scholarly journals Partial reconstruction of in vitro gluconeogenesis arising from mitochondrial l-lactate uptake/metabolism and oxaloacetate export via novel l-lactate translocators

2004 ◽  
Vol 380 (1) ◽  
pp. 231-242 ◽  
Author(s):  
Lidia de BARI ◽  
Anna ATLANTE ◽  
Daniela VALENTI ◽  
Salvatore PASSARELLA
Keyword(s):  
Electron Flow ◽  
Mitochondrial Protein ◽  
Pyridine Nucleotide ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Inner Mitochondrial Membrane ◽  
Lactate Oxidation ◽  
Partial Reconstruction ◽  
Proton Uptake

In the light of the occurrence of l-lactate dehydrogenase inside the mitochondrial matrix, we looked at whether isolated rat liver mitochondria can take up and metabolize l-lactate, and provide oxaloacetate outside mitochondria, thus contributing to a partial reconstruction of gluconeogenesis in vitro. We found that: (1) l-lactate (10 mM), added to mitochondria in the presence of a cocktail of glycolysis/gluconeogenesis enzymes and cofactors, can lead to synthesis of glyceraldehyde-3-phosphate at a rate of about 7 nmol/min per mg mitochondrial protein. (2) Three novel translocators exist to mediate l-lactate traffic across the inner mitochondrial membrane. An l-lactate/H+ symporter was identified by measuring fluorimetrically the rate of endogenous pyridine nucleotide reduction. Consistently, l-lactate oxidation was found to occur with P/O ratio=3 (where P/O ratio is the ratio of mol of ATP synthesized to mol of oxygen atoms reduced to water during oxidative phosphorylation) and with generation of membrane potential. Proton uptake, which occurred as a result of addition of l-lactate to RLM together with electron flow inhibitors, and mitochondrial swelling in ammonium l-lactate solutions were also monitored. l-Lactate/oxaloacetate and l-lactate/pyruvate anti-porters were identified by monitoring photometrically the appearance of l-lactate counter-anions outside mitochondria. These l-lactate translocators, which are distinct from the monocarboxylate carrier, were found to differ from each other in Vmax values and in inhibition and pH profiles, and proved to regulate mitochondrial l-lactate metabolism in vitro. The role of lactate/mitochondria interactions in gluconeogenesis is discussed.

scholarly journals Characterization of a Novel Splicing Variant in Acylglycerol Kinase (AGK) Associated with Fatal Sengers Syndrome

2021 ◽  
Vol 22 (24) ◽  
pp. 13484
Author(s):  
Sofia Barbosa-Gouveia ◽  
Maria E. Vázquez-Mosquera ◽  
Emiliano Gonzalez-Vioque ◽  
Álvaro Hermida-Ameijeiras ◽  
Laura L. Valverde ◽  
...  
Keyword(s):  
Respiratory Chain ◽  
Electron Flow ◽  
Mitochondrial Protein ◽  
Chain Complex ◽  
Inner Mitochondrial Membrane ◽  
Infant Carrying ◽  
Acylglycerol Kinase ◽  
Sengers Syndrome

Mitochondrial functional integrity depends on protein and lipid homeostasis in the mitochondrial membranes and disturbances in their accumulation can cause disease. AGK, a mitochondrial acylglycerol kinase, is not only involved in lipid signaling but is also a component of the TIM22 complex in the inner mitochondrial membrane, which mediates the import of a subset of membrane proteins. AGK mutations can alter both phospholipid metabolism and mitochondrial protein biogenesis, contributing to the pathogenesis of Sengers syndrome. We describe the case of an infant carrying a novel homozygous AGK variant, c.518+1G>A, who was born with congenital cataracts, pielic ectasia, critical congenital dilated myocardiopathy, and hyperlactacidemia and died 20 h after birth. Using the patient’s DNA, we performed targeted sequencing of 314 nuclear genes encoding respiratory chain complex subunits and proteins implicated in mitochondrial oxidative phosphorylation (OXPHOS). A decrease of 96-bp in the length of the AGK cDNA sequence was detected. Decreases in the oxygen consumption rate (OCR) and the OCR:ECAR (extracellular acidification rate) ratio in the patient’s fibroblasts indicated reduced electron flow through the respiratory chain, and spectrophotometry revealed decreased activity of OXPHOS complexes I and V. We demonstrate a clear defect in mitochondrial function in the patient’s fibroblasts and describe the possible molecular mechanism underlying the pathogenicity of this novel AGK variant. Experimental validation using in vitro analysis allowed an accurate characterization of the disease-causing variant.

THE INHIBITION OF OXIDATIVE AND PHOSPHORYLATIVE ENZYMES IN RAT LIVER MITOCHONDRIA BY AMINOAZOBENZENE DERIVATIVES

1960 ◽  
Vol 38 (1) ◽  
pp. 1-11 ◽  
Author(s):  
W. C. McMurray
Keyword(s):  
Cytochrome C ◽  
Rat Liver ◽  
Pyridine Nucleotide ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Succinate Oxidation ◽  
Metabolic Block ◽  
Liver Carcinogen ◽  
Mitochondrial Dehydrogenase Activity

The liver carcinogen, dimethylaminoazobenzene, inhibited in vitro the oxidation of a variety of pyridine nucleotide linked substrates of rat liver mitochondria without affecting the process of oxidative phosphorylation. Cytochrome c oxidase activity was not inhibited by the carcinogen, nor was the succinoxidase activity, but the phosphorylation accompanying succinate oxidation was uncoupled. Similar effects were noted with other aminoazobenzene derivatives, but did not appear to be correlated with the ability of the compounds to evoke tumors.The site of the respiratory inhibition by dimethylaminoazobenzene appears to be at the level between reduced pyridine nucleotide and cytochrome c in the respiratory chain. Mitochondrial dehydrogenase activity was not inhibited, while the oxidation of reduced diphosphopyridine nucleotide was markedly decreased. The reduction of the electron acceptor, ferricyanide, by pyridine nucleotide linked substrates was also strongly inhibited but the reduction of tetrazolium compounds was not affected. The latter observations suggest that dimethylaminoazobenzene produces a metabolic block between reduced flavin and cytochrome c in the mitochondrial electron transport system.

THE INHIBITION OF OXIDATIVE AND PHOSPHORYLATIVE ENZYMES IN RAT LIVER MITOCHONDRIA BY AMINOAZOBENZENE DERIVATIVES

1960 ◽  
Vol 38 (1) ◽  
pp. 1-11
Author(s):  
W. C. McMurray
Keyword(s):  
Cytochrome C ◽  
Rat Liver ◽  
Pyridine Nucleotide ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Succinate Oxidation ◽  
Metabolic Block ◽  
Liver Carcinogen ◽  
Mitochondrial Dehydrogenase Activity

The liver carcinogen, dimethylaminoazobenzene, inhibited in vitro the oxidation of a variety of pyridine nucleotide linked substrates of rat liver mitochondria without affecting the process of oxidative phosphorylation. Cytochrome c oxidase activity was not inhibited by the carcinogen, nor was the succinoxidase activity, but the phosphorylation accompanying succinate oxidation was uncoupled. Similar effects were noted with other aminoazobenzene derivatives, but did not appear to be correlated with the ability of the compounds to evoke tumors.The site of the respiratory inhibition by dimethylaminoazobenzene appears to be at the level between reduced pyridine nucleotide and cytochrome c in the respiratory chain. Mitochondrial dehydrogenase activity was not inhibited, while the oxidation of reduced diphosphopyridine nucleotide was markedly decreased. The reduction of the electron acceptor, ferricyanide, by pyridine nucleotide linked substrates was also strongly inhibited but the reduction of tetrazolium compounds was not affected. The latter observations suggest that dimethylaminoazobenzene produces a metabolic block between reduced flavin and cytochrome c in the mitochondrial electron transport system.

HETEROGENEITY AND DIFFERENTIAL FRAGILITY OF RAT LIVER MITOCHONDRIA

1966 ◽  
Vol 44 (5) ◽  
pp. 497-508 ◽  
Author(s):  
C. V. Lusena ◽  
Florent Depocas
Keyword(s):  
Rat Liver ◽  
High Speed ◽  
Specific Activity ◽  
Mitochondrial Protein ◽  
Total Activity ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Fraction I

Five fractions (I–V) of intact mitochondria were obtained from rat liver by differential centrifugation during isolation. They represented respectively 4, 9, 64, 11, and 11% of the total mitochondrial protein. No striking differences between mitochondria sedimented at low speed (fraction I) and those sedimented at high speed (fraction V) were seen by electron microscopy. In all samples glutamic dehydrogenase (GD) specific activity was the same after deoxycholate treatment and less than 1% of the total activity could be detected in the fresh fractions. Overnight freezing at −5 °C of fractions I, III, and V followed by thawing at 37 °C liberated 25, 11, and 6% respectively of the total GD activity. The greater fragility of fraction I relative to that of fraction V was also apparent in the phase-contrast microscope during warming to room temperature; lysis occurred in 10 minutes in fraction I and in 1 hour in fraction V. The distribution of GD activity after centrifugation on sucrose density gradients indicated that partial disruption of the mitochondria had occurred in decreasing degree from fractions I to V. The different fragilities of the fractions in vitro did not reflect different lability in vivo since all fractions had the same rates of turnover as measured after they were labeled with14C acetate. The results are discussed in terms of heterogeneities observed by other methods.

P1, P5-Bis-(5′-adenosyl)pentaphosphate: Is this Adenylate Kinase Inhibitor Substrate for Mitochondrial Processes?

1977 ◽  
Vol 32 (9-10) ◽  
pp. 786-791 ◽  
Author(s):  
Josef Köhrle ◽  
Joachim Lüstorff ◽  
Eckhard Schlimme
Keyword(s):  
Adenylate Kinase ◽  
Kinase Inhibitor ◽  
Adenine Nucleotide ◽  
Nucleoside Diphosphate Kinase ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Rat Liver Mitochondria ◽  
Intermembrane Space ◽  
Rabbit Muscle ◽  
Inner Mitochondrial Membrane

Abstract 1. P1, P5-Bis-(5′-adenosyl)pentaphosphate (Ap5A) inhibits “soluble” adenylate kinase even when this enzyme is an integral part of the complete mitochondrion. The Ki is 10-5м , i. e. about two orders of magnitude higher than the inhibitor constants determined for the purified adenylate kinase of rabbit muscle and an enzyme preparation separated from the mitochondrial intermembrane space. The weaker inhibitory effect is due to a lower accessibility of the enzyme.2. As to be expected Ap5A which is of the “multisubstrate analogue”-type does not affect mito­ chondrial nucleoside diphosphate kinase.3. Though Ap5A owns the structural elements of both ATP and ADP it is not a substrate of the adenine nucleotide carrier, i.e. neither it is exchanged across the inner mitochondrial membrane nor specifically bound.4. Ap5A is not metabolized by rat liver mitochondria.

Magnetic nanostructured lipid carrier for dual triggered curcumin delivery: Preparation, characterization and toxicity evaluation on isolated rat liver mitochondria

2021 ◽  
pp. 088532822110346
Author(s):  
Mohammad Yoozbashi ◽  
Hamid Rashidzadeh ◽  
Mehraneh Kermanian ◽  
Somayeh Sadighian ◽  
Mir-Jamal Hosseini ◽  
...  
Keyword(s):  
In Vitro Study ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Nanostructured Lipid Carrier ◽  
Mitochondrial Toxicity ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Reducing Ability ◽  
Transmission Electron

In this research, magnetic nanostructured lipid carriers (Mag-NLCs) were synthesized for curcumin (CUR) delivery. NLCs are drug-delivery systems prepared by mixing solid and liquid (oil) lipids. For preparation of NLCs, cetylpalmitate was selected as solid lipid and fish oil as liquid lipid. CUR-Mag-NLCs were prepared using high-pressure homogenization technique and were characterized by methods including X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The CUR-Mag-NLCs were developed as a particle with a size of 140 ± 3.6 nm, a polydispersity index of 0.196, and a zeta potential of −22.6 mV. VSM analysis showed that the CUR-Mag-NLCs have excellent magnetic properties. Release rate of the drug was higher at 42 °C than 37 °C, indicating that release of the synthesized nanoparticles is temperature-dependent. Evaluation of mitochondrial toxicity was done using the isolated rats liver mitochondria including glutathione (GSH), malondialdehyde (MDA), and the ferric- reducing ability of plasma (FRAP) assays to study biosafety of the CUR-Mag-NLCs. Results of In vitro study on the isolated mitochondria revealed that both CUR-Mag-NLCs and curcumin have no specific mitochondrial toxicity.

IN VITRO LIPID PEROXIDATION INHIBITORY AND ANTI-ARTHRITIC ACTIVITIES OF SOME INDIAN MEDICINAL PLANTS

INDIAN DRUGS ◽  
2012 ◽  
Vol 49 (06) ◽  
pp. 31-35
Author(s):  
A. A Rege ◽  
◽  
P. R. Juvekar ◽  
A. R. Juvekar
Keyword(s):  
Lipid Peroxidation ◽  
Liver Mitochondria ◽  
Tinospora Cordifolia ◽  
Ocimum Sanctum ◽  
Rat Liver Mitochondria ◽  
Total Phenolic ◽  
Lipid Peroxidation Inhibitory Activity ◽  
Gallic Acid Equivalent ◽  
Indian Medicinal Plants

Anti-lipid peroxidation effect of aqueous extracts of Ocimum sanctum, Tinospora cordifolia and Withania somnifera was evaluated against Fe2+-ascorbic acid-induced lipid peroxidation using rat liver mitochondria as model system, whereas, anti-arthritic activity was evaluated by proteinase inhibitory assay. O. sanctum showed potent anti-lipid peroxidation and anti-arthritic activities. T. cordifolia exhibited moderate anti-lipid peroxidation activity, but considerable anti-arthritic activity, whereas, W. somnifera revealed least lipid peroxidation inhibitory activity and considerable anti-arthritic activity. Besides, Folin-Ciocalteu reagent in terms of gallic acid equivalent achieved the total phenolic content and the trend was found to be O. sanctum > T. cordifolia > W. somnifera.

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