scholarly journals Regulation of glycolysis and l-glycerol 3-phosphate concentration in rat epididymal adipose tissue in vitro. Role of phosphofructokinase

1969 ◽  
Vol 113 (1) ◽  
pp. 207-214 ◽  
Author(s):  
M L Halperin ◽  
R M Denton
Keyword(s):  
Concentration Ratio ◽  
Adenine Nucleotides ◽  
Phosphate Concentration ◽  
Mass Action ◽  
Epididymal Adipose Tissue ◽  
Glycolytic Flux ◽  
Dihydroxyacetone Phosphate ◽  
Glycolytic Control

1. Attempts were made to define the role of phosphofructokinase in glycolytic control and the factors regulating the concentration of l-glycerol 3-phosphate in rat epididymal fat pads incubated in vitro. 2. Glycolysis rates were altered by anoxia or by additions of insulin, adrenaline or both to the incubation medium, and the changes in rate were related to changes in the steady-state concentrations of hexose phosphates, adenine nucleotides, l-glycerol 3-phosphate and citrate in the whole tissue. Measurements were also made of the lactate/pyruvate concentration ratio in the medium after incubation. 3. The mass-action ratios of phosphofructokinase, calculated from the whole-tissue concentrations of products and substrates, were less than 0·1% of the value of the ratio at pH7·4 at equilibrium. 4. Only in the presence of adrenaline could the observed stimulation of glycolytic flux be related to a possible activation of phosphofructokinase since, in this situation, the concentration of one substrate, fructose 6-phosphate, was not altered and the concentration of the other, ATP, was decreased. Increased glycolytic flux in the presence of insulin may be explained by an observed increase in the concentration of the substrate, fructose 6-phosphate. Under anaerobic conditions, glycolytic flux was decreased but this did not appear to be the result of inhibition of phosphofructokinase, since the concentrations of both substrates, fructose 6-phosphate and ATP, were decreased. The changes in glycolytic flux with insulin and anoxia may be secondary to changes in the rate of glucose uptake. 5. Changes in l-glycerol 3-phosphate concentration appear to be related both to changes in the concentration of dihydroxyacetone phosphate and to changes in the NADH/NAD+ concentration ratio in the cytoplasm. They do not seem to be related directly to alterations in glycolytic rate.

Protein, not adenosine or adenine nucleotides, mediates platelet decrease in endothelial permeability

1997 ◽  
Vol 273 (5) ◽  
pp. H2304-H2311 ◽  
Author(s):  
Sandeep Patil ◽  
John E. Kaplan ◽  
Fred L. Minnear
Keyword(s):  
High Performance ◽  
Adenine Nucleotides ◽  
Endothelial Permeability ◽  
Platelet Response ◽  
Cell Monolayers ◽  
Adenosine Receptor Antagonist ◽  
Albumin Clearance ◽  
Protein Permeability

Platelets and platelet-conditioned medium (PCM) decrease endothelial protein permeability in vitro. Adenosine and a >100-kDa protein have previously been implicated as the soluble factors released from platelets that decrease endothelial permeability. The objective of this study was to further investigate the role of adenosine in this platelet response. Measurements of adenosine and its precursor adenine nucleotides by high-performance liquid chromatography were correlated with the assessment of permeability by125I-labeled albumin clearance and electrical resistance across endothelial cell monolayers derived from the bovine pulmonary artery. PCM contained micromolar concentrations of AMP, ADP, and ATP, but adenosine was below detectable levels (≤0.1 μM). Adenosine deaminase, an enzyme that converts adenosine to inactive inosine, or an adenosine-receptor antagonist did not block the platelet- or PCM-mediated decrease in endothelial permeability. A <3-kDa fraction of PCM that contained micromolar concentrations of AMP and ADP did not affect endothelial permeability, whereas a >3-kDa fraction that contained much reduced levels of AMP and ADP significantly decreased permeability. This activity of PCM was sensitive to insoluble trypsin. This study rules out adenosine and adenine nucleotides as primary factors in the platelet-induced decrease in endothelial permeability and suggests that the active factor is a protein.

scholarly journals Gene deletion reveals roles for annexin A1 in the regulation of lipolysis and IL-6 release in epididymal adipose tissue

2006 ◽  
Vol 291 (6) ◽  
pp. E1264-E1273 ◽  
Author(s):  
James P. Warne ◽  
Christopher D. John ◽  
Helen C. Christian ◽  
John F. Morris ◽  
Roderick J. Flower ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Gene Deletion ◽  
Cell Number ◽  
Receptor Expression ◽  
Epididymal Adipose Tissue ◽  
Wild Type ◽  
Inhibitory Effects ◽  
Tissue Mass

In this study, epididymal adipose tissue from male annexin 1 (ANXA1)-null and wild-type control mice were used to explore the potential role of ANXA1 in adipocyte biology. ANXA1 was detected by Western blot analysis in wild-type tissue and localized predominantly to the stromal-vascular compartment. Epididymal fat pad mass was reduced by ANXA1 gene deletion, but adipocyte size was unchanged, suggesting that ANXA1 is required for the maintenance of adipocyte and/or preadipocyte cell number. Epididymal tissue from wild-type mice responded in vitro to noradrenaline and isoprenaline with increased glycerol release, reduced IL-6 release, and increased cAMP accumulation. Qualitatively similar but significantly attenuated responses to the catecholamines were observed in tissue from ANXA1-null mice, an effect that was not associated with changes in β-adrenoceptor mRNA expression. Lipopolysaccharide (LPS) also stimulated lipolysis in vitro, but its effects were muted by ANXA1 gene deletion. By contrast, LPS failed to influence IL-6 release from wild-type tissue but stimulated the release of the cytokine from tissue from ANXA1-null mice. ANXA1 gene deletion did not affect glucocorticoid receptor expression or the ability of dexamethasone to suppress catecholamine-induced lipolysis. It did, however, augment IL-6 expression and modify the inhibitory effects of glucocorticoids on IL-6 release. Collectively, these studies suggest that ANXA1 supports aspects of adipose tissue mass and alters the sensitivity of epididymal adipose tissue to catecholamines, glucocorticoids, and LPS, thereby modulating lipolysis and IL-6 release.

scholarly journals Alpha Enolase 1 Ubiquitination and Degradation Mediated by Ehrlichia chaffeensis TRP120 Disrupts Glycolytic Flux and Promotes Infection

Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 962
Author(s):  
Bing Zhu ◽  
Jere W. McBride
Keyword(s):  
Host Cell ◽  
Ectopic Expression ◽  
Metabolic Reprogramming ◽  
Glycolytic Flux ◽  
Ehrlichia Chaffeensis ◽  
Direct Role ◽  
Cell Processes

Ehrlichia chaffeensis modulates numerous host cell processes, including gene transcription to promote infection of the mononuclear phagocyte. Modulation of these host cell processes is directed through E. chaffeensis effectors, including TRP120. We previously reported that TRP120 moonlights as a HECT E3 Ub ligase that ubiquitinates host cell transcription and fate regulators (PCGF5 and FBW7) to promote infection. In this study, we identified a novel TRP120 substrate and examined the relationship between TRP120 and α-enolase (ENO1), a metalloenzyme that catalyzes glycolytic pathway substrate dehydration. Immunofluorescence microscopy and coimmunoprecipitation demonstrated interaction between ENO1 and TRP120, and ubiquitination of ENO-1 by TRP120 was detected in vivo and in vitro. Further, ENO-1 degradation was observed during infection and was inhibited by the proteasomal inhibitor bortezomib. A direct role of TRP120 Ub ligase activity in ENO-1 degradation was demonstrated and confirmed by ectopic expression of TRP120 HECT Ub ligase catalytic site mutant. siRNA knockdown of ENO-1 coincided with increased E. chaffeensis infection and ENO-1 knockdown disrupted glycolytic flux by decreasing the levels of pyruvate and lactate that may contribute to changes in host cell metabolism that promote infection. In addition, we elucidated a functional role of TRP120 auto-ubiquitination as an activating event that facilitates the recruitment of the UbcH5 E2 ubiquitin-conjugating enzyme. This investigation further expands the repertoire of TRP120 substrates and extends the potential role of TRP120 Ub ligase in infection to include metabolic reprogramming.

Synthesis and Secretion of Growth Hormone in the Rat Anterior Pituitary

1973 ◽  
Vol 12 (1) ◽  
pp. 23-35
Author(s):  
S. L. HOWELL ◽  
R.B. L. EWART
Keyword(s):  
Growth Hormone ◽  
Adenine Nucleotides ◽  
High Potassium ◽  
Granule Formation ◽  
Intact Cells ◽  
Storage Granule ◽  
Storage Granules ◽  
Ph Range

Partially purified storage granule fractions obtained from rat anterior pituitaries have been utilized to study some properties of the isolated growth hormone granules during incubation in vitro. The isolated granules showed optimal stability at room temperature in the pH range 5.5-6.5 and dissolved progressively with time at a rate which was unaffected by the presence of EDTA, EGTA, ouabain, magnesium ions, or by resuspension in hypotonic media. However, the granules were partially stabilized by the presence of calcium, tyramine or adenosine phosphates; ATP was most effective of the agents tested and induced almost complete stability. Agents known to stimulate the secretion of growth hormone from the intact cells, cyclic 3',5'-AMP, dibutyryl cyclic 3',5'-AMP, theophylline or high potassium concentrations, were each without significant effect on the isolated granules. The granule fraction was ineffective indegrading added 125I-growth hormone over a pH range of 4.5-8.5 and was unable specifically to bind exogenous 125I-growth hormone. Further experiments to elucidate a possible cytological role of nucleotides in stabilization of growth hormone during storage granule formation demonstrated that adenine nucleotides were not constituents of the isolated granules, nor were they secreted into the incubation medium concomitantly with growth hormone. Depletion of intracellular ATP levels has previously been shown to prevent the formation of growth-hormone storage granules, and it is suggested that one role of the nucleotide may be to facilitate the formation and stabilization of storage granules in the Golgi complex by interacting with the growth hormone to induce its precipitation.

scholarly journals Evidence for the rapid direct control both in vivo and in vitro of the efficiency of oxidative phosphorylation by 3,5,3′-tri-iodo-l-thyronine in rats

1979 ◽  
Vol 184 (3) ◽  
pp. 527-538 ◽  
Author(s):  
R Palacios-Romero ◽  
J Mowbray
Keyword(s):  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Respiratory Control ◽  
Focused Attention ◽  
Isolated Mitochondria ◽  
Short Times ◽  
Normal Controls

1. Examination of the distribution of L-tri-iodothyronine among rat liver tissue fractions after its intravenous injection into thyroidectomized rats focused attention on mitochondria at very short times after administration. By 15 min this fraction contained 18.5% of the tissue pool; however, the content had decreased sharply by 60 min and even further over the next 3 h. By contrast, the content in all other fractions was constant or increased over 4 h. About 60% of tissue hormone was bound to soluble protein. 2. Mitochondria isolated from thyroidectomized rats showed P/O ratios that were about 50% of those found in normal controls, with both succinate and pyruvate plus malate as substrates. There was no evidence of uncoupling; the respiratory-control ratio was about 6. 3. Mitochondria isolated 15 min after injection of tri-iodothyronine into thyroidectomized rats showed P/O ratios and respiratory-control ratios that were indistinguishable from those obtained in mitochondria from euthyroid animals. The oxidation rate was, however, not restored. 4. Incubation of homogenates of livers taken from thyroidectomized animals injected with L-tri-iodothyronine before isolation of the mitochondria restored the P/O ratio to normal; by contrast, direct addition of hormone to isolated mitochondria had no effect. The role of extramitochondrial factors in rapid tri-iodothyronine action is discussed. 5. Possible mechanisms by which tri-iodothyronine might rapidly alter phosphorylation efficiency are considered: it is concluded that control of adenine nucleotide translocase is unlikely to be involved. 6. The amounts of adenine nucleotides in liver were measured both after thyroidectomy and 15 min after intravenous tri-iodo-thyronine administration to thyroidectomized animals. The concentrations found are consistent with a decreased phosphorylation efficiency in thyroidectomized animals. Tri-iodothyronine injection resulted in very significant changes in the amounts of ATP, ADP and AMP, and in the [ATP]/[ADP] ratio, consonant with those expected from an increased efficiency of ADP phosphorylation. This suggests that the changes seen in isolated mitochondria may indeed reflect a rapid response of liver in vivo to tri-iodo-thyronine.

The role of silicon in forages: A quantitative X-Ray study

1987 ◽  
Vol 45 ◽  
pp. 416-417
Author(s):  
Janet H. Woodward ◽  
D. E. Akin
Keyword(s):  
Sodium Acetate ◽  
Dry Matter ◽  
Acetate Buffer ◽  
Plant Tissues ◽  
Sodium Acetate Buffer ◽  
X Ray ◽  
Dry Matter Digestibility ◽  
Percent Composition

Silicon (Si) is distributed throughout plant tissues, but its role in forages has not been clarified. Although Si has been suggested as an antiquality factor which limits the digestibility of structural carbohydrates, other research indicates that its presence in plants does not affect digestibility. We employed x-ray microanalysis to evaluate Si as an antiquality factor at specific sites of two cultivars of bermuda grass (Cynodon dactvlon (L.) Pers.). “Coastal” and “Tifton-78” were chosen for this study because previous work in our lab has shown that, although these two grasses are similar ultrastructurally, they differ in in vitro dry matter digestibility and in percent composition of Si.Two millimeter leaf sections of Tifton-7 8 (Tift-7 8) and Coastal (CBG) were incubated for 72 hr in 2.5% (w/v) cellulase in 0.05 M sodium acetate buffer, pH 5.0. For controls, sections were incubated in the sodium acetate buffer or were not treated.

An integrated screening method for evaluating the pulmonary toxicity of inhaled particulates: Role of microscopic techniques in assessing pulmonary macrophage clearance functions

1990 ◽  
Vol 48 (3) ◽  
pp. 826-827
Author(s):  
David B. Warheit ◽  
Lena Achinko ◽  
Mark A. Hartsky
Keyword(s):  
Bronchoalveolar Lavage ◽  
Pulmonary Toxicity ◽  
Screening Method ◽  
Pulmonary Response ◽  
Inhaled Particles ◽  
Cytochemical Analysis ◽  
Pulmonary Macrophages ◽  
Integrated Screening

There is a great need for the development of a rapid and reliable bioassay to evaluate the pulmonary toxicity of inhaled particles. A number of methods have been proposed, including lung clearance studies, bronchoalveolar lavage analysis, and in vitro cytotoxicity tests. These methods are often limited in scope inasmuch as they measure only one dimension of the pulmonary response to inhaled, instilled or incubated dusts. Accordingly, a comprehensive approach to lung toxicity studies has been developed.To validate the method, rats were exposed for 6 hours or 3 days to various concentrations of either aerosolized alpha quartz silica (Si) or carbonyl iron (CI) particles. Cells and fluids from groups of sham and dust-exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, LDH and protein values were measured in BAL fluids at several time points postexposure. Cells were counted and evaluated for viability, as well as differential and cytochemical analysis. In addition, pulmonary macrophages (PM) were cultured and studied for morphology, chemotaxis, and phagocytosis by scanning electron microscopy.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Anti-obesity role of Aster glehni extract: in vivo and in vitro effects

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
HM Lee ◽  
TG Ahn ◽  
CW Kim ◽  
HJ An
Keyword(s):  
In Vitro Effects
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