scholarly journals The Stimulated Glycolytic Pathway Is Able to Maintain ATP Levels and Kinetic Patterns of Bovine Epididymal Sperm Subjected to Mitochondrial Uncoupling

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
João D. A. Losano ◽  
Juan Fernando Padín ◽  
Iago Méndez-López ◽  
Daniel S. R. Angrimani ◽  
Antonio G. García ◽  
...  
Keyword(s):  
Atp Synthesis ◽  
Glycolytic Pathway ◽  
Mitochondrial Uncoupling ◽  
Oxidative Balance ◽  
Atp Levels ◽  
Bovine Spermatozoa ◽  
Epididymal Spermatozoa ◽  
Sperm Movement ◽  
Oxidative Homeostasis

Studies have reported the importance of mitochondria in sperm functionality. However, for some species, the glycolytic pathway appears to be as important as oxidative phosphorylation in ATP synthesis and sperm kinetics. These mechanisms have not been fully elucidated for bovine spermatozoa. Therefore, the aim of this study was to evaluate the role of mitochondria and the glycolytic pathway in ATP synthesis, sperm movement patterns, and oxidative homeostasis of epididymal spermatozoa in bovine specimens. We observed that mitochondrial uncoupling with protonophores significantly reduced ATP levels. However, these levels were reestablished after stimulation of the glycolytic pathway. We verified the same pattern of results for sperm kinetic variables and the production of reactive oxygen species (ROS). Thus, we suggest that, after its appropriate stimulation, the glycolytic pathway is capable of maintaining ATP levels, sperm kinetic patterns, and oxidative balance of bovine epididymal spermatozoa submitted to mitochondrial uncoupling.

143 Stimulated glycolysis is able to maintain ATP levels and motility of bull spermatozoa submitted to mitochondrial depolarisation

2020 ◽  
Vol 32 (2) ◽  
pp. 198
Author(s):  
J. Losano ◽  
J. Padín ◽  
I. Méndez-López ◽  
D. Angrimani ◽  
N. Montez ◽  
...  
Keyword(s):  
Atp Synthesis ◽  
The Other ◽  
Atp Levels ◽  
Other Hand ◽  
Significant Difference ◽  
Carbonyl Cyanide ◽  
Bovine Spermatozoa ◽  
Kinetics Of ◽  
Glucose Supplementation

Studies have reported the importance of mitochondria in sperm metabolism. However, for some species, glycolysis appears to be as essential as oxidative phosphorylation in sperm physiology. On the other hand, these mechanisms have not been fully elucidated for bovine spermatozoa. Therefore, the aim of this study was to evaluate the role of mitochondria and glycolysis in ATP synthesis and sperm kinetics of bovine spermatozoa. For this purpose, sperm from seven bovine epididymides (n=7) was collected and diluted to a concentration of 100×106 spermatozoamL−1 in Tyrode's albumin lactate pyruvate medium. Then, each sample was divided into 10 aliquots and evaluated in a 2×5 factorial design, with the first factor being the presence or absence of glucose (5mM) to stimulate glycolysis and the second factor being treatment with the mitochondrial uncoupler carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP; 0, 0.1, 0.3, 1, and 3 µM) to deplete mitochondrial ATP. Sperm samples were subjected to measurements of ATP levels using a luminescence technique (CellTiter-Glokit, Promega), with ATP levels measured in duplicate. In addition, sperm samples were subjected to computerised analysis of total and progressive motilities (ISAS, Proiser). Statistical analysis was performed using SAS (SAS Institute Inc.), where the interaction between the factors was analysed using PROC GLM and the comparison between groups was performed using means analysis of variance (least significant difference test). It was considered significant at 5%. Adenosine triphosphate was lower at FCCP concentrations of 0.3 µM (180.3±31.9nM), 1 µM (220.2±40.4nM), and 3 µM (272.3±70.4nM) than at 0 µM (control; 448.6±63.7nM) and 0.1 µM (422.4±41.5nM) in the absence of glucose. However, in the groups treated with FCCP supplemented with glucose, ATP concentrations did not differ among the groups (0 µM: 577.2±70.4 nM; 0.1 µM: 610.8±57.8 nM; 0.3 µM: 606.2±64.2 nM; 1 µM: 670.9±61.9 nM; 3 µM: 696.1±68.5nM). Additionally, total motility was lower in FCCP-treated groups without glucose supplementation. On the other hand, total motility increased in the groups treated with 0.3, 0.1, 1, and 3 µM FCCP supplemented with glucose. A similar effect was verified for progressive motility. Based on these results, we can suggest that glucose supplementation is able to maintain ATP levels and motility in bull sperm undergoing FCCP-induced mitochondrial depolarisation.

scholarly journals The role of ATP in the differential ability of Sr2+ to trigger Ca2+ oscillations in mouse and human eggs

2021 ◽  
Author(s):  
Anna Storey ◽  
Khalil Elgmati ◽  
Yisu Wang ◽  
Paul Knaggs ◽  
Karl Swann
Keyword(s):  
Phospholipase C ◽  
Egg Activation ◽  
Apparent Difference ◽  
Free Medium ◽  
Inositol 1 ◽  
Atp Levels ◽  
Mature Mouse ◽  
Differential Ability ◽  
Mouse Eggs

Abstract At fertilization in mice and humans, the activation of the egg is caused by a series of repetitive Ca2+ oscillations which are initiated by phospholipase-C(zeta)ζ that generates inositol-1-4-5-trisphophate (InsP3). Ca2+ oscillations and egg activation can be triggered in mature mouse eggs by incubation in Sr2+ containing medium, but this does not appear to be effective in human eggs. Here we have investigated the reason for this apparent difference using mouse eggs, and human eggs that failed to fertilize after IVF or ICSI. Mouse eggs incubated in Ca2+-free, Sr2+-containing medium immediately underwent Ca2+ oscillations but human eggs consistently failed to undergo Ca2+ oscillations in the same Sr2+ medium. We tested the InsP3-receptor (IP3R) sensitivity directly by photo-release of caged InsP3 and found that mouse eggs were about 10 times more sensitive to InsP3 than human eggs. There were no major differences in the Ca2+ store content between mouse and human eggs. However, we found that the ATP concentration was consistently higher in mouse compared to human eggs. When ATP levels were lowered in mouse eggs by incubation in pyruvate-free medium, Sr2+ failed to cause Ca2+ oscillations. When pyruvate was added back to these eggs, the ATP levels increased and Ca2+ oscillations were induced. This suggests that ATP modulates the ability of Sr2+ to stimulate IP3R-induced Ca2+ release in eggs. We suggest that human eggs may be unresponsive to Sr2+ medium because they have a lower level of cytosolic ATP.

scholarly journals Mitochondrial microRNAs: A Putative Role in Tissue Regeneration

Biology ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 486
Author(s):  
Sílvia C. Rodrigues ◽  
Renato M. S. Cardoso ◽  
Filipe V. Duarte
Keyword(s):  
Tissue Regeneration ◽  
Protein Complexes ◽  
Mitochondrial Protein ◽  
Noncoding Rnas ◽  
Atp Synthesis ◽  
Mitochondrial Proteins ◽  
Cellular Mechanisms ◽  
Small Noncoding Rnas ◽  
Mitochondrial Ribosome

The most famous role of mitochondria is to generate ATP through oxidative phosphorylation, a metabolic pathway that involves a chain of four protein complexes (the electron transport chain, ETC) that generates a proton-motive force that in turn drives the ATP synthesis by the Complex V (ATP synthase). An impressive number of more than 1000 mitochondrial proteins have been discovered. Since mitochondrial proteins have a dual genetic origin, it is predicted that ~99% of these proteins are nuclear-encoded and are synthesized in the cytoplasmatic compartment, being further imported through mitochondrial membrane transporters. The lasting 1% of mitochondrial proteins are encoded by the mitochondrial genome and synthesized by the mitochondrial ribosome (mitoribosome). As a result, an appropriate regulation of mitochondrial protein synthesis is absolutely required to achieve and maintain normal mitochondrial function. Regarding miRNAs in mitochondria, it is well-recognized nowadays that several cellular mechanisms involving mitochondria are regulated by many genetic players that originate from either nuclear- or mitochondrial-encoded small noncoding RNAs (sncRNAs). Growing evidence collected from whole genome and transcriptome sequencing highlight the role of distinct members of this class, from short interfering RNAs (siRNAs) to miRNAs and long noncoding RNAs (lncRNAs). Some of the mechanisms that have been shown to be modulated are the expression of mitochondrial proteins itself, as well as the more complex coordination of mitochondrial structure and dynamics with its function. We devote particular attention to the role of mitochondrial miRNAs and to their role in the modulation of several molecular processes that could ultimately contribute to tissue regeneration accomplishment.

Mitochondrial Inhibition Prior to Oxygen-Withdrawal Facilitates the Occurrence of Hypoxia-Induced Spreading Depression in Rat Hippocampal Slices

2006 ◽  
Vol 96 (1) ◽  
pp. 492-504 ◽  
Author(s):  
Florian J. Gerich ◽  
Sebastian Hepp ◽  
Irmelin Probst ◽  
Michael Müller
Keyword(s):  
Mitochondrial Respiration ◽  
Spreading Depression ◽  
Hippocampal Slices ◽  
Atp Synthesis ◽  
Atp Depletion ◽  
Mitochondrial Uncoupling ◽  
Ca1 Neurons ◽  
Optical Signals ◽  
Nitropropionic Acid ◽  
Carbonyl Cyanide

Oxygen withdrawal blocks mitochondrial respiration. In rat hippocampal slices, this triggers a massive depolarization of CA1 neurons and a negative shift of the extracellular DC potential, the characteristic sign of hypoxia-induced spreading depression (HSD). To unveil the contribution of mitochondria to the sensing of hypoxia and the ignition of HSD, we modified mitochondrial function. Mitochondrial uncoupling by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP, 1 μM) prior to hypoxia hastened the onset and shortened the duration of HSD. Blocking mitochondrial ATP synthesis by oligomycin (10 μg/ml) was without effect. Inhibition of mitochondrial respiration by rotenone (20 μM), diphenyleneiodonium (25 μM), or antimycin A (20 μM) also hastened HSD onset and shortened HSD duration. 3-nitropropionic acid (1 mM) increased HSD duration. Cyanide (100 μM) hastened HSD onset and increased HSD duration. At higher concentrations, cyanide (1 mM), azide (2 mM), and FCCP (10 μM) triggered SD episodes on their own. Compared with control HSD, the spatial extent of the intrinsic optical signals of cyanide- and azide-induced SDs was more pronounced. Monitoring NADH (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) autofluorescence and mitochondrial membrane potential verified the mitochondrial targeting by the drugs used. Except 1 mM cyanide, no treatment reduced cellular ATP levels severely and no correlation was found between ATP, NADH, or FAD levels and the time to HSD onset. Therefore ATP depletion or a cytosolic reducing shift due to NADH/FADH2 accumulation cannot serve as a general explanation for the hastening of HSD onset on mitochondrial inhibition. Additional redox couples (glutathione) or events downstream of the mitochondrial depolarization need to be considered.

Ischemic preconditioning in rats: role of mitochondrial KATP channel in preservation of mitochondrial function

2000 ◽  
Vol 278 (1) ◽  
pp. H305-H312 ◽  
Author(s):  
Ryan M. Fryer ◽  
Janis T. Eells ◽  
Anna K. Hsu ◽  
Michele M. Henry ◽  
Garrett J. Gross
Keyword(s):  
Infarct Size ◽  
Ischemic Preconditioning ◽  
Mitochondrial Function ◽  
Ischemia Reperfusion ◽  
Mitochondrial Protein ◽  
Atp Synthesis ◽  
Area At Risk ◽  
Selective Antagonist ◽  
Mitochondrial Katp Channel

We examined the role of the sarcolemmal and mitochondrial KATPchannels in a rat model of ischemic preconditioning (IPC). Infarct size was expressed as a percentage of the area at risk (IS/AAR). IPC significantly reduced infarct size (7 ± 1%) versus control (56 ± 1%). The sarcolemmal KATP channel-selective antagonist HMR-1098 administered before IPC did not significantly attenuate cardioprotection. However, pretreatment with the mitochondrial KATP channel-selective antagonist 5-hydroxydecanoic acid (5-HD) 5 min before IPC partially abolished cardioprotection (40 ± 1%). Diazoxide (10 mg/kg iv) also reduced IS/AAR (36.2 ± 4.8%), but this effect was abolished by 5-HD. As an index of mitochondrial bioenergetic function, the rate of ATP synthesis in the AAR was examined. Untreated animals synthesized ATP at 2.12 ± 0.30 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1. Rats subjected to ischemia-reperfusion synthesized ATP at 0.67 ± 0.06 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1. IPC significantly increased ATP synthesis to 1.86 ± 0.23 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1. However, when 5-HD was administered before IPC, the preservation of ATP synthesis was attenuated (1.18 ± 0.15 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1). These data are consistent with the notion that inhibition of mitochondrial KATPchannels attenuates IPC by reducing IPC-induced protection of mitochondrial function.

scholarly journals 175 The effects of tbq on cardiac intracellular atp levels; role of oxidative phosphorylation and oxidative stress

Heart ◽  
2017 ◽  
Vol 103 (Suppl 5) ◽  
pp. A122.1-A122
Author(s):  
Natasha Hadgraft ◽  
David Greensmith ◽  
Gina Galli ◽  
Louise Miller
Keyword(s):  
Oxidative Stress ◽  
Oxidative Phosphorylation ◽  
Intracellular Atp ◽  
Atp Levels ◽  
And Oxidative Stress

scholarly journals PAT2 regulates autophagy through vATPase assembly and lysosomal acidification in brown adipocytes

2020 ◽  
Author(s):  
Jiefu Wang ◽  
Martin Krueger ◽  
Stefanie M. Hauck ◽  
Siegfried Ussar
Keyword(s):  
Amino Acid ◽  
Brown Adipocyte ◽  
Amino Acid Transporters ◽  
Mitochondrial Uncoupling ◽  
Brown Adipocytes ◽  
Brown Adipose ◽  
Glucose And Lipid Homeostasis ◽  
Mtorc1 Activation ◽  
Lysosomal Acidification

Brown adipose tissue (BAT) plays a key role in maintaining body temperature as well as glucose and lipid homeostasis by its ability to dissipate energy through mitochondrial uncoupling. To facilitate these tasks BAT needs to adopt its thermogenic activity and substrate utilization to changes in nutrient availability, regulated by a complex network of neuronal, endocrine and nutritional inputs. Amongst this multitude of factors influencing BAT activity changes in the autophagic response of brown adipocytes are an important regulator of its thermogenic capacity and activity. Increasing evidence supports an important role of amino acid transporters in mTORC1 activation and the regulation of autophagy. However, a specific role of amino acid transporters in BAT regulating its function has not been described. Here we show that the brown adipocyte specific proton coupled amino acid transporter PAT2 rapidly translocates from the plasma membrane to the lysosome in response to amino acid withdrawal, where it facilitates the assembly of the lysosomal vATPase. Loss or overexpression of PAT2 therefore impair lysosomal acidification, autophagolysosome formation and starvation induced mTORC1 activation.

scholarly journals The essential role of sodium bioenergetics and ATP homeostasis in the developmental transitions of a cyanobacterium

2020 ◽  
Author(s):  
Sofia Doello ◽  
Markus Burkhardt ◽  
Karl Forchhammer
Keyword(s):  
Energy Homeostasis ◽  
Nitrogen Starvation ◽  
Critical Role ◽  
Quiescent State ◽  
Bacterial Survival ◽  
Bacterial Populations ◽  
Photoautotrophic Growth ◽  
Available Energy ◽  
Atp Levels

The ability to resume growth after a dormant period is an important strategy for the survival and spreading of bacterial populations. Energy homeostasis is critical in the transition into and out of a quiescent state. Synechocystis sp. PCC 6803, a non-diazotrophic cyanobacterium, enters metabolic dormancy as a response to nitrogen starvation. We used Synechocystis as a model to investigate the regulation of ATP homeostasis during dormancy and unraveled a critical role for sodium bioenergetics in dormant cells. During nitrogen starvation, cells reduce their ATP levels and engage sodium bioenergetics to maintain the minimum ATP content required for viability. When nitrogen becomes available, energy requirements rise, and cells immediately increase ATP levels employing sodium bioenergetics and glycogen catabolism. These processes allow them to restore the photosynthetic machinery and resume photoautotrophic growth. Our work reveals a precise regulation of the energy metabolism essential for bacterial survival during periods of nutrient deprivation.

scholarly journals Systemic impact of the expression of the mitochondrial alternative oxidase on Drosophila development

2021 ◽  
Author(s):  
André F. Camargo ◽  
Sina Saari ◽  
Geovana S. Garcia ◽  
Marina M. Chioda ◽  
Murilo F. Othonicar ◽  
...  
Keyword(s):  
Metabolic Regulation ◽  
Alternative Oxidase ◽  
Atp Synthesis ◽  
Biomass Accumulation ◽  
Proton Pumping ◽  
Membrane Phospholipids ◽  
Mitochondrial Uncoupling ◽  
Morphological Alterations ◽  
Beneficial Effects ◽  
Tissue Proliferation

Despite the beneficial effects shown when the mitochondrial alternative oxidase AOX from Ciona intestinalis (Tunicata: Ascidiacea) is xenotopically expressed in mammalian and insect models, important detrimental outcomes have also been reported, raising concerns regarding its envisioned deployment as a therapy enzyme for human mitochondrial and related diseases. Because of its non-proton pumping terminal oxidase activity, AOX can bypass the cytochrome c segment of the respiratory chain and alleviate the possible overload of electrons that occurs upon oxidative phosphorylation (OXPHOS) dysfunction, not contributing though to the proton-motive force needed for mitochondrial ATP synthesis. We have shown previously that AOX-expressing flies present a dramatic drop in pupal viability when the larvae are cultured on a low nutrient diet, indicating that AOX interferes with normal developmental metabolism. Here, we applied combined omics analyses to show that the interaction between low nutrient diet and AOX expression causes a general alteration of larval amino acid metabolism and lipid accumulation, which are associated with functional and morphological alterations of the larval digestive tract and with a drastic decrease in larval biomass accumulation. Pupae at the pre-lethality stage present a general downregulation of mitochondrial metabolism and a signature for starvation and deregulated signaling processes. This AOX-induced lethality is partially rescued when the low nutrient diet is supplemented with tryptophan and/or methionine. The developmental dependence on these amino acids, associated with elevated levels of lactate dehydrogenase, lactate, 2-hydroxyglutarate, choline-containing metabolites and breakdown products of membrane phospholipids, indicates that AOX expression promotes tissue proliferation and growth of the Drosophila larvae, but this is ultimately limited by energy dissipation via mitochondrial uncoupling. We speculate that the combination of diet and AOX expression may be used for the metabolic regulation of proliferative tissues, such as tumors.

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