The Switching of the Type of a ROS Signal from Mitochondria: The Role of Respiratory Substrates and Permeability Transition.

Flashes of superoxide anion (O) in mitochondria are generated spontaneously or during the opening of the permeability transition pore (mPTP) and a sudden change in the metabolic state of a cell. Under certain conditions, O can leave the mitochondrial matrix and perform signaling functions beyond mitochondria. In this work, we studied the kinetics of the release of O and HO from isolated mitochondria upon mPTP opening and the modulation of the metabolic state of mitochondria by the substrates of respiration and oxidative phosphorylation.

Warm Cells, Hot Mitochondria: Achievements and Problems of Ultralocal Thermometry.

Temperature is a crucial regulator of the rate and direction of biochemical reactions and cell processes. The recent data indicating the presence of local thermal gradients associated with the sites of high-rate thermogenesis, on the one hand, demonstrate the possibility for the existence of "thermal signaling" in a cell and, on the other, are criticized on the basis of thermodynamic calculations and models. Here, we review the main thermometric techniques and sensors developed for the determination of temperature inside living cells and diverse intracellular compartments.

Mitochondrial F-ATP Synthase Co-Migrating Proteins and Ca-Dependent Formation of Large Channels.

Monomers, dimers, and individual FF-ATP synthase subunits are, presumably, involved in the formation of the mitochondrial permeability transition pore (PTP), whose molecular structure, however, is still unknown. We hypothesized that, during the Ca-dependent assembly of a PTP complex, the F-ATP synthase (subunits) recruits mitochondrial proteins that do not interact or weakly interact with the F-ATP synthase under normal conditions. Therefore, we examined whether the PTP opening in mitochondria before the separation of supercomplexes via BN-PAGE will increase the channel stability and channel-forming capacity of isolated F-ATP synthase dimers and monomers in planar lipid membranes.

The Effect of Astaxanthin on Mitochondrial Dynamics in Rat Heart Mitochondria under ISO-Induced Injury.

Mitochondria are dynamic organelles that produce ATP in the cell and are sensitive to oxidative damage that impairs mitochondrial function in pathological conditions. Mitochondria are involved not only in a healthy heart but also in the development of heart disease. Therefore, attempts should be made to enhance the body's defense response against oxidative stress with the help of various antioxidants in order to decrease mitochondrial damage and reduce mitochondrial dysfunction.

Regulation of Mitochondrial Permeability Transition Pore Opening by Monovalent Cations in Liver Mitochondria.

The opening of the permeability transition pore (PTP) in mitochondria is a key event in the initiation of cell death in various pathologic states, including ischemia/reperfusion. The activation of K transport into mitochondria protects cells from ischemia/reperfusion. However, the role of K transport in PTP regulation is unclear.

Pioglitazone Is a Mild Carrier-Dependent Uncoupler of Oxidative Phosphorylation and a Modulator of Mitochondrial Permeability Transition.

Pioglitazone (PIO) is an insulin-sensitizing antidiabetic drug, which normalizes glucose and lipid metabolism but may provoke heart and liver failure and chronic kidney diseases. Both therapeutic and adverse effects of PIO can be accomplished through mitochondrial targets. Here, we explored the capability of PIO to modulate the mitochondrial membrane potential (ΔΨ) and the permeability transition pore (mPTP) opening in different models in vitro.

NAD(H) Regulates the Permeability Transition Pore in Mitochondria through an External Site.

The opening of the permeability transition pore (mPTP) in mitochondria initiates cell death in numerous diseases. The regulation of mPTP by NAD(H) in the mitochondrial matrix is well established; however, the role of extramitochondrial (cytosolic) NAD(H) is still unclear. We studied the effect of added NADH and NAD on: (1) the Ca-retention capacity (CRC) of isolated rat liver, heart, and brain mitochondria; (2) the Ca-dependent mitochondrial swelling in media whose particles can (KCl) or cannot (sucrose) be extruded from the matrix by mitochondrial carriers; (3) the Ca-dependent mitochondrial depolarization and the release of entrapped calcein from mitochondria of permeabilized hepatocytes; and (4) the Ca-dependent mitochondrial depolarization and subsequent repolarization.

Dynamics of the permeability transition pore size in isolated mitochondria and mitoplasts.

The size of the permeability transition pore (PTP) is accepted to be ≤1.5 kDa. However, different authors reported values from 650 to 4000 Da.

Isoproterenol-Induced Permeability Transition Pore-Related Dysfunction of Heart Mitochondria Is Attenuated by Astaxanthin.

Mitochondria are key organelles of the cell because their main function is the capture of energy-rich substrates from the cytoplasm and oxidative cleavage with the generation of carbon dioxide and water, processes that are coupled with the synthesis of ATP. Mitochondria are subject to oxidative stress through the formation of the mitochondrial permeability transition pore (mPTP). Various antioxidants are used to reduce damage caused by oxidative stress and to improve the protection of the antioxidant system.

Vitamin B Enhances the Cytotoxicity of Diethyldithiocarbamate in a Synergistic Manner, Inducing the Paraptosis-Like Death of Human Larynx Carcinoma Cells.

We have shown that hydroxycobalamin (vitamin В) increases the toxicity of diethyldithiocarbamate (DDC) to tumor cells by catalyzing the formation of disulfiram (DSF) oxi-derivatives. The purpose of this study was to elucidate the mechanism of tumor cell death induced by the combination DDC + В. It was found that cell death induced by DDC + B differed from apoptosis, autophagy, and necrosis.

Astaxanthin Inhibits Mitochondrial Permeability Transition Pore Opening in Rat Heart Mitochondria.

The mitochondrion is the main organelle of oxidative stress in cells. Increased permeability of the inner mitochondrial membrane is a key phenomenon in cell death. Changes in membrane permeability result from the opening of the mitochondrial permeability transition pore (mPTP), a large-conductance channel that forms after the overload of mitochondria with Ca or in response to oxidative stress.

Fusaricidin-Type Compounds Create Pores in Mitochondrial and Plasma Membranes of Mammalian Cells.

Fusaricidins and related LI-F compounds are effective bactericides and fungicides. Recently, we have found that they are highly toxic to mammalian cells. Here, we studied the effect of fusaricidin-type compounds (FTCs) on the membranes of mammalian cells.

Regulation of permeability transition pore opening in mitochondria by external NAD(H).

Background: The opening of the permeability transition pore (PTP) in mitochondria plays a critical role in the pathogenesis of numerous diseases. Mitochondrial matrix pyridine nucleotides are potent regulators of the PTP, but the role of extramitochondrial nucleotides is unclear.

Methods: The PTP opening was explored in isolated mitochondria and mitochondria in permeabilized differentiated and undifferentiated cells in the presence of added NAD(P)(H) in combination with Mg, adenine nucleotides (AN), and the inhibitors of AN translocase (ANT), voltage-dependent anion channel (VDAC), and cyclophilin D.

Pyridine nucleotides regulate the superoxide anion flash upon permeabilization of mitochondrial membranes: An MCLA-based study.

The permeabilization of mitochondrial membranes via permeability transition pore opening or by the pore-forming peptide alamethicin causes a flash of superoxide anion (SA) and hydrogen peroxide production and the inhibition of matrix aconitase. It was shown using the SA probe 3,7-dihydro-2-methyl-6-(4-methoxyphenyl)imidazol[1,2-a]pyrazine-3-one (MCLA) that the substrates of NAD-dependent dehydrogenases, inhibitors of the respiratory chain, and NAD(P)H at millimolar concentrations suppressed or delayed SA flashes. In the presence of added NADH and NADPH, SA flashes were observed only after considerable oxidation of pyridine nucleotides.

Effect of Melatonin on Rat Heart Mitochondria in Acute Heart Failure in Aged Rats.

Excessive generation of reactive oxygen species (ROS) in mitochondria and the opening of the nonselective mitochondrial permeability transition pore are important factors that promote cardiac pathologies and dysfunction. The hormone melatonin (MEL) is known to improve the functional state of mitochondria via an antioxidant effect. Here, the effect of MEL administration on heart mitochondria from aged rats with acute cardiac failure caused by isoprenaline hydrochloride (ISO) was studied.

Glutamate contributes to alcohol hepatotoxicity by enhancing oxidative stress in mitochondria.

Chronic alcohol intoxication is associated with increased oxidative stress. However, the mechanisms by which ethanol triggers an increase in the production of reactive oxygen species (ROS) and the role of mitochondria in the development of oxidative stress has been insufficiently studied. The biochemical and proteomic data obtained in the present work suggest that one of the main causes of an increase in ROS generation is enhanced oxidation of glutamate in response to long-term alcohol exposure.

Mechanism of triclosan toxicity: Mitochondrial dysfunction including complex II inhibition, superoxide release and uncoupling of oxidative phosphorylation.

Triclosan (5-chloro-2'-(2,4-dichlorophenoxy)phenol), a widely used antibacterial agent, exerts adverse effects on the organism of mammals. Recent research reviled that triclosan at low micromolar concentrations causes mitochondrial dysfunction in many cell types, but the mechanisms of its effect are not fully understood. Here we show that exposure to triclosan disrupted membrane potential, prevented the calcium uptake-driven high-amplitude mitochondrial swelling, stimulated the respiration in the presence of complex I substrates, and suppressed the ADP-stimulated respiration in the presence of complex II substrate, succinate.

External mitochondrial NADH-dependent reductase of redox cyclers: VDAC1 or Cyb5R3?

It was reported that VDAC1 possesses an NADH oxidoreductase activity and plays an important role in the activation of xenobiotics in the outer mitochondrial membrane. In the present work, we evaluated the participation of VDAC1 and Cyb5R3 in the NADH-dependent activation of various redox cyclers in mitochondria. We show that external NADH oxidoreductase caused the redox cycling of menadione ≫ lucigenin>nitrofurantoin.

Rapid fluorescent visualization of multiple NAD(P)H oxidoreductases in homogenate, permeabilized cells, and tissue slices.

Intracellular NAD(P)H oxidoreductases are a class of diverse enzymes that are the key players in a number of vital processes. The method we present and validate here is based on the ability of many NAD(P)H oxidoreductases to reduce the superoxide probe lucigenin, which is structurally similar to flavins, to its highly fluorescent water-insoluble derivative dimethylbiacridene. Two modifications of the method are proposed: (i) an express method for tissue homogenate and permeabilized cells in suspensions and (ii) a standard procedure for cells in culture and acute thin tissue slices.

Cereulide produced by Bacillus cereus increases the fitness of the producer organism in low-potassium environments.

Cereulide, produced by certain Bacillus cereus strains, is a lipophilic cyclic peptide of 1152 Da that binds K(+) ions with high specificity and affinity. It is toxic to humans, but its role for the producer organism is not known. We report here that cereulide operates for B.

Sulfur-containing compounds quench 3,7-dihydro-2-methyl-6-(4-methoxyphenyl)imidazol[1,2-a]pyrazine-3-one chemiluminescence: Discrimination between true antioxidants and quenchers using xanthine oxidase.

The probe 3,7-dihydro-2-methyl-6-(4-methoxyphenyl)imidazol[1,2-a]pyrazine-3-one (MCLA) is widely used for studying the superoxide anion production and the efficiency of antioxidants in biological systems. Here we report that a number of sulfur-containing compounds applied in biochemical and cytological studies are able to suppress MCLA-derived chemiluminescence (MDCL) independent of their capability to scavenge superoxide anion. The most effective MDCL quenchers appeared to be the substances with thiocarbamoyl and thiocarbonyl groups coupled to cyclic molecules and several thiol- and disulfide-containing compounds.

Flow cytometry-based assay for the activity of NAD(P)H oxidoreductases of the outer mitochondrial membrane.

NAD(P)H oxidoreductases of the outer mitochondrial membrane (OMM) are able to activate various xenobiotics and stimulate the production of reactive oxygen species and the opening of the mitochondrial permeability transition pore. However, the role of these systems in the cell damage by xenobiotics and chemotherapeutic drugs is poorly understood because the methods for the selective assessment of their activity have not been elaborated and specific inhibitors are unknown. Here we propose a method for the semiquantitative assessment of the activity of NAD(P)H oxidoreductases of the OMM in intact and permeabilized cells that is based on the flow cytometry detection of dimethylbiacridene, a fluorescent product of two-electron reduction of lucigenin.

Novel mycotoxin from Acremonium exuviarum is a powerful inhibitor of the mitochondrial respiratory chain complex III.

A novel mycotoxin named acrebol, consisting of two closely similar peptaibols (1726 and 1740 Da), was isolated from an indoor strain of the mitosporic ascomycete fungus Acremonium exuviarum. This paper describes the unique mitochondrial toxicity of acrebol, not earlier described for any peptaibol. Acrebol inhibited complex III of the respiratory chain of isolated rat liver mitochondria (1 mg of protein mL(-1)) with an IC(50) of approximately 80 ng mL(-1) (50 nM) after a short preincubation, and 350 ng mL(-1) caused immediate and complete inhibition.

TRIP6, a novel molecular partner of the MAGI-1 scaffolding molecule, promotes invasiveness.

We recently established the critical role of the PTEN/MAGI-1b signalosome in stabilization of cell-cell contacts and suppression of invasiveness. The PTEN tumor suppressor is recruited to E-cadherin junctional complexes through the binding to the second PDZ domain of the MAGI-1b scaffolding molecule, whereas beta-catenin interacts with the fifth PDZ domain. To identify additional effectors of this signalosome, we used yeast 2-hybrid screening.

Redox-cycling compounds can cause the permeabilization of mitochondrial membranes by mechanisms other than ROS production.

The participation of reactive oxygen species (ROS) in the regulation of mitochondrial permeability transition pore (mPTP) opening by the redox-cycling compounds menadione and lucigenin was explored. The level of ROS was modulated by antioxidants, anoxia, and switching the sites of the reduction of redox cyclers, the dehydrogenases of the inner and outer mitochondrial membranes. We found that the reduction of both lucigenin and menadione in the outer mitochondrial membrane caused a strong production of ROS.