SNP application and Ni was reduced significantly. Therefore, this study revealed the efficiency of exogenous SNP in enhancing Ni stress tolerance through upregulating antioxidant and glyoxalase systems.

Silicon-induced antioxidant defense and methylglyoxal detoxification works coordinately in alleviating nickel toxicity in Oryza sativa L.

Abstract: Nickel (Ni), an essential nutrient of plant but very toxic to plant at supra-optimal concentration that causes inhibition of seed germination emergence and growth of plants as a consequence of physiological disorders. Hence, the present study investigates the possible mechanisms of Ni tolerance in rice seedlings by exogenous application of silicon (Si). Thirteen-day-old hydroponically grown rice (Oryza sativa L. cv. BRRI dhan54) were treated with Ni (NiSO4.7H2O, 0.25 and 0.5 mM) sole or in combination with 0.50 mM Na2SiO3 for a period of 3 days to investigate the effect of Si supply for revoking the Ni stress. Nickel toxicity gave rise to reactive oxygen species (ROS) and cytotoxic methylglyoxal (MG), accordingly, initiated oxidative stress in rice leaves, and accelerated peroxidation of lipids and consequent damage to membranes. Reduced growth, biomass accumulation, chlorophyll (chl) content, and water balance under Ni-stress were also found. However, free proline (Pro) content increased in Ni-exposed plants. In contrast, the Ni-stressed seedlings fed with supplemental Si reclaimed the seedlings from chlorosis, water retrenchment, growth inhibition, and oxidative stress. Silicon up-regulated most of the antioxidant defense components as well as glyoxalase systems, which helped to improve ROS scavenging and MG detoxification. Hence, these results suggest that the exogenous Si application can improve rice seedlings’ tolerance to Ni-toxicity.

Melatonin enhances thermotolerance of maize seedlings ( Zea mays L.) by modulating antioxidant defense, methylglyoxal detoxification, and osmoregulation systems

Abstract: Melatonin (MT), derived from tryptophan, is an amazing signaling molecule with multiple functions in plants. Heat stress (HS) induced by high temperature is a major stress factor that limits metabolism, growth, development, and productivity of plants. However, whether MT could enhance the thermotolerance of maize seedlings and the underlying mechanisms is not completely known. In this study, treatment of maize seedlings with MT enhanced the survival percentage of maize seedlings under HS conditions, mitigated an increase in malondialdehyde (MDA, product of membrane lipid peroxidation) and electrolyte leakage, and improved tissue vitality compared with the control without MT treatment, indicating that MT treatment could enhance the theromotolerance of maize seedlings. To understand the mechanisms underlying MT-enhanced thermotolerance of maize seedlings, the antioxidant defense (guaiacol peroxidease: GPX; glutathione reductase: GR; catalase: CAT; ascorbic acid: AsA; and glutathione: GSH), methylglyoxal (MG) detoxification (glyoxalase I: Gly I; and glyoxalase II: Gly II), and osmoregulation (proline: Pro; trehalose: Tre; and total soluble sugar: TSS) systems were assayed. The results showed that MT treatment stimulated the activities of antioxidant enzymes (GPX, GR, and CAT) and MG detoxification enzymes (Gly I and Gly II), increased the contents of nonenzyme antioxidants (AsA and GSH) and osmolytes (Pro, Tre, and TSS) in maize seedlings under normal culture conditions, and maintained a higher abovementioned enzyme activity and antioxidant and osmolyte contents under HS conditions compared with the control. This work reported that MT could enhance the thermotolerance of maize seedlings by modulating the antioxidant defense, MG detoxification, and osmoregulation systems.

Glycolysis-Derived Compounds From Astrocytes That Modulate Synaptic Communication.

Abstract: Based on the concept of the tripartite synapse, we have reviewed the role of glucose-derived compounds in glycolytic pathways in astroglial cells. Glucose provides energy and substrate replenishment for brain activity, such as glutamate and lipid synthesis. In addition, glucose metabolism in the astroglial cytoplasm results in products such as lactate, methylglyoxal, and glutathione, which modulate receptors and channels in neurons. Glucose has four potential destinations in neural cells, and it is possible to propose a crossroads in "X" that can be used to describe these four destinations. Glucose-6P can be used either for glycogen synthesis or the pentose phosphate pathway on the left and right arms of the X, respectively. Fructose-6P continues through the glycolysis pathway until pyruvate is formed but can also act as the initial compound in the hexosamine pathway, representing the left and right legs of the X, respectively. We describe each glucose destination and its regulation, indicating the products of these pathways and how they can affect synaptic communication. Extracellular L-lactate, either generated from glucose or from glycogen, binds to HCAR1, a specific receptor that is abundantly localized in perivascular and post-synaptic membranes and regulates synaptic plasticity. Methylglyoxal, a product of a deviation of glycolysis, and its derivative D-lactate are also released by astrocytes and bind to GABAA receptors and HCAR1, respectively. Glutathione, in addition to its antioxidant role, also binds to ionotropic glutamate receptors in the synaptic cleft. Finally, we examined the hexosamine pathway and evaluated the effect of GlcNAc-modification on key proteins that regulate the other glucose destinations.

Silicon Alleviates Nickel-Induced Oxidative Stress by Regulating Antioxidant Defense and Glyoxalase Systems in Mustard Plants

Abstract: Soil polluted with heavy metals is a continuous threat to global crop production. The present study deals with growth, biochemical attributes, photosynthetic pigments, antioxidant responses and gyloxalase systems of mustard plants under varying concentrations of nickel (Ni) stress. Ni stress (150 µM) reduced growth (shoot length by 34.46% and root length by 52.49%), chlorophyll (57.63%), gas exchange parameters (PN by 36.84%, A by 55.61%), leaf relative water content (LRWC by 24.34%), and enhanced hydrogen peroxide (H2O2 by3.23 fold) malondialdehyde (MDA by 2.07 fold), and methylglyoxal (MG by 3.32 fold) content. Si (10− 5 M) application ameliorated the negative effects of Ni on growth, chlorophyll content, photosynthetic traits and also elevated the activities of antioxidant enzymes and enzymes associated with the ascorbate glutathione (AsA-GSH) cycle and glyoxylase systems. Nevertheless, Si application to Ni-stressed plants had an additive effect on the enzyme activities of antioxidants and enzymes of AsA-GSH cycle. Exogenous Si supplementation elevated endogenous Si content which decreased root to shoot Ni translocation and maintained optimum osmolyte and secondary metabolite accumulation. We conclude that Si-induced Ni stress tolerance in mustard plants could be correlated with the upregulation of enzymes associated with antioxidant defence, glyoxalase detoxification systems and sufficient primary and secondary osmoprotectant accumulation.

Reactive metabolite production is a targetable liability of glycolytic metabolism in lung cancer.

Abstract: Increased glucose uptake and metabolism is a prominent phenotype of most cancers, but efforts to clinically target this metabolic alteration have been challenging. Here, we present evidence that lactoylglutathione (LGSH), a byproduct of methylglyoxal detoxification, is elevated in both human and murine non-small cell lung cancers (NSCLC). Methylglyoxal is a reactive metabolite byproduct of glycolysis that reacts non-enzymatically with nucleophiles in cells, including basic amino acids, and reduces cellular fitness. Detoxification of methylglyoxal requires reduced glutathione (GSH), which accumulates to high levels in NSCLC relative to normal lung. Ablation of the methylglyoxal detoxification enzyme glyoxalase I (Glo1) potentiates methylglyoxal sensitivity and reduces tumor growth in mice, arguing that targeting pathways involved in detoxification of reactive metabolites is an approach to exploit the consequences of increased glucose metabolism in cancer.

Oleuropein-Induced Apoptosis Is Mediated by Mitochondrial Glyoxalase 2 in NSCLC A549 Cells: A Mechanistic Inside and a Possible Novel Nonenzymatic Role for an Ancient Enzyme

Abstract: Oleuropein (OP) is a bioactive compound derived from plants of the genus Oleaceae exhibiting antitumor properties in several human cancers, including non-small-cell lung cancer (NSCLC). Recent evidence suggests that OP has proapoptotic effects on NSCLC cells via the mitochondrial apoptotic pathway. However, the exact molecular mechanisms behind the apoptogenic action of OP in NSCLC are still largely unknown. Glyoxalase 2 (Glo2) is an ancient enzyme belonging to the glyoxalase system involved in the detoxification of glycolysis-derived methylglyoxal. However, emerging evidence suggests that Glo2 may have also nonenzymatic roles in some malignant cells. In the present study, we evaluated whether and how Glo2 participated in the proapoptotic effects of OP in NSCLC A549 cells. Our results indicate that OP is able to induce apoptosis in A549 cells through the upregulation of mitochondrial Glo2 (mGlo2), mediated by the superoxide anion and Akt signaling pathway. Moreover, our data shows that the proapoptotic role of mGlo2, observed following OP exposure, occurs via the interaction of mGlo2 with the proapoptotic Bax protein. Conversely, OP does not alter the behavior of nonmalignant human BEAS-2B cells or mGlo2 expression, thus suggesting a specific anticancer role for this bioactive compound in NSCLC. Our data identify a novel pathway through which OP exerts a proapoptotic effect in NSCLC and suggest, for the first time, a novel, nonenzymatic antiapoptotic role for this ancient enzyme in NSCLC.

Methylglyoxal Acts as a Tumor-Promoting Factor in Anaplastic Thyroid Cancer.

Abstract: Methylglyoxal (MG) is a potent inducer of advanced glycation end products (AGEs). MG, long considered a highly cytotoxic molecule with potential anticancer value, is now being re-evaluated to a protumorigenic agent in some malignancies. Anaplastic thyroid cancer (ATC) is an extremely aggressive and highly lethal cancer for which conventional therapies have proved ineffective. Successful therapeutic intervention in ATC is undermined by our poor understanding of its molecular etiology. In the attempt to understand the role of MG in ATC aggressiveness, we used immunohistochemistry to examine the level of MG protein adducts in ATC and slow-growing papillary thyroid cancer (PTC). We detected a high level of MG adducts in ATC compared to PTC ones, suggesting a protumor role for MG-mediated dicarbonyl stress in ATC. Accordingly, MG adduct accumulation in ATC cells in vitro was associated with a marked mesenchymal phenotype and increased migration/invasion, which were both reversed by aminoguanidine (AG)—a scavenger of MG—and resveratrol—an activator of Glyoxalase 1 (Glo1), the key metabolizing enzyme of MG. Our study represents the first demonstration that MG, via AGEs, acts as a tumor-promoting factor in ATC and suggests that MG scavengers and/or Glo1 activators merit investigations as potential therapeutic strategies for this malignancy.

Methylglyoxal, a glycolysis metabolite, triggers metastasis through MEK/ERK/SMAD1 pathway activation in breast cancer

Abstract: Elevated aerobic glycolysis rate is a biochemical alteration associated with malignant transformation and cancer progression. This metabolic shift unavoidably generates methylglyoxal (MG), a potent inducer of dicarbonyl stress through the formation of advanced glycation end products (AGEs). We have previously shown that the silencing of glyoxalase 1 (GLO1), the main MG detoxifying enzyme, generates endogenous dicarbonyl stress resulting in enhanced growth and metastasis in vivo. However, the molecular mechanisms through which MG stress promotes metastasis development remain to be unveiled. In this study, we used RNA sequencing analysis to investigate gene-expression profiling of GLO1-depleted breast cancer cells and we validated the regulated expression of selected genes of interest by RT-qPCR. Using in vitro and in vivo assays, we demonstrated the acquisition of a pro-metastatic phenotype related to dicarbonyl stress in MDA-MB-231, MDA-MB-468 and MCF7 breast cancer cellular models. Hyperactivation of MEK/ERK/SMAD1 pathway was evidenced using western blotting upon endogenous MG stress and exogenous MG treatment conditions. MEK and SMAD1 regulation of MG pro-metastatic signature genes in breast cancer cells was demonstrated by RT-qPCR. High-throughput transcriptome profiling of GLO1-depleted breast cancer cells highlighted a pro-metastatic signature that establishes novel connections between MG dicarbonyl stress, extracellular matrix (ECM) remodeling by neoplastic cells and enhanced cell migration. Mechanistically, we showed that these metastasis-related processes are functionally linked to MEK/ERK/SMAD1 cascade activation in breast cancer cells. We showed that sustained MEK/ERK activation in GLO1-depleted cells notably occurred through the down-regulation of the expression of dual specificity phosphatases in MG-stressed breast cancer cells. The use of carnosine and aminoguanidine, two potent MG scavengers, reversed MG stress effects in in vitro and in vivo experimental settings. These results uncover for the first time the key role of MG dicarbonyl stress in the induction of ECM remodeling and the activation of migratory signaling pathways, both in favor of enhanced metastatic dissemination of breast cancer cells. Importantly, the efficient inhibition of mitogen-activated protein kinase (MAPK) signaling using MG scavengers further emphasizes the need to investigate their therapeutic potential across different malignancies.

Comparative Physiological and Biochemical Changes in Tomato (Solanum lycopersicum L.) Under Salt Stress and Recovery: Role of Antioxidant Defense and Glyoxalase Systems.

Abstract: Salinity toxicity and the post-stress restorative process were examined to identify the salt tolerance mechanism in tomato, with a focus on the antioxidant defense and glyoxalase systems. Hydroponically grown 15 day-old tomato plants (Solanum lycopersicum L. cv. Pusa Ruby) were treated with 150 and 250 mM NaCl for 4 days and subsequently grown in nutrient solution for a further 2 days to observe the post-stress responses. Under saline conditions, plants showed osmotic stress responses that included low leaf relative water content and high proline content. Salinity induced oxidative stress by the over-accumulation of reactive oxygen species (H2O2 and O2•-) and methylglyoxal. Salinity also impaired the non-enzymatic and enzymatic components of the antioxidant defense system. On the other hand, excessive Na+ uptake induced ionic stress which resulted in a lower content of other minerals (K+, Ca2+, and Mg2+), and a reduction in photosynthetic pigment synthesis and plant growth. After 2 days in the normal nutrient solution, the plants showed improvements in antioxidant and glyoxalase system activities, followed by improvements in plant growth, water balance, and chlorophyll synthesis. The antioxidant and glyoxalase systems worked in concert to scavenge toxic reactive oxygen species (ROS), thereby reducing lipid peroxidation and membrane damage. Taken together, these findings indicate that tomato plants can tolerate salinity and show rapid post-stress recovery by enhancement of their antioxidant defense and glyoxalase systems.

Melanoidins from Coffee, Cocoa, and Bread Are Able to Scavenge α-Dicarbonyl Compounds under Simulated Physiological Conditions

Abstract: Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA and MGO. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGE formation across the gastrointestinal tract.

The combination of loss of glyoxalase1 and obesity results in hyperglycemia

Abstract: The increased formation of methylglyoxal (MG) under hyperglycemia is associated with the development of microvascular complications in patients with diabetes mellitus; however, the effects of elevated MG levels in vivo are poorly understood. In zebrafish, a transient knockdown of glyoxalase 1, the main MG detoxifying system, led to the elevation of endogenous MG levels and blood vessel alterations. To evaluate effects of a permanent knockout of glyoxalase 1 in vivo, glo1-/- zebrafish mutants were generated using CRISPR/Cas9. In addition, a diet-induced-obesity zebrafish model was used to analyze glo1-/- zebrafish under high nutrient intake. Glo1-/- zebrafish survived until adulthood without growth deficit and showed increased tissue MG concentrations. Impaired glucose tolerance developed in adult glo1-/- zebrafish and was indicated by increased postprandial blood glucose levels and postprandial S6 kinase activation. Challenged by an overfeeding period, fasting blood glucose levels in glo1-/- zebrafish were increased which translated into retinal blood vessel alterations. Thus, the data have identified a defective MG detoxification as a metabolic prerequisite and glyoxalase 1 alterations as a genetic susceptibility to the development of type 2 diabetes mellitus under high nutrition intake.

Methylglyoxal stress, the glyoxalase system, and diabetic chronic kidney disease.

Abstract: Purpose of review Chronic kidney disease (CKD) remains a serious diabetic complication despite the use of widely employed interventions such as angiotensin-converting enzyme inhibitors and glucose-lowering treatments. Accumulation of methylglyoxal, a highly reactive glucose metabolite and a major precursor in the formation of advanced glycation end products, may link the hemodynamic, inflammatory, metabolic, and structural changes that drive diabetic CKD. Therefore, methylglyoxal may serve as a potential therapeutic target to prevent diabetic CKD. Recent findings Higher plasma methylglyoxal levels were shown to be associated with a decline in the estimated glomerular filtration rate. Furthermore, interventions that lower methylglyoxal levels reduced albuminuria in rodent models of diabetes. In addition, the glyoxalase system, which detoxifies methylglyoxal into D-lactate, has been identified as a key protective enzymatic system against diabetic CKD in both human and rodent studies. Recently, several promising treatments to lower methylglyoxal directly or to boost the glyoxalase system have been identified. Summary The review highlights the mechanisms through which methylglyoxal is formed in diabetes, and how methylglyoxal contributes to the mechanisms that drive CKD in diabetes. Furthermore, we discuss the role of glyoxalase-1 in diabetic CKD. Finally, we discuss recent data about treatments that lower methylglyoxal stress.

Glycation of Plant Proteins: Regulatory Roles and Interplay with Sugar Signalling?

Abstract: Glycation can be defined as an array of non-enzymatic post-translational modifications of proteins formed by their interaction with reducing carbohydrates and carbonyl products of their degradation. Initial steps of this process rely on reducing sugars and result in the formation of early glycation products—Amadori and Heyns compounds via Schiff base intermediates, whereas their oxidative degradation or reactions of proteins with α-dicarbonyl compounds yield a heterogeneous group of advanced glycation end products (AGEs). These compounds accompany thermal processing of protein-containing foods and are known to impact on ageing, pathogenesis of diabetes mellitus and Alzheimer’s disease in mammals. Surprisingly, despite high tissue carbohydrate contents, glycation of plant proteins was addressed only recently and its physiological role in plants is still not understood. Therefore, here we summarize and critically discuss the first steps done in the field of plant protein glycation during the last decade. We consider the main features of plant glycated proteome and discuss them in the context of characteristic metabolic background. Further, we address the possible role of protein glycation in plants and consider its probable contribution to protein degradation, methylglyoxal and sugar signalling, as well as interplay with antioxidant defense.

Metal-Binding Pharmacophore Library Yields the Discovery of a Glyoxalase 1 Inhibitor

Abstract: Anxiety and depression are common, highly comorbid psychiatric diseases that account for a large proportion of worldwide medical disability. Glyoxalase 1 (GLO1) has been identified as a possible target for the treatment of anxiety and depression. GLO1 is a Zn2+-dependent enzyme that isomerizes a hemithioacetal, formed from glutathione and methylglyoxal, to a lactic acid thioester. To develop active inhibitors of GLO1, fragment-based drug discovery was used to identify fragments that could serve as core scaffolds for lead development. After screening a focused library of metal-binding pharmacophores, 8-(methylsulfonylamino)quinoline (8-MSQ) was identified as a hit. Through computational modeling and synthetic elaboration, a potent GLO1 inhibitor was developed with a novel sulfonamide core pharmacophore. A lead compound was demonstrated to penetrate the blood-brain barrier, elevate levels of methylglyoxal in the brain, and reduce depression-like behavior in mice. These findings provide the basis for GLO1 inhibitors to treat depression and related psychiatric illnesses.

Methylglyoxal-Derived Advanced Glycation Endproducts Accumulate in Multiple Sclerosis Lesions.

Abstract: Multiple sclerosis (MS) is a demyelinating autoimmune disease in which innate and adaptive immune cells infiltrate the central nervous system (CNS) and damage the myelin sheaths surrounding the axons. Upon activation, infiltrated macrophages, CNS-resident microglia, and astrocytes switch their metabolism toward glycolysis, resulting in the formation of α-dicarbonyls, such as methylglyoxal (MGO) and glyoxal (GO). These potent glycating agents lead to the formation of advanced glycation endproducts (AGEs) after reaction with amino acids. We hypothesize that AGE levels are increased in MS lesions due to the inflammatory activation of macrophages and astrocytes. First, we measured tissue levels of AGEs in brain samples of MS patients and controls. Analysis of MS patient and non-demented control (NDC) specimens showed a significant increase in protein-bound Nδ-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H1), the major AGE, compared to white matter of NDCs (107 ± 11 vs. 154 ± 21, p < 0.05). In addition, immunohistochemistry revealed that MGO-derived AGEs were specifically present in astrocytes, whereas the receptor for AGEs, RAGE, was detected on microglia/macrophages. Moreover, in cerebrospinal fluid from MS patients, α-dicarbonyls and free AGEs correlated with their respective levels in the plasma, whereas this was not observed for protein-bound AGEs. Taken together, our data show that MG-H1 is produced by astrocytes. This suggests that AGEs secreted by astrocytes have paracrine effects on RAGE-positive macrophages/microglia and thereby contribute to the pathology of MS.

Aging, Alzheimer’s Disease and Dysfunctional Glycolysis; Similar Effects of Too Much and Too Little

Abstract: Aging and much related dysfunction can be delayed by decreased glycolysis, however dysfunctional glycolysis appears to play a causative role in Alzheimer's disease (AD). It is proposed here that this apparent contradiction can be reconciled by suggesting that both over-use and inhibition of the glycolytic enzyme triosephosphate isomerase can limit NADH generation and increase protein glycation. It is also suggested that excessive glycolysis in erythrocytes may provide a source of systemic methylglyoxal and glycated alpha-synuclein, both of which accelerate aging onset and neurodegeneration.

Comparative analysis of glyoxalase pathway genes in Erianthus arundinaceus and commercial sugarcane hybrid under salinity and drought conditions

Abstract: Glyoxalase pathway is a reactive carbonyl species (RCS) scavenging mechanism involved in the detoxification of methylglyoxal (MG), which is a reactive α-ketoaldehyde. In plants under abiotic stress, the cellular toxicity is reduced through glyoxalase pathway genes, i.e. Glyoxalase I (Gly I), Glyoxalase II (Gly II) and Glyoxalase III (Gly III). Salinity and water deficit stresses produce higher amounts of endogenous MG resulting in severe tissue damage. Thus, characterizing glyoxalase pathway genes that govern the MG metabolism should provide new insights on abiotic stress tolerance in Erianthus arundinaceus, a wild relative of sugarcane and commercial sugarcane hybrid (Co 86032). In this study, three glyoxalase genes (Glyoxalase I, II and III) from E. arundinaceus (a wild relative of sugarcane) and commercial sugarcane hybrid (Co 86032) were characterized. Comparative gene expression profiles (qRT-PCR) of Glyoxalase I, II and III under salinity and water deficit stress conditions revealed differential transcript expression with higher levels of Glyoxalase III in both the stress conditions. Significantly, E. arundinaceus had a higher expression level of glyoxalase genes compared to commercial sugarcane hybrid. On the other hand, gas exchange parameters like stomatal conductance and transpiration rate were declined to very low levels under both salt and drought induced stresses in commercial sugarcane hybrid when compared to E. arundinaceus. E. arundinaceus maintained better net photosynthetic rate compared to commercial sugarcane hybrid. The phylogenetic analysis of glyoxalase proteins showed its close evolutionary relationship with Sorghum bicolor and Zea mays. Glyoxalase I and II were predicted to possess 9 and 7 isoforms respectively whereas, Glyoxalase III couldn’t be identified as it comes under uncharacterized protein identified in recent past. Chromosomal mapping is also carried out for glyoxalase pathway genes and its isoforms. Docking studies revealed the binding affinities of glyoxalase proteins in both E. arundinaceus and commercial sugarcane hybrid with their substrate molecules. This study emphasizes the role of Glyoxalase pathway genes in stress defensive mechanism which route to benefit in progressive plant adaptations and serves as potential candidates for development of salt and drought tolerant crops.