scholarly journals Identifying Site-specific Superoxide and Hydrogen Peroxide Production Rates from the Mitochondrial Electron Transport System Using a Computational Strategy

Function ◽  
2021 ◽  
Author(s):  
Quynh V Duong ◽  
Yan Levitsky ◽  
Maria J Dessinger ◽  
Jasiel O Strubbe-Rivera ◽  
Jason N Bazil
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transport ◽  
Complex I ◽  
Cellular Damage ◽  
Ros Production ◽  
Hydrogen Peroxide Production ◽  
Pathological Conditions ◽  
Redox Sites ◽  
Mitochondrial Ros ◽  
Ros Homeostasis

Abstract Mitochondrial reactive oxygen species (ROS) play important roles in cellular signaling; however, certain pathological conditions such as ischemia/reperfusion (I/R) injury disrupt ROS homeostasis and contribute to cell death. A major impediment to developing therapeutic measures against oxidative stress induced cellular damage is the lack of a quantitative framework to identify the specific sources and regulatory mechanisms of mitochondrial ROS production. We developed a thermodynamically consistent, mass-and-charge balanced, kinetic model of mitochondrial ROS homeostasis focused on redox sites of electron transport chain complexes I, II, and III. The model was calibrated and corroborated using comprehensive data sets relevant to ROS homeostasis. The model predicts that complex I ROS production dominates other sources under conditions favoring a high membrane potential with elevated NADH and QH2 levels. In general, complex I contributes to significant levels of ROS production under pathological conditions, while complexes II and III are responsible for basal levels of ROS production, especially when QH2 levels are elevated. The model also reveals that hydrogen peroxide production by complex I underlies the non-linear relationship between ROS emission and O2 at low O2 concentrations. Lastly, the model highlights the need to quantify scavenging system activity under different conditions to establish a complete picture of mitochondrial ROS homeostasis. In summary, we describe the individual contributions of the ETS complex redox sites to total ROS emission in mitochondria respiring under various combinations of NADH- and Q-linked respiratory fuels under varying workloads.

scholarly journals Identifying Site-specific Superoxide and Hydrogen Peroxide Production Rates from the Mitochondrial Electron Transport System Using a Computational Strategy

2021 ◽  
Author(s):  
Quynh V Duong ◽  
Yan Levitsky ◽  
Maria J Dessinger ◽  
Jason Nolan Bazil
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transport ◽  
Complex I ◽  
Cellular Damage ◽  
Ros Production ◽  
Hydrogen Peroxide Production ◽  
Pathological Conditions ◽  
Redox Sites ◽  
Mitochondrial Ros ◽  
Ros Homeostasis

Mitochondrial reactive oxygen species (ROS) play important roles in cellular signaling; however, certain pathological conditions such as ischemia/reperfusion (I/R) injury disrupt ROS homeostasis and contribute to cell death. A major impediment to developing therapeutic measures against oxidative stress induced cellular damage is the lack of a quantitative framework to identify the specific sources and regulatory mechanisms of mitochondrial ROS production. We developed a thermodynamically consistent, mass-and-charge balanced, kinetic model of mitochondrial ROS homeostasis focused on redox sites of electron transport chain complexes I, II, and III. The model was calibrated and validated using comprehensive data sets relevant to ROS homeostasis. The model predicts that complex I ROS production dominates other sources under conditions favoring a high membrane potential with elevated NADH and QH2 levels. In general, complex I contributes to significant levels of ROS production under pathological conditions, while complexes II and III are responsible for basal levels of ROS production, especially when QH2 levels are elevated. The model also reveals that hydrogen peroxide production by complex I underlies the non-linear relationship between ROS emission and O2 at low O2 concentrations. Lastly, the model highlights the need to quantify scavenging system activity under different conditions to establish a complete picture of mitochondrial ROS homeostasis. In summary, we describe the individual contributions of the ETS complex redox sites to total ROS emission in mitochondria respiring under various combinations of NADH- and Q-linked respiratory fuels under varying work rates.

scholarly journals Complex I-Associated Hydrogen Peroxide Production Is Decreased and Electron Transport Chain Enzyme Activities Are Altered in n-3 Enriched fat-1 Mice

PLoS ONE ◽  
2010 ◽  
Vol 5 (9) ◽  
pp. e12696 ◽  
Author(s):  
Kevork Hagopian ◽  
Kristina L. Weber ◽  
Darren T. Hwee ◽  
Alison L. Van Eenennaam ◽  
Guillermo López-Lluch ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Electron Transport ◽  
Enzyme Activities ◽  
Complex I ◽  
Electron Transport Chain ◽  
Hydrogen Peroxide Production ◽  
Transport Chain

scholarly journals Isoflurane Differentially Modulates Mitochondrial Reactive Oxygen Species Production via  Forward versus  Reverse Electron Transport Flow

2011 ◽  
Vol 115 (3) ◽  
pp. 531-540 ◽  
Author(s):  
Naoyuki Hirata ◽  
Yon Hee Shim ◽  
Danijel Pravdic ◽  
Nicole L. Lohr ◽  
Philip F. Pratt ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Electron Transport ◽  
Complex I ◽  
Ros Generation ◽  
Ros Production ◽  
Oxygen Species ◽  
Submitochondrial Particles ◽  
Anesthetic Preconditioning ◽  
Cardioprotective Effects ◽  
Complex I Activity

Background Reactive oxygen species (ROS) mediate the effects of anesthetic precondition to protect against ischemia and reperfusion injury, but the mechanisms of ROS generation remain unclear. In this study, the authors investigated if mitochondria-targeted antioxidant (mitotempol) abolishes the cardioprotective effects of anesthetic preconditioning. Further, the authors investigated the mechanism by which isoflurane alters ROS generation in isolated mitochondria and submitochondrial particles. Methods Rats were pretreated with 0.9% saline, 3.0 mg/kg mitotempol in the absence or presence of 30 min exposure to isoflurane. Myocardial infarction was induced by left anterior descending artery occlusion for 30 min followed by reperfusion for 2 h and infarct size measurements. Mitochondrial ROS production was determined spectrofluorometrically. The effect of isoflurane on enzymatic activity of mitochondrial respiratory complexes was also determined. Results Isoflurane reduced myocardial infarct size (40 ± 9% = mean ± SD) compared with control experiments (60 ± 4%). Mitotempol abolished the cardioprotective effects of anesthetic preconditioning (60 ± 9%). Isoflurane enhanced ROS generation in submitochondrial particles with nicotinamide adenine dinucleotide (reduced form), but not with succinate, as substrate. In intact mitochondria, isoflurane enhanced ROS production in the presence of rotenone, antimycin A, or ubiquinone when pyruvate and malate were substrates, but isoflurane attenuated ROS production when succinate was substrate. Mitochondrial respiratory experiments and electron transport chain complex assays revealed that isoflurane inhibited only complex I activity. Conclusions The results demonstrated that isoflurane produces ROS at complex I and III of the respiratory chain via the attenuation of complex I activity. The action on complex I decreases unfavorable reverse electron flow and ROS release in myocardium during reperfusion.

scholarly journals ALCAT1 Overexpression Affects Supercomplex Formation and Increases ROS in Respiring Mitochondria

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Bettina Rieger ◽  
Adéla Krajčová ◽  
Patrick Duwe ◽  
Karin B. Busch
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
High Variability ◽  
Ros Production ◽  
Metabolic Plasticity ◽  
Contact Sites ◽  
Chain Complexes ◽  
Mitochondrial Ros ◽  
Transport Chain ◽  
Metabolic Conditions

Cardiolipin (CL) is a multifunctional dimeric phospholipid that physically interacts with electron transport chain complexes I, III, and IV, and ATP synthase (complex V). The enzyme ALCAT1 catalyzes the conversion of cardiolipin by incorporating polyunsaturated fatty acids into cardiolipin. The resulting CL species are said to be more susceptible to oxidative damage. This is thought to negatively affect the interaction of cardiolipin and electron transport chain complexes, leading to increased ROS production and mitochondrial dysfunction. Furthermore, it is discussed that ALCAT1 itself is upregulated due to oxidative stress. Here, we investigated the effects of overexpression of ALCAT1 under different metabolic conditions. ALCAT1 is located at the ER and mitochondria, probably at contact sites. We found that respiration stimulated by galactose supply promoted supercomplex assembly but also led to increased mitochondrial ROS levels. Endogeneous ALCAT1 protein expression levels showed a fairly high variability. Artificially induced ALCAT1 overexpression reduced supercomplex formation, further promoted ROS production, and prevented upregulation of coupled respiration. Taken together, our data suggest that the amount of the CL conversion enzyme ALCAT1 is critical for coupling mitochondrial respiration and metabolic plasticity.

Ischemic defects in the electron transport chain increase the production of reactive oxygen species from isolated rat heart mitochondria

2008 ◽  
Vol 294 (2) ◽  
pp. C460-C466 ◽  
Author(s):  
Qun Chen ◽  
Shadi Moghaddas ◽  
Charles L. Hoppel ◽  
Edward J. Lesnefsky
Keyword(s):  
Electron Transport ◽  
Complex I ◽  
Electron Transport Chain ◽  
Myocardial Injury ◽  
Complex Iii ◽  
Ischemic Damage ◽  
Ros Production ◽  
Oxygen Species ◽  
Net Production ◽  
Transport Chain

Cardiac ischemia decreases complex III activity, cytochrome c content, and respiration through cytochrome oxidase in subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM). The reversible blockade of electron transport with amobarbital during ischemia protects mitochondrial respiration and decreases myocardial injury during reperfusion. These findings support that mitochondrial damage occurs during ischemia and contributes to myocardial injury during reperfusion. The current study addressed whether ischemic damage to the electron transport chain (ETC) increased the net production of reactive oxygen species (ROS) from mitochondria. SSM and IFM were isolated from 6-mo-old Fisher 344 rat hearts following 25 min global ischemia or following 40 min of perfusion alone as controls. H2O2release from SSM and IFM was measured using the amplex red assay. With glutamate as a complex I substrate, the net production of H2O2was increased by 178 ± 14% and 179 ± 17% in SSM and IFM ( n = 9), respectively, following ischemia compared with controls ( n = 8). With succinate as substrate in the presence of rotenone, H2O2increased by 272 ± 22% and 171 ± 21% in SSM and IFM, respectively, after ischemia. Inhibitors of electron transport were used to assess maximal ROS production. Inhibition of complex I with rotenone increased H2O2production by 179 ± 24% and 155 ± 14% in SSM and IFM, respectively, following ischemia. Ischemia also increased the antimycin A-stimulated production of H2O2from complex III. Thus ischemic damage to the ETC increased both the capacity and the net production of H2O2from complex I and complex III and sets the stage for an increase in ROS production during reperfusion as a mechanism of cardiac injury.

scholarly journals Complex I assembly into supercomplexes determines differential mitochondrial ROS production in neurons and astrocytes

2016 ◽  
Vol 113 (46) ◽  
pp. 13063-13068 ◽  
Author(s):  
Irene Lopez-Fabuel ◽  
Juliette Le Douce ◽  
Angela Logan ◽  
Andrew M. James ◽  
Gilles Bonvento ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Complex I ◽  
Structural Organization ◽  
Mitochondrial Respiratory Chain ◽  
Mitochondrial Complex I ◽  
Ros Production ◽  
Oxygen Species ◽  
Mitochondrial Complex ◽  
Mitochondrial Ros ◽  
Complex I Assembly

Neurons depend on oxidative phosphorylation for energy generation, whereas astrocytes do not, a distinctive feature that is essential for neurotransmission and neuronal survival. However, any link between these metabolic differences and the structural organization of the mitochondrial respiratory chain is unknown. Here, we investigated this issue and found that, in neurons, mitochondrial complex I is predominantly assembled into supercomplexes, whereas in astrocytes the abundance of free complex I is higher. The presence of free complex I in astrocytes correlates with the severalfold higher reactive oxygen species (ROS) production by astrocytes compared with neurons. Using a complexomics approach, we found that the complex I subunit NDUFS1 was more abundant in neurons than in astrocytes. Interestingly, NDUFS1 knockdown in neurons decreased the association of complex I into supercomplexes, leading to impaired oxygen consumption and increased mitochondrial ROS. Conversely, overexpression of NDUFS1 in astrocytes promoted complex I incorporation into supercomplexes, decreasing ROS. Thus, complex I assembly into supercomplexes regulates ROS production and may contribute to the bioenergetic differences between neurons and astrocytes.

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