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Glycolysis of red cells suspended in solutions of impermeable solutes. Intracellular pH and glycolysis.

The glycolytic rate human red cells suspended in a sucrose medium of low or physiological pH was higher than that of the cells suspended in Ringer's medium of the same. pH. The medium pHP-glycolytic rate curve of red cells suspended in soucrose media shifted to the acidic side by about one unit compared with that of cells suspended in Ringer's medium. Similarly, the pattern of glycolytic intermediates in red cells suspended in a sucrose medium resembled that in cells suspended in Ringer's solution of about one unit higher pH. These phenomena could be ascribed to the change of intracellular pH, which was measured by the 5,5'-dimethyl-oxazolidine-2,4-dione method. A similar stimulation of glycolysis was observed when sodium citrate was added to red cells suspended in Ringer's solution at constant pH. These observations indicate that membrane-impermeable non-electrolytes or anions stimulate glycolysis of red cells by elevation ofthe intracellular pH. Red cell glycolysis is influenced mainly by the intracellular pH rather than by the pH of the suspending medium.

Adenosine Triphosphate

[Glycolysis in the eye tissues of the rabbit in ontogeny. I. The enzymes of glycolysis and hexosemonophosphate shunt].

The activity of the enzymes of glycolysis (phosphofructokinase, aldolase, pyruvate kinase, lactate dehydrogenase) and hexose monophosphate shunt (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase) was determined in the eye tissues of the rabbit at different stages of ontogenesis. The activity of these enzymes in the retina was shown to be higher than in other eye tissues. In the uveal tract (iris, ciliary bodies, uvea) the activity of glycolytic enzymes changes with the age. The greatest changes in the activity of enzymes were found during the period of the opening of eyelids. The activity of the enzymes of hexose monophosphate shunt in the eye tissues increases with the age. The relative activity of dehydrogenases of the hexose monophosphate shunt after the establishment of visual function is, however, not high and does not exceed that of phosphofructokinase and pyruvate kinase in the eye tissues of the rabbit.

Age Factors

[Quantitative model of human erythrocyte glycolysis. I. Relationship between the stationary rate of glycolysis and the ATP concentration].

A mathematical model is presented of the Embden--Meyerhof pathway in the human red blood cell. The rate of the system stationary flux is determined by the first part of the chain including three enzymatic reactions. The function has been calculated which describes the dependence of the stationary rate of glucose consumption and ATP production on the concentration of ATP. The curve has a bell shape with the physiological normal point situated in the descending segment. The descending segment is a result of the inhibition of the phosphofructokinase by ATP and the strong inhibition of the hexokinase by glucose-6-phosphate.

Adenosine Triphosphate

ARL6IP1 Inhibits Breast Cancer Tumor Progression by Targeting OLFM4 to Regulate Glycolysis.

INTRODUCTION: ARL6IP1 has been linked to cancer progression, but its precise role in BC, particularly in metabolism and its interaction with an OLFM4, remains unclear. AIMS: This study aimed to investigate the role of ADP-ribosylation factor-like 6 interacting protein 1 (ARL6IP1) in breast cancer (BC) cell behavior and metabolism and explore its interaction with an olfactomedin-4 (OLFM4) as a potential therapeutic target. OBJECTIVE: The objective of this study was to determine the effects of ARL6IP1 knockdown on BC cell proliferation, invasion, migration, apoptosis, oxidative stress, and glycolysis. Additionally, this study also explored the interaction between ARL6IP1 and OLFM4 and their combined role in BC progression and metabolism. METHODS: Key gene modules in the GSE73540 dataset were identified through weighted gene co-expression network analysis (WGCNA). Three BC-related datasets (GSE73540, GSE22820, and GSE36295) and The Cancer Genome Atlas (TCGA) were applied for additional examination of differentially expressed genes (DEGs). Intersection analysis selected ARL6IP1 as a hub gene for prognostic analysis. In vitro experiments investigated how ARL6IP1 knockdown influences BC cell proliferation, invasion, migration, apoptosis, epithelial-mesenchymal transition (EMT), oxidative stress, and glycolysis. The connection between ARL6IP1 and an OLFM4 was confirmed using Co-immunoprecipitation (Co-IP), and their roles in BC tumor progression and glycolysis were evaluated. RESULTS: ARL6IP1 was elevated in BC datasets and linked with poor BC prognosis. Experiments demonstrated that knockdown of ARL6IP1 significantly reduced BC cell growth while promoting apoptosis and oxidative stress. Besides, ARL6IP1 knockdown reduced glycolysis, as manifested by decreased extracellular acidification rate (ECAR), glucose consumption, adenosine triphosphate (ATP) levels, and lactate production while increasing mitochondrial respiration (OCR). Co-IP validated the connection between ARL6IP1 and OLFM4, and OLFM4 overexpression partially counteracted the suppression of glycolysis and cell behavior resulting from ARL6IP1 knockdown. CONCLUSION: ARL6IP1 is a critical regulator of BC progression, influencing glycolysis, mitochondrial function, and key cellular behaviors. Targeting the ARL6IP1-OLFM4 axis offers a promising therapeutic strategy for managing BC.

Humans

Glycolysis in quiescent cultures of 3T3 cells. Stimulation by serum, epidermal growth factor, and insulin in intact cells and persistence of the stimulation after cell homogenization.

Addition of serum to quiescent cultures of 3T3 cells rapidly increases lactic acid formation and subsequently stimulates cell division. The stimulation of lactic acid production is seen at high, saturating concentrations of extra-cellular glucose. It is dependent on the time of exposure and on the dose of serum and is not blocked by the addition of cycloheximide, puromycin, or actinomycin D. In contrast, serum only marginally affects glycolysis by rapidly growing 3T6 or SV40-3T3 cells. In addition to serum, epidermal growth factor (0.1 to 10 ng/ml) and insulin (10 to 500 ng/ml) cause a striking stimulation of glycolysis in quiescent 3T3 cells. Neither exogenous cyclic nucleotides nor ouabain effect the glycolytic response, but the presence of Ca2+ markedly influences the activation of glycolysis by epidermal growth factor and by insulin. A novel finding in this study is that homogenates prepared from quiescent cells treated with serum, epidermal growth factor, or insulin show increased glycolysis as compared with homogenates from nonstimulated cultures. This finding will allow further experimental analysis of the cause of increased glycolysis in rapidly proliferating cells.

Blood

[Origination and importance of glycolysis for malignomas and utilization of this property in the chemotherapy of cancer (author's transl)].

Glycolysis is not of importance for the process of carcinogenesis. It is very likely, however, that certain molecular-biological and genetic changes are produced which enable the malignant cell to develop an intensive glycolysis, for instance, to form specialized glycolytic isoenzymes already during oncogenesis, and may possible become effective in the primary tumour. As soon as the capacity of the cancer cell to intensive aerobic and anaerobic glycolysis has become manifest, this process is an irreversible one. The extent of glycolysis of a malignoma is greatly dependent on the degree of its dedifferentiation and vascularization (glucose supply), although a direct correlation between growth and the amount of lactic acid formed does not seem to exist. However, a certain utilization of glucose is essential for cell proliferation (supply of basic substances). In many cases there is a correlation between the extent of glycolysis measurable under optimal conditions in vitro (glycolytic power) in a malignant tumour and its growth rate recognizable in vivo. The formation of a strong capacity for glucose degradation via the Embden-Meyerhof pathway that cannot be fully utilized by the whole tumour in vivo is first of all designed to ensure survival and proliferation of cells even at extremely low levels of glucose supply. This process can be regarded as an adaptation of cancer cells to a situation of unsufficient supply. This circumstance endows the cancer cell with an essential advantage over the normal cell which enables or even promotes its invasive and destructive growth and metastatic dissemination. In this respect they differ, for instance, from benignant neoplasms. The possibility is discussed to control neoplastic growth by adjusting an optimal pH difference between normal and tumour tissue by combined administration of detoxicated drugs which are converted to their toxic forms only in the tumour by means of strongly pH-dependent exogenous enzymes.

Glucose

Glycolysis-dependent reactive oxygen species mediate desmopressin acetate-induced rescue of platelet dysfunction caused by antiplatelet therapy.

Antiplatelet therapy is extensively used in the prevention and treatment of cardiovascular and cerebrovascular diseases; however, life-threatening hemorrhage requires urgent reversal of platelet dysfunction. Desmopressin acetate has been proposed as a rescue strategy, yet its efficacy and underlying mechanisms remain incompletely understood, particularly regarding redox regulation. A mouse carotid artery blood flow injury model was employed to evaluate the effects of desmopressin acetate on platelet and coagulation dysfunction induced by antiplatelet therapy. Proteomic analyses were performed in both patients and mice to identify differentially expressed proteins. Genetic knockout and pharmacological inhibition approaches were used to investigate the mechanistic pathways involved. Desmopressin acetate effectively restored platelet function and coagulation capacity in antiplatelet-treated mice. Proteomic profiling identified peroxiredoxin-5, a key antioxidant enzyme, as significantly upregulated following antiplatelet therapy but markedly downregulated after desmopressin acetate administration; these findings were validated in plasma samples from 10 patients who received dual antiplatelet therapy for unruptured intracranial aneurysms. Functional studies demonstrated that proteomic profiling identified peroxiredoxin-5 supplementation impaired platelet function, whereas proteomic profiling identified peroxiredoxin-5 knockout or inhibition significantly improved platelet activity. Notably, desmopressin acetate primarily suppressed liver-derived proteomic profiling identified peroxiredoxin-5 expression. Mechanistically, desmopressin acetate enhanced platelet glycolysis via phosphofructokinase-2/fructose-2,6-bisphosphatase 3 activation, leading to increased intracellular reactive oxygen species levels. Inhibition of phosphofructokinase-2/fructose-2,6-bisphosphatase 3 attenuated glycolysis, reduced reactive oxygen species generation, and restored proteomic profiling identified peroxiredoxin-5 expression, thereby abolishing the platelet-rescuing effects of desmopressin acetate. Desmopressin acetate rescued platelet dysfunction induced by antiplatelet therapy through a glycolysis-reactive oxygen species-proteomic profiling identified peroxiredoxin-5 axis, in which glycolysis-driven reactive oxygen species generation plays a central regulatory role. These findings indicate redox modulation as a critical mechanism underlying desmopressin acetate-mediated platelet rescue and suggest a potential therapeutic strategy for managing severe bleeding associated with antiplatelet therapy.

Animals

Experimental study on renal and hepatic glucose metabolism in total gastrectomized dogs with special reference to glycolysis and glyconeogenesis.

In spite of the extensive studies on glucose metabolism in surgical field, the postoperative renal and hepatic glucose metabolism and their interrelation have not been reported. The present study was undertaken to interrelate the metabolic states in the kidney and the liver in total gastrectomized dogs. In the kidney, the glycolysis was inhibited in the early postoperative stage whereas the gluconeogenesis was activated. In the late postoperative stage the glycolysis remained slightly inhibited, while the gluconeogenesis remained activated. In the liver, in the early postoperative stage the glycolysis was inhibited, whereas the gluconeogenesis was activated. The glycolysis in the late postoperative stage returned to the preoperative stage, while the gluconeogenesis remained inhibited. The gluconeogenesis in both kidney and liver was disturbed in the early postoperative stage while they were restored, but were reversed, in the late postoperative stage.

Animals

The control of anaerobic glycolysis by glucose transport and ouabain in slices of hepatoma 3924A.

1. The activities of glycolysis and K-+ transport have been studied in slices of Morris hepatoma 3924A incubated under anaerobic conditions in the presence of different concentrations of glucose (1-50 mM). 2. Ouabain-sensitive net transport of K-+ was observed at all glucose concentrations greater than 1 mM; ouabain reduced the rate of glycolysis by about 25% at all glucose concentrations able to support ion transport. 3. The net entry of glucose into the intracellular phase was studied at varying glucose concentrations. The rate of glucose entry was similar to the rate of glucose utilisation by anaerobic glycolysis at medium concentrations of 10 mM and less, but exceeded the rate of glycolysis at 20 mM and above. 4. The glucose entry was not Na-+-dependent and was not inhibited by ouabain. 5. The results suggest (a) that the reduction in glycolytic activity caused by ouabain is not due to an inhibition of glucose transport and (b) that the glucose transport system of this poorly differentiated hepatoma has properties similar to that of normal liver.

Anaerobiosis

Anaerobic glycolysis in normal human erythrocytes incubated in vitro with sodium salicylate.

1. Some effects of sodium salicylate upon anaerobic glycolysis have been studied in normal human erythrocytes incubated for up to 6 h at 37 degrees C in autologous sera. 2. Both glucose consumption and lactate production were stimulated by concentrations of salicylate up to 60 mmol/l but at the highest concentration used (90 mmol/l) an initial stimulus was followed by inhibition of glycolysis. 3. Losses occurred of adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP) and adenosine 5'-phosphate(AMP)at higher concentrations of salicylate and there was a concomitant increase of inorganic phosphate. 4. Other phosphate esters underwent concentration changes at higher concentrations of salicylate that reflected inadequate concentrations of ATP for glycolysis. 5. The rates of sodium efflux from, and potassium influx into, erythrocytes were unaffected by the presence of salicylate at concentrations sufficient to stimulate glycolysis.

Adenosine Diphosphate

31P nuclear magnetic resonance studies of bioenergetics and glycolysis in anaerobic Escherichia coli cells.

31P nuclear magnetic resonance spectra of glycolyzing, anaerobic Escherichia coli cells and their perchloric acid extracts were obtained at 145.7 MHz. Time-dependent intracellular concentrations of nucleoside di- and triphosphates, Pi, and sugar phosphates were measured during glycolysis with 2-min resolution, while intracellular and extra-cellular pH values were monitored simultaneously. Upon glucose addition, anaerobic E. coli cells rapidly produce acids and develop a transmembrane pH gradient (delta pH). Glycolysis rates were calculated from the changes in the external pH. It was found that glycolysis rates are strongly dependent on internal pH, sharply decreasing when the pH drops below approximately 7.2. The ATPase inhibitor, dicyclohexylcarbodiimide (DCCD), prevented NTP hydrolysis and inhibited delta pH formation. The uncoupler, carbonyl cyanide p-triflouromethoxyphenyl hydrazone (FCCP), drastically reduced both the delta pH and the NTP level. When the cells were previously treated with DCCD, FCCP collapsed the delta pH while the NTP levels remained high. It is concluded that ATP produced by glycolysis is hydrolyzed by the membrane ATPase to generate a delta pH and that FCCP stimulates ATP hydrolysis by ATPase and collapses the proton gradient.

Anaerobiosis

Inhibition of glycolysis and interference with protein synthesis in hepatoma cells.

Ascites hepatoma cells grown in Wistar rats were incubated anaerobically in the absence of glucose or in the presence of both glucose and D(+)glucosamine, or monoiodoacetate, or NADH, which interfered with glycolysis at different steps and with different mechanisms: Under all these conditions the incorporation of amino acids into the proteins of hepatoma cells was severely reduced without any clear relationship to the degree of inhibition of glycolysis. The postmitochondrial supernatants showed defective incorporation only when obtained from cells incubated in the absence of glucose or in the presence of monolodoacetate; inhibition of glycolysis by glucosamine and NADH did not seem to affect the subcellular basis for protein synthesis. When present, the defect of the cell sap (monoiodoacetate and absence of glucose) and to disaggregation and reduced functional capacity of the polysomes (absence of glucose). The results suggested that the effects of the inhibition of glycolysis on protein synthesis and on the integrity of the protein-synthesizing machinery--which were primarily due to the depletion of the energy stores--might have been modified by the particular mechanism of action of the inhibitor and by the way low levels of ATP were reached in the cell.

Adenosine Triphosphate

Cow red blood cells. II. Stimulation of bovine red cell glycolysis by plasma.

Cow red cell glycolysis, which can be stimulated by a variety of purines and pyrimidines, was also found to be elevated by its own plasma. Dialyzed or charcoal-treated plasma could no longer stimulate glycolysis, suggesting that the stimulating factors may be purines or pyrimidines. Determination of purines or pyrimidines in plasma revealed the presence of xanthine (0.31 muM), hypoxanthine (0.60 muM), and adenosine (0.05 muM), as well as unknown compounds. A physiologic level of hypoxanthine, with or without xanthine and adenosine approximating their concentrations in plasma, resulted in the stimulation of cow red cell glycolytic rate by 16% (P less than 0.01). These findings suggest that plasma-borne purines may act on cow red cells in concert with as yet unidentified factors. Moreover, exchanging calf and cow plasmas produced no stimulatory effect on either calf or cow red cell glycolysis, suggesting that a) calf red cells lack some of the cellular components that respond to this stimulator and, b) only cow plasma contains this specific stimulator. In other species, including dog, cat, rabbit, rat, guinea pig, and human, stimulation of glycolysis by plasma was not observed.

Aging

Control of glycolysis and the pentose phosphate shunt in transformed 3T3 cultures rendered permeable by ATP.

Exogenous ATP has been shown earlier to activate a permeability change in transformed 3T3 cultures leading to massive efflux of the acid-soluble pools. This leads to reduction of the basal rate of glycolysis to a very low level so that glycolysis becomes almost totally dependent on the addition to the medium of glucose, inorganic phosphate and ADP in order to restore the rate to that of untreated cells. No such depression of glycolysis is observed in untreated transformed cells or in ATP-treated normal 3T3 cells. In such permeabilized cultures, phosphorylated intermediates such as glucose-6-phosphate and fructose-1,6-diphosphate can serve as effective substrates for lactic acid formation. ATP treatment of cultured cells also allows molecules as big as NADP to enter the cells and participate in the pentose phosphate shunt pathway. This ability to temporarily and differentially render transformed cells permeable allows a review of several aspects of cellular metabolism and biosynthesis in the intact cell where the cellular organization is maintained. Furthermore, it deserves serious consideration as a means to achieve differential cytotoxicity of transformed cells by chemotherapeutic agents which, on their own, are indiscriminate in their action.

Adenosine Triphosphate

Glycolysis in human erythrocytes containing elevated concentrations of 2, 3-P2-glycerate.

In studies on the mechanism of the inhibitory effect of 2, 3-diphosphoglycerate on glycolysis in human erythrocytes, the following results were obtained: 1) Glucose consumption and lactate production are reduced by 70 and 40 per cent relative to normal erythrocytes in red blood cells containing five times the normal amount of 2, 3, -P2-glycerate ("high-diphosphoglycerate" cells) at an extracellular pH of 7.4. The marked dependency of glycolysis on the extracellular pH observed in normal erythrocytes is almost completely lost in the "high-diphosphoglycerate" cells. 2) About 50 per cent of the inhibition of glycolysis in "high-diphosphoglycerate" cells can be accounted for by the 2, 3-P2-glycerate-induced decrease of the red-cell pH. This fall of the red-cell pH which occurs as a conswquence of the Donnan effect of the non-pentrating 2, 3-P2-glycerate anion leads to a reduction of the glycolytic rate due to the properties of the enzyme phosphofructokinase. 3) The remaining part of the inhibitory effect must be attributed to an inhibition by 2, 3-P2-glycerate of glycolytic enzymes. From measurements of glycolytic rates and of the concentrations of glycolytic intermediates in the absence and presence of methylene blue it is concluded that the hexokinase reaction is inhibited by an elevation of 2, 3-P2-glycerate concentration in "high-diphosphoglycerate" cells suggests that also the enzyme pyruvate kinase is inhibited by 2, 3-P2-glycerate. 4) The dependencies of net-change of 2, 3-P2-glycerate concentration on the red-cell pH are identical in normal and "high-diphosphoglycerate" cells indicating that the balance between formation and decomposition of 2, 3-P2-glycerate is the same in erythrocytes with normal and very high compositions of 2, 3-P2-glycerate.

Adenosine Triphosphate

Inhibition of lactate transport and glycolysis in Ehrlich ascites tumor cells by bioflavonoids.

Bioflavonoids are potent inhibitors of lactate transport in Ehrlich ascites tumor cells. The most effective bioflavonoids have four to five hydroxyl groups. Sugar substitution at carbon three, or reduction of the double bond between carbons two and three, decreases their inhibitory activity. Quercetin, the most extensively studied of these compounds, inhibits lactate efflux by 50% at 0.1 micrograms/mg of protein. On addition of quercetin to glycolyzing Ehrlich ascites tumor cells, lactate accumulates inside the cell and the intracellular pH drops. Total lactate production is also inhibited. Nigericin prevents the internal acidification that occurs in the presence of quercetin and also reduces the inhibition of glycolysis. Thus, it appears that inhibition of lactate efflux can affect glycolysis through a lowering of the intracellular pH. The inhibitory effect of quercetin on glycolysis can be explained by its effect on lactate efflux and its previously reported effect on the Na+--K+ ATPase [Suolinna, E.--M., et al. (1974) J. Natl. Cancer Inst. 53, 1515].

Animals

Impaired Glycolysis Leads to Defective Efferocytosis and Impaired Plaque Resolution in Tet2 Clonal Hematopoiesis.

BACKGROUND: Clonal hematopoiesis (CH) arising from mutations in hematopoietic genes has been identified as an important risk factor for atherosclerotic cardiovascular disease. Despite the established role of some CH mutations in promoting atherosclerosis progression, their role in clinically relevant LDL (low-density lipoprotein) lowering-induced plaque remodeling or regression has not been extensively studied. METHODS: To assess the effects of TET2 (tet methylcytosine dioxygenase 2) CH on plaque resolution, we prepared control or chimeric Tet2+/- CH mice with conditional deletion of Tet2 in hematopoietic stem cells during LDL lowering-induced plaque remodeling. After establishing atherosclerosis by Western diet feeding for 12 weeks in Ldlr-/- mice, Tet2 was deleted by tamoxifen injection, and hypercholesterolemia was either normalized to simulate clinical lipid management, or mice were continued on the Western diet. RESULTS: Unlike control mice, Tet2+/- CH mice failed to significantly reduce necrotic core area or increase fibrous cap thickness and showed impaired macrophage efferocytosis during LDL lowering. Single-cell RNA sequencing and gene set enrichment analysis of aortic cell populations revealed that Tet2 deficient monocyte/macrophage populations were defective in glycolysis, phagocytosis, and actin polymerization. Tet2-deficient bone marrow-derived macrophages and Tet2+/- induced pluripotent stem cell-derived human macrophages showed defective ability to sustain continuing rounds of efferocytosis. Bone marrow-derived macrophages displayed reduced apoptotic cell binding and internalization and impaired activity of Wiskott-Aldrich syndrome protein and SCAR (suppressor of cyclic AMP receptor) homolog complex mediated actin polymerization. We linked these defects to reduced anaerobic glycolysis and lactate levels and rescued them by lactate supplementation or by treatment with the HIF-1α (hypoxia-inducible factor 1α) activator molidustat. Molidustat treatment reversed the defects in necrotic core and fibrous cap formation during LDL lowering-induced plaque remodeling in Tet2+/- CH mice. Reduced plasma lactate levels were also shown in TET2 clonal hematopoiesis of indeterminate potential carriers in the UK Biobank. CONCLUSIONS: Our data identify impaired efferocytosis and glycolysis-lactate-actin polymerization pathways in advanced atherosclerosis as potential therapeutic targets to induce proresolving restructuring of the plaque immune cells and to promote beneficial atherosclerosis remodeling in subjects with TET2 CH.

LDL lowering

A study of the neurohumoral control of glycolysis in the mouse brain in vivo: role of noradrenaline and dopamine.

Intraventricularly injected noradrenaline, dopamine and isoprenaline increased glycolysis as shown by the decrease in the concentration of "free" glycogen and increase in the concentration of lactate. The effects of noradrenaline and isoprenaline were reduced in mice which had been pretreated with alpha-methyl-p-tyrosin. DL-Propranolol blocked the increase in glycolysis caused by noradrenaline, isoprenaline, sodium fluoride and analogues of 3,5-cyclic adenosine monophosphate. It is suggested that the results of this investigation can be explained by the various drugs and neurohormones acting on the adenyl cyclase system in vivo, either by blocking the action of the neurohormone on the membrane bound enzyme or by antagonizing the effect of 3,5-cyclic adenosine monophosphate on glycolysis.

Animals