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Mitochondria perform crucial roles in many biochemical processes, and mitochondrial depolarization is an early sign of platelet apoptosis. The mitochondrial membrane potential is usually evaluated through JC-1 probe, but it can also be assessed with MitoTracker probes. Our aim was to evaluate mitochondrial viability in stored canine platelet concentrates (PCs) with the fluorescent probes JC-1 and MitoTracker. Platelets from 22 canine PCs were stained with JC-1 and MitoTracker probes on days 1, 3, and 5 of storage. Data on metabolic parameters were also collected for correlation studies. Results of JC-1 and MitoTracker revealed a decrease in mitochondrial membrane potential in day 5 of storage compared to days 1 and 3, providing evidence of mitochondrial depolarization, a finding that was confirmed by the data on metabolic parameters. MitoTracker probes also added information regarding platelet swelling. In conclusion, MitoTracker probes offered a more complete mitochondrial analysis in the evaluation of stored canine PCs. © 2018 International Society for Advancement of Cytometry., (© 2018 International Society for Advancement of Cytometry.)

Mitochondrial morphology is known to be continuously changing via fusion and fission, but it is unclear what the biological importance of this energy-consuming process is and how it develops. Several data have suggested that mitochondrial fission executed by Drp1 is necessary to select out a damaged spot from the interconnected mitochondrial network, but the precise mechanism for the recognition and isolation of a damaged sub-mitochondrial region during mitochondrial fission is yet unclear. Recently, Cho et al. found that the mitochondrial membrane potential (MMP) is transiently reduced by the physical interaction of Drp1 and mitochondrial Zinc transporter, Zip1, at the fission site prior to the typical mitochondrial division, and we found that this event is essential for a mitochondrial quality surveillance. In this review, Cho et al. discuss the role of a mitochondrial fission in the mitochondrial quality surveillance system. [BMB Reports 2019; 52(2): 109-110].

The heavy metal thallium is an emerging pollutant among the most potentially toxic species to which human populations are exposed. Its harmful effects on living organisms are well-known at high doses, typical of acute intoxication. Its harmful effects at low doses are by far less known. In a previous paper, we reported a TlCl-induced metabolic shift to lactate and ethanol production in living hippocampal HN9.10e neurons that appeared after a single short exposure (48 h) at low doses (1-100 μg/L). This metabolic shift to lactate and ethanol suggests a marked impairment of cell bioenergetics. In this work, we provide detailed evidence for TlCl-induced changes of neuronal morphology and mitochondrial activity. Confocal microscopy and fluorescent probes were used to qualitatively and quantitatively analyze, at the subcellular level, living HN9.10e neurons during and after TlCl exposure. An early onset mitochondrial dysfunction appeared, associated with signs of cellular deregulation such as neurite shortening, loss of substrate adhesion, and increase of cytoplasmic calcium. The dose-dependent alteration of mitochondrial ROS (mtROS) level and of transmembrane mitochondrial potential (ΔΨ m ) has been observed also for very low TlCl doses (1 μg/L). The treatment with the ATP synthase inhibitor oligomycin revealed a severe impairment of the mitochondrial function, more significant than that measured by the simple quantification of the tetramethylrhodamine methyl ester (TMRM) fluorescence. These results highlight that mitochondria are a key subcellular target of TlCl neurotoxicity. The transmembrane mitochondrial potential was significantly correlated with the ethanol concentration in cell culture medium ( P < 0.001, r = -0.817), suggesting that ethanol could be potentially used as a biomarker of mitochondrial impairment.

Background: The increasing epidemic of fine particulate matter (PM2.5) is a serious threat to human health. It induces the occurrence of liver fibrosis, but its molecular mechanism is not yet clear. The molecular mechanisms of PM2.5 inducing liver fibrosis were investigated in this study., Methods: The cell viability of LX-2 cells and primary hepatic stellate cells (HSCs) was detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In vitro enzyme-linked immune sorbent assay (ELISA) kits were used to detect the concentrations of antioxidant enzymes and reactive oxygen species (ROS). The mitochondrial transmembrane potential (MTP) was determined by JC-1 dye. Knockdown of Parkin was carried out by Parkin-specific siRNA transfection. Relative mRNA and protein expressions were evaluated by qRT-PCR, Western blotting, and immunofluorescence analysis., Results: PM2.5 activated LX-2 cells and primary HSCs, inducing the liver fibrosis along with down-regulation of the gelatinases MMP-2, and up-regulation of myofibroblast markers collagen type I and α-SMA. The levels of ROS and reactive nitrogen species (RNS), as well as the lipid peroxidation marker malondialdehyde (MDA) were significantly up-regulated in LX-2 cells and primary HSCs treated with PM2.5. Also, the enzymatic antioxidants levels were disturbed by PM2.5. Furthermore, PM2.5 decreased the MTP, releasing cytochrome c from the mitochondria to the cytosol. The dynamics of mitochondria were regulated by PM2.5 via facilitating mitochondrial fission. The excess ROS induced by PM2.5 triggered the mitophagy by activating PINK1/Parkin pathway, and inhibition of mitophagy induced by PM2.5 diminished the liver fibrosis., Conclusion: PM2.5 may induce mitophagy via activating PINK1/Parking signal pathway by increasing ROS, thereby activating HSCs and causing liver fibrosis., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Early studies have shown that moderate levels of calcium overload can cause lower oxidative phosphorylation rates. However, the mechanistic interpretations of these findings were inadequate. And while the effect of excessive calcium overload on mitochondrial function is well appreciated, there has been little to no reports on the consequences of low to moderate calcium overload. To resolve this inadequacy, mitochondrial function from guinea pig hearts was quantified using several well-established methods including high-resolution respirometry and spectrofluorimetry and analyzed using mathematical modeling. We measured key mitochondrial variables such as respiration, mitochondrial membrane potential, buffer calcium, and substrate effects for a range of mitochondrial calcium loads from near zero to levels approaching mitochondrial permeability transition. In addition, we developed a computer model closely mimicking the experimental conditions and used this model to design experiments capable of eliminating many hypotheses generated from the data analysis. We subsequently performed those experiments and determined why mitochondrial ADP-stimulated respiration is significantly lowered during calcium overload. We found that when calcium phosphate levels, not matrix free calcium, reached sufficient levels, complex I activity is inhibited, and the rate of ATP synthesis is reduced. Our findings suggest that calcium phosphate granules form physical barriers that isolate complex I from NADH, disrupt complex I activity, or destabilize cristae and inhibit NADH-dependent respiration., Competing Interests: The authors have declared that no competing interests exist.

Ischemic heart disease is the leading cause of death worldwide. Stem cell therapy to repair and regenerate the infarcted myocardium is a promising approach to address this unmet medical need. However, the poor survival of transplanted cells in the hostile ischemic myocardium has been a major hurdle in achieving an effective cell therapy against myocardial infarction. As such, novel strategies to promote the survival of transplanted cells are highly sought after. Mitochondria are intimately involved in cell survival and have been the main organelles being targeted for cytoprotection. Mitochondrial morphology is linked to mitochondrial function and cell viability. Therefore, quantitative methodologies to obtain reliable and reproducible results of mitochondrial morphology and function are essential for identifying and developing new cytoprotective strategies to enhance the survival of stem cells post-transplantation. Here, we describe methods for assessing mitochondrial morphology, mitochondrial membrane potential, and mitochondrial reactive oxygen species production.

The present study was undertaken to determine the involvement of voltage-gated Na + channel (VGSC) and other mechanism related to insulin secretion in polysaccharides from Portulaca oleracea L. (POP)-induced secretion of insulin from insulin-secreting β-cell line cells (INS-1) cells. Our results showed that the concentration of insulin both in culture medium and inside INS-1 cells were increased under the existing of different concentration of glucose by POP or TTX, respectively. However, the effect POP on insulin secretion and production were blocked by TTX, a VGSC blocker. Meanwhile, POP improved the mitochondrial membrane potential (Δψm), increased adenosine triphosphate (ATP) production, depolarized cell membrane potential (MP) and increased intracellular Ca 2+ levels ([Ca 2+ ] i ). Furthermore, POP treatment increased the expression level of Nav 1.3 and decreased the expression level of Nav 1.7. TTX treatment decreased the expression level of Nav 1.3 and Nav 1.7 . On the other hand, POP also elevated the survival of INS-1 cells. These results suggested that POP induced-secretion/production of insulin in INS-1 cells were mediated by VGSC through its change of function and subunits expression and subsequent VGSC- dependent events such as change of intracellular Ca 2+ releasing, ATP metabolism, cell membrane and mitochondrial membrane potential, and also improvement of INS-1 cell survival. Meanwhile, our data indicated the potentiality of developing POP to be a drug for diabetes treatment and VGSC as a therapeutic target in diabetes treatment is valuable to be investigated further., (Copyright © 2018. Published by Elsevier Masson SAS.)

Study Question: In addition to sperm motility, which major biological characteristics of sperm fertility potential are associated with mitochondrial functionality?, Summary Answer: Sperm fertilization capacities, including acrosin activity, acrosome reaction (AR) capability and chromatin integrity, are related to the mitochondria functionality as evaluated by the mitochondrial membrane potential (MMP)., What Is Known Already: Correlative studies suggest a potential role of sperm MMP in predicting sperm fertilization ability and ensuring sperm motility. However, researches characterizing other determinants of sperm fertility potential according to MMP are lacking., Study Design, Size, Duration: The sperm MMP was examined in 627 young college students in the Male Reproductive Health in Chongqing College Students (MARHCS) cohort study in 2014. Among these participants, acrosin activity and chromatin integrity were measured in 378 and 604 subjects, respectively. These two determinants of sperm fertility potential were first compared among high-, moderate- and low-MMP groups in the college population. The effects of MMP collapse caused by carbonyl cyanide 3-chlorophenylhydrazone (CCCP) on acrosin activity, AR, DNA fragmentation, reactive oxygen species (ROS) production, and ATP content in human spermatozoa were evaluated in vitro., Participants/materials, Setting, Methods: The sperm MMP was evaluated by using JC-1 staining, acrosin activity was measured using a N-α-benzoyl-dl-arginine-para-nitroanilide HCl (BAPNA) substrate method, the integrity of chromatin represented by DNA fragmentation index (DFI) was measured by sperm chromatin structure assay (SCSA), AR was evaluated with chlortetracycline staining, and intracellular ROS production was evaluated with dihydroethidium. ATP concentration was determined with luciferase. Measurements were performed by spectrophotometry or flow cytometry., Main Results and the Role of Chance: Nonparametric analysis revealed significantly higher acrosin activity and a lower DFI in subjects with moderate or high MMP compared to those with low MMP. After adjustment for potential confounders, increases of 7.9 and 44.4% in sperm acrosin activity and deceases of 12.0 and 25.2% in the sperm DFI were found in the moderate- and high-MMP groups, respectively. The MMP dissipation induced by CCCP caused significant declines in acrosin activity and AR capacity and increased DFI in human spermatozoa. Moreover, sperm MMP dissipation induced ROS overproduction and decreased ATP content., Limitations, Reasons for Caution: We cannot exclude a contribution of leukocytes to ROS production and no size gating was used to exclude these cells from the FACS measurements. No simultaneous live-dead staining was done and a contribution of dead sperm to the MMP and acrosome assays cannot be excluded., Wider Implications of the Findings: Mitochondrial functionality might be necessary to maintain sperm acrosin activity, AR and chromatin integrity. Tests of mitochondrial functionality should be developed and used independently of or in addition to conventional semen parameters in infertility diagnosis or risk-assessment processes., Study Funding/competing Interest(s): This study was supported by the Key Program of the National Natural Science Foundation of China (No. 81630087) and the National Natural Science Foundation of China (No. 81703254). None of the authors have any competing interests to declare.

Mitochondria hold a critical role in cell metabolism and homeostasis. Mitochondrial injury plays central part in deciding cell fate especially in programmed cell death pathways. Various nanomaterials lead to different cell death modalities by inducing mitochondrial injury. Mitochondrial injury is manifested as multiple biochemical events ranging from altered energy production, mitochondrial outer membrane permeability, release of pro-apoptotic BCl-2 family proteins, loss of mitochondrial inner membrane potential, mitochondrial swelling, and disruption of mitochondrial structure leading to eventual lysis of mitochondria. Mitochondrial membrane permeability (loss of mitochondrial membrane potential) is a critical event in deciding cell fate. This chapter presents an overview of nanomaterial-induced loss of mitochondrial membrane potential and discusses potential nano-specific artifacts in these assays. Finally, a detailed methodology to accurately quantify and validate the loss of mitochondrial membrane potential after nanomaterial exposures is presented.

Glutamate-mediated cytotoxicity has been implicated in the pathogenesis of neurological diseases, including Parkinson's disease, Alzheimer's disease, and stroke. In this study, we investigated the protective effects of alpha-lipoic acid (ALA), a naturally occurring thiol antioxidant, on glutamate-induced cytotoxicity in cultured C6 astroglial cells. Exposure to high-dose glutamate (10 mM) caused oxidative stress and mitochondrial dysfunction through the elevation of reactive oxygen species, depletion of glutathione, and loss of the mitochondrial membrane potential (ΔΨ m ). Pretreatment with ALA (200 µM), however, significantly inhibited the glutamate-induced oxidative stress and mitochondrial dysfunction. ALA pretreatment dose-dependently suppressed glutamate-induced apoptotic events including altered nuclear morphology and activation of caspase-3. In addition, ALA significantly attenuated glutamate-induced endoplasmic reticulum (ER) stress markers; namely, glucose-regulated protein 78 (GRP78), activating transcription factor 6 (ATF6), protein kinase regulated by RNA (PKR)-like ER-associated kinase (PERK), eukaryotic translation initiation factor 2 alpha (eIF2α), inositol-requiring enzyme 1 (IRE1), CCAAT/enhancer binding protein homologous protein (CHOP), and caspase-12. We confirmed that CHOP and caspase-12 are key mediators of glutamate-induced ER stress. Furthermore, exposure of the cells to a caspase-12-specific inhibitor and CHOP small interfering RNAs (siRNAs) led to restoration of the ΔΨ m that was damaged by glutamate treatment. These results suggest that ALA can effectively suppress oxidative stress, mitochondrial dysfunction, and ER stress in astroglial cells.

Amyotrophic lateral sclerosis (ALS) is a common neurodegenerative disorder, but little is known about the exact causes and pathophysiology of this disease. In transgenic mouse models of ALS, mitochondrial abnormalities develop during the disease and might contribute to the progression of ALS. Gene therapy was recently shown to induce beneficial effects. For example, the delivery of human insulin-like growth factor-1 (hIGF-1) by self-complementary adeno-associated virus (AAV) vectors has been shown to prolong the lifespan of ALS transgenic mice. However, the function of IGF-1 in mitochondria has not been systematically studied in ALS models. In this study, scAAV9-hIGF-1 was intramuscularly injected into transgenic SOD1 G93A mice and administered to cell lines expressing the ∼25-kDa C-terminal fragment of transactive response DNA-binding protein (TDP-25). The mitochondrial electrical transmembrane potential was hyperpolarized, and electron microscopy findings revealed that the abnormal mitochondria were transformed. Moreover, the intrinsic mitochondrial apoptotic process was modified through the upregulation of anti-apoptotic proteins (B-cell lymphoma-extra large (Bcl-xl) and B-cell lymphoma-2 (Bcl-2)), the downregulation of pro-apoptotic proteins (Bcl-2-associated x protein (Bax) and Bcl-2 homologous antagonist killer (Bak)) and a reduction in mitochondrial cytochrome c release. Mitophagy was also increased after scAAV9-hIGF-1 treatment, as evidenced by a decrease in the p62 level and an increase in the LC3-II level. Furthermore, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) system was used to delete the IGF-1 gene in SOD1 G93A model mice via an intrathecal injection of scAAV9-sgRNA-IGF1-Cas9 to confirm these findings. The protective effect of IGF-1 on the mitochondria decreased after genetic deletion. These novel findings demonstrate that IGF-1 strongly protects mitochondria from apoptosis and upregulates mitophagy in mouse and cell models of ALS. Therefore, therapies that specifically protect mitochondrial function might be promising strategies for treating ALS., (Copyright © 2018. Published by Elsevier Inc.)

Introduction: We have recently developed an extra-uterine environment for neonatal development (EXTEND) capable of supporting premature fetal lambs and have been able to replicate hypoxic in utero conditions by controlling fetal oxygen delivery. In this study, we investigated the fetal mitochondrial response to hypoxia., Methods: Eight premature fetal lambs were delivered via hysterotomy and transitioned to extra-uterine support for 3 weeks. The lambs were divided into 2 groups: normoxic fetuses which maintained physiologic oxygen delivery and hypoxic fetuses in which oxygen delivery was significantly reduced. Control fetuses were delivered via hysterotomy but not cannulated. Measurements of mitochondrial membrane potential (MMP) were performed in peripheral blood mononuclear cells., Results: There were no significant differences in MMP between normoxic EXTEND fetuses and controls. Hypoxic fetuses had significantly more depolarized mitochondria compared to normoxic fetuses overall, and these changes were specifically appreciated in weeks 1 and 2, but not by week 3. Hypoxic fetuses had significantly elevated levels of HIF-1α compared to normoxic fetuses in the first 2 weeks., Discussion: Normoxic fetal lambs supported by EXTEND demonstrate normal mitochondrial function as evidenced by equivalent membrane potentials compared to control fetuses. Hypoxic fetuses exhibit mitochondrial dysfunction, though they do show evidence of adaptation after 3 weeks of hypoxic exposure., (© 2018 S. Karger AG, Basel.)

Background: Since the serendipitous discovery of the antitumor activity of cisplatin there has been a continuous surge in studies aimed at the development of new cytotoxic metal complexes. While the majority of these complexes have been designed to interact with nuclear DNA, other targets for anticancer metallodrugs attract increasing interest. In cancer cells the mitochondrial metabolism is deregulated. Impaired apoptosis, insensitivity to antigrowth signals and unlimited proliferation have been linked to mitochondrial dysfunction. It is therefore not surprising that mitochondria have emerged as a major target for cancer therapy. Mitochondria-targeting agents are able to bypass resistance mechanisms and to (re-) activate cell-death programs., Methods: Web-based literature searching tools such as SciFinder were used to search for reports on cytotoxic metal complexes that are taken up by the mitochondria and interact with mitochondrial DNA or mitochondrial proteins, disrupt the mitochondrial membrane potential, facilitate mitochondrial membrane permeabilization or activate mitochondria-dependent celldeath signaling by unbalancing the cellular redox state. Included in the search were publications investigating strategies to selectively accumulate metallodrugs in the mitochondria., Results: This review includes 241 references on antimitochondrial metal complexes, the use of mitochondria-targeting carrier ligands and the formation of lipophilic cationic complexes., Conclusion: Recent developments in the design, cytotoxic potency, and mechanistic understanding of antimitochondrial metal complexes, in particular of cyclometalated Au, Ru, Ir and Pt complexes, Ru polypyridine complexes and Au-N-heterocyclic carbene and phosphine complexes are summarized and discussed., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Parkinson's disease (PD) is currently the second most common neurodegenerative disorder in the world. Major features of cell pathology of the disease include the presence of cytoplasmic inclusions called Lewy bodies, which are composed of aggregated proteins. The presence of Lewy's body is associated with more advanced stages of the disease when considering irreversible changes. Precise identification of the disease stage at a cellular level presents the critical tool in developing early diagnostics and/or prevention of PD. The aim of our work is to introduce sensitive microscopic analysis in living cells, focused on initial intracellular changes and thus capable to detect earlier stages of the disease.

Background: Cobalt chloride (CoCl 2 ) induces chemical hypoxia through activation of hypoxia-inducible factor-1 alpha (HIF-1α). Mammalian target of rapamycin (mTOR) is a multifaceted protein capable of regulating cell growth, angiogenesis, metabolism, proliferation, and survival. In this study, we tested the efficacy of a well-known mTOR inhibitor, rapamycin, in reducing oxidative damage and increasing cell viability in the mouse hippocampal cell line, HT22, during a CoCl 2 -simulated hypoxic insult., Results: CoCl 2 caused cell death in a dose-dependent manner and increased protein levels of cleaved caspase-9 and caspase-3. Rapamycin increased viability of HT22 cells exposed to CoCl 2 and reduced activation of caspases-9 and -3. Cells exposed to CoCl 2 displayed increased reactive oxygen species (ROS) production and hyperpolarization of the mitochondrial membrane, both of which rapamycin successfully blocked. mTOR protein itself, along with its downstream signaling target, phospho-S6 ribosomal protein (pS6), were significantly inhibited with CoCl 2 and rapamycin addition did not significantly lower expression further. Rapamycin promoted protein expression of Beclin-1 and increased conversion of microtubule-associated protein light chain 3 (LC3)-I into LC3-II, suggesting an increase in autophagy. Pro-apoptotic protein, Bcl-2 associated × (Bax), exhibited a slight, but significant decrease with rapamycin treatment, while its anti-apoptotic counterpart, B cell lymphoma-2 (Bcl-2), was to a similar degree upregulated. Finally, the protein expression ratio of phosphorylated mitogen-activated protein kinase (pMAPK) to its unphosphorylated form (MAPK) was dramatically increased in rapamycin and CoCl 2 co-treated cells., Conclusions: Our results indicate that rapamycin confers protection against CoCl 2 -simulated hypoxic insults to neuronal cells. This occurs, as suggested by our results, independent of mTOR modification, and rather through stabilization of the mitochondrial membrane with concomitant decreases in ROS production. Additionally, inhibition of caspase-9 and -3 activation and stimulation of protective autophagy reduces cell death, while a decrease in the Bax/Bcl-2 ratio and an increase in pMAPK promotes cell survival during CoCl 2 exposure. Together these results demonstrate the therapeutic potential of rapamycin against hypoxic injury and highlight potential pathways mediating the protective effects of rapamycin treatment.

Metabolic engagement is intrinsic to immune cell function. Prostaglandin E2 (PGE2) has been shown to modulate macrophage activation, yet how PGE2 might affect metabolism is unclear. Here, we show that PGE2 caused mitochondrial membrane potential (Δψ m ) to dissipate in interleukin-4-activated (M(IL-4)) macrophages. Effects on Δψ m were a consequence of PGE2-initiated transcriptional regulation of genes, particularly Got1, in the malate-aspartate shuttle (MAS). Reduced Δψ m caused alterations in the expression of 126 voltage-regulated genes (VRGs), including those encoding resistin-like molecule α (RELMα), a key marker of M(IL-4) cells, and genes that regulate the cell cycle. The transcription factor ETS variant 1 (ETV1) played a role in the regulation of 38% of the VRGs. These results reveal ETV1 as a Δψ m -sensitive transcription factor and Δψ m as a mediator of mitochondrial-directed nuclear gene expression., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Glycolysis plays a key role in brain energy metabolism. The initial and rate-limiting step of brain glycolysis is catalyzed mainly by hexokinase I (HKI), the majority of which is bound to the mitochondrial outer membrane (MOM), mostly through the mitochondrial inter-membrane contact sites formed by the voltage-dependent anion channel (VDAC, outer membrane) and the adenine nucleotide translocator (ANT, inner membrane). Earlier, we proposed a mechanism for the generation of the mitochondrial outer membrane potential (OMP) as a result of partial application of the inner membrane potential (IMP) to MOM through the electrogenic ANT-VDAC-HK inter-membrane contact sites. According to this previous mechanism, the Gibbs free energy of the hexokinase reaction might modulate the generated OMP (Lemeshko, Biophys. J., 2002). In the present work, a new computational model was developed to perform thermodynamic estimations of the proposed mechanism of IMP-HKI-mediated generation of OMP. The calculated OMP was high enough to electrically regulate MOM permeability for negatively charged metabolites through free, unbound VDACs in MOM. On the other hand, the positive-inside polarity of OMP generated by the IMP-HKI-mediated mechanism is expected to protect mitochondria against elevated concentrations of cytosolic Ca 2+ . This computational analysis suggests that metabolically-dependent generation of OMP in the brain mitochondria, controlled by many factors that modulate VDAC1-HKI interaction, VDAC's voltage-gating properties and permeability, might represent one of the physiological mechanisms of regulation of the brain energy metabolism and of neuronal death resistance, and might also be involved in various neurodegenerative disorders, such as Alzheimer's disease., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Targeting the anti-apoptotic protein Mcl-1 holds a promise to improve therapy of multiple types of Mcl-1 dependent cancers but raises concerns of on-target cardiotoxicity due to the presence and reported role of Mcl-1 in heart. Herein, we investigated the importance of Mcl-1 in the survival and contractile function of human pluripotent stem cell-derived cardiomyocytes in culture. Effective knockdown of Mcl-1 with siRNAs reproducibly resulted in early (measured at Day 3) marginal alterations in caspase 3/7 activity, LDH leakage, ATP content and cellular impedance. After 14 days of Mcl-1 knockdown, loss of mitochondrial membrane potential, deteriorating effects on mitochondrial ultrastructure, and alterations in beat rate and amplitude were revealed. Inhibition of Bcl-xL by siRNA-mediated knockdown or selective inhibitors did not cause any overt cellular responses except for a minimal increase in caspase 3/7 activity; however, loss of Mcl-1 concomitant with down-regulated Bcl-xL activated apoptosis and caused extensive cell death as reflected by an 80% loss in cell index, activation of caspase-3 with associated PARP cleavage, and a decrease in beat amplitude and mitochondrial membrane potential after 3 days of Mcl-1/Bcl-xL knockdown., Together, these findings suggest that Mcl-1 and Bcl-xL provide duplicate safeguard measures in maintaining structural and functional integrity of cardiomyocytes. Hence, BH3-mimetic drugs targeting Mcl-1 may be well tolerated in the presence of intact Bcl-xL., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder manifesting as progressive impairment of motor function and different neuropsychiatric symptoms caused by an expansion of CAG repeats in huntingtin gene (HTT). Mitochondrial dysfunction and bioenergetic defects can contribute to the course of the disease, however, the molecular mechanism underlying this process is still largely unknown. In this study, we aimed to determine several mitochondrial parameters in HD fibroblasts and assess their relevance to the disease progression as well as to value mitochondrial pathology in peripheral cells as disease potential biomarker. We showed that HD fibroblasts demonstrate significantly lower growth rate compared to control fibroblasts despite the lack of cell cycle perturbations. In order to investigate mitochondrial contribution to cell growth differences between HD and healthy cells, we provided insight into various mitochondrial parameters. Conducted experiments have revealed a significant reduction of the ATP level in HD fibroblasts accompanied by a decrease in mitochondrial metabolic activity in relation to the cells from healthy donors. Importantly, there were no differences in the mitochondrial membrane potential (mtΔΨ) and OXPHOS complexes' levels. Slightly increased level of mitochondrial superoxide (mt. O 2 •- ), but not cytosolic reactive oxygen species (cyt. ROS), has been demonstrated. We have also observed significantly elevated levels of some antioxidant enzymes (SOD2 and GR) which may serve as an indicator of antioxidant defense system in HD patients. Thus, we suggest that mitochondrial alterations in skin fibroblasts of Huntington's disease patients might be helpful in searching for novel disease biomarkers.

Mitochondrial permeability transition pore (MPTP) has been associated to calcium homeostasis and reactive oxygen species (ROS) generation in several cell types. While extensively investigated in somatic cells, there are few data regarding MPTP phenomenon in gametes. The aim of the present work was to investigate MPTP occurrence in sea urchin female gametes. The protonophores CCCP and FCCP, and the Ca 2+ ionophore ionomycin, were used as pore inductors. Pore opening was monitored by mitochondrial potential sensitive probes and cobalt-quenched calcein assay. The pore desensitizer cyclosporin A (CsA) prevented the loss of mitochondrial inner membrane potential (ΔΨ m ) and pore opening induced by MPTP activators. The disruption of ΔΨ m led to an increase in ROS generation, which was completely prevented by CsA. Our data also demonstrated that the increase in ROS production induced by MPTP opening requires extracellular Ca 2+ . In summary, the current study provides evidence about the occurrence of MPTP in sea urchin eggs in a similar manner as described in vertebrate somatic cells - CsA-sensitive, voltage- and Ca 2+ -triggered - and shows MPTP as a highly conserved physiological event through the evolution., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The rapid and efficient clearance of apoptotic germ cells (GCs) by Sertoli cells (SCs) is important for spermatogenesis. High mitochondrial activity in phagocytes is critical for continued clearance of apoptotic cells. However, the underlying molecular mechanism is poorly understood. Glycogen synthase kinase-3α (GSK3α) is a protein kinase that participates in the regulation of mitochondrial activity. Immunohistochemistry evidenced the predominant presence of the Ser21 phosphorylation GSK3α (inactivation) signal in SCs. Heat shock-induced apoptosis of GCs and dephosphorylation of GSK3α in SCs is a perfect model to investigate the role of GSK3α in phagocytic action. The number of apoptotic GCs was significantly lower in GSK3α inhibitor pre-treated mice with HS compared to normal control. In vitro phagocytosis assays shown that the phagocytic activity in GSK3α activated SCs was downregulated, while GSK3α inhibitor supplementation restored this process. Moreover, GSK3α activation participates in the alteration of the mitochondrial ultrastructure and activity. In particular, GSK3α activation inhibits mitochondrial fission via phosphorylation of dynamin related protein 1 at Ser637. Changes of mitochondrial activity resulted in the accumulation of lipid droplets and the alteration of metabolism pattern in SCs. In summary, our results demonstrate that inactivation of GSK3α is required for mitochondria-mediated apoptotic GCs phagocytosis in SCs.

The clinically approved drug metformin has been shown to selectively kill persister cancer cells through mechanisms that are not fully understood. To provide further mechanistic insights, we developed a drug surrogate that phenocopies metformin and can be labeled in situ by means of click chemistry. Firstly, we found this molecule to be more potent than metformin in several cancer cell models. Secondly, this technology enabled us to provide visual evidence of mitochondrial targeting with this class of drugs. A combination of fluorescence microscopy and cyclic voltammetry indicated that metformin targets mitochondrial copper, inducing the production of reactive oxygen species in this organelle, mitochondrial dysfunction and apoptosis. Importantly, this study revealed that mitochondrial copper is required for the maintenance of a mesenchymal state of human cancer cells, and that metformin can block the epithelial-to-mesenchymal transition, a biological process that normally accounts for the genesis of persister cancer cells, through direct copper targeting., Competing Interests: RR, SM and TC have filed provisional patent applications related to metformin derivatives, used as therapeutics and diagnostic tools. All other authors declare no competing interests.

Fuchs endothelial corneal dystrophy (FECD) is a bilateral progressive corneal endothelial disease characterized by guttae, which present as partial Descemet membrane thickening, inducing corneal edema at the final stage. Oxidative stress has been reported to play an important role in the pathogenesis of FECD. The electron transport chain and oxidative phosphorylation (oxphos) system in mitochondria are the main sources of endogenous oxidative stress, arising from superoxide generation through premature electron leakage to oxygen. In FECD, corneal endothelial cells have altered mitochondria with mitochondrial DNA damage, decreased oxphos proteins, and lower mitochondrial membrane potential. Mitochondrial dynamics and mitophagy comprise the organelle-level mitochondrial quality control system. Mitochondrial dynamics includes fusion and fission processes. When mitochondria are severely damaged, fission becomes the dominant process to remove damaged mitochondria. Mitophagy is a selective autophagy pathway that removes damaged mitochondria, and is triggered by mitochondrial membrane potential depolarization. In the FECD corneal endothelium, mitochondria have a fission-dominant morphology and low density through mitophagy upregulation because of quality control processes against altered mitochondria.

Apoptosis and oxidative stress are essential for the pathogenesis of acute liver failure and fulminant hepatic failure. Human placental hydrolysate (hPH) has been reported to possess antioxidant and anti‑inflammatory properties. In the present study, the protective effects of hPH against D‑galactosamine (D‑GalN)‑ and lipopolysaccharide (LPS)‑induced hepatocyte apoptosis were investigated in vivo. In addition, the molecular mechanisms underlying the anti‑apoptotic activities of hPH against D‑GalN‑induced cell death in vitro were examined. Male Sprague‑Dawley rats were injected with D‑GaIN/LPS with or without the administration of hPH. Rats were sacrificed 24 h after D‑GaIN/LPS intraperitoneal injection, and the blood and liver samples were collected for future inflammation and hepatotoxicity analyses. Changes in cell viability, apoptosis protein expression, mitochondrial mass, mitochondrial membrane potential, reactive oxygen species generation, and the levels of proteins and mRNA associated with a protective mechanism were determined in HepG2 cells pretreated with hPH for 2 h prior to D‑GalN exposure. The findings suggested that hPH treatment effectively protected against D‑GalN/LPS‑induced hepatocyte apoptosis by reducing the levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, interleukin‑6, and tumor necrosis factor‑α, and increasing the level of proliferating cell nuclear antigen. It was also found that hPH inhibited the apoptotic cell death induced by D‑GalN. hPH activated the expression of antioxidant enzymes, including superoxide dismutase, glutathione peroxidase, and catalase, which were further upregulated by the Kelch‑like ECH2‑associated protein 1‑p62‑nuclear factor‑erythroid 2‑related factor 2 pathway, a component of oxidative stress defense mechanisms. Furthermore, hPH markedly reduced cytosolic and mitochondrial reactive oxygen species and rescued mitochondrial loss and dysfunction through the reduction of damage‑regulated autophagy modulator, p53, and C/EBP homologous protein. Collectively, hPH exhibited a protective role in hepatocyte apoptosis by inhibiting oxidative stress and maintaining cell homeostasis. The underlying mechanisms may be associated with the inhibition of endoplasmic reticulum stress and minimization of the autophagy progress.

Despite causing permanent hearing loss by damaging inner ear sensory cells, aminoglycosides (AGs) remain one of the most widely used classes of antibiotics in the world. Although the mechanisms of cochlear sensory cell damage are not fully known, reactive oxygen species (ROS) are clearly implicated. Mitochondrial-specific ROS formation was evaluated in acutely cultured murine cochlear explants exposed to gentamicin (GM), a representative ototoxic AG antibiotic. Superoxide (O2·-) and hydrogen peroxide (H2O2) were measured using MitoSOX Red and Dihydrorhodamine 123, respectively, in sensory and supporting cells. A 1-h GM exposure significantly increased O2·- formation in IHCs and increased H2O2 formation in all cell types. At the same time point, GM significantly increased manganese superoxide dismutase (MnSOD) levels while significantly decreasing copper/zinc superoxide dismutase (CuZnSOD) in cochlear sensory cells. This suggests (1) a rapid conversion of highly reactive O2·- to H2O2 during the acute stage of ototoxic antibiotic exposure and (2) that the endogenous antioxidant system is significantly altered by AGs. Fluorescence intensity-based measurements of reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H] and mitochondrial membrane potential were measured to determine if increases in GM-induced ROS production were correlated with changes in mitochondrial metabolism. This project provides a basis for understanding the mechanisms of mitochondrial ROS production in cochlear cells exposed to ototoxic antibiotics. Understanding the nature of ototoxic antibiotic-induced changes in mitochondrial metabolism is critical for developing hearing loss treatment and prevention strategies.

Fibroblast growth factor 2 (FGF2) is a multifunctional cell growth factor that regulates cell proliferation, differentiation, adhesion, migration, and apoptosis. FGF2 has multiple isoforms, including an 18-kDa low molecular weight isoform (lo-FGF2) and 22-, 23-, 24-, and 34-kDa high molecular weight isoforms (hi-FGF2). Hi-FGF2 overexpression induces chromatin compaction, which requires the mitochondria and leads to apoptosis. Complement component 1 Q subcomponent-binding protein (C1QBP) plays an important role in mitochondria-dependent apoptosis by regulating the opening of the mitochondrial permeability transition pore. However, the interaction between C1QBP and hi-FGF2 and its role in hi-FGF2-mediated apoptosis remain unclear. Here, we found that hi-FGF2 overexpression induced depolarization of the mitochondrial membrane, cytochrome c release into the cytosol, and a considerable increase in C1QBP messenger RNA and protein expression. Furthermore, coimmunoprecipitation results showed that the mitochondrial protein, C1QBP, interacts with hi-FGF2. C1QBP knockdown using small interfering RNA significantly decreased the localization of hi-FGF2 to the mitochondria and increased the rate of apoptosis. Our results highlight a novel mechanism underlying hi-FGF2-induced, mitochondria-driven cell death involving the direct interaction between hi-FGF2 and C1QBP and the upregulation of C1QBP expression., (© 2018 The Authors. Journal of Cellular Biochemistry Published by Wiley Periodicals, Inc.)

Objective: Analyze the influence of the hyperbaric environment on skeletal muscle mitochondrial bioenergetic end-points of rats submitted to muscle contusion., Methods: Twelve female Wistar rats were randomly assigned to three groups. All rats were submitted to muscle contusion in the right gastrocnemius through a standard protocol. The control group (C) remained under normobaric conditions without any treatment. The hyperbaric air (HB) and the hyperbaric oxygen (HBO2) groups had four sessions of HBO2 therapy 60 minutes, six, 12, 24 and 48 hours after the injury at 253.25 kPa (2.5 atmospheres absolute/ATA) with air or 100% oxygen, respectively. The animals were sacrificed 48 hours after muscle injury, and both muscles (injured and non-injured) were analyzed. Muscle mitochondrial bioenergetics and mitochondrial permeability transition pore (MPTP) susceptibility were evaluated., Results: Significant differences were found in all parameters between the injured and the non-injured gastrocnemius in the C group. In the HB group, significantly better results concerning bioenergetics-related end points with complex I and II substrates where found in the right gastrocnemius, whereas in the HBO2 group the time to Vmax (time that elapsed until the faster swelling kinetics starts) was significantly higher and the swelling amplitude was significantly smaller than in other groups, which suggest a lower susceptibility to MPTP opening., Conclusion: The present data suggest that hyperbaric exposure, particularly with oxygen, positively modulates the efficiency of skeletal muscle mitochondria after muscle contusion., Competing Interests: The authors of this paper declare no conflicts of interest exist with this submission., (Copyright© Undersea and Hyperbaric Medical Society.)

We have previously shown that protein kinase Cε (PKCε) is involved in mitochondrial dysfunction in renal proximal tubular cells (RPTC). This study examined mitochondrial targets of active PKCε in RPTC injured by the model oxidant tert-butyl hydroperoxide (TBHP). TBHP exposure augmented the levels of phosphorylated (active) PKCε in mitochondria, which suggested translocation of PKCε to mitochondria after oxidant exposure. Oxidant injury decreased state 3 respiration, adenosine triphosphate (ATP) production, ATP content, and complex I activity. Further, TBHP exposure increased ΔΨ m and production of reactive oxygen species (ROS), and induced mitochondrial fragmentation and RPTC death. PKCε activation by overexpressing constitutively active PKCε exacerbated decreases in state 3 respiration, complex I activity, ATP content, and augmented RPTC death. In contrast, inhibition of PKCε by overexpressing dnPKCε mutant restored state 3 respiration, respiratory control ratio, complex I activity, ΔΨ m , and ATP production and content, but did not prevent decreases in F 0 F 1 -ATPase activity. Inhibition of PKCε prevented oxidant-induced production of ROS and mitochondrial fragmentation, and reduced RPTC death. We conclude that activation of PKCε mediates: (a) oxidant-induced changes in ΔΨ m , decreases in mitochondrial respiration, complex I activity, and ATP content; (b) mitochondrial fragmentation; and (c) RPTC death. In contrast, oxidant-induced inhibition of F 0 F 1 -ATPase activity is not mediated by PKCε. These results show that, in contrast to the protective effects of PKCε in the heart, PKCε activation is detrimental to mitochondrial function and viability in RPTC and mediates oxidant-induced injury., (© 2018 Wiley Periodicals, Inc.)

Decreasing phosphorylation of AKT‑Foxo1 is closely associated with the onset of insulin resistance and apoptosis during diabetic cardiomyopathy (DCM). Opening of mitochondrial ATP‑sensitive potassium channels (mitoKATP) increases the expression of p‑AKT in the process of reperfusion injury. It was therefore hypothesized that opening of mitoKATP may regulate the AKT‑Foxo1 signaling pathway and improve cardiac function in DCM. In the present study, opening of mitoKATP by diazoxide (DZX) was found to improve cardiac function and attenuate cardiomyocyte apoptosis in db/db mice. DZX also significantly increased the expression of p‑AKT and p‑Foxo1. Similarly, DZX decreased the expression of the heart failure marker NT‑proBNP, increased mitochondrial membrane potential, inhibited apoptosis, and increased the expression of p‑AKT and p‑Foxo1 when mimicking insulin resistance in cultured cardiomyocytes. Moreover, the protective effects of DZX were completely blocked by the specific AKT inhibitor MK‑2206. These data suggest that the regulation of the AKT‑Foxo1 signaling pathway by mitoKATP plays an important role in improving cardiac function and inhibiting apoptosis in DCM, and may therefore be a new potential therapeutic target for DCM.

HIV enters the central nervous system (CNS) during the early stages of infection and can cause neurological dysfunction, including neurodegeneration and neurocognitive impairment. The specific autophagy responsible for removal of damaged mitochondria (mitophagy) and mitochondrial dynamics constitute neuronal mitochondrial quality control mechanisms and are impaired in neurodegenerative disorders and numerous other diseases. The release of HIV proteins gp120 and Tat from infected cells is thought to play an important role in HIV-associated neurocognitive disorders (HAND), but the mechanism(s) leading to impairment are poorly understood. Here, we report that exposure of human primary neurons (HPNs) to HIV gp120 and Tat accelerates the balance of mitochondrial dynamics toward fission (fragmented mitochondria) and induces perinuclear aggregation of mitochondria and mitochondrial translocation of dynamin-related protein 1 (DRP1), leading to neuronal mitochondrial fragmentation. HIV gp120 and Tat increased the expression of microtubule-associated protein 1 light chain 3 beta (LC3B) protein and induced selective recruitment of Parkin/SQSTM1 to the damaged mitochondria. Using either a dual fluorescence reporter system expressing monomeric red fluorescent protein and enhanced green fluorescent protein targeted to mitochondria (mito-mRFP-EGFP) or a tandem light chain 3 (LC3) vector (mCherry-EGFP-LC3), both HIV proteins were found to inhibit mitophagic flux in human primary neurons. HIV gp120 and Tat induced mitochondrial damage and altered mitochondrial dynamics by decreasing mitochondrial membrane potential (ΔΨm). These findings indicate that HIV gp120 and Tat initiate the activation and recruitment of mitophagy markers to damaged mitochondria in neurons but impair the delivery of mitochondria to the lysosomal compartment. Altered mitochondrial dynamics associated with HIV infection and incomplete neuronal mitophagy may play a significant role in the development of HAND and accelerated aging associated with HIV infection. IMPORTANCE Despite viral suppression by antiretrovirals, HIV proteins continue to be detected in infected cells and neurologic complications remain common in infected people. Although HIV is unable to infect neurons, viral proteins, including gp120 and Tat, can enter neurons and can cause neuronal degeneration and neurocognitive impairment. Neuronal health is dependent on the functional integrity of mitochondria, and damaged mitochondria are subjected to mitochondrial control mechanisms. Multiple lines of evidence suggest that specific elimination of damaged mitochondria through mitophagy and mitochondrial dynamics play an important role in CNS diseases. Here, we show that in human primary neurons, gp120 and Tat favor the balance of mitochondrial dynamics toward enhanced fragmentation through the activation of mitochondrial translocation of DRP1 to the damaged mitochondria. However, mitophagy fails to go to completion, leading to neuronal damage. These findings support a role for altered mitophagy in HIV-associated neurological disorders and provide novel targets for potential intervention., (Copyright © 2018 American Society for Microbiology.)

AMP-activated protein kinase AMPK regulates cellular energy by controlling metabolism through the inhibition of anabolic pathways and the simultaneous stimulation of catabolic pathways. Given its central regulator role in cell metabolism, AMPK activity and its regulation have been the focus of relevant investigations, although only a few studies have focused on the AMPK function in the control of spermatozoa's ability to fertilize. This review summarizes the known cellular roles of AMPK that have been identified in mammalian spermatozoa. The involvement of AMPK activity is described in terms of the main physiological functions of mature spermatozoa, particularly in the regulation of suitable sperm motility adapted to the fluctuating extracellular medium, maintenance of the integrity of sperm membranes, and the mitochondrial membrane potential. In addition, the intracellular signaling pathways leading to AMPK activation in mammalian spermatozoa are reviewed. We also discuss the role of AMPK in assisted reproduction techniques, particularly during semen cryopreservation and preservation (at 17 °C). Finally, we reinforce the idea of AMPK as a key signaling kinase in spermatozoa that acts as an essential linker/bridge between metabolism energy and sperm's ability to fertilize.

Introduction: Miscarriage is a common complication during pregnancy. Mitofusin-2 (MFN2) deficiency in trophoblastic cells is reported to be an important cause for early miscarriage. MFN2 can regulate mitochondrial autophagy, although the mechanisms remain unknown. This study aims to investigate the roles of MFN2 and autophagy in early unexplained miscarriage., Methods: Immunohistochemistry and western blotting were used to detect the MFN2 expression in villous tissues from women who had early unexplained miscarriage. Western blotting was used to detect the expression of autophagy-related proteins (ATG5, BECLIN1, and LC3), MMP-2, MMP-9, and integrin β1. Immunofluorescence was used to detect the expression of autophagosome after transfection with GFP-LC3. We used JC-1 to measure the mitochondrial membrane potential and transmission electron microscopy (TEM) to observe the ultrastructure of mitochondria. The levels of β-hCG and progesterone in the trophoblast were determined by the chemiluminescence method., Results: Immunofluorescence analysis demonstrated that MFN2 in the villous tissues of women with early unexplained miscarriage was significantly lower than that of women in the normal pregnancy group. Increased levels of LC3, ATG5, and BECLIN1 were observed by western blotting. After transfection with MFN2-siRNA, the level of MFN2 decreased, whereas LC3, ATG5, and BECLIN1 levels increased significantly in the trophoblasts. More autophagosomes and significant impairment of mitochondrial function were observed by TEM. The levels of β-hCG, progesterone, MMP-2, MMP-9, and integrin β1 were significantly reduced in the MFN2-siRNA group., Conclusion: Low expression of MFN2 leads to mitochondrial dysfunction, increased level of autophagy, and trophoblast cell dysfunction, which could be accounted for early unexplained miscarriage., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Oxygen consumption is a valuable tool to link with measurements of mitochondrial electron leakage to form reactive oxygen species (ROS), which in mitochondria is predominantly superoxide and H 2 O 2 . However, oxygen consumption may respond differently to changes in conditions than superoxide/H 2 O 2 production does, complicating the use of respiration as a sole indicator of mitochondrial energetics. The same equipment that is valuable for fluorescent monitoring of H 2 O 2 efflux provides a straightforward means of estimating membrane potential (ΔΨ), thereby an alternative metric of mitochondrial energetics is readily added to complement studies on the link between mitochondrial energetics and electron leak. By combining multiple aspects of mitochondrial energetics a far more detailed picture emerges on why changes in superoxide/H 2 O 2 formation arise with reduced dependence on assumptions. Here we illustrate integration of experimental methods via demonstration of linkages between mitochondrial ΔΨ, oxygen consumption and superoxide/H 2 O 2 formation (the latter estimated by H 2 O 2 efflux). In doing so we also expand on some pitfalls and cautions for these experimental manipulations of isolated mitochondria and, using these techniques, we raise the possibility that the oxygen affinity for respiration may be higher than the affinity for some sites of electron leak., (Copyright © 2017. Published by Elsevier Inc.)

Yes-associated protein (Yap) is a core transcriptional coactivator in the downstream Hippo pathway that regulates cell proliferation and tissue growth. However, its role in the regulation of myoblast differentiation remains unclear. Regulation of mitochondrial networks by dynamin-related protein 1 (Drp1) and mitofusion 2 (Mfn2) is crucial for the activation of myoblast differentiation. In the present study, we investigated the interplay between the Hippo/Yap pathway and protein contents of Mfn2 and Drp1 during myoblast differentiation. The Hippo/Yap pathway was inactivated at the early stage of myoblast differentiation due to the decreased ratio of phosphorylated mammalian sterile 20 kinases 1/2 (p-Mst1/2) to Mst1/2, phosphorylated large tumor suppressor 1 (p-Lats1) to Lats1, and phosphorylated Yap (serine 112, p-Yap S112) to Yap, which resulted in the translocation of Yap from cytoplasm to nucleus, increased protein content of Drp1, and mitochondrial fission events. Downregulation of Yap inhibited myoblast differentiation and decreased the content of Drp1, which resulted in elongated mitochondria, fused mitochondrial networks, and collapsed mitochondrial membrane potential. Together, our data indicate that inactivation of the Hippo/Yap pathway could induce mitochondrial fission by promoting Drp1 content at the early stage of myoblast differentiation.

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in many developed and developing countries worldwide. It has been well established that the chronic sterile inflammation caused by the NLRP3 inflammasome is closely related to NAFLD development. Kupffer cells (KCs) are involved in the pathogenesis of various liver diseases. We used methionine choline-deficient diets to establish a mouse nonalcoholic steatohepatitis (NASH) model. The expression and formation of the NLRP3 inflammasome in the KCs from the mouse and cell models were determined by Western blotting and co-immunoprecipitation. Evidence of mitochondrial DNA (mtDNA) release was determined by live cell labeling and imaging. KCs and the NLRP3 inflammasome exerted proinflammatory effects on the development and progression of NASH through secretion of the proinflammatory cytokine IL-1β. NLRP3, ASC and Caspase-1 protein expression levels in KCs from NASH mouse livers were significantly higher than those in KCs from NLRP3 -/- mice, and the number of NLRP3 inflammasome protein complexes was significantly higher in KCs from NASH mouse livers, whereas these protein complexes could not be formed in NLRP3 -/- mice. In in vitro experiments, palmitic acid (PA) decreased the mitochondrial membrane potential and subsequently induced mtDNA release from the mitochondria to the cytoplasm. NLRP3 inflammasome expression was substantially increased, and mtDNA-NLRP3 inflammasome complexes formed upon PA stimulation. Our data suggest that mtDNA released from mitochondria during PA stimulation causes NLRP3 inflammasome activation, providing a missing link between NLRP3 inflammasome activation and NASH development, via binding of cytosolic mtDNA to the NLRP3 inflammasome., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The extensive use of artificial insemination in turkeys has led to the development of in vitro semen storage. However, fertility rates from liquid stored and frozen/thawed turkey semen are still unsatisfactory. The aim of the study was to assess spermatozoa viability, mitochondrial membrane potential (MMP), and reactive oxygen species production (ROS) in liquid stored and cryopreserved turkey semen with the use of flow cytometry. Moreover, motility and adenosine triphosphate (ATP) content in sperm were monitored at the same time to link flow cytometry data with sperm movement and energetics. Liquid storage led to a decrease in sperm motility (80.6 vs. 55.6%, for fresh and stored for 48 h), live sperm with an intact MMP (59.9 vs. 30.5% for fresh and stored for 48 h), and a 20-fold decrease in ATP content after 24 h of storage. A 3-fold increase in ROS+ sperm was observed after 48 h of storage (9.3 vs. 26.8% for fresh and stored for 48 h). Semen equilibration before cryopreservation affected only ATP content. However, freezing/thawing led to a dramatic decrease in all of the studied semen quality parameters. A 5-fold decrease in live sperm with intact MMP (59.8 vs. 11.9%) and a 7-fold increase in sperm ROS+ (10.8 vs. 74.4%) were recorded between fresh and frozen/thawed semen. The results strongly suggested that a significant loss of MMP and a disturbance in sperm ATP production during semen storage can be the main reason for the decline in sperm motility. The disturbance of mitochondria activity during storage seems to be associated with the increase in oxidative stress in turkey semen. Turkey sperm mitochondria also appear to be very sensitive to cryodamage. Diminished energy production in turkey spermatozoa, visible as the low percentage of sperm with an intact MMP and low level of ATP after freezing/thawing, which is associated with high ROS generation, could be responsible for the low fertilizing ability of cryopreserved turkey semen.

Background: Diabetic retinopathy (DR) is a microvascular complication induced by high blood glucose. This study was conducted to investigate the effect of metabolic memory on mitochondrial oxidative damage-induced DR., Methods: Rat retinal endothelial cells (rRECs) were isolated from SD rats and treated with high glucose (20 mM) for various times and then cultured in normal glucose (5.6 mM) medium for 2 days. The cells were assayed for the expression of respiratory chain complexes cytochrome c oxidase subunit 1 (CO1) and NADPH-1 using RT-PCR, mitochondrial membrane potentials and reactive oxygen species (ROS) production using flow cytometry and apoptosis using Annexin V/PI flow cytometry., Results: rRECs displayed like short spindles after cultured for 9-10 days and reached 100% confluency. Compared with the control grown in normal glucose (5.6 mM) medium, rRECs exposed to high glucose medium for 3, 12 and 24 h had significantly increased mRNA levels of CO1 and NAPDH-1 even after being shifted back to normal glucose medium. They also had lower mitochondrial membrane potential (89.13% vs 78.21%, p < 0.05), cytochrome C level (1 in control vs 0.25 after 24 h exposure to high glucose, p < 0.05 and higher ROS production (2.77% in control vs 9.00% after 12 h exposure to high glucose, p < 0.05) and apoptosis (7.15% in control vs and 29.91% after 24 h exposure to high glucose, p < 0.05)., Conclusion: It is likely that mitochondrial oxidative damage triggers metabolic memory via ROS overproduction, leading to diabetic retinopathy.

The major loss of myocardial tissue extracellular matrix after infarction is a serious complication that leads to heart failure. Regeneration and integration of damaged cardiac tissue is challenging since the functional restoration of the injured myocardium is an incredible task. The injured micro environment of myocardium fails to regenerate spontaneously. The emergence of nano-biomaterials would be a promising approach to regenerate such a damaged cardiomyocytes tissue. Here, we have fabricated a dual bioactive embedded nanofibrous cardiac patch via coaxial electrospinning technique, to mimic the topographical and chemical cues of the natural cardiac tissue. The proportion and the concentration of the polymers were optimized for tailored delivery of bioactives from a spatio-temporally designed scaffold. The functionalization of polymeric core shell nanofibrous scaffold with dual bioactives enhanced the physico-chemical and bio-mechanical properties of the scaffolds that has resulted in a 3-dimensional topography mimicking the natural cardiac like extracellular matrix. The sustained delivery of bioactive signals, improved cell adhesion, proliferation, migration and differentiation could be attributed to its highly interconnected nanofibrous matrix with good extended morphology. Further, the expression of cardiac specific markers were found to increase on investigation of mRNA by real time PCR studies and proteins by immunofluorescence and western blotting techniques, confirming cell - biomaterial interactions. Flow cytometry analysis authenticated a potent mitochondrial membrane potential of cells treated with nanocomposite. In addition, in ovo studies in chicken chorioallantoic membrane assay confirm the efficacy of the developed scaffold in inducing angiogenesis required for maintaining its viability after transplantation onto the infarcted zone. These promising results demonstrate the potential of the composite nanofibrous scaffold as an effective biomaterial substrate for cardiac regeneration providing cues for development of novel cardiac therapeutics., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The histidine triad nucleotide-binding protein 2 (HINT-2) is a mitochondrial adenosine phosphoramidase expressed in hepatocytes. The phenotype of Hint2 knockout ( Hint2 -/- ) mice includes progressive hepatic steatosis and lysine hyperacetylation of mitochondrial proteins, which are features of respiratory chain malfunctions. We postulated that the absence of HINT-2 induces a defect in mitochondria bioenergetics. Isolated Hint2 -/- hepatocytes produced less ATP and generated a lower mitochondrial membrane potential than did Hint2 +/+ hepatocytes. In extracellular flux analyses with glucose, the basal, ATP-linked, and maximum oxygen consumption rates (OCRs) were decreased in Hint2 -/- hepatocytes and in HepG2 cells lacking HINT-2. Conversely, in HINT-2 overexpressing SNU-449 and HepG2 cells, the basal, ATP-linked, and maximum OCRs were increased. Similarly, with palmitate, basal and maximum OCRs were decreased in Hint2 -/- hepatocytes, but they were increased in HINT-2 overexpressing HepG2 cells. When assayed with radiolabeled substrate, palmitate oxidation was reduced by 25% in Hint2 -/- mitochondria. In respirometry assays, complex I- and II-driven, coupled and uncoupled respirations and complex IV KCN-sensitive respiration were reduced in Hint2 -/- mitochondria. Furthermore, HINT-2 associated with cardiolipin and glucose-regulated protein 75 kDa. Our study shows decreased electron transfer and oxidative phosphorylation capacity in the absence of HINT-2. The bioenergetics deficit accumulated over time in hepatocytes lacking HINT-2 likely leads to the secondary outcome of steatosis.-Rajasekaran, R., Felser, A., Nuoffer, J.-M., Dufour, J.-F., St-Pierre, M. V. The histidine triad nucleotide-binding protein 2 (HINT-2) positively regulates hepatocellular energy metabolism.

Objective: To explore the effects of long non-coding RNA (lncRNA) brain-derived neurotrophic factor anti-sense (BDNF-AS) on the Aβ 25-35 -induced neurotoxicity in PC12 cells., Methods: PC12 cells were induced by Aβ 25-35 to construct cell injury models of Alzheimer's disease (AD), and then transfected with siRNA-BDNF-AS. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect the expressions of BDNF-AS and BDNF. Besides, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Hoechst33342 staining were utilized to analyze the cell viability and apoptosis, respectively, Western blotting to evaluate the protein expressions, immunofluorescence to assess the Cytochrome C (Cyt C) release, and Rhodamine 123 (Rh123) to measure the mitochondrial membrane potential (MMP).The evaluation of oxidative stress was conducted via the determination of the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT)., Results: Aβ 25-35 apparently increased BDNF-AS but decreased BDNF in PC12 cells, which also reduced viability and induced apoptosis of PC12 cells. Silencing of BDNF-AS could significantly up-regulate BDNF in Aβ 25-35 -induced PC12 cells, with the elevated cell viability. Moreover, silencing BDNF-AS inhibited the apoptosis of Aβ 25-35 -induced PC12 cells, suppressed the release of Cyt C, reduced the expression of cleaved caspase-3 and Bax, and lowered the mean fluorescence intensity (MFI) of Rh123, but it elevated the expression of Bcl-2. Besides, silencing BDNF-AS also reduced ROS intensity and MDA content, but enhanced the activities of SOD and CAT., Conclusion: Silencing BDNF-AS exerts protective functions to increase the viability, inhibit the apoptosis and oxidative stress of Aβ 25-35 -induced PC12 cells by negative regulation of BDNF., Abbreviations: Aβ 25-35 : amyloid beta peptide 25-35; AD: Alzheimer's disease; LncRNA BDNF-AS: long non-coding RNA brain-derived neurotrophic factor anti-sense; OS: Oxidative stress.

Sirtuin-3 (Sirt3), a sub-family member of the nicotinamide adenine dinucleotide-dependent histone deacetylases, has been reported to be involved in mitochondrial oxidative stress regulation, mitochondrial calcium management, mitophagy activation, and mitochondrial energy metabolism. The aim of our study was to explore the functional role of Sirt3 in colorectal cancer stress, focusing particularly on its effects on mitochondrial fission. Our study demonstrated that Sirt3 was highly upregulated in colorectal cancer cells compared to normal rectal mucosa cells. However, the genetic ablation of Sirt3 reduced colorectal cancer cell viability, mobility and proliferation. At the molecular level, we found that Sirt3 knockdown suppressed the expression of adhesive factors and cyclins. Furthermore, Sirt3 deletion was also associated with mitochondrial membrane potential reduction, ROS overproduction, mPTP opening, mitochondrial pro-apoptotic upregulation, and caspase-9-related death programme activation. Furthermore, we determined that Sirt3 regulated the colorectal cancer stress response by modulating mitochondrial fission. The loss of Sirt3 triggered fatal mitochondrial fission by suppressing the Akt/PTEN pathway. Re-activation of the Akt/PTEN pathway combatted mitochondrial fission and promoted colorectal cancer mobility, survival, and growth. Altogether, these findings provide an additional rationale for the function of Sirt3 in supporting the growth and survival of colorectal cancer., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Ca 2+ flux across the inner mitochondrial membrane (IMM) regulates cellular bioenergetics, intra-cellular cytoplasmic Ca 2+ signals, and various cell death pathways. Ca 2+ entry into the mitochondria occurs due to the highly negative membrane potential (ΔΨ m ) through a selective inward rectifying MCU channel. In addition to being regulated by various mitochondrial matrix resident proteins such as MICUs, MCUb, MCUR1 and EMRE, the channel is transcriptionally regulated by upstream Ca 2+ cascade, post transnational modification and by divalent cations. The mode of regulation either inhibits or enhances MCU channel activity and thus regulates mitochondrial metabolism and cell fate., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Among the several mechanisms of multidrug resistance (MDR), overexpression of drug efflux pumps CaCdr1p and CaMdr1p belonging to ATP binding cassette (ABC) and major facilitator superfamily (MFS) respectively remain the predominant mechanisms of candidal infections. Therefore inhibiting or modulating the function of these transporters continues to draw attention as effective strategy to combat MDR. We have previously reported the antifungal potential of Geraniol (Ger), a natural monoterpenoid from Palmarosa oil, against Candida albicans. Herein, we explored the fungicidal nature of Ger. The Rhodamine 6G (R6G) and Nile red accumulation confirms the specific effect on CaCdr1p. Mechanistic insights with Candida cells overexpressing CaCdr1p and CaMdr1p revealed that Ger specifically modulates CaCdr1p activity. Kinetic studies further unraveled the competitive inhibition of Ger for R6G efflux as evident from increased apparent Km without affecting Vmax value. The effect of Ger on CaCdr1p was substantiated by molecular docking analyses, which depicted in-silico binding affinity of Ger with CaCdr1p and explored that Ger binds to the active site of CaCdr1p with higher binding energy. Although RT-PCR and western blot revealed no change in expressions of CDR1 and CaCdr1p, confocal microscopy images however depicted CaCdr1p mislocalization in presence of Ger. Interestingly, Ger was synergistic (FICI<0.5) with fluconazole (FLC) which is a well known antifungal drug. Furthermore, Ger sensitizes the FLC sensitive and resistant clinical matched pair of isolates Gu4/Gu5 and led to abrogated R6G efflux and depleted ergosterol. Furthermore, Rhodamine B labeling demonstrates altered mitochondrial potential with Ger which suggest possible linkage of dysfunctional mitochondria with CaCdr1p activity. We also estimated phenotypic virulence marker extracellular phospholipase activity which was considerably diminished along with inhibited cell adherence and biofilm biomass. Lastly, antifungal efficacy of Ger was demonstrated by enhanced survival of Caenorhabditis elegans model and negligible hemolytic activity (20%). Together, modulation of efflux pump activity by Ger and FLC synergism represent a promising approach for combinatorial treatment of candidiasis., Competing Interests: The authors have declared that no competing interests exist.

It is well established that tobacco smoking is associated with vascular endothelial dysfunction in a causative and dose dependent manner primarily related to the tobacco smoke (TS) content of reactive oxygen species (ROS), nicotine, and oxidative stress (OS) -driven inflammation. Preclinical studies have also shown that nicotine (the principal e-liquid's ingredient used in e-cigarettes (e-Cigs) can also cause OS, exacerbation of cerebral ischemia and secondary brain injury. Likewise, chronic e-Cig vaping could be prodromal to vascular endothelial dysfunctions. Herein, we provide direct evidence that similarly to TS, e-Cig promotes mitochondrial depolarization in primary brain vascular endothelial cells as well as the vascular endothelial cell line bEnd3. In addition, both TS and e-Cig exposure upregulated the transmembrane iron exporter Slc40a1 (crucial to maintain cellular iron and redox homeostasis) and that of porphyrin importer Abcb6 (linked to accelerated atherosclerosis). We then investigated in vivo whether gender plays a role in how chronic TS affect vascular endothelial functions. Our results clearly show chronic TS exposure differentially impacts the expression levels of Phase-II enzymes as well as the iron transporters previously investigated in vitro. Although the physiological implications of the gender-specific differential responses to TS are not fully clear, they do demonstrate that gender is a risk factor that needs to be investigated when assessing the potential impact of chronic smoking and perhaps e-Cig vaping., (Published by Elsevier B.V.)

The sperm plasma membrane is a sensitive target to oxidative stress. The most representative reactive oxygen species (ROS) scavengers in the genital tract, hypotaurine and glutathione, require, for their synthesis, cysteine whose availability is associated with the 1-carbon cycle (1-CC). Human, bovine and ascidian spermatozoa were incubated with compounds supporting the 1-CC (Vitamin B6, Methylcobalamin, 5 Methyl Tetrahydrofolate, Zinc Bisglycinate and N-acetyl-cysteine) (TRT) and compared to the effects induced solely by N-acetyl-cysteine (NAC). In control groups (CNTRL), spermatozoa were incubated with medium alone. After 90 and 180 minutes of incubation, the mitochondrial membrane potential (ΔΨM) in TRT and NAC was significantly (P < 0.01) higher than in CNTRL. At H 2 DCFDA evaluation, ROS production differed between species whereas, at 2-OH Ethidium, it significantly decreased in bovine TRT group. Intracellular pH (pH i ) did not significantly vary in relation to treatment. In ascidian spermatozoa, the NAC supplementation decreased external pH, which in turn brought to a pH i lowering. Buffering seawater with NaHCO 3 reversed the beneficial effects of N-acetyl-cysteine supplementation. In conclusion, both fully supporting the 1-CC and treatment with N-acetyl-cysteine alone improved kinetics, ΔΨM and ROS production in mammalian sperm demonstrating for the first time the direct in vitro effects of these compounds on sperm functionality.

The retinal pigment epithelium (RPE) comprises a monolayer of cells located between the neuroretina and the choriocapillaries. The RPE serves several important functions in the eye: formation of the blood-retinal barrier, protection of the retina from oxidative stress, nutrient delivery and waste disposal, ionic homeostasis, phagocytosis of photoreceptor outer segments, synthesis and release of growth factors, reisomerization of all-trans-retinal during the visual cycle, and establishment of ocular immune privilege. Age-related macular degeneration (AMD) is the leading cause of blindness in developed countries. Dysfunction of the RPE has been associated with the pathogenesis of AMD in relation to increased oxidative stress, mitochondrial destabilization and complement dysregulation. Photobiomodulation or near infrared light therapy which refers to non-invasive irradiation of tissue with light in the far-red to near-infrared light spectrum (630-1000 nm), is an intervention that specifically targets key mechanisms of RPE dysfunction that are implicated in AMD pathogenesis. The current evidence for the efficacy of photobiomodulation in AMD is poor but its safety profile and proposed mechanisms of action motivate further research as a novel therapy for AMD., (© 2017 Royal Australian and New Zealand College of Ophthalmologists.)

When the mitochondria of somatic cells are exposed to pathological calcium overload, these trigger mitochondrial permeability transition (MPT) leading to mitochondrial dysfunction and cell death. Cryopreservation procedures expose mammalian spermatozoa to physical and chemical stressors, which affect plasma membrane integrity and induce a pathological calcium overload that gradually promotes loss of sperm quality and ultimately function. Although several studies highlight the role of calcium in many physiological and pathological processes, the MPT induced by an intracellular calcium increase and its effect on the cell quality of mammalian spermatozoa are unknown. The aim of this study was to evaluate the effects of cryopreservation on MPT and its relationship with the deterioration of sperm quality in a bovine model. To do this, frozen bovine spermatozoa were thawed and adjusted to 2 × 10 6  mL -1 and incubated for 4 h at 38 °C. Using flow cytometry, we evaluated MPT by the calcein-AM and cobalt chloride method, intracellular Ca 2+ level using FLUO3-AM, plasma membrane integrity by exclusion of propidium iodide, mitochondrial membrane potential (ΔΨm) with tetramethylrhodamine methyl ester perchlorate and intracellular ROS production with dihydroethidium. ATP levels were assessed by a chemiluminiscent method. The results showed that thawed spermatozoa trigger MPT associated with an intracellular calcium increase and that this was accompanied by ΔΨm dissipation, decrease of ATP levels and ROS production, and deterioration of plasma membrane integrity. In conclusion, cryopreservation induces MPT and this is associated with a loss of sperm quality., (Copyright © 2018. Published by Elsevier Inc.)

Background: To evaluate the relationship between leukocyte-endothelial cell interactions and oxidative stress parameters in non-diabetic patients with different grades of obesity., Material and Methods: For this cross-sectional study, 225 subjects were recruited from January 1, 2014 to December 31, 2016 and divided into groups according to BMI (<30 kg/m 2 , 30-40 kg/m 2 and >40 kg/m²). We determined clinical parameters, systemic inflammatory markers, soluble cellular adhesion molecules, leukocyte-endothelium cell interactions-rolling flux, velocity and adhesion-, oxidative stress parameters-total ROS, total superoxide, glutathione-and mitochondrial membrane potential in leukocytes., Results: We verified that HOMA-IR and hsCRP increased progressively as obesity developed, whereas A1c, IL6 and TNFα were augmented in the BMI > 40 kg/m² group. The cellular adhesion molecule sP-selectin was increased in patients with obesity, while sICAM, total ROS, total superoxide and mitochondrial membrane potential were selectively higher in the BMI > 40 kg/m² group. Obesity induced a progressive decrease in rolling velocity and an enhancement of rolling flux and leukocyte adhesion., Conclusion: Our findings reveal that endothelial dysfunction markers are altered in human obesity and are associated with proinflammatory cytokines and increased oxidative stress parameters., (© 2018 Stichting European Society for Clinical Investigation Journal Foundation.)

Parkinson's disease is a neurodegenerative disease characterized by tremors, muscle stiffness, and muscle weakness. Molecular genetic analysis has confirmed that mutations in PARKIN and PINK1 genes, which play major roles in mitochondrial quality control and mitophagy, are frequently associated with Parkinson's disease. PARKIN is an E3 ubiquitin ligase that translocates to mitochondria during loss of mitochondrial membrane potential to increase mitophagy. Although muscle dysfunction is noted in Parkinson's disease, little is known about the involvement of PARKIN in the muscle phenotype of Parkinson's disease. In this study, we report that the mitochondrial uncoupler CCCP promotes PINK1/PARKIN-mediated mitophagy in myogenic C2C12 cells. As a result of this excess mitophagy, we show that CCCP treatment of myotubes leads to the development of myotube atrophy in vitro. Surprisingly, we also found that siRNA-mediated knockdown of Parkin results in impaired mitochondrial turnover. In addition, knockdown of Parkin led to myotubular atrophy in vitro. Consistent with these in vitro results, Parkin knockout muscles showed impaired mitochondrial function and smaller myofiber area, suggesting that Parkin function is required for post-natal skeletal muscle growth and development.