Mitochondrial Adenosine Triphosphate Research Articles

Synthetic cathinone MDPV enhances reward function through purinergic P2X7 receptor-dependent pathway and increases P2X7 gene expression in nucleus accumbens

Background and purposePurinergic P2X7 receptors are present on neurons, astrocytes and microglia and activated by extracellular ATP. Since P2X7 receptor activation releases endogenous substrates (e.g., pro-inflammatory cytokines, dopamine, and glutamate) that facilitate psychostimulant reward and reinforcement, we investigated the hypothesis that the synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV) produces rewarding effects that are dependent on active P2X7 receptors. MethodsReward function was measured in male mice using intracranial self-stimulation (ICSS). MDPV (0.1, 0.3, 0.5 mg/kg, SC) and a selective P2X7 antagonist (A438079) (5, 10, 50 mg/kg, IP) were tested alone and in combination. In separate mice, gene and protein expression of P2X7 and mitochondrial adenosine triphosphate (ATP) synthase (an enzyme that catalyzes synthesis of ATP, an endogenous ligand for P2X7 receptors) in the nucleus accumbens (NAcc) were quantified following MDPV exposure (0.1, 0.5, 5 mg/kg, SC). Key resultsMDPV (0.5 mg/kg, SC) facilitated ICSS as quantified by a significant reduction in brain reward threshold. A438079 (5, 10, 50 mg/kg, IP) did not affect ICSS by itself; however, for combined administration, A438079 (10 mg/kg, IP) inhibited facilitation of ICSS by MDPV (0.5 mg/kg, SC). At the cellular level, MDPV exposure increased gene and protein expression of P2X7 and ATP synthase in the NAcc. Conclusion and implicationWe provide evidence that a psychostimulant drug produces reward enhancement that is influenced by P2X7 receptor activity and enhances P2X7 receptor expression in the brain reward circuit.

Constitutive Activation of NAD-Dependent Sirtuin 3 Plays an Important Role in Tumorigenesis of Chromium(VI)-Transformed Cells.

Chronic exposure of human bronchial epithelial BEAS-2B cells to hexavalent chromium [Cr(VI)] causes malignant cell transformation. Sirtuin-3 (SIRT3) regulates mitochondrial adaptive response to stress, such as metabolic reprogramming and antioxidant defense mechanisms. In Cr(VI)-transformed cells, SIRT3 was upregulated and mitochondrial adenosine triphosphate (ATP) production and proton leak were reduced. Knockdown of SIRT3 by its shRNA further decreased mitochondrial ATP production, proton leak, mitochondrial mass, and mitochondrial membrane potential, indicating that SIRT3 positively regulates mitochondrial oxidative phosphorylation and maintenance of mitochondrial integrity. Mitophagy is critical to maintain proper cellular functions. In Cr(VI)-transformed cells expressions of Pink 1 and Parkin, twomitophagy proteins, were elevated, and mitophagy remained similar as that in passage-matched normal BEAS-2B cells, indicating that in -Cr(VI)-transformed cells mitophagy is suppressed. Knockdown of SIRT3 induced mitophagy, suggesting that SIRT3 plays an important role in mitophagy suppression of Cr(VI)-transformed cells. In Cr(VI)-transformed cells, nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was constitutively activated, and protein levels of p62 and p-p62Ser349 were elevated. Knockdown of SIRT3 or treatment with carbonyl cyanide m-chlorophenyl hydrazone (CCCP) decreased the binding of p-p62Ser349 to Keap1, resulting in increased binding of Keap1 to Nrf2 and consequently reduced Nrf2 activation. The results from CHIP assay showed that in Cr(VI)-transformed cells binding of Nrf2 to antioxidant response element (ARE) of SIRT3 gene promoter was dramatically increased. Knockdown of SIRT3 suppressed cell proliferation and tumorigenesis of Cr(VI)-transformed cells. Overexpression of SIRT3 in normal BEAS-2B cells exhibited mitophagy suppression phenotype and increased cell proliferation and tumorigenesis. The present study demonstrated that upregulation of SIRT3 causes mitophagy suppression and plays an important role in cell survival and tumorigenesis of Cr(VI)-transformed cells.

Effect of hydrogen sulphide on inflammatory factors of the mitochondria after limb ischaemia-reperfusion injury in rats.

The goal of this study was to evaluate the effect of hydrogen sulphide on inflammatory factors and the energy metabolism of mitochondria after limb reperfusion injury in rats. Sixty Wistar rats were divided into three groups: the sham operated group, the control group (the ischaemia-reperfusion injury [IRI] + normal saline group), and the experimental group (the IRI + H2 S group). An experimental rat model of limb IRI was established. Skeletal muscle samples were collected to observe the content of necrotic products (including myoglobin (MB), lysophosphatidylcholine (LPC), and lipid peroxidation (LPO)); blood samples were collected to observe changes in the contents of interleukin-1 (IL-1), Interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α); and the mitochondria of skeletal muscle cells were extracted for mitochondrial transmembrane potential measurement and adenosine triphosphate (ATP) content determination. The results underwent further statistical analysis. The contents of MB, LPC, and LPO in the limb skeletal muscle, liver, lung, and kidney tissues of rats in the control group were significantly increased (P < 0.05) after IRI, which was markedly attenuated by treatment with hydrogen sulphide (P < 0.05). Ischaemia/reperfusion of the lower extremities in rats triggered a significant increase in serum levels of IL-1, IL-6, and TNF-α, which was significantly inhibited by treatment with H2 S during ischaemia/reperfusion. In addition, the inhibitory effect tended to be time-dependent. After limb ischaemia/reperfusion, the mitochondrial transmembrane potential of skeletal muscle cells in the control group decreased significantly (P < 0.05), while the potential energy of the mitochondrial membrane in the experimental group was significantly higher than that in the control group (P < 0.05). The content of ATP in mitochondria of skeletal muscle cells of ischaemia-reperfusion rats in the control group was significantly lower than that in the sham operated group (P < 0.05), while the content of ATP of mitochondria in the experimental group after H2 S treatment was significantly higher than the control group (P < 0.05). Hydrogen sulphide can alleviate the injury of skeletal muscle and distal organs after limb ischaemia-reperfusion and reduce local inflammatory reaction, which is essential in alleviating mitochondrial transmembrane potential and energy metabolism disorder during reperfusion injury. The purpose of the study is to summarise the available information and provide theoretical support for the application of hydrogen sulphide in the treatment of limb IRI in skeletal muscle and distal organs.

Let's face the fats: palmitate restores cellular redox state in the diabetic heart.

Let's face the fats: palmitate restores cellular redox state in the diabetic heart.

The intestine responds to heart failure by enhanced mitochondrial fusion through glucagon-like peptide-1 signalling.

Glucagon-like peptide-1 (GLP-1) is a neuroendocrine hormone secreted by the intestine. Its receptor (GLP-1R) is expressed in various organs, including the heart. However, the dynamics and function of the GLP-1 signal in heart failure remains unclear. We investigated the impact of the cardio-intestinal association on hypertensive heart failure using miglitol, an α-glucosidase inhibitor known to stimulate intestinal GLP-1 production. Dahl salt-sensitive (DS) rats fed a high-salt diet were assigned to miglitol, exendin (9-39) (GLP-1R blocker) and untreated control groups and treated for 11 weeks. Control DS rats showed marked hypertension and cardiac dysfunction with left ventricular dilatation accompanied by elevated plasma GLP-1 levels and increased cardiac GLP-1R expression as compared with age-matched Dahl salt-resistant (DR) rats. Miglitol further increased plasma GLP-1 levels, suppressed adverse cardiac remodelling, and mitigated cardiac dysfunction. In cardiomyocytes from miglitol-treated DS hearts, mitochondrial size was significantly larger with denser cristae than in cardiomyocytes from control DS hearts. The change in mitochondrial morphology reflected enhanced mitochondrial fusion mediated by protein kinase A activation leading to phosphorylation of dynamin-related protein 1, expression of mitofusin-1 and OPA-1, and increased myocardial adenosine triphosphate (ATP) content. GLP-1R blockade with exendin (9-39) exacerbated cardiac dysfunction and led to fragmented mitochondria with disarrayed cristae in cardiomyocytes and reduction of myocardial ATP content. In cultured cardiomyocytes, GLP-1 increased expression of mitochondrial fusion-related proteins and ATP content. When GLP-1 and exendin (9-39) were administered together, their effects cancelled out. Increased intestinal GLP-1 secretion is an adaptive response to heart failure that is enhanced by miglitol. This could be an effective strategy for treating heart failure through regulation of mitochondrial dynamics.

Metabolomics analysis of gut barrier dysfunction in a trauma-hemorrhagic shock rat model

Intestinal barrier dysfunction has been implicated in the development of multiorgan dysfunction syndrome caused by the trauma-hemorrhagic shock (THS). However, the mechanisms underlying THS-induced gut barrier injury are still poorly understood. In the present study, we used the metabolomics analysis to test the hypothesis that altered metabolites might be related to the development of THS-induced barrier dysfunction in the large intestine. Under the induction of THS, gut barrier failure was characterized by injury of permeability and mucus layer, which were companied by the decreased expression of zonula occludens-1 in the colon and increased levels of inflammatory factors including tumor necrosis factor-α, interferon-γ, interleukin (IL)-6, and IL-1β in the serum. A total of 16 differential metabolites were identified in colonic tissues from THS-treated rats compared with control rats. These altered metabolites included dihydroxy acetone phosphate, ribose-5-phosphate, fructose, glyceric acid, succinic acid, and adenosine, which are critical intermediates or end products that are involved in pentose phosphate pathway, glycolysis, and tricarboxylic acid cycle as well as mitochondrial adenosine triphosphate biosynthesis. These findings may offer important insight into the metabolic alterations in THS-treated gut injury, which will be helpful for developing effective metabolites-based strategies to prevent THS-induced gut barrier dysfunction.

Impact of the platelet washing process on in vitro platelet properties, and the levels of soluble CD40 ligand and platelet-derived microparticles in the storage media.

A new platelet (PLT) additive solution, bicarbonated Ringer's solution supplemented with acid-citrate-dextrose Formula A, termed BRS-A, as well as a new automated closed system cell processor for washing PLTs have recently been developed. This study evaluated the in vitro properties of PLTs with the automated system versus the manual method, using the BRS-A additive solution for washing and storage. ABO-identical apheresis PLTs in 100% plasma were pooled and split equally for control (in 100% plasma or a manual method) and test (ACP215 automated system) units. In vitro characteristics of PLTs washed with the automated system were compared to those of PLTs in 100% plasma (Study 1) or washed with a manual method (Study 2) during the 7-day storage. In Study 1, hypotonic shock response, aggregation response, mitochondrial membrane potential, adenosine triphosphate, and CD42b mean fluorescence intensity were comparable in the control and test groups during the 7-day storage. CD62P expression was lower in the test group than controls on Days 3 and 7. The level of platelet-derived microparticles (PDMPs) in the test group on Days 1 and 2 were higher than those in controls. In contrast, the levels of soluble CD40 ligand (sCD40L) and regulated upon activation of normal T-cell expressed and secreted (RANTES) in the test units were lower than controls. In Study 2, no significant differences were found in all in vitro properties except for PLT count and the levels of PDMPs in the test units were higher than controls during storage. Apheresis PLTs washed with the automated system using BRS-A additive solution maintained in vitro properties during storage. Washing methods influenced PDMP levels but not sCD40L and RANTES.

New life for an old drug: In vitro and in vivo effects of the anthelmintic drug niclosamide against Toxoplasma gondii RH strain

Toxoplasma gondii is the causative agent of toxoplasmosis and causes serious public health problems. However, the current treatment drugs have many limitations, such as serious side effects. Niclosamide is a salicylanilide drug commonly used to treat worm infections. Herein, the effectiveness of niclosamide for the treatment of T. gondii infection was demonstrated. This study was to evaluate the in vitro and in vivo activities of niclosamide against T. gondii and to explore its mechanism of action. The in vitro cytotoxicity of niclosamide on human foreskin fibroblast cells was evaluated by MTT test. Niclosamide displayed low host toxicity and its 50% inhibitory concentration was 8.3 μg/mL. The in vitro anti-proliferation and anti-invasion effects of niclosamide on T. gondii were determined by quantitative PCR and Giemsa staining. Niclosamide also inhibited T. gondii tachyzoite proliferation, with a 50% effective concentration of 45.3 ng/mL, and reduced the invasion of cells by tachyzoites (17.8% for the parasite control versus 1.9% for the niclosamide group treated with 100 ng/mL). A model was established by infecting BALB/c mice with the virulent RH strain of T. gondii and used to determine the in vivo effects of niclosamide on acute infection. The mice infected with tachyzoites and treated with 160, 200 or 240 mg/kg·bw niclosamide for 7 days exhibited 20%, 40% and 50% survival, respectively. In addition, niclosamide reduced the parasite burden in the blood and tissues of acutely infected mice, and niclosamide induced decreases in the mitochondrial membrane potential (ΔΨm) and adenosine triphosphate (ATP) levels in extracellular tachyzoites, as assessed by laser confocal microscopy and a multilabel reader. These findings indicated that the mechanism of action of niclosamide might be associated with T. gondii mitochondria oxidative phosphorylation. In conclusion, our results support the efficacy of niclosamide as a potential compound for the treatment of T. gondii infection.

The role of Bag2 in neurotoxicity induced by the anesthetic sevoflurane.

Sevoflurane is the most commonly used general anesthetic in pediatric patients. But preclinical studies indicate that sevoflurane could have neurotoxicity in newborn and old animals, and this raises concern regarding its safety. In this study, we explored the potential mechanisms of sevoflurane-induced neurotoxicity in human SH-SY5Y neuronal cells. We showed that prolonged exposure to 2% sevoflurane caused a significant increase in the Bag family protein Bag2 in a time- and dose-dependent manner. We investigated the possible role of Bag2 upon exposure to sevoflurane by silencing Bag2 in neuronal cells. Knockdown of Bag2 caused increased overall reactive oxygen species (ROS) and generation of lipid peroxidation products 4-hydroxynonenal (4-HNE). Upon sevoflurane exposure, Bag2-silent cells have reduced glutathione (GSH) and glutathione peroxidase activity. Under the sevoflurane treatment, Bag2-deficient cells have reduced mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) production, while knockdown cells have less viability and higher lactic dehydrogenase (LDH) release as well as a higher percentage of apoptotic cells. The knockdown cells also had higher levels of mitochondrial cytochrome C release, a higher ratio of Bax/Bcl-2 and increased caspase cleavage by sevoflurane. Overall, our data support an important role of Bag2 in sevoflurane-induced neurotoxicity.

N-Acetylcysteine protects against intrauterine growth retardation-induced intestinal injury via restoring redox status and mitochondrial function in neonatal piglets.

Intrauterine growth retardation (IUGR) is detrimental to the intestinal development of neonates, yet satisfactory treatment strategies remain limited. This study was, therefore, conducted using neonatal piglets as a model to investigate the potential of N-acetylcysteine (NAC) to alleviate intestinal damage caused by IUGR. Seven normal birth weight (NBW) and fourteen IUGR neonatal male piglets were selected and then fed a basal milk diet (NBW-CON and IUGR-CON groups) or a basal milk diet supplemented with 1.2g NAC per kg of diet (IUGR-NAC group) from 7 to 21days of age (n = 7). Parameters associated with the severity of intestinal injury, villus morphology and ultrastructural structure, redox status, and mitochondrial function were analyzed. Compared with the NBW-CON piglets, the IUGR-CON piglets exhibited decreased villus height and greater numbers of apoptotic cells in jejunum, along with the increases in malondialdehyde and protein carbonyl concentrations and a decreased adenosine triphosphate (ATP) content. Treatment with NAC significantly increased jejunal superoxide dismutase activity, reduced glutathione: oxidized glutathione ratio, and the mRNA abundance of nuclear respiratory factor 2, heme oxygenase 1, and superoxide dismutase 2 in the IUGR-NAC piglets compared with the IUGR-CON piglets. In addition, NAC improved the efficiency of mitochondrial oxidative metabolism and ATP generation, ameliorated mitochondrial swelling, and inhibited the overproduction of mitochondrial superoxide anion in the jejunal mucosa. Dietary supplementation of NAC shows promise for attenuating the early intestinal injury of young piglets with IUGR, probably through its antioxidant action to restore redox status and mitochondrial function.

Effects of melatonin on oocyte developmental competence and the role of melatonin receptor 1 in juvenile goats.

Melatonin enhances in vitro embryo development in several species by improving the oocyte developmental competence during in vitro maturation (IVM). Melatonin has a wide range of actions, from scavenging reactive oxygen species (ROS) to regulating gene expression, and it can also act by way of melatonin receptors. The aim of this study was to determine the mechanism of action of melatonin during the IVM of juvenile goat oocytes and the role of the membrane receptors. Melatonin receptor 1 was immunolocalized in cumulus cells and oocytes before and after 24hr of IVM. The effect of melatonin on oocyte developmental competence was tested in three experimental IVM groups: (a) control, (b) 10-7 M melatonin, and (c) 10-7 M melatonin +10-7 M luzindole (an inhibitor of both melatonin receptors). After IVM oocytes were assessed for ROS levels, mitochondrial activity, adenosine 5'-triphosphate (ATP) concentration and relative gene expression (ACTB, SLC1A1, SOD1, GPx1, BAX, DNMT1, GCLC and GDF9). IVM-oocytes were in vitro fertilized and cultured under conventional conditions. Blastocyst rate and quality (differential cell count) were assessed at 8days post-fertilization. Melatonin decreased ROS levels, increased mitochondrial activity and ATP content and increased blastocyst quality compared to control group (55.8 vs. 30.4 inner cell mass ICM, p<0.05). There was no effect on the relative gene expression due to treatment with melatonin. In conclusion, we have showed that melatonin improves oocyte developmental competence in juvenile goats by reducing ROS levels and improving mitochondrial activity.

Adenosine Triphosphate Release is Required for Toll-Like Receptor-Induced Monocyte/Macrophage Activation, Inflammasome Signaling, Interleukin-1β Production, and the Host Immune Response to Infection.

Monocytes and macrophages produce interleukin-1β by inflammasome activation which involves adenosine triphosphate release, pannexin-1 channels, and P2X7 receptors. However, interleukin-1β can also be produced in an inflammasome-independent fashion. Here we studied if this mechanism also involves adenosine triphosphate signaling and how it contributes to inflammasome activation. In vitro studies with human cells and randomized animal experiments. Preclinical academic research laboratory. Wild-type C57BL/6 and pannexin-1 knockout mice, healthy human subjects for cell isolation. Human monocytes and U937 macrophages were treated with different inhibitors to study how purinergic signaling contributes to toll-like receptor-induced cell activation and interleukin-1β production. Wild-type and pannexin-1 knockout mice were subjected to cecal ligation and puncture to study the role of purinergic signaling in interleukin-1β production and host immune defense. Toll-like receptor agonists triggered mitochondrial adenosine triphosphate production and adenosine triphosphate release within seconds. Inhibition of mitochondria, adenosine triphosphate release, or P2 receptors blocked p38 mitogen-activated protein kinase and caspase-1 activation and interleukin-1β secretion. Mice lacking pannexin-1 failed to activate monocytes, to produce interleukin-1β, and to effectively clear bacteria following cecal ligation and puncture. Purinergic signaling has two separate roles in monocyte/macrophage activation, namely to facilitate the initial detection of danger signals via toll-like receptors and subsequently to regulate nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain containing 3 inflammasome activation. Further dissection of these mechanisms may reveal novel therapeutic targets for immunomodulation in critical care patients.

PTEN expression by an oncolytic herpesvirus directs T-cell mediated tumor clearance

Engineered oncolytic viruses are used clinically to destroy cancer cells and have the ability to boost anticancer immunity. Phosphatase and tensin homolog deleted on chromosome 10 loss is common across a broad range of malignancies, and is implicated in immune escape. The N-terminally extended isoform, phosphatase and tensin homolog deleted on chromosome 10 alpha (PTENα), regulates cellular functions including protein kinase B signaling and mitochondrial adenosine triphosphate production. Here we constructed HSV-P10, a replicating, PTENα expressing oncolytic herpesvirus, and demonstrate that it inhibits PI3K/AKT signaling, increases cellular adenosine triphosphate secretion, and reduces programmed death-ligand 1 expression in infected tumor cells, thus priming an adaptive immune response and overcoming tumor immune escape. A single dose of HSV-P10 resulted in long term survivors in mice bearing intracranial tumors, priming anticancer T-cell immunity leading to tumor rejection. This implicates HSV-P10 as an oncolytic and immune stimulating therapeutic for anticancer therapy.

Cytotoxicity and Transcriptomic Analysis of Silver Nanoparticles in Mouse Embryonic Fibroblast Cells.

The rapid development of nanotechnology has led to the use of silver nanoparticles (AgNPs) in biomedical applications, including antibacterial, antiviral, anti-inflammatory, and anticancer therapies. The molecular mechanism of AgNPs-induced cytotoxicity has not been studied thoroughly using a combination of cellular assays and RNA sequencing (RNA-Seq) analysis. In this study, we prepared AgNPs using myricetin, an anti-oxidant polyphenol, and studied their effects on NIH3T3 mouse embryonic fibroblasts as an in vitro model system to explore the potential biomedical applications of AgNPs. AgNPs induced loss of cell viability and cell proliferation in a dose-dependent manner, as evident by increased leakage of lactate dehydrogenase (LDH) from cells. Reactive oxygen species (ROS) were a potential source of cytotoxicity. AgNPs also incrementally increased oxidative stress and the level of malondialdehyde, depleted glutathione and superoxide dismutase, reduced mitochondrial membrane potential and adenosine triphosphate (ATP), and caused DNA damage by increasing the level of 8-hydroxy-2′-deoxyguanosine and the expressions of the p53 and p21 genes in NIH3T3 cells. Thus, activation of oxidative stress may be crucial for NIH3T3 cytotoxicity. Interestingly, gene ontology (GO) term analysis revealed alterations in epigenetics-related biological processes including nucleosome assembly and DNA methylation due to AgNPs exposure. This study is the first demonstration that AgNPs can alter bulk histone gene expression. Therefore, our genome-scale study suggests that the apoptosis observed in NIH3T3 cells treated with AgNPs is mediated by the repression of genes required for cell survival and the aberrant enhancement of nucleosome assembly components to induce apoptosis.

Synergistic antitumor effects of rhein and doxorubicin in hepatocellular carcinoma cells.

The aim of this study was to investigate the synergistic antitumor activity of rhein and doxorubicin (DOX) and to elucidate the underlying mechanisms in hepatocellular SMMC-7721 and HepG2 cells. Cell growth curves, caspase-3 activity, and intracellular DOX accumulation were observed using an IncuCyte real-time video imaging system. Combination index was used to calculate synergistic potential of rhein and DOX. Cell apoptosis was detected by the Annexin V-FITC/PI apoptosis kit. Lactate dehydrogenase and adenosine triphosphate (ATP) levels were assessed using an assay kit. Oxygen consumption rates (OCR) and extracellular acidification rates were assessed by the Seahorse XFe96 Extracellular Flux Analyzer. Mitochondrial inner membrane potential (ΔΨm) was monitored with JC-1 fluorescence. Western blot analysis was used to detect the level of P-glycoprotein. Synergistic antiproliferative and proapoptotic effects were exerted by the combination of rhein at 10 μM and DOX at 2 μM in SMMC-7721 and HepG2 cells. Rhein could influenced the accumulation of DOX in both cells, which was associated with remarkably decreased mitochondrial energy metabolism and ATP levels. Rhein could reduce ΔΨm in both cells. mPTP, opener atractyloside (ATR) could accelerate the loss of ΔΨm, and further suppress the OCR induced by rhein. In contrast, the mPTP blocker cyclosporin A (Cs A) inhibited the loss of ΔΨm and the OCR induced by rhein. Our data indicate that a decline in mitochondrial energy metabolism was responsible for the synergistic antitumor effects of rhein and DOX in hepatocellular carcinoma cells. Reduction of ΔΨm and opening of mPTP inhibited the exchange of ATP/adenosine diphosphate between mitochondrial matrix and cytoplasm is the important mechanism.

Linezolid Inhibited Synthesis of ATP in Mitochondria: Based on GC-MS Metabolomics and HPLC Method.

Linezolid has been widely used in serious infections for its effective inhibiting effect against multidrug-resistant gram-positive pathogens. However, linezolid caused severe adverse reactions, such as thrombocytopenia, anaemia, optic neuropathy, and near-fatal serotonin syndrome. In order to investigate the toxicity of linezolid, twenty-four Sprague-Dawley rats were randomly divided into: control group (n=7), low-group (n=8), and high-group (n=9). The rats of low-group and high-group were given by gavage with linezolid 60 and 120 mg/kg/day for 7 days, respectively. The serum concentration of linezolid was determined by high performance liquid chromatography (HPLC); blood metabolic change was analyzed by gas chromatography-mass spectrometer (GC-MS). Adenosine triphosphate (ATP) concentration in HepG2-C3A after being cultured with linezolid was determined by HPLC. The results showed that there were six metabolites and nine metabolites had statistical differences in low-group and high-group (P<0.05). The trimethyl phosphate was the most significant indicator in those changed metabolites. Except for d-glucose which was slightly increased in low-group, octadecanoic acid, cholest-5-ene, hexadecanoic acid, α-linolenic acid, eicosapentaenoic acid, 9,12-Octadecadienoic acid, and docosahexaenoic acid were all decreased in low-group and high-group. ATP concentration was decreased in HepG2-C3A after cultured with linezolid. In conclusion, the toxicity of linezolid is related to its serum concentration. Linezolid may inhibit the synthesis of ATP and fatty acid.

A Fluorescent Chemodosimeter for Organelle-Specific Imaging of Nucleoside Polyphosphate Dynamics in Living Cells

Nucleoside polyphosphates (NPPs) are mainly produced in mitochondria and used as a universal energy source for various cellular events. Although numerous fluorescent probes for adenosine triphosphate (ATP) have been reported, they are not ideally suited for live monitoring of the subtle variation of the mitochondrial ATP level. A new coumarin-based fluorescent probe is synthesized, and this reagent is utilized for specific recognition of NPPs in mitochondria by super-resolution microscopy in physiological condition. Detailed 31P NMR studies reveal that the probe, L·Zn(II), binds to NPPs through their pendent phosphate functionalities. Such binding leads to a substantial enhancement in the luminescence intensity of L·Zn(II) + ADP or L·Zn(II) + ATP as compared to L·Zn(II). This—as well as 1H NMR spectroscopy—has enabled us to evaluate the probe’s binding affinities to these NPPs. Structured illumination and wide field fluorescence microscopy confirmed that this physiologically benign reagent is localized wi...

Quadrupole Orbitrap Mass Spectrometer-Based Metabonomic Elucidation of Influences of Short-Term Di(2-ethylhexyl) phthalate Exposure on Cardiac Metabolism in Male Mice.

Di(2-ethylhexyl) phthalate (DEHP) can cause severe environmental pollution. Effects of DEHP on cardiac metabolism have been reported, but its mechanism(s) of action is not fully clear. Here, we used high-resolution mass spectrometry for metabonomics and molecular biological methods to identify the different endogenous metabolites affected by DEHP that might cause changes in cardiac metabolism in mice, map the network of metabolic pathways, and reveal (at the molecular level) how DEHP affects cardiac metabolism. The results showed that DEHP could inhibit the β-oxidation of fatty acids and gluconeogenesis, promote glycolysis, and inhibit the tricarboxylic acid cycle in cardiomyocytes. DEHP caused mitochondrial dysfunction by inhibiting the synthesis and transport of fatty acids and, thus, inhibiting the synthesis and breakdown of adenosine triphosphate in mitochondria. Pathology revealed that DEHP could change the normal structures and functions of the heart and bodies of mice. DEHP can interfere with the physiological and metabolic function of the heart in mice by disrupting the endogenous metabolite and gene levels.

Endogenous genetic risk factor for serious heatstroke: the thermolabile phenotype of carnitine palmitoyltransferase II variant.

AimIn serious heatstroke, elevated body temperature (>40°C) is considered the main cause of illness. Mitochondrial carnitine palmitoyltransferase II (CPT II) plays an important role in adenosine triphosphate (ATP) generation from long‐chain fatty acids, and its thermolabile phenotype of CPT2 polymorphisms leads to ATP production loss under high fever. Whether by heatstroke or influenza, high fever suppresses mitochondrial ATP production in patients with the thermolabile phenotype of CPT2 polymorphisms. We investigated the relation between CPT2 polymorphism and severity of heatstroke with a body temperature of over 40°C.MethodsWe analyzed blood chemistry test results, Japanese Association for Acute Medicine Disseminated Intravascular Coagulation (JAAM DIC), Acute Physiologic and Chronic Health Evaluation II, and Sequential Organ Failure Assessment (SOFA) scores, and CPT2 polymorphisms in 24 consecutive patients with severe heatstroke at two university hospitals.ResultsEleven patients carried thermolabile CPT II variants (rs2229291; c.1055T˃G [p.Phe352Cys]) (F352C), and the genotype frequency was greater in heatstroke patients than in healthy volunteers. There was no significant difference in body temperature or blood chemistry data at emergency room arrival between patients with and without the CPT II variants. However, hospital days were longer and initial antithrombin activity was significantly lower in the variant group, suggesting a possible link with early phase vascular endothelial cell dysfunction. The JAAM DIC diagnostic criteria and SOFA scores were also higher in the group. There were no differences in the serum albumin, serum creatine kinase, and fibrin degradation product levels, and platelet counts.ConclusionsIn addition to known risks (e.g., environmental temperature and old age), the CPT II polymorphism [F352C] can be a predisposing genetic risk factor for serious heatstroke with organ disfunction, and lower antithrombin activity.

Augmenter of liver regeneration promotes mitochondrial biogenesis in renal ischemia-reperfusion injury.

Mitochondria are the center of energy metabolism in the cell and the preferential target of various toxicants and ischemic injury. Renal ischemia-reperfusion (I/R) injury triggers proximal tubule injury and the mitochondria are believed to be the primary subcellular target of I/R injury. The promotion of mitochondrial biogenesis (MB) is critical for the prevention I/R injury. The results of our previous study showed that augmenter of liver regeneration (ALR) has anti-apoptotic and anti-oxidant functions. However, the modulatory mechanism of ALR remains unclear and warrants further investigation. To gain further insight into the role of ALR in MB, human kidney (HK)-2 cells were treated with lentiviruses carrying ALR short interfering RNA (siRNA) and a model of hypoxia reoxygenation (H/R) injury in vitro was created. We observed that knockdown of ALR promoted apoptosis of renal tubular cells and aggravated mitochondrial injury, as evidenced by the decrease in the mitochondrial respiratory proteins adenosine triphosphate (ATP) synthase subunit β, cytochrome c oxidase subunit 1, and nicotinamide adenine dinucleotide dehydrogenase (ubiquinone) beta subcomplex 8. Meanwhile, the production of reactive oxygen species was increased and ATP levels were decreased significantly in HK-2 cells, as compared with the siRNA/control group (p < 0.05). In addition, the mitochondrial DNA copy number and membrane potential were markedly decreased. Furthermore, critical transcriptional regulators of MB (i.e., peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, mitochondrial transcription factor A, sirtuin-1, and nuclear respiratory factor-1) were depleted in the siRNA/ALR group. Taken together, these findings unveil essential roles of ALR in the inhibition of renal tubular cell apoptosis and attenuation of mitochondrial dysfunction by promoting MB in AKI.