scholarly journals Effects of the cyanine dye 3,3′-dipropylthiocarbocyanine on mitochondrial energy conservation

1979 ◽  
Vol 180 (3) ◽  
pp. 669-672 ◽  
Author(s):  
P H Howard ◽  
S B Wilson
Keyword(s):  
Membrane Potential ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Energy Conservation ◽  
Mitochondrial Respiration ◽  
Cyanine Dye

Mitochondrial respiration and oxidative phosphorylation were inhibited by the membrane potential probe 3,3′-dipropylthiocarbocyanine [diS-C3-(5)]. Evidence is presented that suggests that the dye acts as both an inhibitor of electron transport and an uncoupler of oxidative phosphorylation.

scholarly journals FOXM1 nuclear transcription factor translocates into mitochondria and inhibits oxidative phosphorylation

2020 ◽  
Vol 31 (13) ◽  
pp. 1411-1424
Author(s):  
Markaisa Black ◽  
Paritha Arumugam ◽  
Samriddhi Shukla ◽  
Arun Pradhan ◽  
Vladimir Ustiyan ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Membrane Potential ◽  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Mitochondrial Respiration ◽  
Electron Transport Chain ◽  
Nuclear Transcription Factor ◽  
Transport Chain

It was found that the transcription factor FOXM1 translocates into mitochondria and inhibits mitochondrial respiration and membrane potential, directly binds to mitochondrial PTCD1, and inhibits the electron transport chain by stabilizing PTCD1.

scholarly journals Role of mitochondrial dynamics in microglial activation and metabolic switch

2020 ◽  
Author(s):  
Alejandro Montilla ◽  
Asier Ruiz ◽  
Carlos Matute ◽  
Maria Domercq
Keyword(s):  
Membrane Potential ◽  
Oxidative Phosphorylation ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Respiration ◽  
Mitochondrial Membrane ◽  
Microglial Activation ◽  
Mitochondrial Dynamics ◽  
Mitochondrial Fission ◽  
Metabolic Reprogramming ◽  
Metabolic Switch

Abstract Background Microglia are the endogenous immune cells of the central nervous system (CNS) and act as sensors of injury in the brain, favouring its homeostasis. Their activation and polarization towards a pro-inflammatory phenotype are associated to injury and disease. These processes are linked to a metabolic reprogramming of the cells, characterized by high rates of glycolytic function and suppressed levels of oxidative phosphorylation. This metabolic switch can be reproduced in vitro by stimulation with lipopolysaccharide (LPS) plus Interferon-γ (IFNγ). In an attempt to understand the mechanisms regulating mitochondrial respiration abolishment, we examined potential alterations in mitochondrial features during the metabolic switch. In addition, we studied the possible implication of mitochondrial dynamics in the metabolic switch using the mitochondrial division inhibitor-1 (Mdivi-1), which blocks Drp1-dependent mitochondrial fission. Methods Cultured microglia was treated with LPS + IFNγ to reproduce the metabolic switch under pro-inflammatory stimuli in the absence or in the presence of Mdivi-1 to block mitochondrial fission. Mitochondrial membrane potential and mitochondrial calcium were measured with living cell imaging, and microglial polarization was assessed by immunofluorescence and qRT-PCR. The metabolic profile of the cells was measured using the Seahorse XFe96 Extracellular Flux Analyzer. Results Under conditions of mitochondrial respiration abolishment, microglia did not show any change in mitochondria morphology, nor in mitochondrial membrane potential, indicative of a limited impact in its viability. We provided evidence that reverse operation of F0F1-ATP synthase contributes to mitochondrial membrane potential. On the other hand. mitochondrial fission blockage significantly reduced the expression of pro-inflammatory markers in LPS + IFNγ-treated microglia, such as the inducible nitric oxide synthase (iNOS). However, this inhibition did not lead to a recovery of the oxidative phosphorylation ablation by LPS + IFNγ or to a microglia repolarization. Conclusions Altogether, these results suggest that Drp1-dependent mitochondrial fission, although potentially involved in microglial activation, does not play an essential role in metabolic reprogramming and repolarization of microglia.

Oxidative phosphorylation and related reactions in liver mitochondria from diabetic dogs

1961 ◽  
Vol 200 (4) ◽  
pp. 838-840 ◽  
Author(s):  
Robert E. Beyer ◽  
Charles A. Shamoian
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Energy Conservation ◽  
Exchange Reaction ◽  
Liver Mitochondria ◽  
Primary Lesion ◽  
Metabolic Defect ◽  
Electron Transport Rates ◽  
Diabetic Dogs ◽  
Diabetic Syndrome

Oxidative phosphorylation, dinitrophenol- and Mg++-activated adenosinetriphosphatase and the adenosinetriphosphatein-organic orthophosphate exchange reaction were studied in mitochondria isolated from livers of chronic and acutely diabetic dogs. Although such reactions are readily demonstrable in these preparations, no trends indicating a deficiency of the energy-conservation reactions studied in preparations from diabetic dogs were noted. In addition, electron transport rates with glutamate or succinate as substrate were increased in the diabetic preparations, as was the yield of mitochondria from such animals. This is not in agreement with recently published reports concerning related studies on diabetic cats and rats. The above findings indicate that a metabolic defect in the efficiency of oxidative phosphorylation is not a general primary lesion in the diabetic syndrome.

THE EFFECT OF RIBOFLAVIN DEFICIENCY AND GALACTOFLAVIN FEEDING ON OXIDATIVE PHOSPHORYLATION AND RELATED REACTIONS IN RAT LIVER MITOCHONDRIA

1961 ◽  
Vol 39 (1) ◽  
pp. 73-88 ◽  
Author(s):  
Robert E. Beyer ◽  
Stanley L. Lamberg ◽  
M. Arthur Neyman
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Energy Conservation ◽  
Atpase Activity ◽  
Exchange Rates ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Riboflavin Deficiency

The effect of riboflavin deficiency and feeding of galactoflavin on the flavin content of liver mitochondria, oxidative phosphorylation, Pi–ATP exchange, and ATPase activity was studied. Both dietary riboflavin deprivation and galactoflavin feeding resulted in a depressed flavin content of mitochondria, the latter treatment resulting in a more severe flavin loss. P/O ratios under all treatments were normal as were Pi–ATP exchange rates and the oxidation of succinate. Glutamate and β-hydroxybutyrate oxidations were depressed in mitochondria from rats fed galactoflavin for 15 or 28 days. DNP-activated ATPase was elevated in both flavin-deficient and galactoflavin-fed preparations while Mg++-activated ATPase was depressed in the galactoflavin-fed preparations. These results are discussed in relation to the hypothesis that flavin is involved in energy conservation in the diaphorase region of electron transport.

Anaerobic respiration sustains mitochondrial membrane potential in a prolyl hydroxylase pathway-activated cancer cell line in a hypoxic microenvironment

2014 ◽  
Vol 306 (4) ◽  
pp. C334-C342 ◽  
Author(s):  
Eiji Takahashi ◽  
Michihiko Sato
Keyword(s):  
Membrane Potential ◽  
Electron Transport ◽  
Cell Line ◽  
Mitochondrial Membrane Potential ◽  
Cancer Cell ◽  
Mitochondrial Membrane ◽  
Cancer Cell Line ◽  
Prolyl Hydroxylase ◽  
Complex Ii ◽  
Pathway Activation

To elucidate how tumor cells produce energy in oxygen-depleted microenvironments, we studied the possibility of mitochondrial electron transport without oxygen. We produced well-controlled oxygen gradients (ΔO2) in monolayer-cultured cells. We then visualized oxygen levels and mitochondrial membrane potential (ΔΦm) in individual cells by using the red shift of green fluorescent protein (GFP) fluorescence and a cationic fluorescent dye, respectively. In this two-dimensional tissue model, ΔΦm was abolished in cells >500 μm from the oxygen source [the anoxic front (AF)], indicating limitations in diffusional oxygen delivery. This result perfectly matched GFP-determined ΔO2. In cells pretreated with dimethyloxaloylglycine (DMOG), a prolyl hydroxylase domain-containing protein (PHD) inhibitor, the AF was expanded to 1,500–2,000 μm from the source. In these cells, tissue ΔO2 was substantially decreased, indicating that PHD pathway activation suppressed mitochondrial respiration. The expansion of the AF and the reduction of ΔO2 were much more prominent in a cancer cell line (Hep3B) than in the equivalent fibroblast-like cell line (COS-7). Hence, the results indicate that PHD pathway-activated cells can sustain ΔΦm, despite significantly decreased electron flux to complex IV. Complex II inhibition abolished the effect of DMOG in expanding the AF, although tissue ΔO2 remained shallow. Separate experiments demonstrated that complex II plays a substantial role in sustaining ΔΦm in DMOG-pretreated Hep3B cells with complex III inhibition. From these results, we conclude that PHD pathway activation can sustain ΔΦm in an otherwise anoxic microenvironment by decreasing tissue ΔO2 while activating oxygen-independent electron transport in mitochondria.

Dual Mutations Reveal Interactions Between Components of Oxidative Phosphorylation in Kluyveromyces lactis

Genetics ◽  
2001 ◽  
Vol 159 (3) ◽  
pp. 929-938
Author(s):  
G D Clark-Walker ◽  
X J Chen
Keyword(s):  
Electron Transport ◽  
Oxidative Phosphorylation ◽  
Atp Synthase ◽  
Kluyveromyces Lactis ◽  
Mitochondrial Protein ◽  
Proton Pumping ◽  
Nuclear Genes ◽  
Suppressor Activity ◽  
Inner Membrane ◽  
Atp Production

Abstract Loss of mtDNA or mitochondrial protein synthesis cannot be tolerated by wild-type Kluyveromyces lactis. The mitochondrial function responsible for ρ0-lethality has been identified by disruption of nuclear genes encoding electron transport and F0-ATP synthase components of oxidative phosphorylation. Sporulation of diploid strains heterozygous for disruptions in genes for the two components of oxidative phosphorylation results in the formation of nonviable spores inferred to contain both disruptions. Lethality of spores is thought to result from absence of a transmembrane potential, ΔΨ, across the mitochondrial inner membrane due to lack of proton pumping by the electron transport chain or reversal of F1F0-ATP synthase. Synergistic lethality, caused by disruption of nuclear genes, or ρ0-lethality can be suppressed by the atp2.1 mutation in the β-subunit of F1-ATPase. Suppression is viewed as occurring by an increased hydrolysis of ATP by mutant F1, allowing sufficient electrogenic exchange by the translocase of ADP in the matrix for ATP in the cytosol to maintain ΔΨ. In addition, lethality of haploid strains with a disruption of AAC encoding the ADP/ATP translocase can be suppressed by atp2.1. In this case suppression is considered to occur by mutant F1 acting in the forward direction to partially uncouple ATP production, thereby stimulating respiration and relieving detrimental hyperpolarization of the inner membrane. Participation of the ADP/ATP translocase in suppression of ρ0-lethality is supported by the observation that disruption of AAC abolishes suppressor activity of atp2.1.

scholarly journals Dose Response of Endotoxin on Hepatocyte and Muscle Mitochondrial Respiration In Vitro

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Victor Jeger ◽  
Sebastian Brandt ◽  
Francesca Porta ◽  
Stephan M. Jakob ◽  
Jukka Takala ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Membrane Potential ◽  
Mitochondrial Respiration ◽  
Hepg2 Cells ◽  
Human Hepatocytes ◽  
Atp Content ◽  
Muscle Mitochondria ◽  
Complex Ii ◽  
Skeletal Muscle Mitochondria ◽  
Reduced Time

Introduction.Results on mitochondrial dysfunction in sepsis are controversial. We aimed to assess effects of LPS at wide dose and time ranges on hepatocytes and isolated skeletal muscle mitochondria.Methods.Human hepatocellular carcinoma cells (HepG2) were exposed to placebo or LPS (0.1, 1, and 10 μg/mL) for 4, 8, 16, and 24 hours and primary human hepatocytes to 1 μg/mL LPS or placebo (4, 8, and 16 hours). Mitochondria from porcine skeletal muscle samples were exposed to increasing doses of LPS (0.1–100 μg/mg) for 2 and 4 hours. Respiration rates of intact and permeabilized cells and isolated mitochondria were measured by high-resolution respirometry.Results.In HepG2 cells, LPS reduced mitochondrial membrane potential and cellular ATP content but did not modify basal respiration. Stimulated complex II respiration was reduced time-dependently using 1 μg/mL LPS. In primary human hepatocytes, stimulated mitochondrial complex II respiration was reduced time-dependently using 1 μg/mL LPS. In isolated porcine skeletal muscle mitochondria, stimulated respiration decreased at high doses (50 and 100 μg/mL LPS).Conclusion.LPS reduced cellular ATP content of HepG2 cells, most likely as a result of the induced decrease in membrane potential. LPS decreased cellular and isolated mitochondrial respiration in a time-dependent, dose-dependent and complex-dependent manner.

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