Low steady-state oxidative stress inhibits adipogenesis by altering mitochondrial dynamics and decreasing cellular respiration

Exercise and antioxidants have health benefits that improve cognitive impairment and may act synergistically. In this study, we examined the effects of treadmill exercise (TE) and mitochondria-targeted antioxidant mitoquinone (MitoQ), individually or combined, on learning and memory, mitochondrial dynamics, NADPH oxidase activity, and neuroinflammation and antioxidant activity in the hippocampus of D-galactose-induced aging rats. TE alone and TE combined with MitoQ in aging rats reduced mitochondrial fission factors (Drp1, Fis1) and increased mitochondrial fusion factors (Mfn1, Mfn2, Opa1). These groups also exhibited improved NADPH oxidase activity and antioxidant activity (SOD-2, catalase). TE or MitoQ alone decreased neuroinflammatory response (COX-2, TNF-α), but the suppression was greater with their combination. In addition, aging-increased neuroinflammation in the dentate gyrus was decreased in TE but not MitoQ treatment. Learning and memory tests showed that, contrarily, MitoQ alone demonstrated some similar effects to TE but not a definitive improvement. In conclusion, this study demonstrated that MitoQ exerted some positive effects on aging when used as an isolated treatment, but TE had a more effective role on cognitive impairment, oxidative stress, inflammation, and mitochondria dysfunction. Our findings suggest that the combination of TE and MitoQ exerted no synergistic effects and indicated regular exercise should be the first priority in neuroprotection of age-related cognitive decline.

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Syntaxin-17-Dependent Mitochondrial Dynamics is Essential for Protection Against Oxidative-Stress-Induced Apoptosis

Antioxidants ◽

10.3390/antiox8110522 ◽

2019 ◽

Vol 8 (11) ◽

pp. 522 ◽

Cited By ~ 4

Author(s):

Wang ◽

Xiao ◽

Huang ◽

Liu

Keyword(s):

Oxidative Stress ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Autophagic Flux ◽

Wild Type ◽

Dual Roles ◽

Defective Mutant ◽

U2os Cells ◽

Induced Apoptosis

In this study, cell death induced by the oxidant tert-butylhydroperoxide (tBH) was observed in U2OS cells; this phenotype was rescued by Syntaxin 17 (STX17) knockout (KO) but the mechanism is unknown. STX17 plays dual roles in autophagosome–lysosome fusion and mitochondrial fission. However, the contribution of the two functions of STX17 to apoptosis has not been extensively studied. Here, we sought to dissect the dual roles of STX17 in oxidative-stress-induced apoptosis by taking advantage of STX17 knockout cells and an autophagosome–lysosome fusion defective mutant of STX17. We generated STX17 knockout U2OS cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and the STX17 knockout cells were reconstituted with wild-type STX17 and its autophagosome–lysosome fusion defective mutant. Autophagy was assessed by autophagic flux assay, Monomer red fluorescent protein (mRFP)–GFP–LC3 assay and protease protection assay. Golgi, endoplasmic reticulum (ER)/ER–Golgi intermediate compartment (ERGIC) and mitochondrial dynamics were examined by staining the different indicator proteins. Apoptosis was evaluated by caspase cleavage assay. The general reactive oxygen species (ROS) were detected by flow cytometry. In STX17 complete knockout cells, sealed autophagosomes were efficiently formed but their fusion with lysosomes was less defective. The fusion defect was rescued by wild-type STX17 but not the autophagosome–lysosome fusion defective mutant. No obvious defects in Golgi, ERGIC or ER dynamics were observed. Mitochondria were significantly elongated, supporting a role of STX17 in mitochondria fission and the elongation caused by STX17 KO was reversed by the autophagosome–lysosome fusion defective mutant. The clearance of protein aggregation was compromised, correlating with the autophagy defect but not with mitochondrial dynamics. This study revealed a mixed role of STX17 in autophagy, mitochondrial dynamics and oxidative stress response. STX17 knockout cells were highly resistant to oxidative stress, largely due to the function of STX17 in mitochondrial fission rather than autophagy.

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Harmful Effects of Inorganic Mercury Exposure on Kidney Cells: Mitochondrial Dynamics Disorder and Excessive Oxidative Stress

Biological Trace Element Research ◽

10.1007/s12011-021-02766-3 ◽

2021 ◽

Author(s):

Biqi Han ◽

Zhanjun Lv ◽

Xuemin Han ◽

Siyu Li ◽

Bing Han ◽

...

Keyword(s):

Oxidative Stress ◽

Mitochondrial Dynamics ◽

Inorganic Mercury ◽

Mercury Exposure ◽

Kidney Cells ◽

Harmful Effects

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Acute Hypoxia and Exercise-Induced Blood Oxidative Stress

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.2013-0188 ◽

2014 ◽

Vol 24 (6) ◽

pp. 684-693 ◽

Cited By ~ 15

Author(s):

Graham McGinnis ◽

Brian Kliszczewiscz ◽

Matthew Barberio ◽

Christopher Ballmann ◽

Bridget Peters ◽

...

Keyword(s):

Oxidative Stress ◽

Steady State ◽

Repeated Measures ◽

Acute Hypoxia ◽

Protein Carbonyls ◽

Trolox Equivalent Antioxidant Capacity ◽

Lipid Hydroperoxides ◽

Oxidative Stress Biomarkers ◽

Post Exercise ◽

Reducing Ability

Hypoxic exercise is characterized by workloads decrements. Because exercise and high altitude independently elicit redox perturbations, the study purpose was to examine hypoxic and normoxic steady-state exercise on blood oxidative stress. Active males (n = 11) completed graded cycle ergometry in normoxic (975 m) and hypoxic (3,000 m) simulated environments before programing subsequent matched intensity or workload steady-state trials. In a randomized counterbalanced crossover design, participants completed three 60-min exercise bouts to investigate the effects of hypoxia and exercise intensity on blood oxidative stress. Exercise conditions were paired as such; 60% normoxic VO2peak performed in a normoxic environment (normoxic intensity-normoxic environment, NI-NE), 60% hypoxic VO2peak performed in a normoxic environment (HI-NE), and 60% hypoxic VO2peak performed in a hypoxic environment (HI-HE). Blood plasma samples drawn pre (Pre), 0 (Post), 2 (2HR) and 4 (4HR) hr post exercise were analyzed for oxidative stress biomarkers including ferric reducing ability of plasma (FRAP), trolox equivalent antioxidant capacity (TEAC), lipid hydroperoxides (LOOH) and protein carbonyls (PCs). Repeated-measures ANOVA were performed, a priori significance of p ≤ .05. Oxygen saturation during the HI-HE trial was lower than NI-NE and HI-NE (p < .05). A Time × Trial interaction was present for LOOH (p = .013). In the HI-HE trial, LOOH were elevated for all time points post while PC (time; p = .001) decreased post exercise. As evidenced by the decrease in absolute workload during hypoxic VO2peak and LOOH increased during HI-HE versus normoxic exercise of equal absolute (HI-NE) and relative (NI-NE) intensities. Results suggest acute hypoxia elicits work decrements associated with post exercise oxidative stress.

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Role of Oxidative Stress in Heart Failure: Insights from Gene Transfer Studies

Biomedicines ◽

10.3390/biomedicines9111645 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1645

Author(s):

Bart De Geest ◽

Mudit Mishra

Keyword(s):

Oxidative Stress ◽

Heart Failure ◽

Gene Therapy ◽

Steady State ◽

Gene Transfer ◽

Oxidative Modification ◽

Heme Oxygenase 1 ◽

Therapy Studies ◽

Pathological Remodeling

Under physiological circumstances, there is an exquisite balance between reactive oxygen species (ROS) production and ROS degradation, resulting in low steady-state ROS levels. ROS participate in normal cellular function and in cellular homeostasis. Oxidative stress is the state of a transient or a persistent increase of steady-state ROS levels leading to disturbed signaling pathways and oxidative modification of cellular constituents. It is a key pathophysiological player in pathological hypertrophy, pathological remodeling, and the development and progression of heart failure. The heart is the metabolically most active organ and is characterized by the highest content of mitochondria of any tissue. Mitochondria are the main source of ROS in the myocardium. The causal role of oxidative stress in heart failure is highlighted by gene transfer studies of three primary antioxidant enzymes, thioredoxin, and heme oxygenase-1, and is further supported by gene therapy studies directed at correcting oxidative stress linked to metabolic risk factors. Moreover, gene transfer studies have demonstrated that redox-sensitive microRNAs constitute potential therapeutic targets for the treatment of heart failure. In conclusion, gene therapy studies have provided strong corroborative evidence for a key role of oxidative stress in pathological remodeling and in the development of heart failure.

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MITOL deletion in the brain impairs mitochondrial structure and ER tethering leading to oxidative stress

Life Science Alliance ◽

10.26508/lsa.201900308 ◽

2019 ◽

Vol 2 (4) ◽

pp. e201900308 ◽

Cited By ~ 7

Author(s):

Shun Nagashima ◽

Keisuke Takeda ◽

Nobuhiko Ohno ◽

Satoshi Ishido ◽

Motohide Aoki ◽

...

Keyword(s):

Oxidative Stress ◽

Microglial Activation ◽

Developmental Disorders ◽

Inflammatory Diseases ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Three Dimensional ◽

Abnormal Behavior ◽

Mitochondrial Abnormalities

Mitochondrial abnormalities are associated with developmental disorders, although a causal relationship remains largely unknown. Here, we report that increased oxidative stress in neurons by deletion of mitochondrial ubiquitin ligase MITOL causes a potential neuroinflammation including aberrant astrogliosis and microglial activation, indicating that mitochondrial abnormalities might confer a risk for inflammatory diseases in brain such as psychiatric disorders. A role of MITOL in both mitochondrial dynamics and ER-mitochondria tethering prompted us to characterize three-dimensional structures of mitochondria in vivo. In MITOL-deficient neurons, we observed a significant reduction in the ER-mitochondria contact sites, which might lead to perturbation of phospholipids transfer, consequently reduce cardiolipin biogenesis. We also found that branched large mitochondria disappeared by deletion of MITOL. These morphological abnormalities of mitochondria resulted in enhanced oxidative stress in brain, which led to astrogliosis and microglial activation partly causing abnormal behavior. In conclusion, the reduced ER-mitochondria tethering and excessive mitochondrial fission may trigger neuroinflammation through oxidative stress.

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Inhibition of TLR4 Signaling Affects Mitochondrial Fitness Overcoming Bortezomib Resistance in Myeloma Plasma Cells

Blood ◽

10.1182/blood-2019-129812 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3073-3073

Author(s):

Cesarina Giallongo ◽

Daniele Tibullo ◽

Giuseppina Camiolo ◽

Fabrizio Puglisi ◽

Daniela Cambria ◽

...

Keyword(s):

Oxidative Stress ◽

Er Stress ◽

Mitochondrial Respiration ◽

Research Funding ◽

Mitochondrial Dynamics ◽

Mitochondrial Depolarization ◽

Tlr4 Signaling ◽

Mitochondrial Mass ◽

Atp Production ◽

Inflammatory Microenvironment

BACKGROUND Multiple myeloma (MM) is a B-cell malignancy critically dependent for survival and proliferation on signals coming from its inflammatory microenvironment in which toll-like receptors (TLR) may be potential linking elements between inflammation and cancer. It has been recently demonstrated that TLR4 pathway provides a protective effect against bortezomib (BTZ)-induced endoplasmic reticulum (ER) stress and pre-treatment of MM cells with LPS significantly reduces BTZ-induced apoptosis. AIM Since the acquisition of BTZ resistance is accompanied by an increased reliance on mitochondrial respiration, we investigated the role of TLR4 as stress-responsive mechanism that protect mitochondria during BTZ-induced ER stress as potential mechanism of drug resistance. RESULTS The activation of TLR4 signaling by LPS increased mitochondrial mass in human MM cell lines (HMCL: U266, MM1.S, OPM2, NCI-H929) and induced up-regulation of mitochondrial biogenesis markers (PGC1a, PRC and TFAM). After treatment with BTZ for 24h, all HMCL over-expressed TLR4 and its signaling was functional as suggested by up-regulation of MyD88 and MAPK activation. Compared to BTZ-sensitive cells (U266-S), U266-R showed higher levels of TLR4, p-p38 and p-ERK proteins and higher mitochondrial mass. Using a selective TLR4 inhibitor (TAK-242), we next treated U266-R cells with either 15nM BTZ, 20 μM TAK-242 or their combination. Combinatorial treatment significantly induced cell apoptosis (about 52%; p<0.001) that appeared to result from the deleterious effects of oxidative stress. Indeed, BTZ-induced intracellular ROS returned to normal levels after 3h and cells were able to up-regulate two anti-oxidant enzymes (GPX1 and GSTP1). On the contrary, TAK-242/BTZ activated a strong pro-oxidant status incresing ROS and RNS (reactive nitrogen species) levels, decreasing GSH ones and down-regulating GPX1 and GSTP1. Analyzing the effect of each treatment on mitochondrial polarization status, we observed about 6,7% of depolarized mitochondria after BTZ treatment, while TAK-242/BTZ combination induced a mitochondrial depolarization of about 69,3% (p<0.001). Moreover, cells treated with BTZ alone showed a compensatory up-regulation of the OXPHOS- (NDUFA-6 and MT-ND4) and mitochondrial fusion-related genes (mitofusin and OPA1) and TFAM. On the contrary, all these genes were down-regulated by TAK-242/BTZ combination. Also a dramatic drop in mitochondrial respiration was observed with a marked decrease in ATP production, consequent accumulation of AMP and a decreased NAD+/NADH and NADP+/NADPH ratio. Since high levels of oxidative stress and mitochondrial impairment activate mitophagy sensitizing cells to apoptosis, we evaluated co-localization of mitochondria (stained with MitoTracker) with the autophagosome marker LC3 using confocal microscopy. BTZ and TAK-242/BTZ increased Mitotracker/LC3 co-localization respectively of about 4,5 and 50 fold compared with control (BTZ vs combination: p<0.001). To evaluate whether TLR4 inhibition resensitizes resistant primary cells, CD138+ cells derived from 5 refractory/relapsed MM patients were treated with 5nM BTZ, 10mM TAK-242 or their combination. Compared to BTZ alone, combination treatment induced higher mitochondrial depolarization after 24h and significantly decreased viability of CD138+ cells after 48h. TLR4 inhibitor alone or in combination did never show cytotoxicity toward CD138- cells. CONCLUSION Taken together, these findings indicate thatTLR4 signaling is involved in the acquisition of bortezomib resistance protecting mitochondria during BTZ exposure and sustaining mitochondrial dynamics in BTZ-resitant cells. Inhibition of TLR4 may overcome bortezomib resistance in patients with relapsed/refractory MM. Disclosures Conticello: Celgene: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding. Palumbo:Celgene: Honoraria; Amgen: Honoraria; Hospira: Honoraria; Teva: Honoraria; Novartis: Honoraria; Janssen: Honoraria. Di Raimondo:Takeda: Consultancy; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding.

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Epoxyeicosatrienoic acids pretreatment improves amyloid β-induced mitochondrial dysfunction in cultured rat hippocampal astrocytes

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00001.2013 ◽

2014 ◽

Vol 306 (4) ◽

pp. H475-H484 ◽

Cited By ~ 39

Author(s):

Pallabi Sarkar ◽

Ivan Zaja ◽

Martin Bienengraeber ◽

Kevin R. Rarick ◽

Maia Terashvili ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Mitochondrial Dysfunction ◽

Rat Brain ◽

Clinical Symptoms ◽

Mitochondrial Dynamics ◽

Amyloid Β ◽

Cellular Respiration ◽

Epoxyeicosatrienoic Acids ◽

Hippocampal Astrocytes

Amyloid-β (Aβ) has long been implicated as a causative protein in Alzheimer's disease. Cellular Aβ accumulation is toxic and causes mitochondrial dysfunction, which precedes clinical symptoms of Alzheimer's disease pathology. In the present study, we explored the possible use of epoxyeicosatrienoic acids (EETs), epoxide metabolites of arachidonic acid, as therapeutic target against Aβ-induced mitochondrial impairment using cultured neonatal hippocampal astrocytes. Inhibition of endogenous EET production by a selective epoxygenase inhibitor, MS-PPOH, caused a greater reduction in mitochondrial membrane potential in the presence of Aβ (1, 10 μM) exposure versus absence of Aβ. MS-PPOH preincubation also aggravated Aβ-induced mitochondrial fragmentation. Preincubation of the cells with either 14,15- or 11,12-EET prevented this mitochondrial depolarization and fragmentation. EET pretreatment also further improved the reduction observed in mitochondrial oxygen consumption in the presence of Aβ. Preincubation of the cells with EETs significantly improved cellular respiration under basal condition and in the presence of the protonophore, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP). The uncoupling of ATP synthase from the electron transfer chain that occurred in Aβ-treated cells was also prevented by preincubation with EETs. Lastly, cellular reactive oxygen species production, a hallmark of Aβ toxicity, also showed significant reduction in the presence of EETs. We have previously shown that Aβ reduces EET synthesis in rat brain homogenates and cultured hippocampal astrocytes and neurons (Sarkar P, Narayanan J, Harder DR. Differential effect of amyloid beta on the cytochrome P450 epoxygenase activity in rat brain. Neuroscience 194: 241–249, 2011). We conclude that reduction of endogenous EETs may be one of the mechanisms through which Aβ inflicts toxicity and thus supplementing the cells with exogenous EETs improves mitochondrial dynamics and prevents metabolic impairment.

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Effect of oxidative stress during imbibition of soybean embryonic axes

Proceedings of the Royal Society of Edinburgh Section B Biological Sciences ◽

10.1017/s026972700001424x ◽

1994 ◽

Vol 102 ◽

pp. 279-286 ◽

Cited By ~ 1

Author(s):

Susana Puntarulo

Keyword(s):

Oxidative Stress ◽

Steady State ◽

External Medium ◽

Tocopherol Content ◽

Active Species ◽

Oxygen Species ◽

Steady State Concentration ◽

Embryonic Axes ◽

State Concentration

SynopsisBoth respiration and generation by soybean embryonic axes showed a sharp increase upon germination, leading to a significant increase in the steady-state concentration of and H2O2 after 6 h of imbibition. An assay was developed to assess in vivo generation of reactive oxygen species, based upon DCFH-DA oxidation. Fluorescence of the external medium was dependent on reaction time and axes number and was inhibited by catalase.α-Tocopherol content declined significantly after 24 h of incubation, as compared to the content at the onset of germination. Incubation in the presence of redox cycling agent paraquat (4 mM) for 24 h increased α-tocopherol content to 1.9±0.2 nmol per axis from 1.0 ± 0.1 nmol per axis in the absence of paraquat. Supplementation of the incubation medium with 500 μM Fe-EDTA increased α-tocopherol content to 1.8±0.1 nmol/axis and DCFH-DA oxidation by two-fold.The data presented here showed that active metabolism at the onset of germination increased steady-state concentration of oxygen active species and suggest that cellular content of α-tocopherol is physiologically adjusted as a response to conditions of oxidative stress.

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