Sérgio A. Uyemura
University of São Paulo
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Featured researches published by Sérgio A. Uyemura.
Journal of Inorganic Biochemistry | 2003
Daniel Junqueira Dorta; Samara Leite; Kátia C. DeMarco; Ieda M.R. Prado; Tiago Rodrigues; Fábio E. Mingatto; Sérgio A. Uyemura; Antonio C. Santos; Carlos Curti
Cadmium is a very important environmental toxicant, the cytotoxicity mechanism of which is likely to involve mitochondria as a target. In the present study we addressed the cause/effect relationship between the multiple cadmium-induced responses involving the mitochondrial energetic and oxidative status. Assays were performed with succinate-energized rat liver mitochondria incubated with 5 microM CdCl(2) for 0-25 min, in the absence or presence, respectively, of N-ethylmaleimide (NEM), butylhydroxytoluene (BHT), ruthenium red (RR), and cyclosporine A+ADP. A sequence of events accounting for cadmium-induced mitochondrial impairment is proposed, beginning with an apparent interaction of Cd(2+) with specific protein thiols in the mitochondrial membrane, which stimulates the cations uptake via the Ca(2+) uniporter, and is followed by the onset of mitochondrial permeability transition (MPT); both effects dissipate the transmembrane electrical potential (Deltapsi), causing uncoupling, followed by an early depression of mitochondrial ATP levels. The respiratory chain subsequently undergoes inhibition, generating reactive oxygen species which together with iron mobilized by the cation, cause late, gradual mitochondrial membrane lipid peroxidation.
Biochemical Pharmacology | 1994
Maria Eliza Jordani de Souza; Ana Cristina M. Polizello; Sérgio A. Uyemura; Orlando Castro-Silva; Carlos Curti
The in vitro and in vivo effects of fluoxetine (and its active metabolite norfluoxetine) on mitochondrial respiration and F0F1-ATPase were studied, respectively, in mitochondria and submitochondrial particles isolated from rat liver. Fluoxetine in vitro inhibited state 3 mitochondrial respiration for alpha-ketoglutarate and succinate oxidations (50% of effect at 0.25 and 0.35 mM drug concentrations, respectively); stimulated state 4 for succinate; and induced a decrease in the respiratory control ratio (RCR) for both oxidizable substrates. The F0F1-ATPase activity was determined at various pH levels in the absence and presence of Triton X-100. The solubilized form was not affected markedly, but an inhibition, apparently non-competitive, was observed for the membrane-bound enzyme, with 50% of the effect at a 0.06 mM drug concentration in pH 7.4. These results suggest that fluoxetine in vitro acts on F0F1-ATPase through direct interaction with the membrane F0 component (similar to oligomycin), or first with mitochondrial membrane and then affecting F0. A very similar behavior concerning the respiratory parameters and F0F1-ATPase properties was observed with norfluoxetine. The in vivo studies with fluoxetine showed stimulation of mitochondrial respiration in state 4 for alpha-ketoglutarate or succinate oxidations in acute or prolonged treatments (1 hr after a single i.p. dose of 20 mg of drug/kg of body weight, and 22 hr after 12 days of treatment with a daily dose of 10 mg/kg of body weight, respectively), indicating uncoupling of oxidative phosphorylation. Pronounced changes were not observed in the K0.5 values of F0F1-ATPase catalytic sites, but the Vmax decreased during the prolonged treatment. The results show that fluoxetine (as well as norfluoxetine) has multiple effects on the energy metabolism of rat liver mitochondria, being potentially toxic in high doses. The drug effects seem to be a consequence of the drug and/or metabolite solubilization in the inner membrane of the mitochondria.
British Journal of Pharmacology | 2002
Tiago Rodrigues; Antonio C. Santos; Acácio A. Pigoso; Fábio E. Mingatto; Sérgio A. Uyemura; Carlos Curti
We evaluated the effects of the phenothiazine derivative thioridazine on mechanisms of mitochondria potentially implicated in apoptosis, such as those involving reactive oxygen species (ROS) and cytochrome c release, as well as the involvement of drug interaction with mitochondrial membrane in these effects. Within the 0 – 100 μM range thioridazine did not reduce the free radical 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) nor did it chelate iron. However, at 10 μM thioridazine showed important antioxidant activity on mitochondria, characterized by inhibition of accumulation of mitochondria‐generated O2•−, assayed as lucigenin‐derived chemiluminescence, inhibition of Fe2+/citrate‐mediated lipid peroxidation of the mitochondrial membrane (LPO), assayed as malondialdehyde generation, and inhibition of Ca2+/t‐butyl hydroperoxide (t‐BOOH)‐induced mitochondrial permeability transition (MPT)/protein‐thiol oxidation, assayed as mitochondrial swelling. Thioridazine respectively increased and decreased the fluorescence responses of mitochondria labelled with 1‐aniline‐8‐naphthalene sulfonate (ANS) and 1‐(4‐trimethylammonium phenyl)‐6 phenyl 1,3,5‐hexatriene (TMA‐DPH). The inhibition of LPO and MPT onset correlated well with the inhibition of cytochrome c release from mitochondria. We conclude that thioridazine interacts with the inner membrane of mitochondria, more likely close to its surface, acquiring antioxidant activity toward processes with potential implications in apoptosis such as O2•− accumulation, as well as LPO, MPT and associated release of cytochrome c.
British Journal of Pharmacology | 2000
Fábio E. Mingatto; Antonio C. Santos; Tiago Rodrigues; Acácio A. Pigoso; Sérgio A. Uyemura; Carlos Curti
We investigated the effects of nimesulide, a recently developed non‐steroidal anti‐inflammatory drug, and of a metabolite resulting from reduction of the nitro group to an amine derivative, on succinate‐energized isolated rat liver mitochondria incubated in the absence or presence of 20 μM Ca2+, 1 μM cyclosporin A (CsA) or 5 μM ruthenium red. Nimesulide uncoupled mitochondria through a protonophoretic mechanism and oxidized mitochondrial NAD(P)H, both effects presenting an EC50 of approximately 5 μM. Within the same concentration range nimesulide induced mitochondrial Ca2+ efflux in a partly ruthenium red‐sensitive manner, and induced mitochondrial permeability transition (MPT) when ruthenium red was added after Ca2+ uptake by mitochondria. Nimesulide induced MPT even in de‐energized mitochondria incubated with 0.5 mM Ca2+. Both Ca2+ efflux and MPT were prevented to a similar extent by CsA, Mg2+, ADP, ATP and butylhydroxytoluene, whereas dithiothreitol and N‐ethylmaleimide, which markedly prevented MPT, had only a partial or no effect on Ca2+ efflux, respectively. The reduction of the nitro group of nimesulide to an amine derivative completely suppressed the above mitochondrial responses, indicating that the nitro group determines both the protonophoretic and NAD(P)H oxidant properties of the drug. The nimesulide reduction product demonstrated a partial protective effect against accumulation of reactive oxygen species derived from mitochondria under conditions of oxidative stress like those resulting from the presence of t‐butyl hydroperoxide. The main conclusion is that nimesulide, on account of its nitro group, acts as a potent protonophoretic uncoupler and NAD(P)H oxidant on isolated rat liver mitochondria, inducing Ca2+ efflux or MPT within a concentration range which can be reached in vivo, thus presenting the potential ability to interfere with the energy and Ca2+ homeostasis in the liver cell.
Phytotherapy Research | 2008
Daniel Junqueira Dorta; Acácio A. Pigoso; Fábio E. Mingatto; Tiago Rodrigues; Cezar R. Pestana; Sérgio A. Uyemura; Antonio C. Santos; Carlos Curti
Mitochondria are important intracellular sources and targets of reactive oxygen species (ROS), while flavonoids, a large group of secondary plant metabolites, are important antioxidants. Following our previous study on the energetics of mitochondria exposed to the flavonoids quercetin, taxifolin, catechin and galangin, the present work addressed the antioxidant activity of these compounds (1–50 µmol/L) on Fe2+/citrate‐mediated membrane lipid peroxidation (LPO) in isolated rat liver mitochondria, running in parallel studies of their antioxidant activity in non‐organelle systems. Only quercetin inhibited the respiratory chain of mitochondria and only galangin caused uncoupling. Quercetin and galangin were far more potent than taxifolin and catechin in affording protection against LPO (IC50 = 1.23 ± 0.27 and 2.39 ± 0.79 µmol/L, respectively), although only quercetin was an effective scavenger of both 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and superoxide radicals. These results, together with the previous study, suggest that the 2,3‐double bond in conjugation with the 4‐oxo function in the flavonoid structure are major determinants of the antioxidant activity of flavonoids in mitochondria, the presence of an o‐di‐OH structure on the B‐ring, as occurs in quercetin, favours this activity via superoxide scavenging, while the absence of this structural feature in galangin, favours it via a decrease in membrane fluidity and/or mitochondrial uncoupling. Copyright
Molecular and Cellular Biochemistry | 1999
Carlos Curti; Fábio E. Mingatto; Ana Cristina M. Polizello; L. O. Galastri; Sérgio A. Uyemura; Antonio C. Santos
The effects of fluoxetine on the oxidative phosphorylation of mitochondria isolated from rat brain and on the kinetic properties of submitochondrial particle F1F0-ATPase were evaluated. The state 3 respiration rate supported by pyruvate + malate, succinate, or ascorbate + tetramethyl-p-phenylenediamine (TMPD) was substantially decreased by fluoxetine. The IC50 for pyruvate + malate oxidation was ∼ 0.15 mM and the pattern of inhibition was the typical one of the electron-transport inhibitors, in that the drug inhibited both ADP- and carbonyl cyanide m-chlorophenylhydrazone (CCCP)-stimulated respirations and the former inhibition was not released by the uncoupler. Fluoxetine also decreased the activity of submitochondrial particle F1F0-ATPase (IC50 ∼ 0.08 mM) even though K0.5 and activity of Triton X-100 solubilized enzyme were not changed substantially. As a consequence of these effects, fluoxetine decreased the rate of ATP synthesis and depressed the phosphorylation potential of mitochondria. Incubation of mitochondria or submitochondrial particles with fluoxetine under the conditions of respiration or F1F0-ATPase assays, respectively, caused a dose-dependent enhancement of 1-anilino-8-naphthalene sulfonate (ANS) fluorescence. These results show that fluoxetine indirectly and nonspecifically affects electron transport and F1F0)-ATPase activity inhibiting oxidative phosphorylation in isolated rat brain mitochondria. They suggest, in addition, that these effects are mediated by the drug interference with the physical state of lipid bilayer of inner mitochondrial membrane.
Journal of Pineal Research | 2014
Bruno G. Teodoro; Flávia G. Baraldi; Igor H. Sampaio; Lucas H. M. Bomfim; André L. Queiroz; Madla A. Passos; Everardo M. Carneiro; Luciane C. Alberici; Ramon Gomis; Fernanda Gaspar do Amaral; José Cipolla-Neto; Michel Barbosa de Araújo; Tanes Lima; Sérgio A. Uyemura; Leonardo R. Silveira; Elaine Vieira
Melatonin has a number of beneficial metabolic actions and reduced levels of melatonin may contribute to type 2 diabetes. The present study investigated the metabolic pathways involved in the effects of melatonin on mitochondrial function and insulin resistance in rat skeletal muscle. The effect of melatonin was tested both in vitro in isolated rats skeletal muscle cells and in vivo using pinealectomized rats (PNX). Insulin resistance was induced in vitro by treating primary rat skeletal muscle cells with palmitic acid for 24 hr. Insulin‐stimulated glucose uptake was reduced by palmitic acid followed by decreased phosphorylation of AKT which was prevented my melatonin. Palmitic acid reduced mitochondrial respiration, genes involved in mitochondrial biogenesis and the levels of tricarboxylic acid cycle intermediates whereas melatonin counteracted all these parameters in insulin‐resistant cells. Melatonin treatment increases CAMKII and p‐CREB but had no effect on p‐AMPK. Silencing of CREB protein by siRNA reduced mitochondrial respiration mimicking the effect of palmitic acid and prevented melatonin‐induced increase in p‐AKT in palmitic acid‐treated cells. PNX rats exhibited mild glucose intolerance, decreased energy expenditure and decreased p‐AKT, mitochondrial respiration, and p‐CREB and PGC‐1 alpha levels in skeletal muscle which were restored by melatonin treatment in PNX rats. In summary, we showed that melatonin could prevent mitochondrial dysfunction and insulin resistance via activation of CREB‐PGC‐1 alpha pathway. Thus, the present work shows that melatonin play an important role in skeletal muscle mitochondrial function which could explain some of the beneficial effects of melatonin in insulin resistance states.
Eukaryotic Cell | 2011
Vicente de Paulo Martins; Taísa Magnani Dinamarco; Frederico Marianetti Soriani; Valéria G. Tudella; Sergio C. Oliveira; Gustavo H. Goldman; Carlos Curti; Sérgio A. Uyemura
ABSTRACT Paracoccidioides brasiliensis is a thermodimorphic human pathogenic fungus that causes paracoccidioidomycosis (PCM), which is the most prevalent systemic mycosis in Latin America. Differentiation from the mycelial to the yeast form (M-to-Y) is an essential step for the establishment of PCM. We evaluated the involvement of mitochondria and intracellular oxidative stress in M-to-Y differentiation. M-to-Y transition was delayed by the inhibition of mitochondrial complexes III and IV or alternative oxidase (AOX) and was blocked by the association of AOX with complex III or IV inhibitors. The expression of P. brasiliensis aox (Pbaox) was developmentally regulated through M-to-Y differentiation, wherein the highest levels were achieved in the first 24 h and during the yeast exponential growth phase; Pbaox was upregulated by oxidative stress. Pbaox was cloned, and its heterologous expression conferred cyanide-resistant respiration in Saccharomyces cerevisiae and Escherichia coli and reduced oxidative stress in S. cerevisiae cells. These results reinforce the role of PbAOX in intracellular redox balancing and demonstrate its involvement, as well as that of other components of the mitochondrial respiratory chain complexes, in the early stages of the M-to-Y differentiation of P. brasiliensis.
Food and Chemical Toxicology | 2009
Fabiana S. Paula; Luciana M. Kabeya; Alexandre Kanashiro; Andréa S.G. de Figueiredo; Ana Elisa Caleiro Seixas Azzolini; Sérgio A. Uyemura; Yara Maria Lucisano-Valim
The tamarind (Tamarindus indica L.) is indigenous to Asian countries and widely cultivated in the American continents. The tamarind fruit pulp extract (ExT), traditionally used in spices, food components and juices, is rich in polyphenols that have demonstrated anti-atherosclerotic, antioxidant and immunomodulatory activities. This study evaluated the modulator effect of a crude hydroalcoholic ExT on some peripheral human neutrophil functions. The neutrophil reactive oxygen species generation, triggered by opsonized zymosan (OZ), n-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol myristate acetate (PMA), and assessed by luminol- and lucigenin-enhanced chemiluminescence (LumCL and LucCL, respectively), was inhibited by ExT in a concentration-dependent manner. ExT was a more effective inhibitor of the PMA-stimulated neutrophil function [IC50 (in microg/10(6)cells)=115.7+/-9.7 (LumCL) and 174.5+/-25.9 (LucCL)], than the OZ- [IC50=248.5+/-23.1 (LumCL) and 324.1+/-34.6 (LucCL)] or fMLP-stimulated cells [IC50=178.5+/-12.2 (LumCL)]. The ExT also inhibited neutrophil NADPH oxidase activity (evaluated by O2 consumption), degranulation and elastase activity (evaluated by spectrophotometric methods) at concentrations higher than 200 microg/10(6)cells, without being toxic to the cells, under the conditions assessed. Together, these results indicate the potential of ExT as a source of compounds that can modulate the neutrophil-mediated inflammatory diseases.
Journal of Bioenergetics and Biomembranes | 2008
Taisa Magnani; Frederico Marianetti Soriani; Vicente de Paulo Martins; Anna Carolina de Freitas Policarpo; Carlos A. Sorgi; Lúcia Helena Faccioli; Carlos Curti; Sérgio A. Uyemura
We previously demonstrated that conidia from Aspergillus fumigatus incubated with menadione and paraquat increases activity and expression of cyanide-insensitive alternative oxidase (AOX). Here, we employed the RNA silencing technique in A. fumigatus using the vector pALB1/aoxAf in order to down-regulate the aox gene. Positive transformants for aox gene silencing of A. fumigatus were more susceptible both to an imposed in vitro oxidative stress condition and to macrophages killing, suggesting that AOX is required for the A. fumigatus pathogenicity, mainly for the survival of the fungus conidia during host infection and resistance to reactive oxygen species generated by macrophages.