Increased reactive oxygen species production and maintenance of membrane potential in VDAC-less Neurospora crassa mitochondria Abstract The highly abundant voltage-dependent anion-selective channel (VDAC) allows transit of metabolites across the mitochondrial outer membrane. Previous studies in Neurospora crassa showed that the LoPo strain, expressing 50% of normal VDAC levels, is indistinguishable from wild-type (WT). In contrast, the absence of VDAC (ΔPor-1), or the expression of an N-terminally truncated variant VDAC (ΔN2-12porin), is associated with deficiencies in cytochromes b and aa3 of complexes III and IV and concomitantly increased alternative oxidase (AOX) activity. These observations led us to investigate complex I and complex II activities in these strains, and to explore their mitochondrial bioenergetics. The current study reveals that the total NADH dehydrogenase activity is similar in mitochondria from WT, LoPo, ΔPor-1 and ΔN2-12porin strains; however, in ΔPor-1 most of this activity is the product of rotenone-insensitive alternative NADH dehydrogenases. Unexpectedly, LoPo mitochondria have increased complex II activity. In all mitochondrial types analyzed, oxygen consumption is higher in the presence of the complex II substrate succinate, than with the NADH-linked (complex I) substrates glutamate and malate. When driven by a combination of complex I and II substrates, membrane potentials (Δψ) and oxygen consumption rates (OCR) under non-phosphorylating conditions are similar in all mitochondria. However, as expected, the induction of state 3 (phosphorylating) conditions in ΔPor-1 mitochondria is associated with smaller but significant increases in OCR and smaller decreases in Δψ than those seen in wild-type mitochondria. High ROS production, particularly in the presence of rotenone, was observed under non-phosphorylating conditions in the ΔPor-1 mitochondria. Thus, the absence of VDAC is associated with increased ROS production, in spite of AOX activity and wild-type OCR in ΔPor-1 mitochondria.

Protection from ionizing radiation-induced genotoxicity and apoptosis in rat bone marrow cells by HESA-A: a new herbal-marine compound Abstract HESA-A is an herbal-marine compound which improves the quality of life of end-stage cancer patients. The aim of the present study was to evaluate the possible protective effect of HESA-A against IR-induced genotoxicity and apoptosis in rat bone marrow. Rats were given HESA-A orally at doses of 150 and 300 mg/kg body weight for seven consecutive days. On the seventh day, the rats were irradiated with 4 Gy X-rays at 1 h after the last oral administration. The micronucleus assay, reactive oxygen species (ROS) level analysis, hematological analysis and flow cytometry were used to assess radiation antagonistic potential of HESA-A. Administration of 150 and 300 mg/kg of HESA-A to irradiated rats significantly reduced the frequencies of micronucleated polychromatic erythrocytes (MnPCEs) and micronucleated normochromatic erythrocytes (MnNCEs), and also increased PCE/(PCE + NCE) ratio in bone marrow cells. Moreover, pretreatment of irradiated rats with HESA-A (150 and 300 mg/kg) significantly decreased ROS level and apoptosis in bone marrow cells, and also increased white blood cells count in peripheral blood. For the first time in this study, it was observed that HESA-A can have protective effects against radiation-induced genotoxicity and apoptosis in bone marrow cells. Therefore, HESA-A can be considered as a candidate for future studies to reduce the side effects induced by radiotherapy in cancer patients.

Correction to: The synergistic effect of mefenamic acid with ionizing radiation in colon cancer The original version of this article unfortunately contained a mistake. The name of “Zohreh Noaparast” is now corrected in the author group of this article.

Retraction Note to: Acridine yellow. A novel use to estimate and measure the plasma membrane potential in Saccharomyces cerevisiae The authors have retracted this article [1]. After publication the dye used in this study was analysed by NMR and mass spectroscopy and found not to be acridine yellow, but rather, was identified as thioflavin T.

MicroRNA-141 protects PC12 cells against hypoxia/reoxygenation-induced injury via regulating Keap1-Nrf2 signaling pathway Abstract To understand the role of microRNA-141 (miR-141) in hypoxia/reoxygenation (H/R)-induced PC12 cell injury via modulation of Keap1/Nrf2 signaling pathway. PC12 cells were divided into Control, H/R, H/R + miR-141 mimics, H/R + NC, H/R + miR-141 inhibitor, H/R + siKeap1 and H/R + miR-141 inhibitors+siKeap1 groups. The expression of miR-141 and Keap1/Nrf2 pathway was measured by qRT-PCR and western blotting, cell viability evaluated by MTT assay while cell apoptosis tested by flow cytometry. Besides, MDA (malondialdehyde), SOD (Super Oxide Dismutase) and LDH (lactate dehydrogenase) levels were determined. DCFH-DA and JC-1 staining were used to measure ROS and mitochondrial membrane potential (MMP) respectively. Compared with Controls, PC12 cells induced by H/R exhibited decreased cell viability and increased cell apoptosis rate, with elevated MDA, LDH and ROS and reduced SOD levels; and meanwhile, MMP and miR-141 expression were declined, whereas cytoplasmic Nrf2 levels were enhanced with the downregulated nuclear Nrf2 level (all P < 0.05). However, these cells treated with miR-141 mimics and siKeap1 showed obvious improvement in H/R-induced cell injury, while miR-141 inhibitors presented significantly aggravated cell injury (both P < 0.05). Besides, siKeap1 can reverse the effect of miRNA-141 inhibitors on aggravating H/R-induced PC12 cell injury. miR-141-mediated Keap1/Nrf2 signaling pathway to promote cell viability, inhibit cell apoptosis and reduce oxidative stress of PC12 cells, thereby alleviating H/R-induced cell injury.

Arylboronic acids inhibit P2X7 receptor function and the acute inflammatory response Abstract The P2X7 receptor (P2X7R) is an ion channel which is activated by interactions with the extracellular ATP molecules. The molecular complex P2X7R/ATP induces conformational changes in the protein subunits, opening a pore in the ion channel macromolecular structure. Currently, the P2X7R has been studied as a potential therapeutic target of anti-inflammatory drugs. Based on this, a series of eight boronic acids (NO) analogs were evaluated on the biologic effect of this pharmacophoric group on the human and murine P2X7R. The boronic acids derivatives NO-01 and NO-12 inhibited in vitro human and murine P2X7R function. These analogs compounds showed effect better than compound BBG and similar to inhibitor A740003 for inhibiting dye uptake, in vitro IL-1β release and ATP-induced paw edema in vivo. In both, in vitro and in vivo assays the compound NO-01 showed to be the hit compound in the present series of the arylboronic acids analogs. The molecular docking suggests that the NO derivatives bind into the upper body domain of the P2X7 pore and that the main intermolecular interaction with the two most active NO derivatives occur with the residues Phe 95, 103 and 293 by hydrophobic interactions and with Leu97, Gln98 and Ser101 by hydrogen bonds.. These results indicate that the boronic acid derivative NO-01 shows the lead compound characteristics to be used as a scaffold structure to the development of new P2X7R inhibitors with anti-inflammatory action.

Mitochondria as a possible target for nicotine action Abstract Mitochondria are multifunctional and dynamic organelles deeply integrated into cellular physiology and metabolism. Disturbances in mitochondrial function are involved in several disorders such as neurodegeneration, cardiovascular diseases, metabolic diseases, and also in the aging process. Nicotine is a natural alkaloid present in the tobacco plant which has been well studied as a constituent of cigarette smoke. It has also been reported to influence mitochondrial function both in vitro and in vivo. This review presents a comprehensive overview of the present knowledge of nicotine action on mitochondrial function. Observed effects of nicotine exposure on the mitochondrial respiratory chain, oxidative stress, calcium homeostasis, mitochondrial dynamics, biogenesis, and mitophagy are discussed, considering the context of the experimental design. The potential action of nicotine on cellular adaptation and cell survival is also examined through its interaction with mitochondria. Although a large number of studies have demonstrated the impact of nicotine on various mitochondrial activities, elucidating its mechanism of action requires further investigation.

Hyperthermia potentiates cisplatin cytotoxicity and negative effects on mitochondrial functions in OVCAR-3 cells Abstract The aim of this study was to determine the effects of hyperthermia, cisplatin and their combination on mitochondrial functions such as glutamate dehydrogenase (GDH) activity and mitochondrial respiration rates, as well as survival of cultured ovarian adenocarcinoma OVCAR-3 cells. Cells treated for 1 h with hyperthermia (40 and 43 °C) or cisplatin (IC50) or a combination of both treatments were left for recovery at 37 °C temperature for 24 h or 48 h. The obtained results revealed that 43 °C hyperthermia potentiated effects of cisplatin treatment: combinatory treatment more strongly suppressed GDH activity and expression, mitochondrial functions, and decreased survival of OVCAR-3 cells in comparison to separate single treatments. We obtained evidence that in the OVCAR-3 cell line GDH was directly activated by hyperthermia (cisplatin eliminated this effect); however, this effect was followed by GDH inhibition after 48 h recovery. A combination of 43 °C hyperthermia with cisplatin induced stronger GDH inhibition in comparison to separate treatments, and negative effects exerted on GDH activity correlated with suppression of mitochondrial respiration with glutamate + malate. Cisplatin did not induce uncoupling of oxidative phosphorylation in OVCAR-3 cells but induced impairment of the outer mitochondrial membrane in combination with 43 °C hyperthermia. Hyperthermia (43 °C) potentiated cytotoxicity of cisplatin in an OVCAR-3 cell line.

Effect of hypoxia on mitochondrial enzymes and ultrastructure in the brain cortex of rats with different tolerance to oxygen shortage Abstract The mitochondrial structure and the contents of subunits (NDUFV2, SDHA, Cyt b, COX1) of mitochondrial respiratory complexes I–IV as well as of the hypoxia-inducible factor (HIF-1α) in the brain cortex (BC) of rats with high resistance (HR) and low resistance (LR) to hypoxia were studied for the first time depending on the severity of hypoxia. Different regimes of 30-min hypobaric hypoxia (pO2 14, 10, and 8%) were used. It was found that cortical mitochondria responded to 30-min hypobaric hypoxia of different severity with typical and progressing changes in mitochondrial structure and function of mitochondrial enzymes. Under 14 and 10% hypoxia, animals developed compensatory structural and metabolic responses aimed at supporting the cell energy homeostasis. Consequently, these hypoxia regimes can be used for treatment in pressure chambers. At the same time, decreasing the oxygen concentration in the inhaled air to 8% led to the appearance of destructive processes in brain mitochondria. The features of mitochondrial ultrastructure and the function of respiratory enzymes in the BC of HR and LR rats exposed to normoxic and hypoxic conditions suggest that the two types of animals had two essentially distinct functional and metabolic patterns determined by different efficiency of the energy apparatus. The development of adaptive and destructive responses involved different metabolic pathways of the oxidation of energy substrates and different efficiency of the functioning of mitochondrial respiratory carriers.

Effect of hypothermia on the functional activity of liver mitochondria of grass snake ( Natrix natrix ): inhibition of succinate-fueled respiration and K + transport, ROS-induced activation of mitochondrial permeability transition Abstract The article considers the comparative analysis of the functional activity of mitochondria isolated from the liver of grass snakes, Natrix natrix (Linnaeus, 1758) that were kept at different temperatures (23–26 °C and 4-5 °C). It was found that liver mitochondria of hypothermia-exposed grass snakes are characterized by weak coupling of oxidative phosphorylation as compared to mitochondria of active animals which is caused by inhibition of succinate-fuelled respiration in ADP-stimulated state, as well as by activation of basal non-phosphorylating rate. Inhibition of mitochondrial respiration in hibernating animals is associated with a decrease in the activity of the respiratory chain complexes of organelles. A significant decrease in the rate of K+ transport in the liver mitochondria of hibernating animals has been established. Under these conditions, a decrease in the calcium capacity of the organelles was also revealed, which indicates a decrease in the resistance of the mitochondria of hibernating animals to the induction of the Ca2+-dependent mitochondrial pore. All these changes in the functional activity of mitochondria are observed on the background of increasing H2O2 production as well as increasing the proportion of polyunsaturated fatty acids in phospholipid composition of mitochondrial membranes, which are the targets of reactive oxygen species. It can lead to increased formation of lipid peroxides and activation of destructive processes associated with the induction of Ca2+-dependent mitochondrial pore.