Degradation of glyceraldehyde-3-phosphate dehydrogenase triggered by 4-hydroxy-2-nonenal and 4-hydroxy-2-hexenal

Redox remodeling of central metabolism as a driving force for cellular protection, proliferation, differentiation, and dysfunction

The production of reactive oxygen species (ROS) is elevated via metabolic hyperactivation in response to a variety of stimuli such as growth factors and inflammation. Tolerable amounts of ROS moderately inactivate enzymes via oxidative modification, which can be reversed back to the native form in a redox-dependent manner. The excessive production of ROS, however, causes cell dysfunction and death. Redox-reactive enzymes are present in primary metabolic pathways such as glycolysis and the tricarboxylic acid cycle, and these act as floodgates for carbon flux. Oxidation of a specific form of cysteine inhibits glyceraldehyde-3-phosphate dehydrogenase, which is reversible, and causes an accumulation of upstream intermediary compounds that increases the flux of glucose-6-phosphate to the pentose phosphate pathway. These reactions increase the NADPH and ribose-5-phosphate that are available for reductive reactions and nucleotide synthesis, respectively. On the other hand, oxidative inactivation of mitochondrial aconitase increases citrate, which is then recruited to synthesize fatty acids in the cytoplasm. Decreases in the use of carbohydrate for ATP production can be compensated via amino acid catabolism, and this metabolic change makes nitrogen available for nucleic acid synthesis. Coupling of the urea cycle also converts nitrogen to urea and polyamine, the latter of which supports cell growth. This metabolic remodeling stimulates the proliferation of tumor cells and fibrosis in oxidatively damaged tissues. Oxidative modification of these enzymes is generally reversible in the early stages of oxidizing reactions, which suggests that early treatment with appropriate antioxidants promotes the maintenance of natural metabolism.

Renal denervation ameliorated salt-induced hypertension by improving cardiac work, cardiac enzyme and oxidative balance in Sprague-Dawley rats

Background

Hypertension is associated with cardiovascular dysfunction, dysregulation of the antioxidant system and alteration of the level of some enzymes in the metabolic pathway. The possible modulatory effect of acute renal denervation (ARD) on cardiovascular function and the antioxidant system is still a subject of intense debate. This study sought to ascertain the ameliorative effects of ARD on cardiovascular parameters, antioxidant system, creatine kinase and lactate dehydrogenase levels.

Methods

Thirty-six Sprague-Dawley rats (5-6 weeks old) were divided into 6 groups of 6 animals each consisting of Normal Salt, High Salt, Normal Salt + Sham Denervation, High Salt + Sham Denervation, Normal Salt + Renal Denervation and High Salt + Renal Denervation. Induction of hypertension with 8 % salt in the diet lasted for 8 weeks. Renal or Sham denervation was thereafter done on selected groups. At the end of the experimental period, cardiovascular parameters, plasma antioxidant status, plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels were assessed. Significance level was set at p < 0.05.

Results

Salt-loading significantly increased systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MABP), rate pressure product (RPP) while reducing superoxide dismutase (SOD), reduced glutathione (GSH) and catalase (CAT). Acute renal denervation significantly (p < 0.0001) reduced SBP, DBP, MABP, RPP, LDH and norepinephrine level while increasing SOD, GSH and CAT. ARD did not significantly alter CK level.

Conclusion

Acute renal denervation, by reducing sympathetic activity, ameliorates cardiovascular and antioxidant functions as well as reduces LDH level without significantly altering CK level in salt-induced hypertension.

Aldehyde perception induces specific molecular responses in Laminaria digitata and affects algal consumption by a specialist grazer

In the marine environment, distance signaling based on water-borne cues occurs during interactions between macroalgae and herbivores. In the brown alga Laminaria digitata from North-Atlantic Brittany, oligoalginates elicitation or grazing was shown to induce chemical and transcriptomic regulations, as well as emission of a wide range of volatile aldehydes, but their biological roles as potential defense or warning signals in response to herbivores remain unknown. In this context, bioassays using the limpet Patella pellucida and L. digitata were carried out for determining the effects of algal transient incubation with 4-hydroxyhexenal (4-HHE), 4-hydroxynonenal (4-HNE) and dodecadienal on algal consumption by grazers. Simultaneously, we have developed metabolomic and transcriptomic approaches to study algal molecular responses after treatments of L. digitata with these chemical compounds. The results indicated that, unlike the treatment of the plantlets with 4-HNE or dodecadienal, treatment with 4-HHE decreases algal consumption by herbivores at 100 ng.ml-1 . Moreover, we showed that algal metabolome was significantly modified according to the type of aldehydes, and more specifically the metabolite pathways linked to fatty acid degradation. RNAseq analysis further showed that 4-HHE at 100 ng.ml-1 can activate the regulation of genes related to oxylipin signaling pathways and specific responses, compared to oligoalginates elicitation. As kelp beds constitute complex ecosystems consisting of habitat and food source for marine herbivores, the algal perception of specific aldehydes leading to targeted molecular regulations could have an important biological role on kelps/grazers interactions.

Oxylipins and Reactive Carbonyls as Regulators of the Plant Redox and Reactive Oxygen Species Network under Stress

Reactive oxygen species (ROS), and in particular H2O2, serve as essential second messengers at low concentrations. However, excessive ROS accumulation leads to severe and irreversible cell damage. Hence, control of ROS levels is needed, especially under non-optimal growth conditions caused by abiotic or biotic stresses, which at least initially stimulate ROS synthesis. A complex network of thiol-sensitive proteins is instrumental in realizing tight ROS control; this is called the redox regulatory network. It consists of sensors, input elements, transmitters, and targets. Recent evidence revealed that the interplay of the redox network and oxylipins–molecules derived from oxygenation of polyunsaturated fatty acids, especially under high ROS levels–plays a decisive role in coupling ROS generation and subsequent stress defense signaling pathways in plants. This review aims to provide a broad overview of the current knowledge on the interaction of distinct oxylipins generated enzymatically (12-OPDA, 4-HNE, phytoprostanes) or non-enzymatically (MDA, acrolein) and components of the redox network. Further, recent findings on the contribution of oxylipins to environmental acclimatization will be discussed using flooding, herbivory, and establishment of thermotolerance as prime examples of relevant biotic and abiotic stresses.

Pomegranate Seeds Extract Possesses a Protective Effect against Tramadol-Induced Testicular Toxicity in Experimental Rats

Tramadol is a centrally acting opioid analgesic that is extensively used. The chronic exposure to tramadol induces oxidative stress and toxicity especially for patients consuming it several times a day. Previously, we and others reported that tramadol induces testicular damage in rats. This study was conducted to investigate the possible protective effect of pomegranate seed extract (PgSE) against tramadol-induced testicular damage in adult and adolescent rats. Male rats were orally treated with tramadol or in a combination with PgSE for three weeks. Testes were then dissected and analyzed. Histological and ultrastructural examinations indicated that tramadol induced many structural changes in the testes of adult and adolescent rats including hemorrhage of blood vessels, intercellular spaces, interstitial vacuoles, exfoliation of germ cells in lumen, cell apoptosis, chromatin degeneration of elongated spermatids, and malformation of sperm axonemes. Interestingly, these abnormalities were not observed in tramadol/PgSE cotreated rats. The morphometric analysis revealed that tramadol disrupted collagen metabolism by elevating testicular levels of collagen fibers but that was protected in tramadol/PgSE cotreatment at both ages. In addition, DNA ploidy revealed that S phase of the cell cycle was diminished when adult and adolescent rats were treated with tramadol. However, the S phase had a normal cell population in the cotreated adult rats, but adolescent rats had a lower population than controls. Furthermore, the phytochemistry of PgSE revealed a high content of total polyphenols and total flavonoids within this extract; besides, the DPPH free radical scavenging activity was high. In conclusion, this study indicated that PgSE has a prophylactic effect against tramadol-induced testicular damage in both adult and adolescent ages, although the tramadol toxicity was higher in adolescent age to be completely protected. This prophylactic effect might be due to the high antioxidant compounds within the pomegranate seeds.

Oxidative stress impairs energy metabolism in primary cells and synovial tissue of patients with rheumatoid arthritis

Background

In this study, we examined the effect of oxidative stress on cellular energy metabolism and pro-angiogenic/pro-inflammatory mechanisms of primary rheumatoid arthritis synovial fibroblast cells (RASFC) and human umbilical vein endothelial cells (HUVEC).

Methods

Primary RASFC and HUVEC were cultured with the oxidative stress inducer 4-hydroxy-2-nonenal (4-HNE), and extracellular acidification rate, oxygen consumption rate, mitochondrial function and pro-angiogenic/pro-inflammatory mechanisms were assessed using the Seahorse analyser, complex I–V activity assays, random mutation mitochondrial capture assays, enzyme-linked immunosorbent assays and functional assays, including angiogenic tube formation, migration and invasion. Expression of angiogenic growth factors in synovial tissue (ST) was assessed by IHC in patients with rheumatoid arthritis (RA) undergoing arthroscopy before and after administration of tumour necrosis factor inhibitors (TNFi).

Results

In RASFC and HUVEC, 4-HNE-induced oxidative stress reprogrammed energy metabolism by inhibiting mitochondrial basal, maximal and adenosine triphosphate-linked respiration and reserve capacity, coupled with the reduced enzymatic activity of oxidative phosphorylation complexes III and IV. In contrast, 4-HNE elevated basal glycolysis, glycolytic capacity and glycolytic reserve, paralleled by an increase in mitochondrial DNA mutations and reactive oxygen species. 4-HNE activated pro-angiogenic responses of RASFC, which subsequently altered HUVEC invasion and migration, angiogenic tube formation and the release of pro-angiogenic mediators. In vivo markers of angiogenesis (vascular endothelial growth factor, angiopoietin 2 [Ang2], tyrosine kinase receptor [Tie2]) were significantly associated with oxidative damage and oxygen metabolism in the inflamed synovium. Significant reduction in ST vascularity and Ang2/Tie2 expression was demonstrated in patients with RA before and after administration of TNFi.

Conclusions

Oxidative stress promotes metabolism in favour of glycolysis, an effect that may contribute to acceleration of inflammatory mechanisms and subsequent dysfunctional angiogenesis in RA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1592-1) contains supplementary material, which is available to authorized users.

Small molecules preventing GAPDH aggregation are therapeutically applicable in cell and rat models of oxidative stress

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is one of the most abundant targets of the oxidative stress. Oxidation of the enzyme causes its inactivation and the formation of intermolecular disulfide bonds, and leads to the accumulation of GAPDH aggregates and ultimately to cell death. The aim of this work was to reveal the ability of chemicals to break the described above pathologic linkage by inhibiting GAPDH aggregation. Using the model of oxidative stress based on SK-N-SH human neuroblastoma cells treated with hydrogen peroxide, we found that lentivirus-mediated down- or up-regulation of GAPDH content caused inhibition or enhancement of the protein aggregation and respectively reduced or increased the level of cell death. To reveal substances that are able to inhibit GAPDH aggregation, we developed a special assay based on dot ultrafiltration using the collection of small molecules of plant origin. In the first round of screening, five compounds were found to possess anti-aggregation activity as established by ultrafiltration and dynamic light scattering; some of the substances efficiently inhibited GAPDH aggregation in nanomolar concentrations. The ability of the compounds to bind GAPDH molecules was proved by the drug affinity responsive target stability assay, molecular docking and differential scanning calorimetry. Results of experiments with SK-N-SH human neuroblastoma treated with hydrogen peroxide show that two substances, RX409 and RX426, lowered the degree of GAPDH aggregation and reduced cell death by 30%. Oxidative injury was emulated in vivo by injecting of malonic acid into the rat brain, and we showed that the treatment with RX409 or RX426 inhibited GAPDH-mediated aggregation in the brain, reduced areas of the injury as proved by magnetic resonance imaging, and augmented the behavioral status of the rats as established by the "beam walking" test. In conclusion, the data show that two GAPDH binders could be therapeutically relevant in the treatment of injuries stemming from hard oxidative stress.

Hydrogen Peroxide-Induced Oxidative Stress Activates Proteasomal Trypsin-Like Activity in Human U373 Glioma Cells

Degradation of oxidized or oxidatively modified proteins is an essential part of the cellular antioxidant defense system. 4-Hydroxy-2-nonenal, a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. The major proteolytic system for modified protein degradation is the ubiquitin-proteasome pathway. However, our previous studies using U937 human leukemic cells showed that 4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is degraded by cathepsin G. In the present study, U373 human glioma cells were cultured in the presence of hydrogen peroxide (H2O2) to investigate the relationships of proteasome and/or cathepsin G activities and H2O2-induced GAPDH degradation. Treatment of cells with H2O2 for 5 h in culture decreased GAPDH activity as well as its protein concentration in a concentration-dependent manner. Two proteasomal activities (peptidylglutamyl-peptide hydrolase and chymotrypsin-like hydrolase activities) and cathepsin G activity were decreased by H2O2 treatment in a concentration-dependent manner, but proteasomal trypsin-like hydrolase activity increased with cell exposure to high H2O2 concentrations. Among the protease inhibitors examined here, H2O2-induced activation of trypsin-like activity and GAPDH degradation were inhibited by the proteasome inhibitor lactacystin. Furthermore, H2O2-induced activation of trypsin-like activity was also inhibited by another proteasome inhibitor MG-132. These results suggested that proteasomal trypsin-like activity played an important role in eliminating oxidatively modified GAPDH formed in these cells during H2O2 exposure.

4-Hydroxy-nonenal-A Bioactive Lipid Peroxidation Product

This review on recent research advances of the lipid peroxidation product 4-hydroxy-nonenal (HNE) has four major topics: I. the formation of HNE in various organs and tissues, II. the diverse biochemical reactions with Michael adduct formation as the most prominent one, III. the endogenous targets of HNE, primarily peptides and proteins (here the mechanisms of covalent adduct formation are described and the (patho-) physiological consequences discussed), and IV. the metabolism of HNE leading to a great number of degradation products, some of which are excreted in urine and may serve as non-invasive biomarkers of oxidative stress.

High-fat diet induces changes in adipose tissue trans-4-oxo-2-nonenal and trans-4-hydroxy-2-nonenal levels in a depot-specific manner

Protein carbonylation is the covalent modification of proteins by α,β-unsaturated aldehydes produced by nonenzymatic lipid peroxidation of polyunsaturated fatty acids. The most widely studied aldehyde product of lipid peroxidation, trans-4-hydroxy-2-nonenal (4-HNE), is associated with obesity-induced metabolic dysfunction and has demonstrated reactivity toward key proteins involved in cellular function. However, 4-HNE is only one of many lipid peroxidation products and the lipid aldehyde profile in adipose tissue has not been characterized. To further understand the role of oxidative stress in obesity-induced metabolic dysfunction, a novel LC-MS/MS method was developed to evaluate aldehyde products of lipid peroxidation and applied to the analysis of adipose tissue. 4-HNE and trans-4-oxo-2-nonenal (4-ONE) were the most abundant aldehydes present in adipose tissue. In high fat-fed C57Bl/6J and ob/ob mice the levels of lipid peroxidation products were increased 5- to 11-fold in epididymal adipose, unchanged in brown adipose, but decreased in subcutaneous adipose tissue. Epididymal adipose tissue of high fat-fed mice also exhibited increased levels of proteins modified by 4-HNE and 4-ONE, whereas subcutaneous adipose tissue levels of these modifications were decreased. High fat feeding of C57Bl/6J mice resulted in decreased expression of a number of genes linked to antioxidant biology selectively in epididymal adipose tissue. Moreover, TNFα treatment of 3T3-L1 adipocytes resulted in decreased expression of GSTA4, GPx4, and Prdx3 while upregulating the expression of SOD2. These results suggest that inflammatory cytokines selectively downregulate antioxidant gene expression in visceral adipose tissue, resulting in elevated lipid aldehydes and increased protein carbonylation.

Role of the immune system in hypertension: modulation by dietary antioxidants

Hypertension is a major health problem worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease, and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Insulin resistance is a common feature of hypertension in both humans and animal models affecting glucose and lipid metabolism producing excess aldehydes including methylglyoxal. These aldehydes react with proteins to form conjugates called advanced glycation end products (AGEs). This alters protein structure and function and can affect vascular and immune cells leading to their activation and secretion of inflammatory cytokines. AGEs also act via receptors for advanced glycation end products on these cells altering the function of antioxidant and metabolic enzymes, and ion channels. This results in an increase in cytosolic free calcium, decrease in nitric oxide, endothelial dysfunction, oxidative stress, peripheral vascular resistance, and infiltration of vascular and kidney tissue with inflammatory cells leading to hypertension. Supplementation with dietary antioxidants including vitamins C, E, or B(6), thiols such as cysteine and lipoic acid, have been shown to lower blood pressure and plasma inflammatory cytokines in animal models and humans with essential hypertension. A well-balanced diet rich in antioxidants that includes vegetables, fruits, low fat dairy products, low salt, and includes whole grains, poultry, fish and nuts, lowers blood pressure and vascular inflammation. These antioxidants may achieve their antihypertensive and anti-inflammatory/immunomodulatory effects by reducing AGEs and improving insulin resistance and associated alterations. Dietary supplementation with antioxidants may be a beneficial, inexpensive, front-line alterative treatment modality for hypertension.

The antihypertensive effect of arginine

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at increased risk of stroke, heart disease and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Reducing dietary salt is effective in lowering blood pressure in salt-sensitive individuals. Insulin resistance and altered glucose metabolism are common features of hypertension in humans and animal models, with or without salt sensitivity. Altered glucose metabolism leads to increased formation of advanced glycation end products. Insulin resistance is also linked to oxidative stress, and alterations in the nitric oxide pathway and renin angiotensin system. A diet rich in protein containing the semiessential amino acid, arginine, and arginine treatment, lowers blood pressure in humans and in animal models. This may be due to the ability of arginine to improve insulin resistance, decrease advanced glycation end products formation, increase nitric oxide, and decrease levels of angiotensin II and oxidative stress, with improved endothelial cell function and decreased peripheral vascular resistance. The Dietary Approaches to Stop Hypertension (DASH) study demonstrated that the DASH diet, rich in vegetables, fruits and low-fat dairy products; low in fat; and including whole grains, poultry, fish and nuts, lowered blood pressures even more than a typical North American diet with similar reduced sodium content. The DASH diet is rich in protein; the blood pressure-lowering effect of the DASH diet may be due to its higher arginine-containing protein, higher antioxidants and low salt content.

4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase is degraded by cathepsin G in rat neutrophils

Degradation of oxidized or oxidatively modified proteins is an essential part of the antioxidant defenses of cells. 4-Hydroxy-2-nonenal, a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. It has been reported that 4-hydroxy-2-nonenal-modified proteins are degraded by the ubiquitin-proteasome pathway or, in some cases, by the lysosomal pathway. However, our previous studies using U937 cells showed that 4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase is degraded by cathepsin G. In the present study, we isolated the 4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase-degrading enzyme from rat neutrophils to an active protein fraction of 28 kDa. Using the specific antibody, the 28 kDa protein was identified as cathepsin G. Moreover, the degradation activity was inhibited by cathepsin G inhibitors. These results suggest that cathepsin G plays a crucial role in the degradation of 4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase.

Reactive electrophilic oxylipins: pattern recognition and signalling

Oxidized lipids in plants comprise a variety of reactive electrophiles that contain an alpha,beta-unsaturated carbonyl group. While some of these compounds are formed enzymatically, many of them are formed by non-enzymatic pathways. In addition to their chemical reactivity/toxicity low levels of these compounds are also biologically active. Despite their structural diversity and biosynthetic origin, common biological activities such as induction of defense genes, activation of detoxification responses and growth inhibition have been documented. However, reactive electrophilic oxylipins are poorly defined as a class of compounds but have at least two properties in common, i.e., lipophilicity and thiol-reactivity. Thiol-reactivity is a property of reactive oxylipins (RES) shared by reactive oxygen and nitrogen species (ROS and RNS) and enables these agents to modify proteins in vivo. Thiol-modification is assumed to represent a key mechanism involved in signal transduction. A metaanalysis of proteomic studies reveals that RES oxylipins, ROS and RNS apparently chemically modify a similar set of highly sensitive proteins, virtually all of which are targets for thioredoxins. Moreover, most of these proteins are redox-regulated, i.e., posttranslational thiol-modification alters the activity or function of these proteins. On the transcriptome level, effects of RES oxylipins and ROS on gene induction substantially overlap but are clearly different. Besides electrophilicity other structural properties such as target affinity apparently determine target selectivity and biological activity. In this context, different signalling mechanisms and signal transduction components identified in plants and non-plant organisms as well as putative functions of RES oxylipins are discussed.

4-Hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase is degraded by cathepsin G

Degradation of oxidized or oxidatively modified proteins is an essential part of the antioxidant defenses of cells. 4-Hydroxy-2-nonenal (HNE), a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. It has been reported that HNE-modified proteins are degraded by the ubiquitin-proteasome pathway or, in some cases, by the lysosomal pathway. However, our previous studies using U937 cells showed that HNE-modified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is degraded by an enzyme that is sensitive to a serine protease inhibitor, diisopropyl fluorophosphate (DFP), but not a proteasome inhibitor, MG-132, and that its degradation is not catalyzed in the acidic pH range where lysosomal enzymes are active. In the present study, we purified an HNE-modified GAPDH-degrading enzyme from a U937 cell extract to a final active fraction containing two proteins of 28 kDa (P28) and 27 kDa (P27) that became labeled with [(3)H]DFP. Using peptide mass fingerprinting and a specific antibody, P28 and P27 were both identified as cathepsin G. The degradation activity was inhibited by cathepsin G inhibitors. Furthermore, a cell extract from U937 cells transfected with a cathepsin G-specific siRNA hardly degraded HNE-modified GAPDH. These results suggest that cathepsin G plays a role in the degradation of HNE-modified GAPDH.

Life span and stress resistance of Caenorhabditis elegans are differentially affected by glutathione transferases metabolizing 4-hydroxynon-2-enal

The lipid peroxidation product 4-hydroxynon-2-enal (4-HNE) forms as a consequence of oxidative stress, and acts as a signaling molecule or, at superphysiological levels, as a toxicant. The steady-state concentration of the compound reflects the balance between its generation and its metabolism, primarily through glutathione conjugation. Using an RNAi-based screen, we identified in Caenorhabditis elegans five glutathione transferases (GSTs) capable of catalyzing 4-HNE conjugation. RNAi knock-down of these GSTs (products of the gst-5, gst-6, gst-8, gst-10, and gst-24 genes) sensitized the nematode to electrophilic stress elicited by exposure to 4-HNE. However, interference with the expression of only two of these genes (gst-5 and gst-10) significantly shortened the life span of the organism. RNAi knock-down of the other GSTs resulted in at least as much 4-HNE adducts, suggesting tissue specificity of effects on longevity. Our results are consistent with the oxidative stress theory of organismal aging, broadened by considering electrophilic stress as a contributing factor. According to this extended hypothesis, peroxidation of lipids leads to the formation of 4-HNE in a chain reaction which amplifies the original damage. 4-HNE then acts as an "aging effector" via the formation of 4-HNE-protein adducts, and a resulting change in protein function.

Novel effect of oxidized low-density lipoprotein: cellular ATP depletion via downregulation of glyceraldehyde-3-phosphate dehydrogenase

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a classical glycolytic enzyme that is involved in cellular energy production and has important housekeeping functions. We used the natural prooxidant and proatherogenic molecule oxidized low-density lipoprotein (OxLDL) to determine a potential link between OxLDL-promoted oxidative stress, GAPDH expression, and smooth muscle cell energy metabolism. OxLDL but not native LDL (nLDL) produced a 60% to 100% dose- and time-dependent reduction of GAPDH protein. OxLDL increased reactive oxygen species (ROS) formation, including rapid elevation of H2O2 levels. OxLDL decreased intracellular catalase expression, likely contributing to the increase in H2O2. Antioxidants, anti-CD36 receptor antibody, NADPH oxidase, or lipoxygenase blockers decreased OxLDL-specific ROS and prevented GAPDH downregulation. 12/15-Lipoxygenase or p47phox deficiency resulted in attenuation of GAPDH downregulation, but 5-lipoxygenase suppression had no effect. OxLDL or exogenous H2O2 oxidized GAPDH thiols, decreasing GAPDH protein half-life and increasing GAPDH sensitivity to proteasome-mediated protein degradation in vitro. OxLDL- or small interfering RNA-specific downregulation of GAPDH resulted in 65% reduction in glycolysis rate and 82% decrease in ATP levels. In conclusion, our data demonstrate that OxLDL downregulated GAPDH via a H2O2-dependent decrease in protein stability. GAPDH protein damage resulted in marked depletion of cellular ATP levels. Our data have important implications for understanding the metabolic effect of OxLDL on the vessel wall and mechanism of atherogenesis.