Pyruvate-fortified cardioplegia suppresses oxidative stress and enhances phosphorylation potential of arrested myocardium

Cardioplegic arrest for bypass surgery imposes global ischemia on the myocardium, which generates oxyradicals and depletes myocardial high-energy phosphates. The glycolytic metabolite pyruvate, but not its reduced congener lactate, increases phosphorylation potential and detoxifies oxyradicals in ischemic and postischemic myocardium. This study tested the hypothesis that pyruvate mitigates oxidative stress and preserves the energy state in cardioplegically arrested myocardium. In situ swine hearts were arrested for 60 min with a 4:1 mixture of blood and crystalloid cardioplegia solution containing 188 mM glucose alone (control) or with additional 23.8 mM lactate or 23.8 mM pyruvate and then reperfused for 3 min with cardioplegia-free blood. Glutathione (GSH), glutathione disulfide (GSSG), and energy metabolites [phosphocreatine (PCr), creatine (Cr), P(i)] were measured in myocardium, which was snap frozen at 45 min arrest and 3 min reperfusion to determine antioxidant GSH redox state (GSH/GSSG) and PCr phosphorylation potential {[PCr]/([Cr][P(i)])}. Coronary sinus 8-isoprostane indexed oxidative stress. Pyruvate cardioplegia lowered 8-isoprostane release approximately 40% during arrest versus control and lactate cardioplegia. Lactate and pyruvate cardioplegia dampened (P < 0.05 vs. control) the surge of 8-isoprostane release following reperfusion. Pyruvate doubled GSH/GSSG versus lactate cardioplegia during arrest, but GSH/GSSG fell in all three groups after reperfusion. Myocardial [PCr]/([Cr][P(i)]) was maintained in all three groups during arrest. Pyruvate cardioplegia doubled [PCr]/([Cr][P(i)]) versus control and lactate cardioplegia after reperfusion. Pyruvate cardioplegia mitigates oxidative stress during cardioplegic arrest and enhances myocardial energy state on reperfusion.     

Local exercise and oxidative stress in chronic obstructive broncho-pneumopathies: preliminary results

The role of altered peripheral muscle function in exercise intolerance of chronic obstructive pulmonary disease (COPD) is now well established. However, the mechanisms underlying this phenomen, have not been determined. One hypothesis is that the oxidative stress, that leads to tissue injury may be involved. A recent study has shown that general exercise caused systemic oxidative stress in COPD patients. However, the origin of this stress was not absolutely clear: airways, muscle, both, or other? The aim of this study was first to determine with a systemic approach, whether systemic oxidative stress occur in patients who perform local exercise and then with a muscular needle biopsy approach, to confirm the muscular origin of this oxidative stress. METHODS: In each approach, 7 COPD patients moderate to severe and 7 age-matched subjects performed an endurance test consisting of dynamic strength of the quadriceps against 40% (systemic approach) or 30% (biopsy approach) of maximal voluntary strength at an imposed regular pace until exhaustion. RESULTS: The results showed in each approach, that endurance test duration was significantly decreased in the COPD patients (p < 0.05). In systemic approach, the results showed that blood vitamin E at rest was significantly decreased in the COPD (p < 0.001), with a significant increase in superoxide anion release by stimulated phagocytes (p < 0.001). Local exercise induced, only in COPD, a significant increase in serum MDA (p < 0.05), which is an index of oxidative stress. In the biopsy approach, the results showed that local exercise induced in COPD an increase in muscular levels of MDA. A significant increase in muscular peroxidase glutathion activity (antioxidant) occurred after exercise only in normal subjects (p < 0.05). In conclusion, this study in COPD, confirms the altered peripheral muscle function, reveals a deficit in blood vitamin E and suggest that local muscular exercise causes a muscular oxidative stress in these patients. Further studies are needed to confirm these results and evaluate the implication of this oxidative stress in the myopathy of COPD.     

Penicillamine increases free copper and enhances oxidative stress in the brain of toxic milk mice

Wilson disease (WD) is characterized by the accumulation of copper arising from a mutation in the ATP7B gene. Penicillamine (PA) makes 10-50% of the patients with neurologic symptoms neurologically worse at the early stage of administration. The aim of this study was to determine how the copper metabolism changes and whether the change impairs the brain of toxic milk (tx) mice, an animal model of WD, during the PA administration. The free copper and protein-bound copper concentrations in the serum, cortex and basal ganglia of tx mice with PA administration for 3 days, 10 days and 14 days, respectively, were investigated. The expression of copper transporters, ATP7A and CTR1,was analyzed by real-time quantitative PCR, immunofluorescence and Western blot. Then SOD, MDA and GSH/GSSG were detected to determine whether the oxidative stress changed correspondingly. The results revealed the elevated free copper concentrations in the serum and brain, and declined protein-bound copper concentrations in the brain of tx mice during PA administration. Meanwhile, transiently increased expression of ATP7A and CTR1 was observed generally in the brain parenchyma by immunofluorescence, real-time quantitative PCR and Western blot. Additionally, ATP7A and CTR1 were observed to locate mainly at Golgi apparatus and cellular membrane respectively. Intense staining of ATP7A in the choroid plexus was found in tx mice on the 3rd and 10th day of PA treatment, but rare staining of ATP7A and CTR1 in the blood-brain barrier (BBB). Decreased GSH/GSSG and increased MDA concentrations were also viewed in the cortex and basal ganglia. Our results suggested the elevated free copper concentrations in the brain might lead to the enhanced oxidative stress during PA administration. The increased free copper in the brain might come from the copper mobilized from brain parenchyma cells but not from the serum according to the ATP7A and CTR1 expression analysis.     

Atorvastatin treatment reduces exercise capacities in rats: involvement of mitochondrial impairments and oxidative stress

Physical exercise exacerbates the cytotoxic effects of statins in skeletal muscle. Mitochondrial impairments may play an important role in the development of muscular symptoms following statin treatment. Our objective was to characterize mitochondrial function and reactive oxygen species (ROS) production in skeletal muscle after exhaustive exercise in atorvastatin-treated rats. The animals were divided into four groups: resting control (CONT; n = 8) and exercise rats (CONT+EXE; n = 8) as well as resting (ATO; n = 10) and exercise (ATO+EXE; n = 8) rats that were treated with atorvastatin (10 mg·kg(-1)·day(-1) for 2 wk). Exhaustive exercise showed that the distance that was covered by treated animals was reduced (P < 0.05). Using dihydroethidium staining, we showed that the ROS level was increased by 60% in the plantaris muscle of ATO compared with CONT rats and was highly increased in ATO+EXE (226%) compared with that in CONT+EXE rats. The maximal mitochondrial respiration (V(max)) was decreased in ATO rats compared with that in CONT rats (P < 0.01). In CONT+EXE rats, V(max) significantly increased compared with those in CONT rats (P < 0.05). V(max) was significantly lower in ATO+EXE rats (-39%) compared with that in CONT+EXE rats (P < 0.001). The distance that was covered by rats significantly correlated with V(max) (r = 0.62, P < 0.01). The glycogen content was decreased in ATO, CONT+EXE, and ATO+EXE rats compared with that in CONT rats (P < 0.05). GLUT-4 mRNA expression was higher after exhaustive exercise in CONT+EXE rats compared with the other groups (P < 0.05). Our results show that exhaustive exercise exacerbated metabolic perturbations and ROS production in skeletal muscle, which may reduce the exercise capacity and promote the muscular symptoms in sedentary atorvastatin-treated animals.     

Marginal zinc deficiency increases oxidative DNA damage in the prostate after chronic exercise

Approximately 12% of Americans do not consume the recommended level of zinc and could be at risk for marginal zinc deficiency. Zinc functions in antioxidant defense and DNA repair and could be important for prostate health. We hypothesized that marginal zinc deficiency sensitizes the prostate to oxidative stress and DNA damage. Rats were fed a zinc-adequate (ZA; 30 mg Zn/kg) or marginally zinc-deficient (MZD; 5–6 mg Zn/kg) diet for 6 weeks. MZD increased p53 and PARP expression but no change in 8-hydroxy-2′-deoxyguanosine levels was detected. To examine the susceptibility to exogenous oxidative stress, rats fed a ZA or MZD diet were assigned to exercising (EXE) or sedentary (SED) groups for 9 weeks. MZD or EXE alone did not affect oxidative DNA damage in the prostate; however, combined MZD + EXE increased DNA damage in the dorsolateral lobe. PARP and p53 expression was not further induced with MZD + EXE, suggesting that MZD interferes with DNA repair responses to stress. Finally, the addition of phytase to the MZD diet successfully restored zinc levels in the prostate and decreased DNA damage back to ZA levels. Overall, this study suggests that marginal zinc deficiency sensitizes the prostate to oxidative stress and demonstrates the importance of maintaining optimal zinc nutrition in physically active populations.     

Endurance exercise causes mitochondrial and oxidative stress in rat liver: Effects of a combination of mitochondrial targeting nutrients

AimsEndurance exercise causes fatigue due to mitochondrial dysfunction and oxidative stress. In order to find an effective strategy to prevent fatigue or enhance recovery, the effects of a combination of mitochondrial targeting nutrients on physical activity, mitochondrial function and oxidative stress in exercised rats were studied.Main methodsRats were subjected to a four-week endurance exercise regimen following four weeks of training. The effects of exercise and nutrient treatment in rat liver were investigated by assaying oxidative stress biomarkers and activities of mitochondrial complexes.Key findingsEndurance exercise induced an increase in activities of complexes I, IV, and V and an increase in glutathione (GSH) levels in liver mitochondria; however, levels of ROS and malondialdehyde (MDA) and activities of complexes II and III remained unchanged. Exercise also induced a significant increase in MDA and activities of glutathione S-transferase and NADPH-quinone-oxidoreductase 1 (NQO-1) in the liver homogenate. Nutrient treatment caused amelioration of complex V and NQO-1 activities and enhancement of activities of complex I and IV, but had no effect on other parameters.SignificanceThese results show that endurance exercise can cause oxidative and mitochondrial stress in liver and that nutrient treatment can either ameliorate or enhance this effect, suggesting that endurance exercise-induced oxidative and mitochondrial stress may be either damaging by causing injury or beneficial by activating defense systems.     

Beneficial effects of moderate exercise on mice aging: survival, behavior, oxidative stress, and mitochondrial electron transfer

Moderate exercise in a treadmill (10, 15, and 20 cm/s, for 5 min each, weekly) from 28 to 78 wk of age extended male and female mice life span by 19 and 9% accompanied by 36 and 13% and 13 and 9% increased performance in behavioral assays (tightrope and T-maze tests) at 52 wk of age. Moderate exercise significantly decreased the aging-associated development of oxidative stress by preventing 1) the increase in protein carbonyls and thiobarbituric acid-reactive substances contents of submitochondrial membranes; 2) the decrease in antioxidant enzyme activities (Mn- and Cu,Zn-superoxide dismutase and catalase); and 3) the decrease in mitochondrial NADH-cytochrome-c reductase and cytochrome oxidase activities observed at 52 wk of mice age in brain, heart, liver, and kidney. These effects were no longer significant at 78 wk of age in mice. Moderate exercise, started at young age in mice, increased life span, decreased oxidative stress, and prevented the decline of cytochrome oxidase activity and behavioral performance at middle age but not at old age.     

Alteration of mitochondrial oxidative capacity during porcine preadipocyte differentiation and in response to leptin

Mitochondrial apparatus is a fundamental aspect in cell, serving for amino acid biosynthesis, fatty acid oxidation (FAO), and ATP production. In this article, we investigated the change of mitochondrial oxidative capacity during porcine adipocyte differentiation and in response to leptin. Rhodamine 123 staining analysis showed about 2-fold increase of mitochondrial membrane electric potential in differentiated adipocyte in comparison with preadipocyte. The mRNA expression of Cytochromes c (Cyt c), carnitine palmitoyltransferase 1 (CPT1), and malate dehydrogenases (MDH) increased markedly (P < 0.05), but that of UCP2 decreased (P < 0.05). Moreover PGC-1α and UCP3 was very low and showed no changes during the adipocyte differentiation. The protein expression of Cyt c and the enzyme activity of Cytochrome c oxidase (COX) increased with preadipocyte differentiation, but cellular ATP level decreased. Furthermore, at the level of 10 and 100 ng/ml leptin not only selectively increased the gene expression of PGC-1α, CPT1, Cyt c, UCP2, and UCP3 (P < 0.05), but also enhanced COX enzyme activity which related to mitochondrial FAO. There is no change of Mitochondrial membrane electric potential and ATP level in cell treated by leptin. These results suggested Mitochondrial is not only critical in FAO, but also play an important role in adipogenesis.     

Simvastatin impairs ADP-stimulated respiration and increases mitochondrial oxidative stress in primary human skeletal myotubes

Statins, the widely prescribed cholesterol-lowering drugs for the treatment of cardiovascular disease, cause adverse skeletal muscle side effects ranging from fatigue to fatal rhabdomyolysis. The purpose of this study was to determine the effects of simvastatin on mitochondrial respiration, oxidative stress, and cell death in differentiated primary human skeletal muscle cells (i.e., myotubes). Simvastatin induced a dose-dependent decrease in viability of proliferating and differentiating primary human muscle precursor cells, and a similar dose-dependent effect was noted in differentiated myoblasts and myotubes. Additionally, there were decreases in myotube number and size following 48 h of simvastatin treatment (5 μM). In permeabilized myotubes, maximal ADP-stimulated oxygen consumption, supported by palmitoylcarnitine+malate (PCM, complex I and II substrates) and glutamate+malate (GM, complex I substrates), was 32-37% lower (P<0.05) in simvastatin-treated (5 μM) vs control myotubes, providing evidence of impaired respiration at complex I. Mitochondrial superoxide and hydrogen peroxide generation were significantly greater in the simvastatin-treated human skeletal myotube cultures compared to control. In addition, simvastatin markedly increased protein levels of Bax (proapoptotic, +53%) and Bcl-2 (antiapoptotic, +100%, P<0.05), mitochondrial PTP opening (+44%, P<0.05), and TUNEL-positive nuclei in human skeletal myotubes, demonstrating up-regulation of mitochondrial-mediated myonuclear apoptotic mechanisms. These data demonstrate that simvastatin induces myotube atrophy and cell loss associated with impaired ADP-stimulated maximal mitochondrial respiratory capacity, mitochondrial oxidative stress, and apoptosis in primary human skeletal myotubes, suggesting that mitochondrial dysfunction may underlie human statin-induced myopathy.     

Antioxidants and oxidative stress in exercise

Strenuous exercise increases oxygen consumption and causes disturbance of intracellular pro-oxidant-antioxidant homeostasis. The mitochondrial electron transport chain, polymorphoneutrophil, and xanthine oxidase have been identified as major sources of intracellular free radical generation during exercise. Reactive oxygen species pose a serious threat to the cellular antioxidant defense system, such as diminished reserve of antioxidant vitamins and glutathione, and increased tissue susceptibility to oxidative damage. However, enzymatic and nonenzymatic antioxidants have demonstrated great adaptation to acute and chronic exercise. The delicate balance between pro-oxidants and antioxidants suggests that supplementation of antioxidants may be desirable for physically active individuals under certain physiological conditions by providing a larger protective margin.     

Endogenous antioxidant changes in the myocardium in response to acute and chronic stress conditions

Oxygen is a diradical and because of its unique electronic configuration, it has the potential to form strong oxidants (e.g. superoxide radical, hydrogen peroxide and hydroxyl radical) called oxygen free radicals or partially reduced forms of oxygen (PRFO). These highly reactive oxygen species can cause cellular injury by oxidizing lipids and proteins as well as by causing strand breaks in nucleic acids. PRFO are produced in the cell during normal redox reactions including respiration and there are various antioxidants in the cell which scavenge these radicals. Thus in order to maintain a normal cell structure and function, a proper balance between free radical production and antioxidant levels is absolutely essential. Production of PRFO in the myocardium is increased during variousin vivo as well asin vitro pathological conditions and these toxic radicals are responsible for causing functional, biochemical and ultrastructural changes in cardiac myocytes. Indirect evidence of free radical involvement in myocardial injury is provided by studies in which protection against these alterations is seen in the presence of exogenous administration of antioxidants. Endogenous myocardial antioxidants have also been reported to change under various physiological as well as pathophysiological conditions. It appears that endogenous antioxidants respond and adjust to different stress conditions and failure of these compensatory changes may also contribute in cardiac dysfunction. Thus endogenous and/or exogenous increase in antioxidants might have a therapeutic potential in various pathological conditions which result from increased free radical production.     

Ethanol and age enhances fluoride toxicity through oxidative stress and mitochondrial dysfunctions in rat intestine

Fluoride toxicity and alcohol abuse are the two serious public health problems in many parts of the world. The current study was an attempt to investigate the effect of alcohol administration and age on fluoride toxicity in rat intestine. Six and 18 months old female Sprague Dawley rats were exposed to sodium fluoride (NaF, 25 mg/kg), 30 % ethanol (EtOH, 1 ml/kg), and NaF+EtOH (25 mg/kg+1 ml/kg) for a period of 20, 40, and 90 days. The levels of lipid peroxidation were increased, while the content of reduced glutathione, total, and protein thiol was decreased with NaF treatment. Under these conditions, animals showed an age-related decline in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase which were further aggravated upon NaF or/and EtOH treatment. Mitochondrial respiration rate and the activities of complexes I, II, and IV enzymes of electron transport chain were decreased, while the levels of nitric oxide and citrulline were increased with age and NaF or/and EtOH treatment. Histological examination revealed large reactive lymphoid follicles, excess of lymphocytes in lamina propria of villi, villous edema, focal ileitis, necrosis of villi, and ulceration in NaF- or/and EtOH-treated animals in both the age groups. These findings suggest that fluoride mediate its toxic effects on intestine through oxidative stress and mitochondrial dysfunctions which are further augmented with alcohol consumption and advancing age.     

Effects of exercise and lifestyle intervention on oxidative stress in chronic kidney disease

Objectives: Determine the effects of a 12-month exercise and lifestyle intervention program on changes in plasma biomarkers of oxidative stress in pre-dialysis chronic kidney disease (CKD) patients.

Methods: A total of 136 stage 3–4 CKD patients were randomized to receive standard nephrological care with (N?=?72) or without (N?=?64) a lifestyle and exercise intervention for 12 months. Plasma total F₂-isoprostanes (IsoP), glutathione peroxidase (GPX) activity, total antioxidant capacity (TAC), anthropometric and biochemical data were collected at baseline and at 12 months.

Results: There were no significant differences between groups at baseline. There were no significant differences in changes for standard care and lifestyle intervention, respectively, in IsoP (p?=?0.88), GPX (p?=?0.87), or TAC (p?=?0.56). Patients identified as having high IsoP at baseline (>250 pg/mL) had a greater decrease in IsoP with lifestyle intervention compared to standard care; however, the difference was not statistically significant (p?=?0.06). There was no difference in the change in kidney function (eGFR) between standard care and lifestyle intervention (p?=?0.33).

Discussion: Exercise and lifestyle modification in stage 3–4 CKD did not produce changes in systemic biomarkers of oxidative stress over a 12-month period, but patients with high IsoP may benefit most from the addition of intervention to standard care.     

The mitochondrial antioxidant defence system and its response to oxidative stress

The antioxidant systems of mitochondria are not well known. Using a proteomics-based approach, we defined these mitochondrial antioxidant systems and analyzed their response to oxidative stress. It appears that the major mitochondrial antioxidant system is made of manganese superoxide dismutase on the one hand, and of peroxiredoxin III, mitochondrial thioredoxin and mitochondrial thioredoxin reductase on the other hand. With the exception of thioredoxin reductase, all these proteins are induced by oxidative stress. In addition, a change in the peroxiredoxin III pattern can also be observed.     

Overexpression of plant uncoupling mitochondrial protein in transgenic tobacco increases tolerance to oxidative stress

An Arabidopsis thaliana cDNA clone encoding a plant uncoupling mitochondrial protein (AtPUMP1) was overexpressed in transgenic tobacco plants. Analysis of the AtPUMP1 mRNA content in the transgenic lines, determined by Northernblot, revealed variable levels of transgene expression. Antibody probing ofWestern blots of mitochondrial proteins from three independent transgenic lines showed significant accumulation of AtPUMP1 in this organelle. Overproduction of AtPUMP1 in transgenic tobacco plants led to a significantincrease in tolerance to oxidative stress promoted by exogenous hydrogen peroxide as compared to wild-type control plants. These results provide thefirst biological evidence for a role of PUMP in protection of plant cells against oxidative stress damage.     

Vaccination prepartum enhances the beneficial effects of melatonin on the immune response and reduces platelet responsiveness in sheep

Background

Eradication of bovine tuberculosis (bTB) through the application of test-and-cull programs is a declared goal of developed countries in which the disease is still endemic. Here, longitudinal data from more than 1,700 cattle herds tested during a 12?year-period in the eradication program in the region of Madrid, Spain, were analyzed to quantify the within-herd transmission coefficient (??) depending on the herd-type (beef/dairy/bullfighting). In addition, the probability to recover the officially bTB free (OTF) status in infected herds depending on the type of herd and the diagnostic strategy implemented was assessed using Cox proportional hazard models.

Results

Overall, dairy herds showed higher ?? (median 4.7) than beef or bullfighting herds (2.3 and 2.2 respectively). Introduction of interferon-gamma (IFN-??) as an ancillary test produced an apparent increase in the ?? coefficient regardless of production type, likely due to an increase in diagnostic sensitivity. Time to recover OTF status was also significantly lower in dairy herds, and length of bTB episodes was significantly reduced when the IFN-?? was implemented to manage the outbreak.

Conclusions

Our results suggest that bTB spreads more rapidly in dairy herds compared to other herd types, a likely cause being management and demographic-related factors. However, outbreaks in dairy herds can be controlled more rapidly than in typically extensive herd types. Finally, IFN-?? proved its usefulness to rapidly eradicate bTB at a herd-level.     

Specific modification of mitochondrial protein thiols in response to oxidative stress: a proteomics approach

Mitochondria play a central role in redox-linked processes in the cell through mechanisms that are thought to involve modification of specific protein thiols, but this has proved difficult to assess. In particular, specific labeling and quantitation of mitochondrial protein cysteine residues have not been achieved due to the lack of reagents available that can be applied to the intact organelle or cell. To overcome these problems we have used a combination of mitochondrial proteomics and targeted labeling of mitochondrial thiols using a novel compound, (4-iodobutyl)triphenylphosphonium (IBTP). This lipophilic cation is accumulated by mitochondria and yields stable thioether adducts in a thiol-specific reaction. The selective uptake into mitochondria, due to the large membrane potential across the inner membrane, and the high pH of the matrix results in specific labeling of mitochondrial protein thiols by IBTP. Individual mitochondrial proteins that changed thiol redox state following oxidative stress could then be identified by their decreased reaction with IBTP and isolated by two-dimensional electrophoresis. We demonstrate the selectivity of IBTP labeling and use it to show that glutathione oxidation and exposure to an S-nitrosothiol or to peroxynitrite cause extensive redox changes to mitochondrial thiol proteins. In conjunction with blue native gel electrophoresis, we used IBTP labeling to demonstrate that thiols are exposed on the matrix faces of respiratory Complexes I, II, and IV. This novel approach enables measurement of the thiol redox state of individual mitochondrial proteins during oxidative stress and cell death. In addition the methodology has the potential to identify novel redox-dependent modulation of mitochondrial proteins.     

SIRT3 deficiency increases mitochondrial oxidative stress and promotes migration of retinal pigment epithelial cells

Retinal pigment epithelial cells are closely associated with the pathogenesis of diabetic retinopathy. The mechanism by which diabetes impacts retinal pigment epithelial cell function is of significant interest. Sirtuins are an important class of proteins that primarily possess nicotinamide adenine dinucleotide-dependent deacetylases activity and involved in various cellular physiological and pathological processes. Here, we aimed to examine the role of sirtuins in the induction of diabetes-associated retinal pigment epithelial cell dysfunction. High glucose and platelet-derived growth factor (PDGF) treatment induced epithelial–mesenchymal transition and the migration of retinal pigment epithelial cells, and decreased sirtuin-3 expression. Sirtuin-3 knockdown using siRNA increased epithelial–mesenchymal transition and migration of retinal pigment epithelial cells. In contrast, sirtuin-3 overexpression attenuated the effects caused by high glucose and PDGF on epithelial–mesenchymal transition and migration of retinal pigment epithelial cells, suggesting that sirtuin-3 deficiency contributed to retinal pigment epithelial cell dysfunction induced by high glucose and PDGF. Mechanistically, sirtuin-3 deficiency induced retinal pigment epithelial cell dysfunction by the overproduction of mitochondrial reactive oxygen species. These results suggest that sirtuin-3 deficiency mediates the migration of retinal pigment epithelial cells, at least partially by increasing mitochondrial oxidative stress, and shed light on the importance of sirtuin-3 and mitochondrial reactive oxygen species as potential targets in diabetic retinopathy therapy.     

Deficiency in a mitochondrial aldehyde dehydrogenase increases vulnerability to oxidative stress in PC12 cells

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) plays a major role in acetaldehyde detoxification. The alcohol sensitivity is associated with a genetic deficiency of ALDH2. We have previously reported that this deficiency influences the risk for late-onset Alzheimer's disease. However, the biological effects of the deficiency on neuronal cells are poorly understood. Thus, we obtained ALDH2-deficient cell lines by introducing mouse mutant Aldh2 cDNA into PC12 cells. The mutant ALDH2 repressed mitochondrial ALDH activity in a dominant negative fashion, but not cytosolic activity. The resultant ALDH2-deficient transfectants were highly vulnerable to exogenous 4-hydroxy-2-nonenal, an aldehyde derivative generated by the reaction of superoxide with unsaturated fatty acid. In addition, the ALDH2-deficient transfectants were sensitive to oxidative insult induced by antimycin A, accompanied by an accumulation of proteins modified with 4-hydroxy-2-nonenal. Thus, these findings suggest that mitochondrial ALDH2 functions as a protector against oxidative stress.