Search results for "cellular respiration"

Enniatin B induces expression changes in the electron transport chain pathway related genes in lymphoblastic T-cell line

2018

Abstract Enniatin B is a ionophoric and lipophilic mycotoxin which reaches the bloodstream and has the ability to penetrate into cellular membranes. The purpose of this study was to reveal changes in the gene expression profile caused by enniatin B in human Jurkat lymphoblastic T-cells after 24 h of exposure at 1.5, 3 and 5 μM by next generation sequencing. It was found that up to 27% of human genome expression levels were significantly altered (5750 genes for both down-regulation and up-regulation). In the three enniatin B concentrations studied 245 differentially expressed genes were found to be overlapped, 83 were down and 162 up-regulated. ConsensusPathDB analysis of over-representation…

Revisiting the Warburg effect: historical dogma versus current understanding

2020

Contrary to Warburg's original thesis, accelerated aerobic glycolysis is not a primary, permanent and universal consequence of dysfunctional or impaired mitochondria compensating for poor ATP yield per mole of glucose. Instead, in most tumours the Warburg effect is an essential part of a 'selfish' metabolic reprogramming, which results from the interplay between (normoxic/hypoxic) hypoxia-inducible factor-1 (HIF-1) overexpression, oncogene activation (cMyc, Ras), loss of function of tumour suppressors (mutant p53, mutant phosphatase and tensin homologue (PTEN), microRNAs and sirtuins with suppressor functions), activated (PI3K-Akt-mTORC1, Ras-Raf-MEK-ERK-cMyc, Jak-Stat3) or deactivated (LKB…

The HMGB1 protein induces a metabolic type of tumour cell death by blocking aerobic respiration

2016

The high-mobility group box 1 (HMGB1) protein has a central role in immunological antitumour defense. Here we show that natural killer cell-derived HMGB1 directly eliminates cancer cells by triggering metabolic cell death. HMGB1 allosterically inhibits the tetrameric pyruvate kinase isoform M2, thus blocking glucose-driven aerobic respiration. This results in a rapid metabolic shift forcing cells to rely solely on glycolysis for the maintenance of energy production. Cancer cells can acquire resistance to HMGB1 by increasing glycolysis using the dimeric form of PKM2, and employing glutaminolysis. Consistently, we observe an increase in the expression of a key enzyme of glutaminolysis, malic …

2016

The cellular prion protein (PrPc) and hypoxia appear to be tightly intertwined. Beneficial effects of PrPc on neuronal survival under hypoxic conditions such as focal cerebral ischemia are strongly supported. Conversely, increasing evidence indicates detrimental effects of increased PrPc expression on cancer progression, another condition accompanied by low oxygen tensions. A switch between anaerobic and aerobic metabolism characterizes both conditions. A cellular process that might unite both is glycolysis. Putative role of PrPc in stimulation of glycolysis in times of need is indeed thought provoking. A significance of astrocytic PrPc expression for neuronal survival under hypoxic conditi…

Mitochondrial CB1 receptors regulate neuronal energy metabolism

2012

The mammalian brain is one of the organs with the highest energy demands, and mitochondria are key determinants of its functions. Here we show that the type-1 cannabinoid receptor (CB(1)) is present at the membranes of mouse neuronal mitochondria (mtCB(1)), where it directly controls cellular respiration and energy production. Through activation of mtCB(1) receptors, exogenous cannabinoids and in situ endocannabinoids decreased cyclic AMP concentration, protein kinase A activity, complex I enzymatic activity and respiration in neuronal mitochondria. In addition, intracellular CB(1) receptors and mitochondrial mechanisms contributed to endocannabinoid-dependent depolarization-induced suppres…

The inefficient aerobic energetics ofZymomonas mobilis: Identifying the bottleneck

2014

To investigate the mechanisms of Zymomonas mobilis uncoupled aerobic metabolism, growth properties of the wild-type strain Zm6 were compared to those of its respiratory mutants cytB and cydB, and the effects of the ATPase inhibitor DCCD on growth and intracellular ATP concentration were studied. The effects of the ATPase inhibitor DCCD on growth and intracellular ATP concentration strongly indicated that the apparent lack of oxidative phosphorylation in aerobically growing Z. mobilis culture might be caused by the ATP hydrolyzing activity of the H(+) -dependent ATPase in all analyzed strains. Aerobic growth yields of the mutants, and their capacity of oxidative ATP synthesis with ethanol we…

Anaerobic respiration of Bacillus macerans with fumarate, TMAO, nitrate and nitrite and regulation of the pathways by oxygen and nitrate

1995

In Bacillus macerans, anaerobic respiratory pathways and the regulation of facultatively anaerobic catabolism by electron acceptors were analysed. In addition to fermentative growth, B. macerans was able to grow anaerobically by fumarate, trimethylamine N-oxide, nitrate, and nitrite respiration with glycerol as donor. During growth by fumarate respiration, a membrane-bound fumarate reductase was present that was different from succinate dehydrogenase. The end product of nitrate and nitrite respiration was ammonia. No N2 or NO and only traces of N2O could be detected. O2 repressed the activity of nitrate and fumarate reductases and the fermentation of glucose, presumably at the transcription…

Alternative respiratory pathways of Escherichia coli: energetics and transcriptional regulation in response to electron acceptors

1997

AbstractThe electron-transport chains of Escherichia coli are composed of many different dehydrogenases and terminal reductases (or oxidases) which are linked by quinones (ubiquinone, menaquinone and demethylmenaquinone). Quinol:cytochrome c oxido-reductase (`bc1 complex') is not present. For various electron acceptors (O2, nitrate) and donors (formate, H2, NADH, glycerol-3-P) isoenzymes are present. The enzymes show great variability in membrane topology and energy conservation. Energy is conserved by conformational proton pumps, or by arrangement of substrate sites on opposite sides of the membrane resulting in charge separation. Depending on the enzymes and isoenzymes used, the H+/e− rat…

Modulation of tumor oxygenation

1998

There is a large body of evidence suggesting that deficiencies in the O2 supply of tumors exist due to restrictions (i) in the O2 delivery by perfusion and/or diffusion, and (ii) in the O2 transport capacity. Whereas the former are mostly based on inadequate and heterogeneous microcirculatory functions, the latter are predominantly due to tumor-associated anemia. Possible uses and limitations of measures are discussed which can increase the microvascular O2 content and thus may preferentially serve to enhance diffusion-limited O2 availability. In addition, means are described for improving and increasing the uniformity of microcirculation thus possibly enhancing perfusion-limited O2 deliver…

Energy Transduction in Anaerobic Bacteria

2013

Anaerobic or facultatively anaerobic bacteria are able to grow in the absence of molecular oxygen by fermentation, anaerobic respiration, anoxygenic photosynthesis, and some other membrane-dependent reactions. Fermentation uses substrate-level phosphorylation for adenosine diphosphate phosphorylation, whereas the other processes rely on the formation of a H + or Na + potential over the membrane and a membrane-potential-driven ATP synthase. In growth reactions providing only a small free energy change, the latter reactions and use of a membrane potential is the preferred mechanism for energy conservation. Fermentation reactions supply products of biotechnological interest like short chain fa…