scholarly journals 009 * LEVOSIMENDAN IMPAIRS ATP PRODUCTION BY LIMITATION OF ELECTRON TRANSPORT CHAIN FUNCTION FOLLOWED BY LOSS OF CA2+ RETENTION CAPACITY IN HEALTHY MYOCARDIAL MITOCHONDRIA AND DURING ISCHAEMIA REPERFUSION INJURY

2014 ◽  
Vol 19 (suppl 1) ◽  
pp. S3-S3
Author(s):  
S. Sommer ◽  
M. Leistner ◽  
I. Aleksic ◽  
C. Schimmer ◽  
K. Alhussini ◽  
...  
Keyword(s):  
Electron Transport ◽  
Reperfusion Injury ◽  
Electron Transport Chain ◽  
Ischaemia Reperfusion Injury ◽  
Retention Capacity ◽  
Atp Production ◽  
Myocardial Mitochondria ◽  
Ischaemia Reperfusion ◽  
Transport Chain

scholarly journals Age-Dependent Loss of Mitochondrial Function in Epithelial Tissue Can Be Reversed by Coenzyme Q10

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Daniel Schniertshauer ◽  
Daniel Gebhard ◽  
Jörg Bergemann
Keyword(s):  
Electron Transport ◽  
Coenzyme Q10 ◽  
Mitochondrial Respiration ◽  
Electron Transport Chain ◽  
Epithelial Tissue ◽  
Atp Production ◽  
Transport Chain ◽  
Respiratory Parameters ◽  
Age Dependent ◽  
Theory Of Aging

The process of aging is characterized by the increase of age-associated disorders as well as severe diseases. Due to their role in the oxidative phosphorylation and thus the production of ATP which is crucial for many cellular processes, one reason for this could be found in the mitochondria. The accumulation of reactive oxygen species damaged mitochondrial DNA and proteins can induce mitochondrial dysfunction within the electron transport chain. According to the “mitochondrial theory of aging,” understanding the impact of harmful external influences on mitochondrial function is therefore essential for a better view on aging in general, but the measurement of mitochondrial respiration in skin cells from cell cultures cannot completely reflect the real situation in skin. Here, we describe a new method to measure the mitochondrial respiratory parameters in epithelial tissue derived from human skin biopsies using a XF24 extracellular flux analyzer to evaluate the effect of coenzyme Q10. We observed a decrease in mitochondrial respiration and ATP production with donor age corresponding to the “mitochondrial theory of aging.” For the first time ex vivo in human epidermis, we could show also a regeneration of mitochondrial respiratory parameters if the reduced form of coenzyme Q10, ubiquinol, was administered. In conclusion, an age-related decrease in mitochondrial respiration and ATP production was confirmed. Likewise, an increase in the respiratory parameters by the addition of coenzyme Q10 could also be shown. The fact that there is a significant effect of administered coenzyme Q10 on the respiratory parameters leads to the assumption that this is mainly caused by an increase in the electron transport chain. This method offers the possibility of testing age-dependent effects of various substances and their influence on the mitochondrial respiration parameters in human epithelial tissue.

scholarly journals Cysteine 202 of cyclophilin D is a site of multiple post-translational modifications and plays a role in cardioprotection

2020 ◽  
Author(s):  
Georgios Amanakis ◽  
Junhui Sun ◽  
Maria M Fergusson ◽  
Shane McGinty ◽  
Chengyu Liu ◽  
...  
Keyword(s):  
Reperfusion Injury ◽  
Mitochondrial Permeability Transition ◽  
Cysteine Residue ◽  
Cardiac Mitochondria ◽  
Cyclophilin D ◽  
Ischaemia Reperfusion Injury ◽  
Retention Capacity ◽  
Post Translational Modifications ◽  
Ischaemia Reperfusion ◽  
Ptp Opening

Abstract Aims Cyclophilin-D is a well-known regulator of the mitochondrial permeability transition pore (PTP), the main effector of cardiac ischaemia/reperfusion injury. However, the binding of CypD to the PTP is poorly understood. Cysteine 202 (C202) of CypD is highly conserved among species and can undergo redox-sensitive post-translational modifications. We investigated whether C202 regulates the opening of PTP. Methods and results We developed a knock-in mouse model using CRISPR where CypD-C202 was mutated to a serine (C202S). Infarct size is reduced in CypD-C202S Langendorff perfused hearts compared to wild type (WT). Cardiac mitochondria from CypD-C202S mice also have higher calcium retention capacity compared to WT. Therefore, we hypothesized that oxidation of C202 might target CypD to the PTP. Indeed, isolated cardiac mitochondria subjected to oxidative stress exhibit less binding of CypD-C202S to the proposed PTP component F1F0-ATP-synthase. We previously found C202 to be S-nitrosylated in ischaemic preconditioning. Cysteine residues can also undergo S-acylation, and C202 matched an S-acylation motif. S-acylation of CypD-C202 was assessed using a resin-assisted capture (Acyl-RAC). WT hearts are abundantly S-acylated on CypD C202 under baseline conditions indicating that S-acylation on C202 per se does not lead to PTP opening. CypD C202S knock-in hearts are protected from ischaemia/reperfusion injury suggesting further that lack of CypD S-acylation at C202 is not detrimental (when C is mutated to S) and does not induce PTP opening. However, we find that ischaemia leads to de-acylation of C202 and that calcium overload in isolated mitochondria promotes de-acylation of CypD. Furthermore, a high bolus of calcium in WT cardiac mitochondria displaces CypD from its physiological binding partners and possibly renders it available for interaction with the PTP. Conclusions Taken together the data suggest that with ischaemia CypD is de-acylated at C202 allowing the free cysteine residue to undergo oxidation during the first minutes of reperfusion which in turn targets it to the PTP.

scholarly journals The dynamin-related GTPase Opa1 is required for glucose-stimulated ATP production in pancreatic beta cells

2011 ◽  
Vol 22 (13) ◽  
pp. 2235-2245 ◽  
Author(s):  
Zhongyan Zhang ◽  
Nobunao Wakabayashi ◽  
Junko Wakabayashi ◽  
Yasushi Tamura ◽  
Woo-Jin Song ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Electron Transport ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Electron Transport Chain ◽  
Chain Complex ◽  
Atp Production ◽  
Transport Chain

Previous studies using in vitro cell culture systems have shown the role of the dynamin-related GTPase Opa1 in apoptosis prevention and mitochondrial DNA (mtDNA) maintenance. However, it remains to be tested whether these functions of Opa1 are physiologically important in vivo in mammals. Here, using the Cre-loxP system, we deleted mouse Opa1 in pancreatic beta cells, in which glucose-stimulated ATP production in mitochondria plays a key role in insulin secretion. Beta cells lacking Opa1 maintained normal copy numbers of mtDNA; however, the amount and activity of electron transport chain complex IV were significantly decreased, leading to impaired glucose-stimulated ATP production and insulin secretion. In addition, in Opa1-null beta cells, cell proliferation was impaired, whereas apoptosis was not promoted. Consequently, mice lacking Opa1 in beta cells develop hyperglycemia. The data suggest that the function of Opa1 in the maintenance of the electron transport chain is physiologically relevant in beta cells.

scholarly journals Electron Transport Chain Inhibition Suppresses CD40 Expression and Sensitizes Chronic Lymphocytic Leukaemia Cells to Venetoclax

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 35-35
Author(s):  
Zhenghao Chen ◽  
Gaspard Cretenet ◽  
Valeria Carnazzo ◽  
Gerritje J. W. van der Windt ◽  
Arnon P. Kater ◽  
...  
Keyword(s):  
Electron Transport ◽  
Research Funding ◽  
Electron Transport Chain ◽  
Specific Inhibitor ◽  
Cd40 Ligation ◽  
Atp Production ◽  
Transport Chain ◽  
Cd40 Stimulation ◽  
Cd40 Expression

Alterations in expression of specifically BCL-XL and MCL-1 dictate sensitivity of CLL cells to the Bcl-2 specific inhibitor venetoclax (VEN). We and others have shown upregulation of these anti-apoptotic proteins by interaction of CLL cells with CD4+ T helper cells within their lymph node microenvironment (LN-ME) mediated by CD40 signalling. We also reported significant metabolic changes of LN-ME activated CLL cells but whether metabolic alterations can be linked to VEN resistance remains unclear. As VEN is increasingly used in early stages of CLL, better understanding and tools to circumvent VEN resistance are highly needed. We aim to reveal the metabolic adaption of CLL to CD40 signalling in connection with VEN resistance. After in vitro CD40 signalling stimulation of peripheral blood (PB) CLL cells, mitochondrial mass and glucose uptake were measured by flow cytometry, oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were measured on Seahorse XF Analyser. The result demonstrated that CD40 stimulation enhances both oxidative phosphorylation (OXPHOS) and glycolysis. This was also confirmed by microarray and metabolomics analyses, as genes and metabolites involved in these two metabolic pathways are significantly upregulated by CD40 stimulation. To find out whether these pathways are linked to VEN resistance, PB CLL cells were treated with OXPHOS or glycolysis inhibitors during CD40 stimulation. Remarkably, OXPHOS inhibition by electron transport chain (ETC) inhibitors (rotenone, antimycin A and oligomycin) counteracted strongly for VEN resistance, while glycolysis inhibition by 2-Deoxy-D-glucose (2DG) did not. The three ETC inhibitors also attenuated CLL activation, ATP production and NAD levels. Interestingly, complex II inhibition of the ETC (TTFA and DMM) did not affect VEN resistance. Regarding BCL-2 family members induced by CD40 ligation, both MCL-1 and BCL-XL were downregulated by these ETC inhibitors. In addition, OXPHOS inhibition strongly elevates glycolysis, and vice versa, which illustrates a strong metabolic plasticity of CLL cells. To further investigate the cross-talk between CD40 signalling, VEN resistance and mitochondrial metabolism, the three main fuels of the TCA cycle were inhibited: pyruvate (by UK5099), glutamine (by DON) and fatty acids (by etomoxir). Even though the OCR and ECAR were slightly decreased by (combinations of) these fuel inhibitors, neither CD40 signalling nor VEN sensitivity was affected. Next, we inhibited PI3K by idelalisib, BTK by ibrutinib and mTOR by rapamycin, which are three downstream targets of CD40 signalling. The results showed that only rapamycin inhibited CD40 activation and metabolic activities, and none of the three inhibitors counteracts VEN resistance. Lastly, we investigated CD40 splicing and overall expression. Interestingly, CD40 stimulation has a huge impact on CD40 expression itself, and these changes were blocked by ETC inhibition. These data indicate that ETC inhibition affects CD40 signals to counteract VEN resistance, by directly affecting the expression of CD40 protein on the cell membrane. In conclusion, after CD40 stimulation, CLL cells become metabolically activated and highly flexible in the use of mitochondrial fuels. The enhanced OXPHOS but not glycolysis contributes to VEN resistance, while ETC inhibition reverses CLL VEN resistance by directly suppressing CD40 expression on CLL. These findings link CLL metabolism directly to CD40 transcription and signalling, which may contribute to clinical VEN resistance. Disclosures van der Windt: genmab: Current Employment. Kater:Abbvie: Research Funding; Roche: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Genentech: Research Funding. Eldering:Genentech: Research Funding; Celgene: Research Funding; Janssen: Research Funding.

scholarly journals Slow TCA flux implies low ATP production in tumors

2021 ◽  
Author(s):  
Caroline R. Bartman ◽  
Yihui Shen ◽  
Won Dong Lee ◽  
Tara TeSlaa ◽  
Connor S.R. Jankowski ◽  
...  
Keyword(s):  
Electron Transport ◽  
Warburg Effect ◽  
Electron Transport Chain ◽  
Aerobic Glycolysis ◽  
Tca Cycle ◽  
High Energy ◽  
Glycolytic Flux ◽  
Atp Production ◽  
Transport Chain ◽  
The Warburg Effect

SummaryThe tricarboxylic acid (TCA) cycle oxidizes carbon substrates to carbon dioxide, with the resulting high energy electrons fed into the electron transport chain to produce ATP by oxidative phosphorylation. Healthy tissues derive most of their ATP from oxidative metabolism, and the remainder from glycolysis. The corresponding balance in tumors remains unclear. Tumors upregulate aerobic glycolysis (the Warburg effect), yet they also typically require an intact TCA cycle and electron transport chain1–6. Recent studies have measured which nutrients contribute carbon to the tumor TCA metabolites7,8, but not tumor TCA flux: how fast the cycle turns. Here, we develop and validate an in vivo dynamic isotope tracing-mass spectrometry strategy for TCA flux quantitation, which we apply to all major mouse organs and to five tumor models. We show that, compared to the tissue of origin, tumor TCA flux is markedly suppressed. Complementary glycolytic flux measurements confirm tumor glycolysis acceleration, but the majority of tumor ATP is nevertheless made aerobically, and total tumor ATP production is suppressed compared to healthy tissues. In murine pancreatic cancer, this is accommodated by downregulation of the major energy-using pathway in the healthy exocrine pancreas, protein synthesis. Thus, instead of being hypermetabolic as commonly assumed, tumors apparently make ATP at a lower than normal rate. We propose that, as cells de-differentiate into cancer, they eschew ATP-intensive processes characteristic of the host tissue, and that the resulting suppressed ATP demand contributes to the Warburg effect and facilitates cancer growth in the nutrient-poor tumor microenvironment.

Abstract P455: Acetylated Cyclophilin D Regulates Mitochondrial Electron Transport Chain Activity In The Developing Heart

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Gisela Beutner ◽  
Jonathan Burris ◽  
George A Porter
Keyword(s):  
Electron Transport ◽  
Enzymatic Activity ◽  
Electron Transport Chain ◽  
Isolated Heart ◽  
Permeability Transition ◽  
Mouse Heart ◽  
Cyclophilin D ◽  
Retention Capacity ◽  
Adult Heart ◽  
Transport Chain

Background: Mitochondria generate energy in form of ATP in mature eukaryotic cells. The components of the electron transport chain (ETC) are expressed at embryonic (E) day 9.5 in mouse hearts, but ETC activity and oxidative phosphorylation (OXPHOS) are uncoupled, because the permeability transition pore (PTP) is open. In mouse hearts the mPTP closes around E11.5. Opening and closing of the PTP is regulated by cyclophilin D (CypD), but the regulatory mechanism are not understood. Hypothesis: Maturation of ETC activity is regulated by acetylated CypD. Methods: Cardiac tissue homogenates or isolated heart mitochondria from mice, ranging in age from E 9.5 to adult, were used to measure oxygen consumption and the calcium retention capacity. The expression of proteins of the ETC and their assembly into supercomplexes was followed by denaturing and native electrophoresis. The expression of CypD and its acetylation status were assessed by western blotting and densitometry. The enzymatic activity of the ETC complexes and CypD was measured using spectrophotometry. Results: In the heart of mouse embryos at E 9.5 mitochondrial ETC activity and OXPHOS are not coupled (respiratory control ratio (RCR) 1.48 ± 0.17, n=9). Addition of 1 μM cyclosporin A, an inhibitor of CypD and the PTP acutely increases the RCR to 3.69 ± 0.59 (n=5). At E13.5, the end of the embryonic period in the mouse, OXPHOS is coupled and not significantly different from the adult heart. The enzymatic activity of the ETC complexes I, II, III and V increases significantly from E9.5 to the adult heart and the assembly of mitochondrial supercomplexes begins at about E13.5. The total expression of CypD increases as the mouse heart matures, but the enzymatic activity of CypD decreases. In addition, the ratio of acetylated CypD to the total expressed CypD decreased from 1.1 ± 0.16 (n=3) at E9.5 to 0.54 ± 0.06 (n=3) in the adult heart. Conclusion: The activity of acetylated CypD regulates maturation of mitochondrial ETC activity in the developing mouse heart.

scholarly journals Novel MenA Inhibitors Are Bactericidal againstMycobacterium tuberculosisand Synergize with Electron Transport Chain Inhibitors

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Bryan J. Berube ◽  
Dara Russell ◽  
Lina Castro ◽  
Seoung-ryoung Choi ◽  
Prabagaran Narayanasamy ◽  
...  
Keyword(s):  
Electron Transport ◽  
Drug Treatment ◽  
Electron Transport Chain ◽  
Drug Targets ◽  
Content Type ◽  
Atp Production ◽  
Highly Active ◽  
Enhanced Activity ◽  
Transport Chain ◽  
Long Course

ABSTRACTMycobacterium tuberculosisis the leading cause of morbidity and death resulting from infectious disease worldwide. The incredible disease burden, combined with the long course of drug treatment and an increasing incidence of antimicrobial resistance amongM. tuberculosisisolates, necessitates novel drugs and drug targets for treatment of this deadly pathogen. Recent work has produced several promising clinical candidates targeting components of the electron transport chain (ETC) ofM. tuberculosis, highlighting this pathway’s potential as a drug target. Menaquinone is an essential component of theM. tuberculosisETC, as it functions to shuttle electrons through the ETC to produce the electrochemical gradient required for ATP production for the cell. We show that inhibitors of MenA, a component of the menaquinone biosynthetic pathway, are highly active againstM. tuberculosis. MenA inhibitors are bactericidal againstM. tuberculosisunder both replicating and nonreplicating conditions, with 10-fold higher bactericidal activity against nutrient-starved bacteria than against replicating cultures. MenA inhibitors have enhanced activity in combination with bedaquiline, clofazimine, and inhibitors of QcrB, a component of the cytochromebc1oxidase. Together, these data support MenA as a viable target for drug treatment againstM. tuberculosis. MenA inhibitors not only killM. tuberculosisin a variety of physiological states but also show enhanced activity in combination with ETC inhibitors in various stages of clinical trial testing.

scholarly journals The Agr Quorum-Sensing System Regulates Fibronectin Binding but Not Hemolysis in the Absence of a Functional Electron Transport Chain

2014 ◽  
Vol 82 (10) ◽  
pp. 4337-4347 ◽  
Author(s):  
Vera Pader ◽  
Ellen H. James ◽  
Kimberley L. Painter ◽  
Sivaramesh Wigneshweraraj ◽  
Andrew M. Edwards
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
Content Type ◽  
Atp Production ◽  
Transport Chain ◽  
Mutant Strains ◽  
Enhanced Expression ◽  
Fibronectin Binding Protein ◽  
Small Colony ◽  
Fibronectin Binding

ABSTRACTStaphylococcus aureusis responsible for numerous chronic and recurrent infections, which are frequently associated with the emergence of small-colony variants (SCVs) that lack a functional electron transport chain. SCVs exhibit enhanced expression of fibronectin-binding protein (FnBP) and greatly reduced hemolysin production, although the basis for this is unclear. One hypothesis is that these phenotypes are a consequence of the reduced Agr activity of SCVs, while an alternative is that the lack of a functional electron transport chain and the resulting reduction in ATP production are responsible. Disruption of the electron transport chain ofS. aureusgenetically (hemBandmenD) or chemically, using 2-n-heptyl-4-hydroxyquinolineN-oxide (HQNO), inhibited both growth and Agr activity and conferred an SCV phenotype. Supplementation of the culture medium with synthetic autoinducing peptide (sAIP) significantly increased Agr expression in bothhemBmutant strains andS. aureusgrown with HQNO and significantly reduced staphylococcal adhesion to fibronectin. However, sAIP did not promote hemolysin expression inhemBmutant strains orS. aureusgrown with HQNO. Therefore, while Agr regulates fibronectin binding in SCVs, it cannot promote hemolysin production in the absence of a functional electron transport chain.

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