scholarly journals Degradation of the Gluconeogenic Enzymes Fructose-1,6-bisphosphatase and Malate Dehydrogenase Is Mediated by Distinct Proteolytic Pathways and Signaling Events

2004 ◽  
Vol 279 (47) ◽  
pp. 49138-49150 ◽  
Author(s):  
Guo-Chiuan Hung ◽  
C. Randell Brown ◽  
Allison B. Wolfe ◽  
Jingjing Liu ◽  
Hui-Ling Chiang
Keyword(s):  
Malate Dehydrogenase ◽  
Gluconeogenic Enzymes ◽  
Fructose 1,6 Bisphosphatase ◽  
Signaling Events ◽  
Proteolytic Pathways

scholarly journals Glucose-induced inactivation of mitochondrial enzymes in the yeast Saccharomyces cerevisiae

1981 ◽  
Vol 198 (2) ◽  
pp. 281-287 ◽  
Author(s):  
M Takeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Malate Dehydrogenase ◽  
Mitochondrial Enzymes ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cytoplasmic Proteins ◽  
Fructose 1,6 Bisphosphatase ◽  
Specific Activities

1. Addition of glucose induced an inactivation of mitochondrial enzymes in the yeast Saccharomyces cerevisiae containing normal mitochondrial particles. 2. The glucose-induced inactivation of mitochondrial enzymes was inhibited by the presence of cycloheximide. 3. Pepstatin also inhibited the inactivation, but phenylmethanesulphonyl fluoride accelerated the inactivation. 4. The specific activities of fructose 1,6-bisphosphatase and cytoplasmic malate dehydrogenase were decreased on the exposure to glucose, as well as those of the mitochondrial enzymes. However, the glucose-induced inactivation of cytoplasmic enzymes was not inhibited by the presence of pepstatin. 5. The specific activities of hexokinase and phosphofructokinase, which are cytoplasmic enzymes were increased by the addition of glucose, and this effect was not affected by pepstatin. 6. Addition of glucose resulted in an increase in the synthesis of proteins of the mitochondria and the cytosol, and simultaneously in degradation of these mitochondrial and cytoplasmic proteins.

scholarly journals Fructose-responsive genes in the small intestine of neonatal rats

2004 ◽  
Vol 18 (2) ◽  
pp. 206-217 ◽  
Author(s):  
Xue-Lin Cui ◽  
Patricia Soteropoulos ◽  
Peter Tolias ◽  
Ronaldo P. Ferraris
Keyword(s):  
Small Intestine ◽  
De Novo ◽  
Mrna Abundance ◽  
Metabolic Intermediate ◽  
Gluconeogenic Enzymes ◽  
Fructose Metabolism ◽  
High Fructose ◽  
Fructose 1,6 Bisphosphatase ◽  
Dietary Fructose

The intestinal brush border fructose transporter GLUT5 (SLC2A5) typically appears in rats after weaning is completed. However, precocious consumption of dietary fructose or in vivo perfusion for 4 h of the small intestine with high fructose (HF) specifically stimulates de novo synthesis of GLUT5 mRNA and protein before weaning is completed. Intermediary signals linking the substrate, fructose, to GLUT5 transcription are not known but should also respond to fructose perfusion. Hence, we used microarray hybridization and RT-PCR to identify genes whose expression levels change during HF relative to high-glucose (HG) perfusion. Expression of GLUT5 and NaPi2b, the intestinal Na+-dependent phosphate transporter, dramatically increased and decreased, respectively, with HF perfusion for 4 h. Expression of >20 genes, including two key gluconeogenic enzymes, glucose-6-phosphatase (G6P) and fructose-1,6-bisphosphatase, also increased markedly, along with fructose-2,6-bisphosphatase, an enzyme unique to fructose metabolism and regulating fructose-1,6-bisphosphatase activity. GLUT5 and G6P mRNA abundance, which increased dramatically with HF relative to HG, α-methylglucose, and normal Ringer perfusion, may be tightly and specifically linked to changes in intestinal luminal fructose but not glucose concentrations. G6P but not GLUT5 mRNA abundance increased after just 20 min of HF perfusion. This cluster of gluconeogenic enzymes and their common metabolic intermediate fructose-6-phosphate may regulate fructose metabolism and GLUT5 expression in the small intestine.

scholarly journals Hypoglycaemic activity of Coccinia indica and Momordica charantia in diabetic rats: depression of the hepatic gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and elevation of both liver and red-cell shunt enzyme glucose-6-phosphate dehydrogenase

1993 ◽  
Vol 292 (1) ◽  
pp. 267-270 ◽  
Author(s):  
B A Shibib ◽  
L A Khan ◽  
R Rahman
Keyword(s):  
Blood Glucose ◽  
Diabetic Rats ◽  
Momordica Charantia ◽  
Red Cell ◽  
Gluconeogenic Enzymes ◽  
Hepatic Glucose ◽  
Fructose 1,6 Bisphosphatase ◽  
Streptozotocin Diabetic Rats ◽  
Coccinia Indica ◽  
Glucose 6 Phosphate Dehydrogenase

Coccinia indica leaves were extracted with 60% ethanol, solvents were evaporated and the residue was suspended in water. This suspension was administered orally at a dose of 200 mg/kg body wt. after 18 h of fasting to normal fed and streptozotocin-induced male diabetic rats (180-250 g). After 90 min the rats were killed, and blood-glucose, hepatic glucose-6-phosphatase, fructose-1,6-bisphosphatase and glucose-6-phosphate dehydrogenase (G6PDH) and red-cell G6PDH were assayed. Blood sugar was depressed by 23% (P < 0.01) and 27% (P < 0.001) in the normal fed and streptozotocin-diabetic rats respectively compared with controls which were given distilled water. Hepatic glucose-6-phosphatase and fructose-1,6-bisphosphatase activities were depressed by 32% (P < 0.001) 30% (P < 0.05) respectively in the streptozotocin-diabetic rats, compared with 19% (P < 0.02) and 20% (P < 0.01) depression in the normal fed controls, whereas both the red-cell and hepatic G6PDH activities were found to be elevated by feeding the extract in the streptozotocin-diabetic and in the normal fed controls. Similar results were obtained with the 95%-ethanolic extract of Momordica charantia. Taken together, these results indicate that Coccinia indica and Momordica charantia extracts lowered blood glucose by depressing its synthesis, on the one hand through depression of the key gluconeogenic enzymes glucose-6-phosphatase and fructose-1,6-bisphosphatase and on the other by enhancing glucose oxidation by the shunt pathway through activation of its principal enzyme G6PDH.

scholarly journals Fructose 2,6-bisphosphate and its phosphorothioate analogue. Comparison of their hydrolysis and action on glycolytic and gluconeogenic enzymes

1988 ◽  
Vol 253 (2) ◽  
pp. 597-601 ◽  
Author(s):  
M H Rider ◽  
D A Kuntz ◽  
L Hue
Keyword(s):  
Pyruvate Kinase ◽  
Chicken Liver ◽  
Gluconeogenic Enzymes ◽  
Fructose 2 ◽  
Fructose 1,6 Bisphosphatase ◽  
Enzyme Intermediate

Purified chicken liver 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase was phosphorylated either from fructose 2,6-bis[2-32P]phosphate or fructose 2-phosphoro[35S]thioate 6-phosphate. The turnover of the thiophosphorylated enzyme intermediate as well as the overall phosphatase reaction was four times faster than with authentic fructose 2,6-bisphosphate. Fructose 2-phosphorothioate 6-phosphate was 10-100-fold less potent than authentic fructose 2,6-bisphosphate in stimulating 6-phosphofructo-1-kinase and pyrophosphate:fructose 6-phosphate phosphotransferase, but about 10 times more potent in inhibiting fructose 1,6-bisphosphatase. The analogue was twice as effective as authentic fructose 2,6-bisphosphate in stimulating pyruvate kinase from trypanosomes.

Glyconeogenic and glycogenic enzymes in chronically active and normal skeletal muscle

1991 ◽  
Vol 71 (1) ◽  
pp. 182-191 ◽  
Author(s):  
R. J. Talmadge ◽  
H. Silverman
Keyword(s):  
Dehydrogenase Activity ◽  
Malate Dehydrogenase ◽  
Malic Enzyme ◽  
Glycogen Phosphorylase ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Fructose 1,6 Bisphosphatase ◽  
Fast Twitch ◽  
Whole Muscle

The chronically active (pseudomyotonic) gastrocnemius muscle in the C57B16J dy2J/dy2J mouse contains both elevated lactate and glycogen as well as fibers that have high amounts of glycogen and enhanced glyconeogenic activity. In the present study we analyze the activities of some key glyconeogenic enzymes to assess the causes of elevated muscle glycogen and to determine the pathway for glycogen synthesis from lactate. Glycogen synthase, malate dehydrogenase, phosphoenolpyruvate carboxykinase, and malic enzyme were all elevated in homogenates of the chronically active muscle. Activities of glycogen phosphorylase and fructose 1,6-bisphosphatase were decreased in whole muscle homogenates. Histochemistry demonstrated that the high-glycogen fibers were typically fast-twitch glycolytic fibers that had high glycogen synthase, glycogen phosphorylase, and malic enzyme activities. Malate dehydrogenase activity followed succinate dehydrogenase activity and did not correlate to high-glycogen fibers. Thus the high-glycogen fibers have an elevated enzymatic capacity for glycogen synthesis from lactate, and the pathway may involve use of the pyruvate kinase bypass enzymes.

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