Thioredoxin and glutaredoxin regulate metabolism through different multiplex thiol switches

The aim of the present study was to define the role of Trx and Grx on metabolic thiol redox regulation and identify their protein and metabolite targets. The hepatocarcinoma-derived HepG2 cell line under both normal and oxidative/nitrosative conditions by overexpression of NO synthase (NOS3) was used as experimental model. Grx1 or Trx1 silencing caused conspicuous changes in the redox proteome reflected by significant changes in the reduced/oxidized ratios of specific Cys's including several glycolytic enzymes. Cys⁹¹ of peroxiredoxin-6 (PRDX6) and Cys¹⁵³ of phosphoglycerate mutase-1 (PGAM1), that are known to be involved in progression of tumor growth, are reported here for the first time as specific targets of Grx1. A group of proteins increased their Cys_RED/Cys_OX ratio upon Trx1 and/or Grx1 silencing, including caspase-3 Cys¹⁶³, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) Cys²⁴⁷ and triose-phosphate isomerase (TPI) Cys²⁵⁵ likely by enhancement of NOS3 auto-oxidation. The activities of several glycolytic enzymes were also significantly affected. Glycolysis metabolic flux increased upon Trx1 silencing, whereas silencing of Grx1 had the opposite effect. Diversion of metabolic fluxes toward synthesis of fatty acids and phospholipids was observed in siRNA-Grx1 treated cells, while siRNA-Trx1 treated cells showed elevated levels of various sphingomyelins and ceramides and signs of increased protein degradation. Glutathione synthesis was stimulated by both treatments. These data indicate that Trx and Grx have both, common and specific protein Cys redox targets and that down regulation of either redoxin has markedly different metabolic outcomes. They reflect the delicate sensitivity of redox equilibrium to changes in any of the elements involved and the difficulty of forecasting metabolic responses to redox environmental changes.

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Trx1 and Grx1 Cys redox targets are abundant among Glycolytic enzymes.

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PRDX6-Cys⁹¹ and PGAM-Cys¹⁵³ are specific targets of Grx1.

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Down regulation of thioredoxin and glutaredoxin have different metabolic outcomes.

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Glutathione synthesis and membrane lipid composition are sensitive to Trx1 and Grx1 down regulation.

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Redoxins down regulation also induce target Cys reductive changes under NOS3 overexpression.

[State of acute phase markers and oxidative stress in patients with kidney stones in the urinary tract]

OBJECTIVE

This present study has aimed to assess the state of acute phase markers and oxidative stress in patients with kidney stones.

MATERIAL AND METHODS

A prospective study was carried out on 100 patients with kidney stones and 25 healthy controls. Albumin, ß2 microglobulin, Gamma-glutamyl transpepsidase, Lactate dehydrogenase, Tumor necrosis factor alpha, Interleukin 1 and Interleukin-6 were evaluated as acute phase markers and lipid peroxidation products, Superoxide dismutase and Glutathione peroxidase levels acted as oxidative stress markers.

RESULTS

An increase in renal cell damage markers as expressed by the ß2 microglobulin (p=0.04), albumin (p=0.004), Lactate dehydrogenase (p=0.001) and Gamma glutamyl transpepsidasa (p=0.01) was observed in the patient group. There was a direct correlation between levels of ß2 microglobulin and stone size (r=0.3, p=0.03). The association between stone size and cytokine activation was observed to be stronger in patients with staghorn calculi. In these patients, Tumor necrosis factor alpha (p=0.011), Interleukin 1 (p=0.004) and Interleukin 6 (p=0.004) were significantly higher. Patients with stones in the urinary tract showed data of significantly higher oxidative stress, expressed as an increase in levels of lipid peroxidation products (p=0.03) and a decrease in the antioxidant activity of Superoxide dismutase (p=0.03) and Glutathione peroxidase (p=0.002).

CONCLUSIONS

Patients undergoing urolithiasis showed an elevation of acute phase markers, associated with oxidative stress as expressed by an increase in lipid peroxidation products and a decrease in the antioxidant enzyme activity.

Effect of dietary coenzyme Q and fatty acids on the antioxidant status of rat tissues

Wistar rats were fed with different diets with or without supplement coenzyme Q(10) (CoQ(10)) and with oil of different sources (sunflower or virgin olive oil) for six or twelve months. Ubiquinone contents (CoQ(9) and CoQ(10)) were quantified in homogenates of livers and brains from rats fed with the four diets. In the brain, younger rats showed a 3-fold higher amount of ubiquinone than older ones for all diets. In the liver, however, CoQ(10) supplementation increased the amount of CoQ(9) and CoQ(10) in both total homogenates and plasma membranes. Rats fed with sunflower oil as fat source showed higher amounts of ubiquinone content than those fed with olive oil, in total liver homogenates, but the total ubiquinone content in plasma membranes was similar with both fat sources. Older rats showed a higher amount of ubiquinone after diets supplemented with CoQ(10). Two ubiquinone-dependent antioxidant enzyme activities were measured. NADH-ferricyanide reductase activity in hepatocyte plasma membranes was unaltered by ubiquinone accumulation, but this activity increased slightly with age. Both cytosolic and membrane-bound dicumarol-sensitive NAD(P)H:(quinone acceptor) oxidoreductase (DT-diaphorase, EC 1.6.99.2) activities were decreased by diets supplemented with CoQ(10). Animals fed with olive oil presented lower DT-diaphorase activity than those fed with sunflower oil, suggesting that the CoQ(10) antioxidant protection is strengthened by olive oil as fat source.