scholarly journals A study of the Crabtree effect in Novikoff ascites-hepatoma cells

1966 ◽  
Vol 99 (2) ◽  
pp. 413-418 ◽  
Author(s):  
V N Nigam
Keyword(s):  
Glucose Uptake ◽  
Adenine Nucleotides ◽  
Glycogen Synthesis ◽  
Hepatoma Cells ◽  
Significant Loss ◽  
Crabtree Effect ◽  
Ascites Hepatoma ◽  
Short Term ◽  
Mitochondrial Structure ◽  
Glucose Metabolites

Novikoff ascites-hepatoma cells show no Crabtree effect on the addition of glucose to tumour-cell suspensions, and convert a significant part of the added glucose into glycogen. Treatment of the cells with 2-deoxyglucose or glucose in the presence of iodoacetate inhibits respiration and decreases glycogen synthesis from glucose. Short-term experiments indicate a slight inhibition of glucose uptake for a brief period, due either to ATP accumulation in the mitochondria or to glucose 6-phosphate-mediated inhibition of hexokinase. Utilization of glucose metabolites and ATP for glycogen synthesis appears to remove inhibition of glucose uptake, and perhaps accounts for the absence of respiratory inhibition, by relieving a deficiency of ADP for the mitochondria. Decreased respiration in the presence of 2-deoxyglucose or glucose in the presence of iodoacetate could be due to the change in mitochondrial structure or permeability, caused by the significant loss of adenine nucleotides.

scholarly journals Pathways of glycogen synthesis in Novikoff ascites-hepatoma cells

1969 ◽  
Vol 115 (2) ◽  
pp. 315-322 ◽  
Author(s):  
V. N. Nigam
Keyword(s):  
Intact Cell ◽  
Glycogen Synthesis ◽  
Hepatoma Cells ◽  
Tumour Cells ◽  
The Other ◽  
Ascites Hepatoma ◽  
Saturation Concentration ◽  
Glucan Phosphorylase ◽  
Glycogen Formation

Affinity of glucose, fructose and mannose for tumour hexokinase and their rates of phosphorylation at saturation concentration have been correlated with rates of glycogen synthesis by intact tumour cells at different concentrations of the three substrates. Competition experiments with one sugar labelled and the other sugar unlabelled indicate inhibition of glycogen synthesis by the sugar with a low Km for hexokinase. Glycogen synthesis from glucose 1-phosphate in aged cells and from nucleoside in freshly prepared cells is stimulated by fructose and inhibited by glucose. The decrease in glycogen formation from glucose 1-phosphate by oligomycin is partially overcome by increased fructose concentrations. These results are explained by an activation of α-glucan phosphorylase by fructose and an inhibition of this enzyme by glucose. It is suggested that differences in localization of glucose 6-phosphate, available to the intact cell in various ways, determine its transformation into glycogen by either the UDP-glucose–α-glucan glucosyltransferase reaction or by the α-glucan phosphorylase reaction.

scholarly journals Multisite control of the Crabtree effect in ascites hepatoma cells

2001 ◽  
Vol 268 (8) ◽  
pp. 2512-2519 ◽  
Author(s):  
Sara Rodríguez-Enríquez ◽  
Oscar Juárez ◽  
José S. Rodríguez-Zavala ◽  
Rafael Moreno-Sánchez
Keyword(s):  
Hepatoma Cells ◽  
Crabtree Effect ◽  
Ascites Hepatoma

scholarly journals Glycogen synthesis in the perfused liver of adrenalectomized rats

1976 ◽  
Vol 156 (3) ◽  
pp. 585-592 ◽  
Author(s):  
P D Whitton ◽  
D A Hems
Keyword(s):  
Intact Animal ◽  
Glycogen Synthesis ◽  
Hepatic Metabolism ◽  
Hepatic Glycogen ◽  
Perfused Liver ◽  
Short Term ◽  
Glycogen Accumulation ◽  
Glycogen Deposition ◽  
Adrenalectomized Rats

1. A total loss of capacity for net glycogen synthesis was observed in experiments with the perfused liver of starved adrenalectomized rats. 2. This lesion was corrected by insulin or cortisol in vivo (over 2-5h), but not by any agent tested in perfusion. 3. The activity of glycogen synthetase a, and its increase during perfusion, in the presence of glucose plus glucogenic substrates, were proportional to the rate of net glycogen accumulation. 4. This complete inherent loss of capacity for glycogen synthesis after adrenalectomy is greater than any defect in hepatic metabolism yet reported in this situation, and is not explicable by a decrease in the rate of gluconegenesis (which supports glycogen synthesis in the liver of starved rats). The short-term (2-5h) stimulatory effect of glucocorticoids in the intact animal, on hepatic glycogen deposition, may be mediated partly through insulin action, although neither insulin or cortisol appear to act directly on the liver to stimulate glycogen synthesis.

Global and targeted gene expression and protein content in skeletal muscle of young men following short-term creatine monohydrate supplementation

2008 ◽  
Vol 32 (2) ◽  
pp. 219-228 ◽  
Author(s):  
Adeel Safdar ◽  
Nicholas J. Yardley ◽  
Rodney Snow ◽  
Simon Melov ◽  
Mark A. Tarnopolsky
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Mrna Expression ◽  
Protein Content ◽  
Cellular Response ◽  
Glycogen Synthesis ◽  
Creatine Monohydrate ◽  
Fat Free Mass ◽  
Cell Swelling ◽  
Short Term

Creatine monohydrate (CrM) supplementation has been shown to increase fat-free mass and muscle power output possibly via cell swelling. Little is known about the cellular response to CrM. We investigated the effect of short-term CrM supplementation on global and targeted mRNA expression and protein content in human skeletal muscle. In a randomized, placebo-controlled, crossover, double-blind design, 12 young, healthy, nonobese men were supplemented with either a placebo (PL) or CrM (loading phase, 20 g/day × 3 days; maintenance phase, 5 g/day × 7 days) for 10 days. Following a 28-day washout period, subjects were put on the alternate supplementation for 10 days. Muscle biopsies of the vastus lateralis were obtained and were assessed for mRNA expression (cDNA microarrays + real-time PCR) and protein content (Kinetworks KPKS 1.0 Protein Kinase screen). CrM supplementation significantly increased fat-free mass, total body water, and body weight of the participants ( P < 0.05). Also, CrM supplementation significantly upregulated (1.3- to 5.0-fold) the mRNA content of genes and protein content of kinases involved in osmosensing and signal transduction, cytoskeleton remodeling, protein and glycogen synthesis regulation, satellite cell proliferation and differentiation, DNA replication and repair, RNA transcription control, and cell survival. We are the first to report this large-scale gene expression in the skeletal muscle with short-term CrM supplementation, a response that suggests changes in cellular osmolarity.

Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle

2008 ◽  
Vol 294 (1) ◽  
pp. E28-E35 ◽  
Author(s):  
Michale Bouskila ◽  
Michael F. Hirshman ◽  
Jørgen Jensen ◽  
Laurie J. Goodyear ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Wild Type ◽  
Muscle Glycogen Synthesis ◽  
Mutant Forms

Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6- P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3α and -β genes are replaced with mutant forms (GSK3α/βS21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3α/βS21A/S21A/S9A/S9Amice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6- P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6- P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.

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