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Parkinson's disease (PD) is the second most common neurodegenerative disorder. Dopamine (DA) neurons in the substantia nigra pars compacta, which have axonal projections to the dorsal striatum (dSTR), degenerate in PD. In contrast, DA neurons in the ventral tegmental area, with axonal projections to the ventral striatum, including the nucleus accumbens (NAcc) shell, are largely spared. This study aims to uncover the relative contributions of glycolysis and oxidative phosphorylation (OxPhos) to DA release in the striatum. We measured evoked DA release in mouse striatal brain slices using fast-scan cyclic voltammetry applied every two minutes. Blocking OxPhos resulted in a greater reduction in evoked DA release in the dSTR when compared to the NAcc shell, while blocking glycolysis caused a more significant decrease in evoked DA release in the NAcc shell than in the dSTR. Furthermore, when glycolysis was bypassed in favor of direct OxPhos, evoked DA release in the NAcc shell decreased by approximately 50% over 40 min, whereas evoked DA release in the dSTR was largely unaffected. These results demonstrate that the dSTR relies primarily on OxPhos for energy production to maintain evoked DA release, whereas the NAcc shell depends more on glycolysis. Consistently, two-photon imaging revealed higher oxidation levels of DA terminals in the dSTR than in the NAcc shell. Together, these findings partly explain the selective vulnerability of DA terminals in the dSTR to degeneration in PD. [ABSTRACT FROM AUTHOR]

We studied the respiratory activity of mitochondria in peripheral blood leukocytes from 36 patients with coronary heart disease (CHD) and a history of ventricular tachyarrhythmias required cardioverter-defibrillator implantation. The measurements were carried out in incubation buffers with different oxidation substrates (succinate and pyruvate-malate mixture). In pyruvate-malate incubation buffer, oxygen consumption rate and respiratory control coefficients in patients with triggered device did not differ significantly from those in patients without cardioverter-defibrillator triggering. At the same time, respiratory control coefficients were below the reference values. In succinate buffer, values of mitochondrial parameters were significantly lower in patients with triggered devices. Our findings indicate that mitochondria of patients with non-triggered cardioverters-defibrillators have better functional and metabolic plasticity. It was concluded that activity of respiratory processes in mitochondria could be an indicator that should be taken into the account when assessing the risk of developing ventricular tachyarrhythmias. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in young adults, characterized by primary and secondary injury. Primary injury is the immediate mechanical damage, while secondary injury results from delayed neuronal death, often linked to mitochondrial damage accumulation. Hyperbaric oxygen therapy (HBOT) has been proposed as a potential treatment for modulating secondary post-traumatic neuronal death. However, the specific molecular mechanism by which HBOT modulates secondary brain damage through mitochondrial protection remains unclear. Spatial learning, reference memory, and motor performance were measured in rats before and after Controlled Cortical Impact (CCI) injury. The HBOT (2.5 ATA) was performed 4 h following the CCI and twice daily (12 h intervals) for four consecutive days. Mitochondrial functions were assessed via high-resolution respirometry on day 5 following CCI. Moreover, IHC was performed at the end of the experiment to evaluate cortical apoptosis, neuronal survival, and glial activation. The current result indicates that HBOT exhibits a multi-level neuroprotective effect. Thus, we found that HBOT prevents cortical neuronal loss, reduces the apoptosis marker (cleaved-Caspase3), and modulates glial cell proliferation. Furthermore, HBO treatment prevents the reduction in mitochondrial respiration, including non-phosphorylation state, oxidative phosphorylation, and electron transfer capacity. Additionally, a superior motor and spatial learning performance level was observed in the CCI group treated with HBO compared to the CCI group. In conclusion, our findings demonstrate that HBOT during the critical period following the TBI improves cognitive and motor damage via regulating glial proliferation apoptosis and protecting mitochondrial function, consequently preventing cortex neuronal loss. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in young adults, characterized by primary and secondary injury. Primary injury is the immediate mechanical damage, while secondary injury results from delayed neuronal death, often linked to mitochondrial damage accumulation. Hyperbaric oxygen therapy (HBOT) has been proposed as a potential treatment for modulating secondary post-traumatic neuronal death. However, the specific molecular mechanism by which HBOT modulates secondary brain damage through mitochondrial protection remains unclear. Spatial learning, reference memory, and motor performance were measured in rats before and after Controlled Cortical Impact (CCI) injury. The HBOT (2.5 ATA) was performed 4 h following the CCI and twice daily (12 h intervals) for four consecutive days. Mitochondrial functions were assessed via high-resolution respirometry on day 5 following CCI. Moreover, IHC was performed at the end of the experiment to evaluate cortical apoptosis, neuronal survival, and glial activation. The current result indicates that HBOT exhibits a multi-level neuroprotective effect. Thus, we found that HBOT prevents cortical neuronal loss, reduces the apoptosis marker (cleaved-Caspase3), and modulates glial cell proliferation. Furthermore, HBO treatment prevents the reduction in mitochondrial respiration, including non-phosphorylation state, oxidative phosphorylation, and electron transfer capacity. Additionally, a superior motor and spatial learning performance level was observed in the CCI group treated with HBO compared to the CCI group. In conclusion, our findings demonstrate that HBOT during the critical period following the TBI improves cognitive and motor damage via regulating glial proliferation apoptosis and protecting mitochondrial function, consequently preventing cortex neuronal loss.

Acute lymphoblastic leukaemia (ALL) is the most common childhood malignancy. In the last decades, the survival rate of paediatric patients diagnosed with ALL has been significantly improved due to standardised treatment protocols based on risk stratification. Platelet mitochondrial dysfunction has been recently reported to occur in most chronic diseases, including malignancies. Permeable succinate (NV118) is a novel mitochondria-targeted compound capable to alleviate disease and drug-induced mitochondrial dysfunction. It is reported here that ex vivo incubation with NV811 elicited an increase in platelet mitochondrial respiration in a paediatric patient with acute lymphoblastic leukaemia in remission.

Alpinumisoflavone is a prenylated isoflavonoid derived from the Cudrania tricuspidate fruit and Genista pichisermolliana. Alpinumisoflavone has anticancer properties in a variety of cancer cells, including colorectal, esophageal, renal and hepatocellular carcinoma. However, its mechanisms and effects in ovarian cancer remain unexplored. Our findings indicate that alpinumisoflavone triggers anti-proliferation in 2D- and 3D-cultured human ovarian cancer (ES2 and OV90) cells, including a reduction in the proliferating cell nuclear antigen expression and sub-G1 phase arrest of the cell cycle. Both alpinumisoflavone-treated ES2 and OV90 cells exhibited an augmentation in late apoptotic cells and the depolarization of mitochondrial membrane potential (MMP). We also observed a decrease in respiratory chain activity in ovarian cancer cells, owing to lower energy output by the alpinumisoflavone. In addition, combining cisplatin (a chemotherapeutic drug used in several malignancies) with alpinumisoflavone boosted apoptosis in ES2 and OV90 cells via a reduction in cell proliferation, induction of late apoptotic cells, and depolarization of MMP. Furthermore, alpinumisoflavone also regulated the PI3K/AKT, MAPK and endoplasmic reticulum (ER) stress regulatory signaling pathways, leading to cell death in both ES2 and OV90 cells. In general, our findings verified that alpinumisoflavone inhibited ovarian cancer cell growth via mitochondrial malfunction. [ABSTRACT FROM AUTHOR]

Background: Previous research has suggested that curcumin potentially induces mitochondrial biogenesis in skeletal muscle via increasing cyclic AMP (cAMP) levels. However, the regulatory mechanisms for this phenomenon remain unknown. The purpose of the present study was to clarify the mechanism by which curcumin activates cAMP-related signalling pathways that upregulate mitochondrial biogenesis and respiration in skeletal muscle. Methods: The effect of curcumin treatment (i.p., 100 mg/kg-BW/d for 28 d) on mitochondrial biogenesis was determined in rats. The effects of curcumin and exercise (swimming for 2 h/d for 3 d) on the cAMP signalling pathway were determined in the absence and presence of phosphodiesterase (PDE) or protein kinase A (PKA) inhibitors. Mitochondrial respiration, citrate synthase (CS) activity, cAMP content and protein expression of cAMP/PKA signalling molecules were analysed. Results: Curcumin administration increased cytochrome c oxidase subunit (COX-IV) protein expression, and CS and complex I activity, consistent with the induction of mitochondrial biogenesis by curcumin. Mitochondrial respiration was not altered by curcumin treatment. Curcumin and PDE inhibition tended to increase cAMP levels with or without exercise. In addition, exercise increased the phosphorylation of phosphodiesterase 4A (PDE4A), whereas curcumin treatment strongly inhibited PDE4A phosphorylation regardless of exercise. Furthermore, curcumin promoted AMP-activated protein kinase (AMPK) phosphorylation and PPAR gamma coactivator (PGC-1α) deacetylation. Inhibition of PKA abolished the phosphorylation of AMPK. Conclusion: The present results suggest that curcumin increases cAMP levels via inhibition of PDE4A phosphorylation, which induces mitochondrial biogenesis through a cAMP/PKA/AMPK signalling pathway. Our data also suggest the possibility that curcumin utilises a regulatory mechanism for mitochondrial biogenesis that is distinct from the exercise-induced mechanism in skeletal muscle. [ABSTRACT FROM AUTHOR]

Conflicting functions of EFEMP1 in cancer have been reported. Using two syngeneic glioma cell lines (U251 and U251-NS) carrying two different principal cell subpopulations that express high or low EGFR, and that are able to interconvert via mis-segregation of chromosome 7 (Chr7), we studied EFEMP1's cell-context-dependent functions in regulating subpopulation equilibrium, here defined by the percentage of cells carrying different copies of Chr7. We found that EFEMP1 attenuated levels of EGFR and cellular respiration in high-EGFR-expressing cells, but increased levels of NOTCH1, MMP2, cell invasiveness, and both oxidative phosphorylation and glycolytic respiration in low-EGFR-expressing cells. Consistently, EFEMP1 suppressed intracranial xenograft formation in U251 and promoted its formation in U251-NS. Interestingly, subpopulation equilibria in xenografts of U251-NS without EFEMP1 overexpression were responsive to inoculum size (1, 10 and 100 thousand cells), which may change the tumor-onset environment. It was not observed in xenografts of U251-NS with EFEMP1 overexpression. The anti-EGFR function of EFEMP1 suppressed acceleration of growth of U251-NS, but not the subpopulation equilibrium, when serially passed under a different (serum-containing adherent) culture condition. Overall, the data suggest that the orthotopic environment of the brain tumor supports EFEMP1 in carrying out both its anti-EGFR and pro-invasive/cancer stem cell-transforming functions in the two glioma cell subpopulations during formation of a single tumor, where EFEMP1 stabilizes the subpopulation equilibrium in response to alterations of the growth environment. This finding implies that EFEMP1 may restrain cancer plasticity in coping with ever-changing tumor microenvironments and/or therapeutic-intervention stresses.

The poor outcomes in retinoblastoma necessitate new treatments. Salinomycin is an attractive candidate, and has demonstrated selective anti-cancer properties in different cancer types. This work addressed the efficacy of salinomycin in retinoblastoma models and probe the associated mechanisms. Cellular functional assays were conducted to determine the effects salinomycin in vitro. Xenograft retinoblastoma mouse model was established to investigate the efficacy of salinomycin in vivo. Biochemical assays were conducted to analyze the mechanism of salinomycin's action focusing on mitochondrial functions, energy reduction-related signaling pathways. Salinomycin has positive effects towards retinoblastoma cells regardless of heterogeneity through suppressing growth and inducing apoptosis. Salinomycin also specifically inhibits cells displaying stemness and highly invasive phenotypes. Using retinoblastoma xenograft mouse model, we show that salinomycin at non-toxic dose effectively inhibits growth and induces apoptosis. Mechanistic studies show that salinomycin inhibits mitochondrial respiration via specifically suppressing complex I and II activities, reduces mitochondrial membrane potential and decreases energy reduction, followed by induction of oxidative stress and damage, AMPK activation and mTOR inhibition. Our study highlights that adding salinomycin to the existing treatment armamentarium for retinoblastoma is beneficial. [ABSTRACT FROM AUTHOR]

Background: Fluorescence-based enhanced reality (FLER) is a computer-based quantification method of fluorescence angiographies to evaluate bowel perfusion. The aim of this prospective trial was to assess the clinical feasibility and to correlate FLER with metabolic markers of perfusion, during colorectal resections. Methods: FLER analysis and visualization was performed in 22 patients (diverticulitis n = 17; colorectal cancer n = 5) intra- and extra-abdominally during distal and proximal resection, respectively. The fluorescence signal of indocyanine green (0.2 mg/kg) was captured using a near-infrared camera and computed to create a virtual color-coded cartography. This was overlaid onto the bowel (enhanced reality). It helped to identify regions of interest (ROIs) where samples were subsequently obtained. Resections were performed strictly guided according to clinical decision. On the surgical specimen, samplings were made at different ROIs to measure intestinal lactates (mmol/L) and mitochondria efficiency as acceptor control ratio (ACR). Results: The native (unquantified) fluorescent signal diffused to obvious ischemic areas during the distal appreciation. Proximally, a lower diffusion of ICG was observed. Five anastomotic complications occurred. The expected values of local capillary lactates were correlated with the measured values both proximally (3.62 ± 2.48 expected vs. 3.17 ± 2.8 actual; rho 0.89; p = 0.0006) and distally (4.5 ± 3 expected vs. 4 ± 2.5 actual; rho 0.73; p = 0.0021). FLER values correlated with ACR at the proximal site (rho 0.76; p = 0.04) and at the ischemic zone (rho 0.71; p = 0.01). In complicated cases, lactates at the proximal resection site were higher (5.8 ± 4.5) as opposed to uncomplicated cases (2.45 ± 1.5; p = 0.008). ACR was reduced proximally in complicated (1.3 ± 0.18) vs. uncomplicated cases (1.68 ± 0.3; p = 0.023). Conclusions: FLER allows to image the quantified fluorescence signal in augmented reality and provides a reproducible estimation of bowel perfusion (NCT02626091). [ABSTRACT FROM AUTHOR]

Living at high altitudes is extremely challenging as it entails exposure to hypoxia, low temperatures, and high levels of UV radiation. However, the Tibetan population has adapted to such conditions on both a physiological and genetic level over 30,000–40,000 years. It has long been speculated that fetal growth restriction is caused by abnormal placental development. We previously demonstrated that placentas from high-altitude Tibetans were protected from oxidative stress induced by labor compared to those of European descent. However, little is known about how placental mitochondria change during high-altitude adaptation. In this study, we aimed to uncover the mechanism of such adaptation by studying the respiratory function of the placental mitochondria of high-altitude Tibetans, lower-altitude Tibetans, and lower-altitude Chinese Han. We discovered that mitochondrial respiration was greater in high-altitude than in lower-altitude Tibetans in terms of OXPHOS via complexes I and I+II, ETSmax capacity, and non-phosphorylating respiration, whereas non-ETS respiration, LEAK/ETS, and OXPHOS via complex IV did not differ. Respiration in lower-altitude Tibetans and Han was similar for all tested respiratory states. Placentas from high-altitude Tibetan women were protected from acute ischemic/hypoxic insult induced by labor, and increased mitochondrial respiration may represent an acute response that induces mitochondrial adaptations.

Living at high altitudes is extremely challenging as it entails exposure to hypoxia, low temperatures, and high levels of UV radiation. However, the Tibetan population has adapted to such conditions on both a physiological and genetic level over 30,000–40,000 years. It has long been speculated that fetal growth restriction is caused by abnormal placental development. We previously demonstrated that placentas from high-altitude Tibetans were protected from oxidative stress induced by labor compared to those of European descent. However, little is known about how placental mitochondria change during high-altitude adaptation. In this study, we aimed to uncover the mechanism of such adaptation by studying the respiratory function of the placental mitochondria of high-altitude Tibetans, lower-altitude Tibetans, and lower-altitude Chinese Han. We discovered that mitochondrial respiration was greater in high-altitude than in lower-altitude Tibetans in terms of OXPHOS via complexes I and I+II, ETSmax capacity, and non-phosphorylating respiration, whereas non-ETS respiration, LEAK/ETS, and OXPHOS via complex IV did not differ. Respiration in lower-altitude Tibetans and Han was similar for all tested respiratory states. Placentas from high-altitude Tibetan women were protected from acute ischemic/hypoxic insult induced by labor, and increased mitochondrial respiration may represent an acute response that induces mitochondrial adaptations. [ABSTRACT FROM AUTHOR]

• A 2 -h sevoflurane exposure induces age-dependent mitochondrial changes in young mice. • Blocking mitochondrial upregulation prevents sevoflurane-induced synaptic changes. • Sevoflurane activates the mitochondrial unfolded protein response (UPRmt) in young mice. • Mitochondria and UPRmt are potential targets for anesthesia-induced neurotoxicity. General anesthesia induces changes in dendritic spine number and synaptic transmission in developing mice. These changes are rather disturbing, as similar changes are seen in animal models of neurodevelopmental disorders. We previously suggested that mTor-dependent upregulation of mitochondrial function may be involved in such changes. To further understand the significance of mitochondrial changes after general anesthesia during neurodevelopment, we exposed young mice to 2.5 % sevoflurane for 2 h followed by injection of rotenone, a mitochondrial complex I inhibitor. In postnatal day 17 (PND17) mice, intraperitoneal injection of rotenone not only blocked sevoflurane-induced increases in mitochondrial function, it also prevented sevoflurane-induced changes in excitatory synaptic transmission. Interestingly, similar changes were not observed in younger, neonatal mice (PND7). We next assessed whether the mitochondrial unfolded protein response (UPRmt) acted as a link between anesthetic exposure and mitochondrial function. Expression of UPRmt proteins, which help maintain protein-folding homeostasis and increase mitochondrial function, was increased 6 h after sevoflurane exposure. Our results show that a single, brief sevoflurane exposure induces age-dependent changes in mitochondrial function that constitute an important mechanism for the increase in excitatory synaptic transmission in late postnatal mice, and also suggest mitochondria and UPRmt as potential targets for preventing anesthesia toxicity. [ABSTRACT FROM AUTHOR]

Abstract Mutations and deletions in PTEN-induced kinase 1 (PINK1) cause autosomal recessive Parkinson's disease (PD), the second most common neurodegenerative disorder. PINK1 is a nuclear-genome encoded Ser/Thr kinase in mitochondria. PINK1 deletion was reported to affect dopamine (DA) levels in the striatum and mitochondrial functions but with conflicting results. The role of PINK1 in mitochondrial function and in PD pathogenesis remains to be elucidated thoroughly. In this study, we measured DA release using fast-scan cyclic voltammetry in acute striatal slices from both PINK1 knockout (KO) and wild-type (WT) mice at different ages. We found that single pulse-evoked DA release in the dorsal striatum of PINK1 KO mice was decreased in an age-dependent manner. Furthermore, the decrease was because of less DA release instead of an alteration of DA transporter function or DA terminal degeneration. We also found that PINK1 KO striatal slices had significantly lower basal mitochondria respiration compared with that of WT controls, and this impairment was also age-dependent. These results suggest that the impaired DA release is most likely because of mitochondrial dysfunction and lower ATP production. Highlights • Loss of PINK1 reduces DA release in dorsal striatum in an age-dependent manner. • The decrease is due to less DA release instead of an alteration of DAT function. • There is an age-dependent decrease in basal mitochondrial respiration and ATP synthesis. • Developed an approach to measure mitochondrial respiration by OCR in striatal slices. [ABSTRACT FROM AUTHOR]

Purpose: Mitochondrial dysfunction in adipose tissue has emerged as key to the development of obesity and diabetes. Salvianolic acid B (SalB) is a water-soluble ingredient derived from Salvia miltiorrhiza that has been shown to possess potential anti-obese and anti-diabetic activities. However, the cellular mechanism of SalB on mitochondrial function with respect to these metabolic disorders has not been elucidated. Therefore, we aim to investigate the effects of SalB on mitochondrial function in 3T3-L1 adipocytes and analyze the underlying molecular mechanism.Methods: The effects of SalB on adipocyte differentiation, glucose uptake, and glycerol release were evaluated in 3T3-L1 adipocytes. Differentiated adipocytes were treated with SalB (50 μM) with or without PPARγ antagonist (GW9662, 20 μM) for 48 h, and mitochondrial oxygen consumption rate (OCR) as well as extracellular acidification rate (ECAR) were assessed using an XF Extracellular Flux Analyzer. The mitochondrial distribution of adipocytes was assessed using Mito Tracker Green (MTG) and observed under a fluorescent microscope. In addition, the mRNA expression levels of peroxisome proliferators-activated receptor γ/α (PPARγ/α), CCAAT/enhancer binding proteinα (C/EBPα), Nuclear respiratory factor 1/2 (NRF1/2), Uncoupling protein 2 (UCP2), and phosphofructokinase 2/fructose-2, 6-bisphosphatase 2 (PFKFB2) were detected by RT-PCR. Finally, changes in the protein levels of peroxisome proliferators-activated receptor γ coactivator-1α (PGC-1α) were determined by western blotting and immunofluorescence analysis.Results: Treatment with SalB increased glucose uptake and mitochondrial respiration, reduced glycerol release and promoted adipocyte differentiation by increasing mRNA expression of adipogenic transcription factors including PPARγ, C/EBPα, and PPARα. Furthermore, SalB enhanced adipocytes mitochondrial content, mitochondrial respiration and glycolysis capacity, which had been attenuated by GW9662 treatment through the increased expression of PGC-1α.Conclusion: Our results provide novel insights into the role of PGC-1α and mitochondria as probable mediators of SalB activity in the regulation of adipocyte differentiation in 3T3-L1 adipocytes.

Highlights • A three-electrode, Clark-type biosensor for mitochondrial respirometry in single oocytes and embryos is presented. • The sensor measured basal respiration, respiration associated with proton leak, and the maximal respiratory capacity. • The sensor can be used to analyze mitochondrial function in oocytes to determine the quality and viability of their development into embryos. Abstract This paper presents a disposable three-electrode, Clark-type biosensor suitable for mitochondrial respirometry in single oocytes and embryos. The biosensor was embedded in a PMMA (polymethyl methacrylate) micro-chamber to allow investigation of single oocytes/embryos immersed in up to 100 μl of respiration buffer. The micro-chamber was sealed to avoid oxygen exchange between the inside of the chamber and the atmosphere, while being maintained at a temperature of 38.5 °C to preserve cell viability. Using amperometry, the oxygen consumption of cells inside the micro-chamber was measured. The measurements from the sensor system revealed basal cell respiration supported by endogenous substrates, respiration associated with proton leak induced by inhibition of the adenosine triphosphate (ATP) synthase (complex V) with oligomycin, and the maximal non-coupled respiratory capacity revealed by carbonyl cyanide-4-(trifluoromethoxy)phenylhydrazone (FCCP) titration. Potential applications of this oxygen sensor system include evaluating effects of metabolic therapies on oocyte bioenergetics and monitoring mitochondrial function throughout oocyte maturation and blastocyst development to predict embryo viability to compliment assisted reproductive technologies. [ABSTRACT FROM AUTHOR]

Phenols are classified as polar narcotics, which are thought to cause toxicity by non-specific mechanisms, possibly by disrupting membrane structure and function. Here we test three phenolic chemicals, phenol, 2,4-dichlorphenol and pentachlorophenol on embryo development, heartbeat rate and mitochondrial respiration in fathead minnow ( Pimephales promelas ). While these chemicals have been used on isolated mitochondria, they have not yet been used to verify respiration in intact embryos. Mitochondrial respiration in intact embryos was measured after optimizing the Seahorse XFe24 Extracellular Flux Analyzer. Heartbeat rate and mitochondrial respiration patterns of fathead minnow embryos at different developmental stages were also characterized. Exposures of embryos at developmental stage 20 occurred for 24 h with five concentrations of each phenolic compound ranging from 0.85 to 255 μM for phenol, 0.49 to 147 μM for 2,4-dichlorophenol and 0.3 to 90 μM for pentachlorophenol. Exposure to phenol at the concentrations tested had no effects on development, heartbeat or mitochondrial respiration. However, both 2,4-dichlorophenol and pentachlorophenol showed dose-dependent effects on development, heartbeat rate, and mitochondrial respiration, with the effects occurring at lower concentrations of pentachlorophenol, compared to 2,4-dichlorophenol, highlighting the higher toxicity of the more chlorinated phenols. Both 2,4-dichlorophenol and pentachlorophenol decreased basal mitochondrial respiration of embryos and ATP production. These results indicate that higher chlorinated phenolic chemicals cause developmental toxicity in fathead minnow embryos by decreasing mitochondrial respiration and heartbeat rate. [ABSTRACT FROM AUTHOR]

Copper oxide nanoparticles (nCuO) are widely used in boat antifouling paints and are released into the environment, potentially inducing toxicity to aquatic organisms. The present study aimed to understand the effects of nCuO and dissolved copper (Cu) on two ornamental Amazon fish species: dwarf cichlid ( Apistogramma agassizii ) and cardinal tetra ( Paracheirodon axelrodi ). Fish were exposed to 50% of the LC 50 for nCuO (dwarf cichlid 58.31 μg L −1 and cardinal tetra 69.6 μg L −1 ) and Cu (dwarf cichlid 20 μg L −1 and cardinal tetra 22.9 μg L −1 ) for 24, 48, 72 and 96 h. Following exposure, aerobic metabolic rate ( Ṁ O 2 ), gill osmoregulatory physiology and mitochondrial function, oxidative stress markers, and morphological damage were evaluated. Our results revealed species specificity in metabolic stress responses. An increase of Ṁ O 2 was noted in cardinal tetra exposed to Cu, but not nCuO, whereas Ṁ O 2 in dwarf cichlid showed little change with either treatment. In contrast, mitochondria from dwarf cichlid exhibited increased proton leak and a resulting decrease in respiratory control ratios in response to nCuO and Cu exposure. This uncoupling was directly related to an increase in reactive oxygen species (ROS) levels. Our findings reveal different metabolic responses between these two species in response to nCuO and Cu, which are probably caused by the differences between species natural histories, indicating that different mechanisms of toxic action of the contaminants are associated to differential osmoregulatory strategies among species. [ABSTRACT FROM AUTHOR]

Fungicides and plant growth regulators can impact plant growth outside of their effects on fungal pathogens. Although many of these chemicals are inhibitors of mitochondrial oxygen uptake, information remains limited as to whether they are able to modify other mitochondrial constituents. Fourier transform mid-infrared spectroscopy (FT-mIR) offers a high sample throughput method to comparatively and qualitatively evaluate the effects of exogenously added compounds on mitochondrial components. Therefore the objective of this study was to determine the ability of FT-mIR to detect effects mitochondrial fractions isolated from wheat ( Triticum aestivum L.) seedlings in response to several agrochemical treatments, with an emphasis on fungicides. The accessed need was to develop FT-mIR analytical and statistical routines as an effective approach to differentiate spectra obtained from chemically-treated or untreated mitochondria. An NADH-dependent oxygen uptake approach was initially used as a comparative method to determine whether the fungicides (azoxystrobin, boscalid, cyazofamid, fluazinam, isopyrazam, and pyraclostrobin) and the plant growth regulator, (trinexapac-ethyl) reduced respiration inhibition on isolated mitochondria. Pyraclostrobin was the most effective inhibitor, whereas amisulbrom did not impact oxygen uptake. However, hierarchical clustering of FT-mIR spectra of isolated mitochondria treated with these different compounds separated into clades consistent with each of their expected mode of action. Analysis of the FT-mIR amide protein region indicated that amisulbrom and pyraclostrobin interacted with the isolated wheat mitochondria. Both chemicals were statistically different from the control signifying that respiration was indeed influenced by these treatments. Moreover, the entire FT-mIR region showed differences in various biological bands thereby providing additional information on mitochondria responses to agrochemicals, if so warranted. [ABSTRACT FROM AUTHOR]

Adrenergic receptors couple to Gs-proteins leading to transmembrane adenylyl cyclase activation and cytosolic cyclic adenosine monophosphate (cAMP) production. Cyclic AMP is also produced in the mitochondrial matrix, where it regulates respiration through protein kinase A (PKA)-dependent phosphorylation of respiratory chain complexes. We hypothesized that a blunted mitochondrial cAMP-PKA pathway would participate in sepsis-induced heart dysfunction. Adult male mice were subjected to intra-abdominal sepsis. Mitochondrial respiration of cardiac fibers and myocardial contractile performance were evaluated in response to 8Br-cAMP, PKA inhibition (H89), soluble adenylyl cyclase inhibition (KH7), and phosphodiesterase inhibition (IBMX; BAY60-7550). Adenosine diphosphate (ADP)-stimulated respiratory rates of cardiac fibers were reduced in septic mice. Compared with controls, stimulatory effects of 8Br-cAMP on respiration rates were enhanced in septic fibers, whereas inhibitory effects of H89 were reduced. Ser-58 phosphorylation of cytochrome c oxidase subunit IV-1 was reduced in septic hearts. In vitro, incubation of septic cardiac fibers with BAY60-7550 increased respiratory control ratio and improved cardiac MVO2 efficiency in isolated septic heart. In vivo, BAY60-7550 pre-treatment of septic mice have limited impact on myocardial function. Mitochondrial cAMP-PKA signaling is impaired in the septic myocardium. PDE2 phosphodiesterase inhibition by BAY60-7550 improves mitochondrial respiration and cardiac MVO2 efficiency in septic mice. [ABSTRACT FROM AUTHOR]

Mitochondrial respiratory chain complexes enzymatic (MRCCE) activities were successfully evaluated in frozen brain samples. Epilepsy surgery offers an ethical opportunity to study human brain tissue surgically removed to treat drug resistant epilepsies. Epilepsy surgeries are done with hemodynamic and laboratory parameters to maintain physiology, but there are no studies analyzing the association among these parameters and MRCCE activities in the human brain tissue. We determined the intra-operative parameters independently associated with MRCCE activities in middle temporal neocortex (Cx), amygdala (AMY) and head of hippocampus (HIP) samples of patients (n = 23) who underwent temporal lobectomy using multiple linear regressions. MRCCE activities in Cx, AMY and HIP are differentially associated to trans-operative mean arterial blood pressure, O saturation, hemoglobin, and anesthesia duration to time of tissue sampling. The time-course between the last seizure occurrence and tissue sampling as well as the sample storage to biochemical assessments were also associated with enzyme activities. Linear regression models including these variables explain 13-17 % of MRCCE activities and show a moderate to strong effect (r = 0.37-0.82). Intraoperative hemodynamic and laboratory parameters as well as the time from last seizure to tissue sampling and storage time are associated with MRCCE activities in human samples from the Cx, AMYG and HIP. Careful control of these parameters is required to minimize confounding biases in studies using human brain samples collected from elective neurosurgery. [ABSTRACT FROM AUTHOR]

Polyunsaturated fatty acid (PUFA) peroxidation is initiated by hydrogen atom abstraction at bis-allylic sites and sets in motion a chain reaction that generates multiple toxic products associated with numerous disorders. Replacement of bis-allylic hydrogens of PUFAs with deuterium atoms (D-PUFAs), termed site-specific isotope reinforcement, inhibits PUFA peroxidation and confers cell protection against oxidative stress. We demonstrate that structurally diverse deuterated PUFAs similarly protect against oxidative stress-induced injury in both yeast and mammalian (myoblast H9C2) cells. Cell protection occurs specifically at the lipid peroxidation step, as the formation of isoprostanes, immediate products of lipid peroxidation, is drastically suppressed by D-PUFAs. Mitochondrial bioenergetics function is a likely downstream target of oxidative stress and a subject of protection by D-PUFAs. Pretreatment of cells with D-PUFAs is shown to prevent inhibition of maximal uncoupler-stimulated respiration as well as increased mitochondrial uncoupling, in response to oxidative stress induced by agents with diverse mechanisms of action, including t -butylhydroperoxide, ethacrynic acid, or ferrous iron. Analysis of structure–activity relationships of PUFAs harboring deuterium at distinct sites suggests that there may be a mechanism supplementary to the kinetic isotope effect of deuterium abstraction off the bis-allylic sites that accounts for the protection rendered by deuteration of PUFAs. Paradoxically, PUFAs with partially deuterated bis-allylic positions that retain vulnerable hydrogen atoms (e.g., monodeuterated 11-D 1 -Lin) protect in a manner similar to that of PUFAs with completely deuterated bis-allylic positions (e.g., 11,11-D 2 -Lin). Moreover, inclusion of just a fraction of deuterated PUFAs (20–50%) in the total pool of PUFAs preserves mitochondrial respiratory function and confers cell protection. The results indicate that the therapeutic potential of D-PUFAs may derive from the preservation of mitochondrial function. [ABSTRACT FROM AUTHOR]

Monensin is a carrier of cations through lipid membranes capable of exchanging sodium (potassium) cations for protons by an electroneutral mechanism, whereas its ethyl ester derivative ethyl-monensin is supposed to transport sodium (potassium) cations in an electrogenic manner. To elucidate mechanistic details of the ionophoric activity, ion fluxes mediated by monensin and ethyl-monensin were measured on planar bilayer lipid membranes, liposomes, and mitochondria. In particular, generation of membrane potential on liposomes was studied via the measurements of rhodamine 6G uptake by fluorescence correlation spectroscopy. In mitochondria, swelling experiments were expounded by the additional measurements of respiration, membrane potential, and matrix pH. It can be concluded that both monensin and ethyl-monensin can perform nonelectrogenic exchange of potassium (sodium) ions for protons and serve as electrogenic potassium ion carriers similar to valinomycin. The results obtained are in line with the predictions based on the crystal structures of the monensin complexes with sodium ions and protons (Huczyński et al., Biochim. Biophys. Acta, 1818 (2012) pp. 2108–2119). The functional activity observed for artificial membranes and mitochondria can be applied to explain the activity of ionophores in living systems. It can also be important for studying the antitumor activity of monensin. [ABSTRACT FROM AUTHOR]

Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate-induced gliotoxicity. Exposure to 10-mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non-mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP-linked respiration of astrocytes was reduced. The glutamate-induced astrocyte damage can be mimicked by the non-metabolized substrate d-aspartate but reversed by the non-selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate-induced gliotoxicity in cortical astrocytes. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Chronic D-galactose administration induces accelerated aging in rodents. The aim of the study was to find by in vivo 31P MRS suitable markers of early stages of brain degeneration on this metabolic model in rats. Additionally, we studied the therapeutic effect of antidiabetic drug metformin. The study has been extended by in vitro determination of mitochondrial function in brain, skeletal muscle and liver mitochondria, oxidative stress parameter thiobarbituric acid reactive substances (TBARS), and lipophilic antioxidants levels. In vivo 31P MRS revealed lower intracellular pH (pH i) and lower inorganic phosphate to ATP ratio (Pi/ATP), with higher index of oxidative phosphorylation – phosphocreatine (PCr) to Pi ratio – in brain of rats chronically administered with D-galactose. The function of brain mitochondria was not affected. Administration of metformin diminished changes in brain pH i and plasma TBARS. The function of skeletal muscle mitochondria and their coenzyme Q (CoQ) content were considerably reduced after D-galactose administration. Metformin administered simultaneously with D-galactose did not prevent these changes. The results of in vivo 31P MRS revealed evidence of early stage of neurodegeneration that may indicate pre-inflammation. Our data show different susceptibility of brain, skeletal muscle, and liver to the chronic exposure to D-galactose and metformin. The D-galactose model presented in the literature as a model for "age-related dementia" had much more devastating effects on skeletal muscle than on the brain. • In vivo 31P MRS revealed acidosis of rat brain tissue in D-galactose model of aging. • Brain mitochondria function was preserved in rat model of D-galactose-induced aging. • D-galactose model of aging impaired skeletal muscle mitochondria function in rats. • Coenzyme Q content in skeletal muscle mitochondria was reduced in D-galactose rats. • Metformin reduced oxidative stress and the decrease in brain pH of D-galactose rats. [ABSTRACT FROM AUTHOR]

Volumetric muscle loss (VML) injuries represent a majority of military service member casualties and are common in civilian populations following blunt and/or penetrating traumas. Characterized as a skeletal muscle injury with permanent functional impairments, there is currently no standard for rehabilitation, leading to lifelong disability. Toward developing rehabilitative strategies, previous research demonstrates that the remaining muscle after a VML injury lacks similar levels of plasticity or adaptability as healthy, uninjured skeletal muscle. This may be due, in part, to impaired innervation and vascularization of the remaining muscle, as well as disrupted molecular signaling cascades commonly associated with muscle adaptation. The primary objective of this study was to assess the ability of four pharmacological agents with a strong record of modulating muscle contractile and metabolic function to improve functional deficits in a murine model of VML injury. Male C57BL/6 mice underwent a 15% multimuscle VML injury of the posterior hindlimb and were randomized into drug treatment groups (formoterol [FOR], 5-aminoimidazole-4-carboxamide riboside [AICAR], pioglitazone [PIO], or sildenafil [SIL]) or untreated VML group. At the end of 60 days, the injury model was first validated by comparison to age-matched injury-naive mice. Untreated VML mice had 22% less gastrocnemius muscle mass, 36% less peak-isometric torque, and 27% less maximal mitochondrial oxygen consumption rate compared to uninjured mice ( p  < 0.01). Experimental drug groups were, then, compared to VML untreated, and there was minimal evidence of efficacy for AICAR, PIO, or SIL in improving contractile and metabolic functional outcomes. However, FOR-treated VML mice had 18% greater peak isometric torque ( p  < 0.01) and permeabilized muscle fibers had 36% greater State III mitochondrial oxygen consumption rate ( p  < 0.01) compared to VML untreated mice, suggesting an overall improvement in muscle condition. There was minimal evidence that these benefits came from greater mitochondrial biogenesis and/or mitochondrial complex protein content, but could be due to greater enzyme activity levels for complex I and complex II. These findings suggest that FOR treatment is candidate to pair with a rehabilitative approach to maximize functional improvements in VML-injured muscle. Impact statement Volumetric muscle loss (VML) injuries result in deficiencies in strength and mobility, which have a severe impact on patient quality of life. Despite breakthroughs in tissue engineering, there are currently no treatments available that can restore function to the affected limb. Our data show that treatment of VML injuries with clinically available and FDA-approved formoterol (FOR), a beta-agonist, significantly improves strength and metabolism of VML-injured muscle. FOR is therefore a promising candidate for combined therapeutic approaches (i.e., regenerative rehabilitation) such as pairing FOR with structured rehabilitation or cell-seeded biomaterials as it may provide greater functional improvements than either strategy alone.

Abstract: Molecular features of cadmium (Cd) and calcium (Ca) uptake and toxicity in rainbow trout liver mitochondria were studied using modulators of mitochondrial permeability transition pore (MPTP), mitochondrial calcium uniporter (MCU) and rapid uptake mode (RaM). Malate-glutamate energized mitochondria were exposed to 20μM Cd and 50μM Ca, singly and in combination, with and without addition of ruthenium red (RR), cyclosporin A (CsA), bongkrekic acid (BKA) or dithiothreitol (DTT). State 3 mitochondrial respiration was inhibited by 50% by either Cd or Ca, and by 70% when the two cations were added simultaneously. All the modulators tested reduced the inhibition of state 3 respiration with DTT completely reversing the Cd effect. While state 4 respiration was unaffected by Ca and/or Cd, 1.5–3 fold stimulation was observed on addition of the modulators. Uncoupler-stimulated respiration was inhibited by Cd, Ca and Cd+Ca with complete (DTT) and partial (RR, CsA, BKA) protection of the Cd and Cd+Ca effects. All the modulators completely reversed the Ca-induced inhibition. Swelling, the hallmark of MPTP, measured following incubation of mitochondria with 0–100μM of the two cations, singly and in combination, was abolished by all the modulators. Overall these data show the existence of membrane channels in rainbow trout liver mitochondria with some characteristics similar to mammalian MPTP, MCU and RaM. Moreover, entry of Ca and Cd into mitochondria is important in the toxicity of these cations. [Copyright &y& Elsevier]

Mitochondria are essential organelles in neurons providing appropriate energetic needs to maintain resting and action potentials as well as to modulate synaptic plasticity. Although neuronal events underlie various behavioral events, the behavior itself, such as voluntary exercise, feeds back to affect neuronal morphology and function as well as glial morphology and function. The hippocampal formation is a main site of synaptic plasticity induced by voluntary exercise. Here we show that voluntary exercise induces uncoupling protein 2 (UCP2) mRNA expression and mitochondrial oxygen consumption in coupled as well as uncoupled respiratory states in the hippocampus. These changes in mitochondrial metabolism coincided with an increase in mitochondrial number and dendritic spine synapses in granule cells of the dentate gyrus and the stratum radiatum of the CA1 region and were dependent on UCP2 expression, because in UCP2 knock-out mice such changes were not observed. Together, these observations reveal that a mitochondrial mechanism related to UCP2 function is essential for appropriate bioenergetic adaptation of neurons to increased neuronal activity and synaptic plasticity in response to exercise. [ABSTRACT FROM AUTHOR]

Cardiovascular complications are the primary cause of death for diabetic patients. Clinical and experimental observation has showed the development of dysfunctional cardiomyopathy as one of the main complications of diabetes. Whether the cardiomyopathy results from an increased susceptibility of cardiac tissue to ischemic insult or from a specific functional defect of cardiac mitochondria is a controversial issue. The investigation of possible functional defect in cardiac mitochondria from diabetic rats indicates a decline in state 3 respiration only in animals presenting a marked decrease in body weight. Mitochondria from rats presenting a level of hyperglycemia similar to diabetic animals but not the marked weight loss typical of the latter group show no decline in state 3 respiration, the values being indistinguishable from those of control mitochondria. Mitochondria from hyperglycemic rats, however, show a 15–20% increase in state 4 oxygen consumption but only when glutamate is used as energetic substrate, as compared to a 40–50% increase in state 4 respiration in mitochondria from diabetic rats under similar experimental conditions. This phenomenon is unrelated to diabetes duration, as it is observed at 2 as well as 8 weeks after diabetes onset. Taken together, these data argue against hyperglycemia per se being a direct cause of the decline in state 3 oxygen consumption observed in cardiac mitochondria of type-I diabetic rats and indicate that differences exist in cardiac mitochondrial function in rats generically labeled as diabetic. These differences can contribute to explain discrepancies in experimental results reported by various groups in the field and provide an additional parameter to be taken into consideration in evaluating the varying sensitivity of diabetic hearts to ischemia–reperfusion injury. [Copyright &y& Elsevier]

This review focuses on three independent and complementary approaches to obtain information on the combined function of respiratory complexes when present in different structural situations, either as individual complexes or when superassembled with other complexes. We review the utility of in-gel activity after blue native electrophoresis, integrated oxygen consumption of supercomplexes containing complex IV, and spectrophotometric activity measurements., (© 2020 Elsevier Inc. All rights reserved.)

Summary Autophagy is essential for maintaining glucose homeostasis, but the mechanism by which energy deprivation activates autophagy is not fully understood. We show that Mec1/ATR, a member of the DNA damage response pathway, is essential for glucose starvation-induced autophagy. Mec1, Atg13, Atg1, and the energy-sensing kinase Snf1 are recruited to mitochondria shortly after glucose starvation. Mec1 is recruited through the adaptor protein Ggc1. Snf1 phosphorylates Mec1 on the mitochondrial surface, leading to recruitment of Atg1 to mitochondria. Furthermore, the Snf1-mediated Mec1 phosphorylation and mitochondrial recruitment of Atg1 are essential for maintaining mitochondrial respiration during glucose starvation, and active mitochondrial respiration is required for energy deprivation-activated autophagy. Thus, formation of a Snf1-Mec1-Atg1 module on mitochondria governs energy deprivation-induced autophagy by regulating mitochondrial respiration. [ABSTRACT FROM AUTHOR]

The clinical management of pediatric acute lymphoblastic leukemia (ALL) is still changeling and identification of agents that can sensitize standard chemotherapy is needed for its better management. In this work, we demonstrate that tigecycline, a FDA-approved antibiotic, is an attractive candidate for ALL treatment. Tigecycline inhibits growth and induces apoptosis of multiple ALL cell lines. Compared to normal hematopoietic cells, tigecycline is more active against primary lymphocytes and CD34 progenitors from ALL patients through decreasing survival and clonogenic growth. Notably, tigecycline significantly augments the efficacy of chemotherapeutic drugs, such as doxorubicin and vincristine, in ALL cell lines, primary samples and xenograft mouse model. Tigecycline acts on ALL via inhibiting mitochondrial respiration, leading to energy crisis and oxidative stress and damage. We show that the enhanced mitochondrial biogenesis and increased oxygen consumption rate in ALL versus normal hematopoietic cells are important for their different sensitivity to tigecycline. We further show that ATP production and growth rate are largely affected in mitochondrial respiration-deficient ρ0 ALL cells. Our work provides pre-clinical evidence for repurposing tigecycline for ALL treatment and highlights the therapeutic value of targeting mitochondrial metabolism in sensitizing ALL to chemotherapy., Competing Interests: None.

MicroRNAs are critical in various human cancers, including gastric cancer (GC). However, the mechanism underlying the GC development remains elusive. In this study, we demonstrate that miR-448 is increased in GC samples and cell lines. Overexpression of miR-448 facilitated the proliferation of GC cells by stimulating glycolysis. Mechanistically, we identified KDM2B, a reader for methylated CpGs, as the target of miR-448 that represses glycolysis and promotes oxidative phosphorylation. Overexpression of miR-448 reduced both the mRNA and protein levels of KDM2B, whereas KDM2B re-expression abrogated the miR-448-mediated glycolytic activities. Furthermore, we discovered Myc as a key target of KDM2B that controls metabolic switch in GC. Importantly, a cohort of 81 GC tissues revealed that miR-448 level closely associated with a battery of glycolytic genes, in which KDM2B showed the strongest anti-correlation coefficient. In addition, enhanced miR-448 level was significantly associated with poor clinical outcomes of GC patients. Hence, we identified a previously unappreciated mechanism by which miR-448 orchestrate epigenetic, transcriptional and metabolic networks to promote GC progression, suggesting the possibility of therapeutic intervention against cancer metabolic pathways., Competing Interests: The authors declare no conflicts of interest.