ATP Synthesis in Mitochondrial Oxidative Phosphorylation

Hepatocellular carcinoma (HCC) that is triggered by metabolic defects is one of the most malignant liver cancers. A much higher incidence of HCC among men than women suggests the protective roles of estrogen in HCC development and progression. To begin to understand the mechanisms involving estrogenic metabolic effects, we compared cell number, viability, cytotoxicity, and apoptosis among HCC-derived HepG2 cells that were treated with different concentrations of 2-deoxy-d-glucose (2-DG) that blocks glucose metabolism, oxamate that inhibits lactate dehydrogenase and glycolysis, or oligomycin that blocks ATP synthesis and mitochondrial oxidative phosphorylation. We confirmed that HepG2 cells primarily utilized glycolysis followed by lactate fermentation, instead of mitochondrial oxidative phosphorylation, for cell growth. We hypothesized that estrogen altered energy metabolism via its receptors to carry out its anticancer effects in HepG2 cells. We treated cells with 17β-estradiol (E2), 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT) an estrogen receptor (ER) α (ERα) agonist, or 2,3-bis(4-hydroxyphenyl)-propionitrile (DPN), an ERβ agonist. We then used transcriptomic and metabolomic analyses and identified differentially expressed genes and unique metabolite fingerprints that are produced by each treatment. We further performed integrated multi-omics analysis, and identified key genes and metabolites in the gene–metabolite interaction contributed by E2 and ER agonists. This integrated transcriptomic and metabolomic study suggested that estrogen acts on estrogen receptors to suppress liver cancer cell growth via altering metabolism. This is the first exploratory study that comprehensively investigated estrogen and its receptors, and their roles in regulating gene expression, metabolites, metabolic pathways, and gene–metabolite interaction in HCC cells using bioinformatic tools. Overall, this study provides potential therapeutic targets for future HCC treatment.

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Murburn model of mitochondrial aerobic respiration is robust in comparison to the ‘chemiosmotic rotary or two-ion torsional’ ATP-synthesis proposals

10.31219/osf.io/j27dy ◽

2020 ◽

Author(s):

Daniel Andrew Gideon

Keyword(s):

Oxidative Phosphorylation ◽

Experimental Research ◽

Atp Synthesis ◽

Reaction Scheme ◽

Aerobic Respiration ◽

Evidence Based ◽

Mitochondrial Oxidative Phosphorylation ◽

Paul Boyer ◽

Intense Debate ◽

Biophysical Chemistry

One of the most fundamental questions in biology pertains to how mechano-chemical energy is derived from metabolic fuels. In particular, how oxidation of NADH is linked to ATP synthesis in mitochondrial oxidative phosphorylation (mOxPhos) has been a topic of intense debate. Together, the Peter Mitchell-Paul Boyer proposals for mOxPhos are termed herein as “chemiosmotic rotary ATP synthesis” (or CRAS) model, which was recently defended/advocated by Pedro Silva in Biophysical Chemistry . Over the last two decades, Sunil Nath had questioned some aspects of the CRAS proposal, and made subtle alterations on the roles of Complex V and ions within the reaction scheme, and continues to advocate his framework as “two-ion torsional ATP synthesis” (abbreviated herein as TITAS) model in Biophysical Chemistry . Kelath Murali Manoj had revisited the data on the respiratory machinery’s structures/distributions and based on two-decades of evidence-based experimental research in redox enzymology of heme/flavin proteins, had formulated the murburn model for mOxPhos. In this work, the ETC-CRAS hypothesis and its off-shoot, the TITAS proposal, are questioned in the light of the convincing chemicophysical logic provided by the murburn hypothesis.

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Substrate- and Calcium-Dependent Differential Regulation of Mitochondrial Oxidative Phosphorylation and Energy Production in the Heart and Kidney

Cells ◽

10.3390/cells11010131 ◽

2021 ◽

Vol 11 (1) ◽

pp. 131

Author(s):

Xiao Zhang ◽

Namrata Tomar ◽

Sunil M. Kandel ◽

Said H. Audi ◽

Allen W. Cowley ◽

...

Keyword(s):

Oxidative Phosphorylation ◽

Mitochondrial Respiration ◽

Atp Synthesis ◽

Heart Mitochondria ◽

Mitochondrial Oxidative Phosphorylation ◽

Inhibitory Effects ◽

Atp Production ◽

Calcium Dependent ◽

Palmitoyl Carnitine ◽

Regulatory Effects

Mitochondrial dehydrogenases are differentially stimulated by Ca2+. Ca2+ has also diverse regulatory effects on mitochondrial transporters and other enzymes. However, the consequences of these regulatory effects on mitochondrial oxidative phosphorylation (OxPhos) and ATP production, and the dependencies of these consequences on respiratory substrates, have not been investigated between the kidney and heart despite the fact that kidney energy requirements are second only to those of the heart. Our objective was, therefore, to elucidate these relationships in isolated mitochondria from the kidney outer medulla (OM) and heart. ADP-induced mitochondrial respiration was measured at different CaCl2 concentrations in the presence of various respiratory substrates, including pyruvate + malate (PM), glutamate + malate (GM), alpha-ketoglutarate + malate (AM), palmitoyl-carnitine + malate (PCM), and succinate + rotenone (SUC + ROT). The results showed that, in both heart and OM mitochondria, and for most complex I substrates, Ca2+ effects are biphasic: small increases in Ca2+ concentration stimulated, while large increases inhibited mitochondrial respiration. Furthermore, significant differences in substrate- and Ca2+-dependent O2 utilization towards ATP production between heart and OM mitochondria were observed. With PM and PCM substrates, Ca2+ showed more prominent stimulatory effects in OM than in heart mitochondria, while with GM and AM substrates, Ca2+ had similar biphasic regulatory effects in both OM and heart mitochondria. In contrast, with complex II substrate SUC + ROT, only inhibitory effects on mitochondrial respiration was observed in both the heart and the OM. We conclude that the regulatory effects of Ca2+ on mitochondrial OxPhos and ATP synthesis are biphasic, substrate-dependent, and tissue-specific.

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Dependence of Platelet Adenyl Cyclase System on Oxidative Phosphorylation

Thrombosis and Haemostasis ◽

10.1055/s-0038-1651444 ◽

1975 ◽

Vol 34 (01) ◽

pp. 042-049 ◽

Cited By ~ 1

Author(s):

Shuichi Hashimoto ◽

Sachiko Shibata ◽

Bokro Kobayashi

Keyword(s):

Cyclic Amp ◽

Oxidative Phosphorylation ◽

Sodium Succinate ◽

Potassium Cyanide ◽

Adenyl Cyclase ◽

Mitochondrial Oxidative Phosphorylation ◽

Adenyl Cyclase Activity ◽

Intact Rabbit ◽

Adenyl Cyclase System ◽

Cyclic Amp Synthesis

SummaryThe radioactive adenosine 3′,5′-monophosphate (cyclic AMP) level derived from 8-14C adenine in intact rabbit platelets decreased in the presence of mitochondrial inhibitor (potassium cyanide) or uncoupler (sodium azide), and markedly increased by the addition of NaF, monoiodoacetic acid (MIA), or 2-deoxy-D-glucose. The stimulative effect of the glycolytic inhibitors was distinctly enhanced by the simultaneous addition of sodium succinate. MIA did neither directly stimulate the adenyl cyclase activity nor inhibit the phosphodiesterase activity. These results suggest that cyclic AMP synthesis in platelets is closely linked to mitochondrial oxidative phosphorylation.

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Impairment of mitochondrial oxidative phosphorylation in skin fibroblasts of SALS and FALS patients is rescued by in vitro treatment with ROS scavengers

Experimental Neurology ◽

10.1016/j.expneurol.2021.113620 ◽

2021 ◽

Vol 339 ◽

pp. 113620

Author(s):

Grazyna Debska-Vielhaber ◽

Irina Miller ◽

Viktoriya Peeva ◽

Werner Zuschratter ◽

Jaroslaw Walczak ◽

...

Keyword(s):

Oxidative Phosphorylation ◽

Skin Fibroblasts ◽

Mitochondrial Oxidative Phosphorylation ◽

Ros Scavengers ◽

In Vitro Treatment

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Nanoscopic quantification of sub-mitochondrial morphology, mitophagy and mitochondrial dynamics in living cells derived from patients with mitochondrial diseases

Journal of Nanobiotechnology ◽

10.1186/s12951-021-00882-9 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Weiwei Zou ◽

Qixin Chen ◽

Jesse Slone ◽

Li Yang ◽

Xiaoting Lou ◽

...

Keyword(s):

Oxidative Phosphorylation ◽

Optic Atrophy ◽

Respiratory Function ◽

Clinical Symptoms ◽

Mitochondrial Dynamics ◽

Cerebellar Atrophy ◽

Mitochondrial Diseases ◽

Living Cells ◽

Mitochondrial Morphology ◽

Mitochondrial Oxidative Phosphorylation

AbstractSLC25A46 mutations have been found to lead to mitochondrial hyper-fusion and reduced mitochondrial respiratory function, which results in optic atrophy, cerebellar atrophy, and other clinical symptoms of mitochondrial disease. However, it is generally believed that mitochondrial fusion is attributable to increased mitochondrial oxidative phosphorylation (OXPHOS), which is inconsistent with the decreased OXPHOS of highly-fused mitochondria observed in previous studies. In this paper, we have used the live-cell nanoscope to observe and quantify the structure of mitochondrial cristae, and the behavior of mitochondria and lysosomes in patient-derived SLC25A46 mutant fibroblasts. The results show that the cristae have been markedly damaged in the mutant fibroblasts, but there is no corresponding increase in mitophagy. This study suggests that severely damaged mitochondrial cristae might be the predominant cause of reduced OXPHOS in SLC25A46 mutant fibroblasts. This study demonstrates the utility of nanoscope-based imaging for realizing the sub-mitochondrial morphology, mitophagy and mitochondrial dynamics in living cells, which may be particularly valuable for the quick evaluation of pathogenesis of mitochondrial morphological abnormalities.

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