Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.1.1 (hexokinase)
5,274 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Chick embryo hepatocytes were maintained in monolayer culture in a serum-free chemically defined medium for periods of up to 2 days. Over this time period, insulin provoked selective increases (up to 5-fold) in factors relevant to the control of glycolysis: the activities of phosphofructokinase-1 (PFK-1), phosphofructokinase-2 (PFK-2) and hexokinase isoenzymes and the content of fructose 2,6-bisphosphate (F26BP). Half-maximal effects of insulin on pFK-1 activity were in the physiological range (0.1 nM). Changes in enzyme activities and F26BP content in response to insulin were correlated with stimulation of glycolytic flux as estimated by radioisotopic flux. These data are discussed in relation to known changes which occur in hepatic glycolytic activity and PFK-1 activity in the intact chick around hatching. The effects of insulin on F26BP content, PFK-1 activity and glycolytic flux were mimicked by epidermal growth factor (EGF). In contrast, phorbol esters produced minimal actions on any of the above parameters. Our data indicate that protein kinase C is not involved in the actions of insulin or EGF in control of F26BP content or PFK-1 activity. This work indicates that the related tyrosyl kinase receptors of insulin and EGF may provoke identical responses within hepatocytes, but through the utilization of different transduction systems which merge to common control points.
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PMID:Control of glycolysis in cultured chick embryo hepatocytes. Fructose 2,6-bisphosphate content and phosphofructokinase-1 activity are stimulated by insulin and epidermal growth factor. 214 94

Levels of triiodothyronine, thyroxine, insulin, glucose and free fatty acids in the blood; contents of adrenaline, noradrenaline in adrenals and glycogen in the liver; activity of phenylethanolamine-N-methyltransferase in adrenals, hexokinase and glucose-6-phosphatase in the liver were studied in male Wistar rats and rats with inherited stress-induced arterial hypertension /ISIAH/. It was found that genetically caused rise of hypophyseal-thyroid systems activity in ISIAH-rats leads to a decrease of insulin blood level, activation of lipolysis and breach of glucose tolerance.
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PMID:[Endocrine-metabolic relations in rats with genetic arterial hypertension]. 216 74

Interleukin-1 beta (IL-1 beta) has been implicated in the pathogenesis of insulin-dependent diabetes mellitus. In the present study we have investigated the effects of IL-1 beta on glucose metabolism in clonal HIT-T15 beta cells. In the short-term (1 h), 25 U/ml IL-1 beta significantly increased the rates of insulin release and glucose utilisation, but not glucose oxidation. In contrast, after 48 h, IL-1 beta inhibited insulin release and glucose utilisation and oxidation. By assaying enzymes (hexokinase, glucokinase, pyruvate dehydrogenase, glucose 6-phosphatase) and nucleotides (ATP, ADP) associated with the regulation of glycolysis and glucose oxidation, we conclude that the inhibitory effects of IL-1 beta may be due to impaired glucokinase activity.
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PMID:Interleukin-1 beta inhibits glucokinase activity in clonal HIT-T15 beta-cells. 219 15

We assessed our speculation that 2-cyclohexen-1-one (CHX) impairs glucose-induced insulin secretion through inactivation of glucokinase. Treatment of pancreatic islets with CHX at concentrations (0-5 mM) that caused a dose-dependent inactivation of glucokinase activity similarly inhibited glucose-induced insulin secretion. Another glucose-phosphorylating enzyme (hexokinase) in pancreatic islets was little affected by CHX. CHX-induced inactivation of glucokinase was blocked by the presence of its substrates (glucose and mannose) and an inhibitor (N-acetylglucosamine), all of which also protected against the inhibitory effect of the drug on glucose-induced insulin secretion. CHX also impaired insulin secretion induced by D-glyceraldehyde and dimethyl succinate, which are believed to stimulate the release of the hormone by being directly oxidized by glyceraldehyde-3-phosphate dehydrogenase, by entering the midstream of the glycolytic pathway as glyceraldehyde 3-phosphate, or by entering the tricarboxylic acid cycle in mitochondria after intracellular hydrolysis. The inhibitory effect of CHX on glucose-induced insulin secretion, however, was far more marked than that on insulin secretion evoked by D-glyceraldehyde and dimethyl succinate at any CHX concentrations used. Our study revealed that the inhibitory action of CHX on glucose-induced insulin secretion is exerted mainly, but not solely, through inactivation of glucokinase. This conclusion supports the view that glucokinase is a key enzyme in the recognition of glucose as an insulin secretagogue in pancreatic islets.
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PMID:Participation of glucokinase inactivation in inhibition of glucose-induced insulin secretion by 2-cyclohexen-1-one. 221 70

In this study, we have used isolated pancreatic islets cultured for 7 days in 3 or 30 mM glucose to explore whether glucokinase is induced or activated by high glucose concentrations and has related enzyme activity to glucose-stimulated insulin release. Islets cultured in low glucose medium or low glucose medium plus 350 ng/ml insulin did not respond to high glucose stimulation. Islets cultured in medium containing high glucose concentrations showed a high rate of basal insulin secretion when perifused with 5 mM glucose, and the insulin release was greatly augmented in a biphasic secretion profile when the glucose concentration was raised to 16 mM. Islet glucokinase and hexokinase activities were determined by a sensitive and specific fluorometric method. Glucokinase activity was reduced to approximately 50% in islets cultured in low glucose medium with or without insulin present compared to results with fresh islets. However, islets cultured in 30 mM glucose showed that glucokinase activity was elevated to 236% compared to results with fresh islets. It is concluded that (a) glucose is the physiological regulator of glucokinase in the islet of Langerhans and that (b) the activity of glucokinase plays a crucial role in glucose-induced insulin secretion.
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PMID:Glucose regulates glucokinase activity in cultured islets from rat pancreas. 221 98

The effects of streptozotocin-induced diabetes mellitus on the activity of discrete regions of the brain were studied with histochemical localization and photodensitometric quantification of the metabolic enzyme, hexokinase. Two weeks after a single injection of streptozotocin (65 mg/kg, i.p.), plasma glucose and osmolarity levels were elevated, and plasma sodium concentrations were depressed. These changes were reversed in diabetic rats treated with insulin. Accompanying these symptoms of diabetes were significant increases in hexokinase activity in the magnocellular division of the paraventricular nucleus of the hypothalamus (mPVH, 12.1%), the medial subdivision of the nucleus of the tractus solitarius (mNTS, 15.5%), and the commissural subdivision of the NTS (cNTS, 10.9%). An increase, though just below the level of significance, was also observed in the supraoptic nucleus of the hypothalamus (SON, 11.5%). The increases in hexokinase activity were completely reversed in the cNTS (and SON) and only partly reversed in the mPVH and mNTS of insulin-treated diabetic rats. No changes in hexokinase activity were seen in the subfornical organ, medial preoptic area, parvocellular division of the PVH, locus coeruleus, or dorsal motor nucleus of the vagus of diabetic rats. These results reinforce the idea that the brain is not exempt from changes associated with diabetes mellitus and suggest that metabolic alterations in the mPVH (and SON) and two divisions of the NTS are likely related to changes in vasopressin production and blood volume, respectively.
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PMID:Alterations in brain hexokinase activity associated with streptozotocin-induced diabetes mellitus in the rat. 222 10

The intestinal metabolism of glucose and glutamine was studied in rats made septic by cecal ligation and puncture technique. Sepsis resulted in negative nitrogen balance and produced increases in the concentrations of blood pyruvate, lactate, alanine, and glutamine, and decreases in those of 3-hydroxybutyrate and acetoacetate. Both plasma insulin and glucagon concentrations were increased by 2.2- and 3.2-fold in septic rats, respectively. Portal-drained visceral blood flow increased in septic rats, and was accompanied by a decrease in the rates of utilization of glutamine and production of lactate, glutamate, and ammonia compared with those rates in sham-operated animals. Enterocytes isolated from septic rats showed decreased rates of glucose and glutamine utilization compared with cells isolated from corresponding controls. The maximal activities of hexokinase, 6-phosphofructokinase, pyruvate kinase, and glutaminase were decreased in intestinal mucosal scrapings of septic rats. It is concluded that a moderate form of sepsis decreases the rates of glucose and glutamine utilization (both in vivo and in vitro) by the epithelial cells of the small intestine. This may be caused by changes in the maximal activities of key enzymes in the pathways of glucose and glutamine metabolism in these cells as a metabolic adaptation to spare glucose and glutamine for use by other tissues.
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PMID:Glucose and glutamine metabolism in the small intestine of septic rats. 236 28

The effects of amylin on glucose metabolism and glycogenolysis were examined in vivo and in vitro. Eighteen-hour-fasted rats were infused with 5 nmol.kg-1.min-1 amylin and [3-3H]glucose for 120 min. Blood glucose levels increased an average of 45% during the infusion. Glucose turnover measurements indicated that the overall rate of glucose appearance (Ra) did not change, but the metabolic clearance rate of glucose was decreased by 42%. Samples of liver, gastrocnemius, and soleus muscles were freeze-clamped at the end of the infusion period and analyzed for glycogen and glucose 6-phosphate levels. Glycogen levels were decreased in all tissue samples, whereas glucose 6-phosphate was elevated in gastrocnemius and soleus muscles. Isolated soleus muscles were incubated in vitro with 200 microU/ml of insulin and 1, 10, or 100 nM amylin. Amylin treatment had no effect on 3-O-methyl-D-glucose transport; however, 2-deoxy-D-glucose uptake was inhibited by 33 or 48% at 10 or 100 nM amylin, respectively. Glycogen levels were also decreased after treatment with 10 and 100 nM amylin. Glucose 6-phosphate levels were not affected by amylin treatment in the presence of insulin but were increased nearly twofold in its absence. The data suggest that amylin stimulates glycogenolysis and inhibits glucose uptake both in vivo and in vitro and that the inhibition of glucose uptake is due to inhibition of glucose phosphorylation (i.e., hexokinase).
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PMID:Effects of amylin on glucose metabolism and glycogenolysis in vivo and in vitro. 239 78

Catecholamines are known to have short-term regulatory effects on fat cell hexose uptake. We examined the long-term effects of catecholamines on the insulin-sensitive 2-deoxyglucose (dGlc) uptake in cultured 3T3-L1 adipocytes. Prolonged exposure (48 h) to isoproterenol (beta-adrenergic agonist) stimulated the basal dGlc uptake up to 90%. The effect was specific, time, concentration, and protein synthesis dependent and reversible. The effect of insulin was unaltered and superimposed on the increase in basal dGlc uptake. The long-term effect of isoproterenol was mimicked by epinephrine, dibutyryl cAMP (DBcAMP), and 1-methyl-3-isobutylxanthine (IBMX). By contrast, short-term exposure to isoproterenol (and epinephrine) induced a protein synthesis-independent increase in basal dGlc uptake (30%) not accompanied by an increase in insulin responsiveness. Moreover, on short-term basis, DBcAMP and IBMX suppressed both the basal and insulin-stimulated uptake up to 50%. Determination of the intracellular nonphosphorylated dGlc during the uptake and of the hexokinase activity revealed that the long-term effect of isoproterenol was most likely due to alterations low in dGlc transport. In conclusion, long-term regulators of hexose uptake are in cultured 3T3-L1 adipocytes, isoproterenol, and other cAMP stimulators. The long-term effect is independent from the short-term regulatory effect of the agents and from the effect of insulin.
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PMID:Long-term regulation of hexose uptake by isoproterenol in cultured 3T3 adipocytes. 240 80

In order to further investigate insulin insensitivity in pregnancy, the activities of key enzymes in glycolysis and lipid metabolism were measured in adipose and muscle tissue biopsies from 20 normal pregnant women undergoing caesarean section at term, and 23 non-pregnant women of similar age and body weight undergoing gynaecological surgery. The activity of pyruvate kinase was decreased in pregnant women in both adipose tissue (0.015 (0.009-0.024) (median and range) vs 0.020 (0.009-0.038) Ug-1 wet weight, p less than 0.05) and muscle tissue (6.7 (3.6-10.9) vs 12.0 (2.8-16.2) U g-1 wet weight, p less than 0.001). The activity of hexokinase was decreased in adipose tissue only (0.045 (0.022-0.085) vs 0.057 (0.025-0.097) U g-1 wet weight, p less than 0.05), while the activity of phosphofructokinase was decreased in muscle tissue only (1.3 (0.7-2.6) vs 2.1 (0.3-4.5) U g-1 wet weight, p less than 0.01). Glucose-6-phosphate dehydrogenase activity was increased in muscle tissue (0.30 (0.11-0.59) vs 0.17 (0.09-0.48) U g-1 wet weight, p less than 0.05), while the activity of hydroxyacyl-CoA dehydrogenase was decreased in adipose tissue (0.5 (0.3-1.1) vs 1.0 (0.5-2.3) U g-1 wet weight p less than 0.001) from the pregnant women. Similar results were found when enzyme activities were calculated per gram of protein, but with poorer reproducibility.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Activity of enzymes of glucose and triglyceride metabolism in adipose and muscle tissue from normal pregnant women at term. 252 54


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