Mitochondria-targeted antioxidant SkQ1 reverses glaucomatous lesions in rabbits

Original article is published in: Frontiers in Bioscience, Landmark, 20, 892–901, January 1, 2015Glaucoma is the main cause of irreversible blindness worldwide. This disease is characterized by apoptosis of retinal ganglion cells (RGC) and visual field loss that seems to be related to elevated intraocular pressure (IOP). Several lines of evidences have implicated the crucial role of mitochondrial dysfunction in the pathogenesis of glaucoma. Increased mitochondrial oxidative stress in RGC may underlie or contribute to susceptibility of RGC to apoptosis. In our work we (i) designed a rabbit model of chronic, moderately elevated IOP for studying glaucoma and (ii) demonstrated efficacy of mitochondria-targeted antioxidant SkQ1 as a tool to reverse several traits of experimental glaucoma induced by a series of injections of hydroxypropylmethylcellulose (HPMC) to the anterior chamber of the rabbit eye. It is shown that 6 months instillations of drops of 0.2.5–5 µM solution of SkQ1 normalize IOP and eye hydrodynamics and abolish an increase in lens thickness that accompanies glaucoma.Original article is published in: Frontiers in Bioscience, Landmark, 20, 892–901, January 1, 2015Glaucoma is the main cause of irreversible blindness worldwide. This disease is characterized by apoptosis of retinal ganglion cells (RGC) and visual field loss that seems to be related to elevated intraocular pressure (IOP). Several lines of evidences have implicated the crucial role of mitochondrial dysfunction in the pathogenesis of glaucoma. Increased mitochondrial oxidative stress in RGC may underlie or contribute to susceptibility of RGC to apoptosis. In our work we (i) designed a rabbit model of chronic, moderately elevated IOP for studying glaucoma and (ii) demonstrated efficacy of mitochondria-targeted antioxidant SkQ1 as a tool to reverse several traits of experimental glaucoma induced by a series of injections of hydroxypropylmethylcellulose (HPMC) to the anterior chamber of the rabbit eye. It is shown that 6 months instillations of drops of 0.2.5–5 µM solution of SkQ1 normalize IOP and eye hydrodynamics and abolish an increase in lens thickness that accompanies glaucoma

Diffusion-controlled generation of a proton-motive force across a biomembrane

Respiration in bacteria involves a sequence of energetically-coupled electron and proton transfers creating an electrochemical gradient of protons (a proton-motive force) across the inner bacterial membrane. With a simple kinetic model we analyze a redox loop mechanism of proton-motive force generation mediated by a molecular shuttle diffusing inside the membrane. This model, which includes six electron-binding and two proton-binding sites, reflects the main features of nitrate respiration in E. coli bacteria. We describe the time evolution of the proton translocation process. We find that the electron-proton electrostatic coupling on the shuttle plays a significant role in the process of energy conversion between electron and proton components. We determine the conditions where the redox loop mechanism is able to translocate protons against the transmembrane voltage gradient above 200 mV with a thermodynamic efficiency of about 37%, in the physiologically important range of temperatures from 250 to 350 K.Comment: 26 pages, 4 figures. A similar model is used in arXiv:0806.3233 for a different biological system. Minor changes in the Acknowledgements sectio

Mitochondria-targeted antioxidant SkQR1 selectively protects MDR (Pgp 170)-negative cells against oxidative stress

AbstractA conjugate of plastoquinone with decylrhodamine 19 (SkQR1) selectively accumulates in mitochondria of normal and tumor cells. SkQR1 protected the cellular pool of reduced glutathione under oxidative stress. Overexpression of P-glycoprotein (Pgp 170) multidrug resistance pump strongly suppresses accumulation of SkQR1. The inhibitors of Pgp 170 stimulate accumulation of SkQR1 in various cell lines indicating that SkQR1 is a substrate of Pgp 170. The protective effect of SkQR1 against oxidative stress is diminished in the cells overexpressing Pgp 170. It is suggested that mitochondria-targeted antioxidants could selectively protect normal (Pgp 170-negative) cells against the toxic effect of anti-cancer treatments related to oxidative stress

Role of mitochondria in the pheromone- and amiodarone-induced programmed death of yeast

Although programmed cell death (PCD) is extensively studied in multicellular organisms, in recent years it has been shown that a unicellular organism, yeast Saccharomyces cerevisiae, also possesses death program(s). In particular, we have found that a high doses of yeast pheromone is a natural stimulus inducing PCD. Here, we show that the death cascades triggered by pheromone and by a drug amiodarone are very similar. We focused on the role of mitochondria during the pheromone/amiodarone-induced PCD. For the first time, a functional chain of the mitochondria-related events required for a particular case of yeast PCD has been revealed: an enhancement of mitochondrial respiration and of its energy coupling, a strong increase of mitochondrial membrane potential, both events triggered by the rise of cytoplasmic [Ca2+], a burst in generation of reactive oxygen species in center o of the respiratory chain complex III, mitochondrial thread-grain transition, and cytochrome c release from mitochondria. A novel mitochondrial protein required for thread-grain transition is identified

Mitochondria-Targeted Antioxidant SkQ1 Improves Dermal Wound Healing in Genetically Diabetic Mice

Oxidative stress is widely recognized as an important factor in the delayed wound healing in diabetes. However, the role of mitochondrial reactive oxygen species in this process is unknown. It was assumed that mitochondrial reactive oxygen species are involved in many wound-healing processes in both diabetic humans and animals. We have applied the mitochondria-targeted antioxidant 10-(6′-plastoquinonyl)decyltriphenylphosphonium (SkQ1) to explore the role of mitochondrial reactive oxygen species in the wound healing of genetically diabetic mice. Healing of full-thickness excisional dermal wounds in diabetic C57BL/KsJ-db−/db− mice was significantly enhanced after long-term (12 weeks) administration of SkQ1. SkQ1 accelerated wound closure and stimulated epithelization, granulation tissue formation, and vascularization. On the 7th day after wounding, SkQ1 treatment increased the number of α-smooth muscle actin-positive cells (myofibroblasts), reduced the number of neutrophils, and increased macrophage infiltration. SkQ1 lowered lipid peroxidation level but did not change the level of the circulatory IL-6 and TNF. SkQ1 pretreatment also stimulated cell migration in a scratch-wound assay in vitro under hyperglycemic condition. Thus, a mitochondria-targeted antioxidant normalized both inflammatory and regenerative phases of wound healing in diabetic mice. Our results pointed to nearly all the major steps of wound healing as the target of excessive mitochondrial reactive oxygen species production in type II diabetes

Real-time kinetics of electrogenic Na+ transport by rhodopsin from the marine flavobacterium Dokdonia sp. PRO95

Discovery of the light-driven sodium-motive pump Na+-rhodopsin (NaR) has initiated studies of the molecular mechanism of this novel membrane-linked energy transducer. In this paper, we investigated the photocycle of NaR from the marine flavobacterium Dokdonia sp. PRO95 and identified electrogenic and Na+-dependent steps of this cycle. We found that the NaR photocycle is composed of at least four steps: NaR519 + hv -> K-585 -> (L-450 M-495) -> O-585 -> NaR519. The third step is the only step that depends on the Na+ concentration inside right-side-out NaR-containing proteoliposomes, indicating that this step is coupled with Na+ binding to NaR. For steps 2, 3, and 4, the values of the rate constants are 4x10(4) s(-1), 4.7 x 10(3) M-1 s(-1), and 150 s(-1), respectively. These steps contributed 15, 15, and 70% of the total membrane electric potential (Delta psi similar to 200 mV) generated by a single turnover of NaR incorporated into liposomes and attached to phospholipid-impregnated collodion film. On the basis of these observations, a mechanism of light-driven Na+ pumping by NaR is suggested.Peer reviewe

Исследование антиоксидантного эффекта митохондриально-направленного антиоксиданта SkQ1 на модели изолированного сердца крысы

Mitochondrially targeted antioxidants based on Skulachev ions (SkQ1) are extremely attractive for neutralizing reactive oxygen species directly in the mitochondrial matrix.The aim was to examine the antioxidant and cardioprotective status of the SkQ1 mitochondrially targeted antioxidant in an isolated rat heart model of ischemia and reperfusion after cold cardioplegia.Material and methods. The effects of different concentrations of SkQ1 (1200 ng/ml, 120 ng/ml, 12 ng/ml) were explored on isolated hearts of Wistar rats (n=50) during 240-min cold cardioplegia. The levels of oxidative stress, changes in myocardial damage markers (classical and highly specific) and cardiac function (coronary flow velocity, heart rate, systolic pressure) were assessed.Results. The use of SkQ1 at 12 ng/ml resulted in a significant neutralization of oxidative stress manifestations (P<0.05). The minimum concentration of NO metabolites (nitrates and nitrites) (36.2 [30.8; 39.8] µmol/ml) was maintained at pre-ischemic level throughout the 30-minute reperfusion period, while the malonic dialdehyde concentration (49.5 [41.1; 58.9] µmol/g) was lower compared with SkQ1 use at 120 ng/ml dose. Due to the «mitigation» of oxidative stress, intracellular enzymes and highly specific markers of myocardial damage rose more slowly during reperfusion, while cardiac function recovery occurred at a higher rate and showed stability upon restoration of perfusion.Conclusion. SkQ1 at 12 ng/ml concentration showed strong antioxidant and cardioprotective properties in an ex vivo study.Митохондриально-направленные антиоксиданты на основе ионов Скулачёва (SkQ1) крайне привлекательны для нейтрализации активных форм кислорода непосредственно в матриксе митохондрий.Цель — изучить антиоксидантный и кардиопротективный эффект митохондриально-направленного антиоксиданта — SkQ1 на модели ишемии и реперфузии изолированного сердца крысы в условиях холодовой кардиоплегии.Материалы и методы. Исследование эффектов SkQ1 (1200 нг/мл, 120 нг/мл, 12 нг/мл) провели на изолированных сердцах крыс линии Wistar (n=50) в условиях 240-минутной холодовой кардиоплегии. Оценили уровень окислительного стресса, динамику маркеров повреждения миокарда (классические и высокоспецифичные) и функцию сердечной мышцы (скорость коронарного протока, частоту сердечных сокращений, систолическое давление).Результаты. Использование SkQ1 в концентрации 12 нг/мл привело к статистически значимой нейтрализации проявлений окислительного стресса (р<0,05): минимальное содержание NO-метаболитов — нитратов и нитритов (36,2 [30,8; 39,8] мкмоль/мл) поддерживалось на доишемическом уровне всю 30-минутную реперфузию, а концентрация малонового диальдегида (49,5 [41,1; 58,9] мкмоль/г) была ниже в сравнении с применением SkQ1 в концентрации 120 нг/мл. Вследствие «смягчения» окислительного стресса внутриклеточные ферменты и высокоспецифичные маркеры повреждения миокарда при реперфузии нарастали медленно, а восстановление сердечной функции произошло более высокими темпами и показало свою стабильность при возобновлении перфузии.Заключение. SkQ1 в концентрации 12 нг/мл проявил выраженные антиоксидантные и кардиопротективные свойства в исследовании ex vivo