Activities Of Mitochondrial Respiratory Complexes Research Articles

A deafness-associated mitochondrial DNA mutation altered the tRNASer(UCN) metabolism and mitochondrial function

Mutations in mitochondrial DNA (mtDNA) have been associated with deafness and their pathophysiology remains poorly understood. In this study, we investigated the pathogenic mechanism of deafness-associated 7505A > G variant in the mitochondrial tRNASer(UCN). The m.7505A > G variant affected the highly conserved adenine at position 11 (A11), disrupted the highly conserved A11-U24 base-pairing of DHU stem of tRNASer(UCN) and introduced a tertiary base pairing (G11-C56) with the C56 in the TΨC loop. We therefore hypothesized that the m.7505A > G variant altered both structure and function of tRNASer(UCN). We demonstrated that the m.7505A > G variant perturbed the conformation and stability of tRNASer(UCN), as indicated by an increased melting temperature and electrophoretic mobility of the mutated tRNA compared with the wild type molecule. Using the cybrids constructed by transferring mitochondria from the Chinese family into mitochondrial DNA (mtDNA)-less cells, we demonstrated the m.7505A > G variant led to significantly decreased steady-state levels of tRNASer(UCN) in the mutant cybrids, as compared with those of control cybrids. The aberrant tRNASer(UCN) metabolism resulted in the variable decreases in mtDNA-encoded polypeptides in the mutant cybrids. Furthermore, we demonstrated that the m.7505A > G variant decreased the activities of mitochondrial respiratory complexes I, III and IV, markedly diminished mitochondrial ATP levels and membrane potential, and increased the production of reactive oxygen species in the mutant cybrids. These results demonstrated that the m.7505A > G variant affected both structure and function of tRNASer(UCN) and consequently altered mitochondrial function. Our findings highlighted critical insights into the pathophysiology of maternally inherited deafness, which is manifested by the aberrant tRNA metabolism.

Colonic levels of vasoactive intestinal peptide decrease during infection and exogenous VIP protects epithelial mitochondria against the negative effects of IFNγ and TNFα induced during Citrobacter rodentium infection

Citrobacter rodentium infection is a model for infection with attaching and effacing pathogens, such as enteropathogenic Escherichia coli. The vasoactive intestinal peptide (VIP) has emerged as an anti-inflammatory agent, documented to inhibit Th1 immune responses and successfully treat animal models of inflammation. VIP is also a mucus secretagogue. Here, we found that colonic levels of VIP decrease during murine C. rodentium infection with a similar time dependency as measurements reflecting mitochondrial function and epithelial integrity. The decrease in VIP appears mainly driven by changes in the cytokine environment, as no changes in VIP levels were detected in infected mice lacking interferon gamma (IFNγ). VIP supplementation alleviated the reduction of activity and levels of mitochondrial respiratory complexes I and IV, mitochondrial phosphorylation capacity, transmembrane potential and ATP generation caused by IFNγ, TNFα and C. rodentium infection, in an in vitro mucosal surface. Similarly, VIP treatment regimens that included the day 5–10 post infection period alleviated decreases in enzyme complexes I and IV, phosphorylation capacity, mitochondrial transmembrane potential and ATP generation as well as increased apoptosis levels during murine infection with C. rodentium. However, VIP treatment failed to alleviate colitis, although there was a tendency to decreased pathogen density in contact with the epithelium and in the spleen. Both in vivo and in vitro, NO generation increased during C. rodentium infection, which was alleviated by VIP. Thus, therapeutic VIP administration to restore the decreased levels during infection had beneficial effects on epithelial cells and their mitochondria, but not on the overall infection outcome.

The saturation degree of fatty acids and their derived acylcarnitines determines the direct effect of metabolically active thyroid hormones on insulin sensitivity in skeletal muscle cells.

Using differentiated rat L6 cells, we studied the direct effect of 3,5,3'-triiodo-l-thyronine (T3) and 3,5-diiodo-l-thyronine (T2) on the response to insulin in presence of fatty acids with a varying degree of saturation. We found that T3 and T2 both invert the response to insulin by modulating Akt Ser473 phosphorylation in the presence of palmitate and oleate. Both hormones prevented palmitate-induced insulin resistance, whereas increased insulin sensitivity in the presence of oleate was reduced, with normalization to (or, in the case of T3, even below) control levels. Both hormones effectively reduced intracellular acylcarnitine concentrations. Interestingly, insulin sensitization was lowered by incubation of the myotubes with relevant concentrations of palmitoylcarnitines (C16) and increased by oleylcarnitines and linoleylcarnitines (C18:1 and C18:2, respectively). The efficiency of mitochondrial respiration decreased in the order palmitate-oleate-linoleate; in the presence of palmitate, only T3 increased ATP synthesis-independent cellular respiration and mitochondrial respiratory complex activities. Both hormones modulated gene expression and enzyme activities related to insulin sensitivity, glucose metabolism, and lipid handling. Although T2 and T3 differentially regulated the expression of relevant genes involved in glucose metabolism, they equally stimulated related metabolic activities. T2 and T3 differentially modulated mitochondrial fatty acid uptake and oxidation in the presence of each fatty acid. The results show that T2 and T3 both invert the fatty acid-induced response to insulin but through different mechanisms, and that the outcome depends on the degree of saturation of the fatty acids and their derived acylcarnitines.-Giacco, A., delli Paoli, G., Senese, R., Cioffi, F., Silvestri, E., Moreno, M., Ruoppolo, M., Caterino, M., Costanzo, M., Lombardi, A., Goglia, F., Lanni, A., de Lange, P. The saturation degree of fatty acids and their derived acylcarnitines determines the direct effect of metabolically active thyroid hormones on insulin sensitivity in skeletal muscle cells.

Innovative Approach of Non-Thermal Plasma Application for Improving the Growth Rate in Chickens.

As an innovative technology in biological applications—non-thermal plasma technique—has recently been applied to living cells and tissues. However, it is unclear whether non-thermal plasma treatment can directly regulate the growth and development of livestock. In this study, we exposed four-day-incubated fertilized eggs to plasma at 11.7 kV for 2 min, which was found to be the optimal condition in respect of highest growth rate in chickens. Interestingly, plasma-treated male chickens conspicuously grew faster than females. Plasma treatment regulated the reactive oxygen species homeostasis by controlling the mitochondrial respiratory complex activity and up-regulating the antioxidant defense system. At the same time, growth metabolism was improved due to the increase of growth hormone and insulin-like growth factor 1 and their receptors expression, and the rise of thyroid hormones and adenosine triphosphate levels through the regulation of demethylation levels of growth and hormone biosynthesis-related genes in the skeletal muscles and thyroid glands. To our knowledge, this study was the first to evaluate the effects of a non-thermal plasma treatment on the growth rate of chickens. This safe strategy might be beneficial to the livestock industry.

Sex-associated differences in mitochondrial function in human peripheral blood mononuclear cells (PBMCs) and brain

BackgroundAlzheimer’s disease (AD) is the most common form of dementia, and it affects more women than men. Mitochondrial dysfunction (MD) plays a key role in AD, and it is detectable at an early stage of the degenerative process in peripheral tissues, such as peripheral mononuclear blood cells (PBMCs). However, whether these changes are also reflected in cerebral energy metabolism and whether sex-specific differences in mitochondrial function occur are not clear. Therefore, we estimated the correlation between mitochondrial function in PBMCs and brain energy metabolites and examined sex-specific differences in healthy participants to elucidate these issues.MethodsThe current pilot study included 9 male and 15 female healthy adults (mean age 30.8 ± 7.1 years). Respiration and activity of mitochondrial respiratory complexes were measured using a Clarke-electrode (Oxygraph-2k system), and adenosine triphosphate (ATP) levels were determined using a bioluminescence-based assay in isolated PBMCs. Citrate synthase activity as a mitochondrial marker was measured using a photometric assay. Concentrations of brain energy metabolites were quantified in the same individuals using 1H-magnetic resonance spectroscopy (MRS).ResultsWe detected sex-associated differences in mitochondrial function. Mitochondrial complexes I, I+II, and IV and uncoupled respiration and electron transport system (ETS) capacity in PBMCs isolated from blood samples of females were significantly (p < 0.05; p < 0.01) higher compared to males. ATP levels in the PBMCs of female participants were approximately 10% higher compared to males. Citrate synthase (CS) activity, a marker of mitochondrial content, was significantly (p < 0.05) higher in females compared to males. Sex-associated differences were also found for brain metabolites. The N-acetylaspartate (NAA) concentration was significantly higher in female participants compared to males in targeted regions. This difference was observed in white matter (WM) and an area with a high percentage (> 50%) of gray matter (GM) (p < 0.05; p < 0.01). The effect sizes indicated a strong influence of sex on these parameters. Sex-associated differences were found in PBMCs and brain, but the determined parameters were not significantly correlated.ConclusionsOur study revealed sex-associated differences in mitochondrial function in healthy participants. The underlying mechanisms must be elucidated in more detail, but our study suggests that mitochondrial function in PBMCs is a feasible surrogate marker to detect differences in mitochondrial function and energy metabolism in humans and it underscores the necessity of sex-specific approaches in therapies that target mitochondrial dysfunction.

Low-concentration exposure to glyphosate-based herbicide modulates the complexes of the mitochondrial respiratory chain and induces mitochondrial hyperpolarization in the Danio rerio brain

Glyphosate (N-phosphonomethyl-glycine) (GLY) is the active ingredient of the most used herbicides in the world. GLY is applied in formulated products known as glyphosate-based herbicides (GBH), which could induce effects that are not predicted by toxicity assays with pure GLY. This herbicide is classified as organophosphorus compound, which is known to induce neurotoxic effects. Although this compound is classified as non-neurotoxic by regulatory agencies, acute exposure to GBH causes neurological symptoms in humans. However, there is no consensus in relation to neurotoxic effects of GBH. Thus, the aim of this study was to investigate the neurotoxic effects of the GBH in the zebrafish Danio rerio, focusing on acute toxicity, the activity and transcript levels of mitochondrial respiratory chain complexes, mitochondrial membrane potential, reactive species (RS) formation, and behavioral repertoire. Adult zebrafish were exposed in vivo to three concentrations of GBH Scout®, which contained GLY in formulation (fGLY) (0.065, 1.0 and 10.0 mg L−1 fGLY) for 7 d, and an in vitro assay was performed using also pure GLY. Our results show that GBH induced in zebrafish brain a decrease in cell viability, inhibited mitochondrial complex enzymatic activity, modulated gene expression related to mitochondrial complexes, induced an increase in RS production, promoted hyperpolarization of mitochondrial membrane, and induced behavioral impairments. Together, our data contributes to the knowledge of the neurotoxic effects of GBH. Mitochondrial dysfunction has been recognized as a relevant cellular response that should not be disregarded. Moreover, this study pointed to the mitochondria as an important target of GBH.

Mitochondrial function is impaired in the skeletal muscle of pre-frail elderly

Aging is accompanied by a gradual decline in both muscle mass and strength over time, which can eventually lead to pathologies, such as frailty and sarcopenia. While these two conditions are well characterized, further investigation of the early biological signs present in pre-frail elderly is still needed to help identify strategies for preventative therapeutic intervention. The goal of the present clinical study was to evaluate the level of mitochondrial (dys)function in a well-defined population of pre-frail elderly (>60 years of age). Pre-frail elderly were compared with an age-matched population of active elderly. Muscle mitochondrial function was assessed in vivo using phosphorus magnetic resonance spectroscopy (31P-MRS) and a comprehensive set of biological biomarkers were measured ex vivo in vastus lateralis muscle biopsies. In pre-frail subjects, phosphocreatine recovery was impaired and mitochondrial respiratory complex protein and activity levels were significantly lower when compared with active elderly. Analysis of microarray data showed that mitochondrial genes were also significantly down-regulated in muscle of pre-frail compared to active elderly. These results show that mitochondrial impairment is a hallmark of pre-frailty development and the onset of decline in muscle function in the elderly.

Mitoregulin: A lncRNA-Encoded Microprotein that Supports Mitochondrial Supercomplexes and Respiratory Efficiency

Mitochondria are composed of many small proteins that control protein synthesis, complex assembly, metabolism, and ion and reactive oxygen species (ROS) handling. We show that a skeletal muscle- and heart-enriched long non-coding RNA, LINC00116, encodes a highly conserved 56-amino-acid microprotein that we named mitoregulin (Mtln). Mtln localizes to the inner mitochondrial membrane, where it binds cardiolipin and influences protein complex assembly. In cultured cells, Mtln overexpression increases mitochondrial membrane potential, respiration rates, and Ca2+ retention capacity while decreasing mitochondrial ROS and matrix-free Ca2+. Mtln-knockout mice display perturbations in mitochondrial respiratory (super)complex formation and activity, fatty acid oxidation, tricarboxylic acid (TCA) cycle enzymes, and Ca2+ retention capacity. Blue-native gel electrophoresis revealed that Mtln co-migrates alongside several complexes, including the complex I assembly module, complex V, and supercomplexes. Under denaturing conditions, Mtln remains in high-molecular-weight complexes, supporting its role as a sticky molecular tether that enhances respiratory efficiency by bolstering protein complex assembly and/or stability.

Herbal formula Xinshuitong capsule exerts its cardioprotective effects via mitochondria in the hypoxia-reoxygenated human cardiomyocytes

BackgroundThe collapse of mitochondrial membrane potential (ΔΨm) resulted in the cell apoptosis and heart failure. Xinshuitong Capsule (XST) could ameliorate left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) classes and the quality of life in patients with chronic heart failure in our clinical study, however, its cardioprotective mechanisms remain unclear.MethodsPrimary human cardiomyocytes were subjected to hypoxia-reoxygenation and treated with XST200, 400 and 600 μg/ml. The model group was free of XST and the control group was cultured in normal conditions. Cell viability, ΔΨm, the activity of mitochondrial respiratory chain complexes, ATPase activity, reactive oxygen species (ROS) and apoptosis cells were determined in all the groups.ResultsThe cell viability in the XST-treated groups was significantly higher than that in the model group (P < 0.05). Coupled with the restoration of the ΔΨm, the number of polarized cells increased dose dependently in the XST-treated groups. XST also restored the lost activities of mitochondrial respiratory chain complexes I-IV induced by the oxidative stress. The total of mitochondrial ATPase activity was significantly elevated at XST400 and 600 μg/ml compared to the model group (P < 0.05). The levels of mitochondrial ROS and the number of apoptosis cells declined in the XST-treated groups compared to those in the model group (P < 0.05).ConclusionsXST, via restoration of ΔΨm and the mitochondrial respiratory chain complexes I-IV activities, and suppression of mitochondrial ROS generation and the apoptosis cells, maintained the integrity of the mitochondrial membrane to exert its cardioprotective effects in the hypoxia-reoxygenated human cardiomyocytes.

Prenatal Lipopolysaccharide Exposure Promotes Dyslipidemia in the Male Offspring Rats.

Inflammation is critical to the pathogenesis of cardiovascular diseases (CVDs). We have uncovered intrauterine inflammation induced by lipopolysaccharide (LPS) increases CVDs in adult offspring rats. The present study aimed to explore the role of prenatal exposure to LPS on the lipid profiles in male offspring rats and to further assess their susceptibility to high fat diet (HFD). Maternal LPS (0.79 mg/kg) exposure produced a significant increase in serum and hepatic levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, aspartate amino transferase as well as liver morphological abnormalities in 8-week-old offspring rats. Meanwhile, disturbed gene expressions involved in hepatic lipid metabolism and related signaling pathways were found, especially the up-regulated very-low density lipoprotein receptor (VLDLR) and down-regulated transmembrane 7 superfamily member 2 (TM7SF2). Following HFD treatment, however, the lipid profile shifts and liver dysfunction were exacerbated compared to the offsprings treated with prenatal LPS exposure alone. Compared with that in control offsprings, the hepatic mitochondria (Mt) in offspring rats solely treated with HFD exhibited remarkably higher ATP level, enforced Complex IV expression and a sharp reduction of its activity, whereas the offsprings from LPS-treated dams showed the loss of ATP content, diminished membrane potential, decline in protein expression and activity of mitochondrial respiratory complex IV, increased level of MtDNA deletion as well. Furthermore, treatment with HFD deteriorated these mitochondrial disorders in the prenatally LPS-exposed offspring rats. Taken together, maternal LPS exposure reinforces dyslipidemia in response to a HFD in adult offsprings, which should be associated with mitochondrial abnormalities and disturbed gene expressions of cholesterol metabolism.

N-(3-oxododecanoyl)-l-homoserine lactone modulates mitochondrial function and suppresses proliferation in intestinal goblet cells

AimsThe quorum-sensing molecule N‑(3‑oxododecanoyl)‑l‑homoserine lactone (C12-HSL), produced by the Gram negative human pathogenic bacterium Pseudomonas aeruginosa, modulates mammalian cell behavior. Our previous findings suggested that C12-HSL rapidly decreases viability and induces apoptosis in LS174T goblet cells. Main methodsIn this study, the effects of 100 μM C12-HSL on mitochondrial function and cell proliferation in LS174T cells treated for 4 h were evaluated by real-time PCR, enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Key findingsThe results showed that the activities of mitochondrial respiratory chain complexes IV and V were significantly increased (P < 0.05) in LS174T cells after C12-HSL treatment, with elevated intracellular ATP generation (P < 0.05). Flow cytometry analysis revealed significantly increased intracellular Ca2+ levels (P < 0.05), as well as disrupted mitochondrial activity and cell cycle arrest upon C12-HSL treatment. Apoptosis and cell proliferation related genes showed markedly altered expression levels (P < 0.05) in LS174T cells after C12-HSL treatment. Moreover, the paraoxonase 2 (PON2) inhibitor TQ416 (1 μM) remarkably reversed the above C12-HSL associated effects in LS174T cells. SignificanceThese findings indicated that C12-HSL alters mitochondrial energy production and function, and inhibits cell proliferation in LS174T cells, with PON2 involvement.

Skeletal muscle overexpression of short isoform Sirt3 altered mitochondrial cardiolipin content and fatty acid composition.

Cardiolipin (CL) is a phospholipid at the heart of mitochondrial metabolism, which plays a key role in mitochondrial function and bioenergetics. Among mitochondrial activity regulators, SIRT3 plays a crucial role in controlling the acetylation status of many enzymes participating in the energy metabolism in particular concerning lipid metabolism and fatty acid oxidation. Data suggest that possible connection may exist between SIRT3 and CL status that has not been evaluated in skeletal muscle. In the present study, we have characterized skeletal muscle lipids as well as mitochondrial lipids composition in mice overexpressing long (SIRT3-M1) and short (SIRT3-M3) isoforms of SIRT3. Particular attention has been paid for CL. We reported no alteration in muscle lipids content and fatty acids composition between the two mice SIRT3 strains and the control mice. However, mitochondrial CL content was significantly decreased in SIRT3-M3 mice and associated to an upregulation of tafazzin gene expression. In addition, mitochondrial phospholipids and fatty acids composition was altered with an increase in the PC/PE ratio and arachidonic acid content and a reduction in the MUFA/SFA ratio. These modifications in mitochondrial membrane composition are associated with a reduction in the enzymatic activities of mitochondrial respiratory chain complexes I and IV. In spite of these mitochondrial enzymatic alterations, skeletal muscle mitochondrial respiration remained similar in SIRT3-M3 and control mice. Surprisingly, none of those metabolic alterations were detected in mitochondria from SIRT3-M1 mice. In conclusion, our data indicate a specific action of the shorter SIRT3 isoform on lipid mitochondrial membrane biosynthesis and functioning.

Placental mitochondrial biogenesis and function was slightly changed by gestational hypercholesterolemia in full-term pregnant women.

It was reported that high blood cholesterol levels increased the susceptibility to mitochondrial dysfunction. This study hypothesized that the gestational hypercholesterolemia (HC) could induce the mitochondrial dysfunction in term human placenta. The eligible pregnant women were recruited from Xuanwu Hospital in Beijing during their first prenatal visit (before their 10th week of pregnancy). In total, 19 pregnant women whose serum total cholesterol levels were higher than 7.25 mm at third trimester (measured at 36-38 weeks) were selected as gestational HC. Other 19 pregnant women with normal cholesterol level matched with age, pre-gestational body mass index, and the neonatal gender were included as the control group. Full-term placenta samples were collected. The mitochondrial DNA (mtDNA) copy number, messenger RNA (mRNA) expression of cytochrome c oxidase subunit I, adenosine triphosphate monophosphatase 6 (ATP6ase), citrate synthase, peroxisome proliferator-activated receptor-γ (PPARγ) co-activator 1α, PPARγ co-activator 1β and estrogen-related receptor-α, and the activity of mitochondrial respiratory chain enzyme complex were measured. Pregnancy outcomes were obtained by extraction from medical records and the labor ward register. The results showed that only placental mtDNA copy number and mRNA expression of ATP6ase were significantly decreased in HC group. No significant differences were detected of other measurements between the two groups. These findings indicated that gestational HC might not induce the damage of placental function seriously.

Insights into the potential antidepressant mechanisms of cilostazol in chronically restraint rats: impact on the Nrf2 pathway.

Ample evidence has pointed to a close link between oxidative stress, mitochondrial dysfunction, and depression. Nuclear factor-erythroid 2-related factor-2 (Nrf2) is a master regulator of cellular redox homeostasis and affects mitochondrial function. Nrf2 holds promise for depression prevention and treatment. This study aimed to investigate the potential prophylactic antidepressant effect of cilostazol and the contribution of the Nrf2 pathway toward the putative neuroprotection. The behavioral and neurochemical effects of concomitant treatment of oral cilostazol at doses of 7.5, 15, and 30 mg/kg/day in Wistar rats exposed to chronic restraint stress (CRS) for 4 weeks were assayed. Cilostazol prevented CRS-induced depressive-like behavior shown in sucrose-preference, forced-swimming, and open-field tests, and hypothalamus-pituitary-adrenal axis hyperactivity (adrenal gland weight and serum corticosterone). Cilostazol prevented CRS-induced increase in hippocampal lipid peroxidation and 8-hydroxy-2'-deoxyguanosine, and a decrease in antioxidant activities (glutathione level, superoxide dismutase, and catalase). Western blot and PCR showed that cilostazol favorably modulated the Nrf2 protein and heme oxygenase-1 and NAD(P)H: quinone oxidoreductase-1 gene expression in the hippocampus of CRS rats. Cilostazol also prevented the decrease in the hippocampal activities of mitochondrial respiratory enzyme complexes I-IV. These behavioral and biochemical findings indicated the potential prophylactic antidepressant effect and mechanism of cilostazol by preventing oxidative stress by activation of redox defense mechanisms mediated through the Nrf2 pathway and restoring mitochondrial dysfunction.

An investigation of the mechanism of dexmedetomidine in improving postoperative cognitive dysfunction from the perspectives of alleviating neuronal mitochondrial membrane oxidative stress and electrophysiological dysfunction.

The aim of this study was to investigate the mechanism of dexmedetomidine in improving postoperative cognitive dysfunction from the perspectives of alleviating neuronal mitochondrial membrane oxidative stress and electrophysiological dysfunction. A total of 120 patients undergoing elective surgery under general anesthesia from June 2013 to May, 2016 were selected as the subjects of the study and randomly divided into the propofol + remifentanil and dexmedetomidine groups. The Rey Auditory Verbal Learning Test (AVLT) and Beck Depression Inventory (BDI) were performed at day 1 before operation and at day 1, 3, 5 and 15 after operation. The mitochondrial membrane potential was detected using a flow cytometer after staining and labeling for mitochondria in leukocytes via JC-1 fluorescence staining using a fluorescence probe at day 1 before operation and at day 1, 3, 5 and 15 after operation. The activities of mitochondrial respiratory chain complexes at day 1 before and after operation were detected via enzyme-linked immunosorbent assay (ELISA). The results showed that there were no statistically significant differences in the comparisons of general conditions (age, body weight, sex ratio, body mass index, anesthesia time, operation time, and length of stay in the ICU and hospital) for the dexmedetomidine and propofol + remifentanil groups (P>0.05). At day 3 and 5 after operation, the National Institutes of Health Stroke Scale (NIHSS) scores and AVLT scores in the two groups were decreased in different degrees, but the decrease range in the dexmedetomidine group was smaller than that in the propofol + remifentanil group, and the differences were statistically significant (P<0.05). At day 3, 5 and 15 after operation, the BDI scores of the two groups were increased in different degrees, but the increase range in the dexmedetomidine group was smaller than that in the propofol + remifentanil group, and the differences were statistically significant (P<0.05). At day 1, 3 and 5 after operation, the mitochondrial membrane potentials of the two groups were decreased in different degrees, but the decrease range in the dexmedetomidine group was smaller than that in the propofol + remifentanil group, and the differences were statistically significant (P<0.05). The mitochondrial membrane potentials of the two groups returned to the preoperative levels at day 15 after operation. The activities of mitochondrial respiratory chain complex I–IV in the propofol + remifentanil group at day 1 after operation were significantly decreased compared with those before operation, and the differences were statistically significant (P<0.05). The decrease in activities of mitochondrial respiratory chain complex I–IV in the propofol + remifentanil group at day 1 after operation was more significant than that in the dexmedetomidine group, and the difference was statistically significant (P<0.05). The results suggest that dexmedetomidine can relieve neuronal damage that may be caused by mitochondrial membrane oxidative stress, alleviate the damage to mitochondrial related enzyme system activity, and reduce the damage to the activities of mitochondrial respiratory chain enzyme complex I, II, III and IV, ultimately improving the postoperative cognitive dysfunction of patients.

The effect of carabrone on mitochondrial respiratory chain complexes in Gaeumannomyces graminis.

To evaluate the effect of carabrone on mitochondrial respiratory chain complexes in Gaeumannomyces graminis to identify carabrone targets. The influence of carabrone on mitochondria in G.graminis mycelia was determined, and the activity of complexes I-V, citrate synthase, and respiratory chain complexes I+III and II+III was evaluated following treatment with 30% effective concentration (EC30 ) as well as EC50 and EC70 of carabrone for 0, 6, 12 and 24h. Quantitative real-time PCR analysis of the relative expression of genes encoding mitochondrial respiratory chain complexes was then conducted. Carabrone treatment influenced the activity of mitochondrial respiratory chain complexes III, I+III, and II+III in G.graminis in a dose- and time-dependent manner with a marked decrease (c. 50% compared to the control) in mitochondrial respiratory chain complex III activity following treatment with carabrone at the EC50 . The GgCyc1 was downregulated following carabrone treatment at the EC50 , and the other genes were upregulated with respect to the control. This study showed that mitochondrial respiratory chain complex III in G.graminis is highly sensitive to carabrone and is a potential target of this botanical fungicidal agent. Carabrone is a promising botanical fungicidal agent that is environmentally friendly and can control plant diseases and reduce chemical fungicides in agricultural production.

Antagomirs Targeting MiroRNA-134 Attenuates Epilepsy in Rats through Regulation of Oxidative Stress, Mitochondrial Functions and Autophagy.

The effects of the existing anti-epileptic drugs are unsatisfactory to almost one third of epileptic patients. MiR-134 antagomirs prevent pilocarpine-induced status epilepticus. In this study, a lithium chloride-pilocarpine-induced status epilepticus model was established and treated with intracerebroventricular injection of antagomirs targeting miR-134 (Ant-134). The Ant-134 treatment significantly improved the performance of rats in Morris water maze tests, inhibited mossy fiber sprouting in the dentate gyrus, and increased the survival neurons in the hippocampal CA1 region. Silencing of miR-134 remarkably decreased malonaldehyde and 4-hydroxynonenal levels and increased superoxide dismutase activity in the hippocampus. The Ant-134 treatment also significantly increased the production of ATP and the activities of mitochondrial respiratory enzyme complexes and significantly decreased the reactive oxygen species generation in the hippocampus compared with the status epilepticus rats. Finally, the Ant-134 treatment remarkably downregulated the hippocampal expressions of autophagy-associated proteins Atg5, beclin-1 and light chain 3B. In conclusion, Ant-134 attenuates epilepsy via inhibiting oxidative stress, improving mitochondrial functions and regulating autophagy in the hippocampus.

Inhibition of mitochondrial translation effectively sensitizes renal cell carcinoma to chemotherapy

The functional importance of mitochondrial protein translation has been recently documented in the context of various cancers but not renal cell carcinoma (RCC). In lines with these efforts, our work demonstrates that mitochondrial translation inhibition by tigecycline or depletion of EF-Tu mitochondrial translation factor effectively targets RCC and significantly sensitizes RCC response to chemotherapy. We show that antibiotic tigecycline inhibits multiple biological functions of RCC, including growth, colony formation and survival. It also significantly enhances in vitro and in vivo efficacy of paclitaxel in RCC. Tigecycline preferentially inhibits translation of mitochondrial DNA-encoded proteins, activities of mitochondrial respiratory complexes that contain mitochondrially encoded subunits. As a consequence of mitochondrial respiratory chain inhibition, decreased mitochondrial respiration is observed in RCC cells exposed to tigecycline. In contrast, tigecycline is ineffective in RCC ρ0 cells that lack mitochondrial DNA and subsequent mitochondrial respiration, further confirm mitochondrial translation inhibition as the mechanism of tigecycline's action in RCC. Importantly, genetic inhibition of mitochondrial translation by EF-Tu knockdown reproduced the inhibitory effects of tigecycline. Finally, we show the association between mitochondrial translation inhibition and suppression of PI3K/Akt/mTOR signaling pathway. Our work used pharmacological and genetic strategies to demonstrate the important roles of mitochondrial translation in RCC and emphasize the therapeutic value of sensitizing RCC to chemotherapy.

The antagonistic effect of selenium on lead-induced apoptosis via mitochondrial dynamics pathway in the chicken kidney

Selenium (Se) is known to have antagonistic effects against lead (Pb) toxicity in animal. The aim of this study was to evaluate the roles of mitochondrial dynamics on Pb-induced apoptosis in the chicken kidney and investigate the antagonistic effect of Se. In the present study, brown layer chickens were randomly allocated to four groups, and each group were exposed to a basic diet (0.2 mg kg−1 Se and 0.5 mg kg−1 Pb), a Se-adequate diet (1 mg kg−1 Se and 0.5 mg kg−1 Pb), a Se and Pb compound diet (1 mg kg−1 Se and 350 mg kg−1 Pb) or a Pb supplemented diet (0.2 mg kg−1 Se and 350 mg kg−1 Pb). On the 90th day, the kidney was removed to determine the activities of mitochondrial respiratory chain complexes, ATPases and oxidative indexes. The expression levels of mitochondrial dynamics and apoptosis-related genes were also determined. The results showed that Pb treatment significantly decreased the activities of mitochondrial complexes and ATPases, and increased oxidative stress, and mitochondrial dynamics and anti-apoptosis-related genes had a lower expression, whereas mitochondrial pro-apoptosis related genes presented higher expressions in the Pb group compared with control group (P < 0.05). However, the co-treatment of Se and Pb significantly alleviated those changes compared with the Pb group (P < 0.05). In conclusion, we speculated that Pb could increase the oxidative stress and promote the apoptosis via regulating mitochondrial dynamics and apoptosis-related genes, and Se exhibited antagonistic roles against the Pb-induced apoptosis in the kidney of chickens.

Prepregnancy maternal diabetes combined with obesity impairs placental mitochondrial function involving Nrf2/ARE pathway and detrimentally alters metabolism of offspring

Metabolic disorders usually increase the level of reactive oxygen species (ROS) and damage mitochondrial function. The placenta supplies nutrients and hormonal signals to the fetus for regulating fetal metabolism, and is also prone to injury by oxidants. The aim of this study was to determine the effect of pre-existing maternal type 2 diabetes mellitus (DM) combined with obesity on placental mitochondrial function and metabolism disorders of offspring. The study included 96 pregnant women. The women were put into the following groups: healthy women (control, n=24), women with DM (DM, n=24), women with obesity (OB, n=24) and women with both DM and obesity (DM+OB, n=24). The ROS level, mitochondrial content, and the mitochondrial respiratory complex activities of the placenta were measured in the four groups. The expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) was detected by immunofluorescence staining and western blotting. In addition, serum levels of insulin, glucose, leptin, nonesterified fatty acid (NEFA), adiponectin and triglycerides of their offspring were also measured. Maternal DM combined with obesity markedly increased ROS level, reduced mitochondrial DNA (mtDNA) content and mitochondrial respiratory complex I, II-III activities in placenta compared to the placenta from the control group and the DM group. Maternal DM combined with obesity significantly decreased Nrf2 and HO-1 expression. Furthermore, maternal DM combined with obesity influenced the glucose and lipid metabolism in their offspring. In conclusion, women with both DM and obesity detrimentally alter placenta function in oxidative stress regulation, and the Nrf2/ARE (antioxidant responsive element) pathway is involved. This may increase metabolic disturbance susceptibility in their offspring.