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

---

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

d-Glucose metabolism in cerebral cells prepared from aged senescence-accelerated mouse (SAM), was investigated in consideration of a sex difference. The production of 14CO2 from 6-[14C]D-glucose was reduced in female senescence-accelerated-prone mouse (SAMP) 8, a prone substrain, in comparison with that in female senescence-accelerated-resistant mouse (SAMR) 2, a control substrain, whereas there was no difference in males. The 2-deoxy-D-glucose uptake into cerebral cells from female SAMP8 was also lower than that of control mice. But, the 3-O-methyl-D-glucose uptake in SAMP8 was higher than that of SAMR2, suggesting that the low hexokinase activity was involved in the decreased glucose metabolism in cerebrum of SAMP8 females irrespective of glucose transporter. This possibility was supported by the finding that the contents of glucose 6-phosphate produced from glucose added to cerebral cells from SAMP8 was lower than that in ICR mice.
...
PMID:Evidence that glucose metabolism is decreased in the cerebrum of aged female senescence-accelerated mouse; possible involvement of a low hexokinase activity. 887 28

In this review, the results of a series of NMR experiments investigating glucose storage and synthesis in NIDDM patients and normal controls have been summarized. These have shown: 1. The deficit in nonoxidative glucose disposal in NIDDM subjects results from a defect in the muscle glycogen synthesis pathway. 2. Reduced activity of glucose transporter/hexokinase step in this pathway accounts for the reduced rate of glycogen synthesis in NIDDM patients. 3. This reduced activity of GT/Hk is a genetic defect present before the clinical onset of disease in prediabetic descendants of diabetic parents. 4. In muscle from normal, healthy subjects the rate of glycogen synthesis is controlled by the glucose transport/hexokinase activity step and not by the activity of the muscle glycogen synthase enzyme. 5. Hepatic gluconeogenesis is responsible for most hepatic glucose production during an overnight fast in both normal and NIDDM subjects, and increases in gluconeogenic flux are responsible for the increased rate of hepatic glucose production in NIDDM subjects. 6. In contrast to human muscle, where glycogenesis ceases at rest, in the liver gluconeogenesis and glycogenolysis are always active. Numerous previous studies were considered prior to embarking in each of these NMR experiments. In the original research articles we published, the earlier studies were discussed in terms of the relevant literature. Here, however, I have chosen to present the NMR data as simply as possible, in the hope of exposing the significance of these studies by disentangling the results from the complexities of NMR methodology.
...
PMID:Nuclear magnetic resonance studies of glucose metabolism in non-insulin-dependent diabetes mellitus subjects. 889 70

In order to establish whether growth of glioma cells is associated with glucose transport and metabolism, we investigated expression of the glucose transporter and hexokinase, as well as glucose transport and glucose phosphorylation in rat C6 glioma cells growing at different rates. Rat C6 glioma cells were subcloned to produce four different cell lines (CL1, CL2, CL3 and CL4) differing in growth, differentiation and morphology: CL1 cells were slow-growing with an astrocytic appearance whereas CL4 cells grew rapidly and were small and spindle-shaped. Immunocytochemical analysis using glial fibrillary acidic protein and galactocerebroside antibodies revealed that CL1 and CL4 cells differentiate to astrocytes and oligodendrocytes respectively. Both of these cell lines expressed GLUT1 mRNA predominantly, whereas little GLUT3 mRNA was evident by Northern-blot analysis. The GLUT1 mRNA level was much higher in CL4 than in CL1 cells, and the uptake of 2-deoxy-D-glucose and 3-O-methyl-D-glucose by CL4 cells was markedly higher than that by CL1 cells, indicating a correlation between the growth rate, glucose transporter (GLUT1) level and glucose-transport rate of C6 glioma cells. We then studied glucose metabolism by CL1 and CL4 cells by measuring their hexokinase activities and intracellular concentrations of glucose and ATP. The mitochondrial hexokinase activity of CL4 cells was about three times higher than that of CL1 cells, whereas the cytosolic hexokinase activity of CL4 cells was only about half that of CL1 cells. As the total amount of cellular hexokinase protein in CL4 cells was only slightly higher (about 20%) than that in CL1 cells, the hexokinase protein of CL4 cells was considered to have moved from the cytosol to the mitochondrial membranes. Consistent with the increased mitochondrial hexokinase activity of CL4 cells, the intracellular glucose concentration was undetectable, and the ATP concentration was higher than that of CL1 cells, suggesting that glucose transport is the rate-limiting factor for overall glucose metabolism is rapidly growing C6 cells. Therefore the present data demonstrate that glioma cell growth is related to glucose transport, which is closely associated with glucose metabolism.
...
PMID:Rat C6 glioma cell growth is related to glucose transport and metabolism. 891 84

In trypanosomes the first part of glycolysis takes place in specialized microbodies, the glycosomes. Most glycolytic enzymes of Trypanosoma brucei have been purified and characterized kinetically. In this paper a mathematical model of glycolysis in the bloodstream form of this organism is developed on the basis of all available kinetic data. The fluxes and the cytosolic metabolite concentrations as predicted by the model were in accordance with available data as measured in non-growing trypanosomes, both under aerobic and under anaerobic conditions. The model also reproduced the inhibition of anaerobic glycolysis by glycerol, although the amount of glycerol needed to inhibit glycolysis completely was lower than experimentally determined. At low extracellular glucose concentrations the intracellular glucose concentration remained very low, and only at 5 mM of extracellular glucose, free glucose started to accumulate intracellularly, in close agreement with experimental observations. This biphasic relation could be related to the large difference between the affinities of the glucose transporter and hexokinase for intracellular glucose. The calculated intraglycosomal metabolite concentrations demonstrated that enzymes that have been shown to be near-equilibrium in the cytosol must work far from equilibrium in the glycosome in order to maintain the high glycolytic flux in the latter.
...
PMID:Glycolysis in bloodstream form Trypanosoma brucei can be understood in terms of the kinetics of the glycolytic enzymes. 901 56

The purpose of this study was to test the hypothesis that the rate and extent of glycogen supercompensation in skeletal muscle are increased by endurance exercise training. Rats were trained by using a 5-wk-long swimming program in which the duration of swimming was gradually increased to 6 h/day over 3 wk and then maintained at 6 h/day for an additional 2 wk. Glycogen repletion was measured in trained and untrained rats after a glycogen-depleting bout of exercise. The rats were given a rodent chow diet plus 5% sucrose in their drinking water and libitum during the recovery period. There were remarkable differences in both the rates of glycogen accumulation and the glycogen concentrations attained in the two groups. The concentration of glycogen in epitrochlearis muscle averaged 13.1 +/- 0.9 mg/g wet wt in the untrained group and 31.7 +/- 2.7 mg/g in the trained group (P < 0.001) 24 h after the exercise. This difference could not be explained by a training effect on glycogen synthase. The training induced approximately 50% increases in muscle GLUT-4 glucose transporter protein and in hexokinase activity in epitrochlearis muscles. We conclude that endurance exercise training results in increases in both the rate and magnitude of muscle glycogen supercompensation in rats.
...
PMID:Effect of endurance exercise training on muscle glycogen supercompensation in rats. 904 57

The transient change in uptake of deoxyglucose (DG) and expression of glycolysis-associated gene products in cultured tumor cells (LS180 human colon adenocarcinoma cells) immediately after single-dose X irradiation were examined to acquire basic data for use in the early assessment of tumor responses to radiation treatment by position emission tomography. An increase in accumulation of DG was found 3-5 h postirradiation. Inhibitors of both mRNA and protein synthesis and glycoprotein transport suppressed the increase in accumulation of DG to the control level. Both the glucose transporter-1 mRNA expression and the enzymatic activity of hexokinase in the cells were significantly elevated in conjunction with high DG accumulation. These findings indicate that the transiently elevated glucose metabolism occurred via processes at the levels of gene expression. These transient tumor cell responses might be useful for the early assessment of radiation damage.
...
PMID:Transient increase in glycolytic metabolism in cultured tumor cells immediately after exposure to ionizing radiation: from gene expression to deoxyglucose uptake. 918 72

This study tested the hypothesis that alterations in the metabolic integrity of grafted muscle contribute to its diminished ability to sustain power. Compared with control muscles, muscles studied 120 days after the grafting procedure had lower specific force and sustained power. The sustained power protocol resulted in a depletion of muscle glycogen in control (83%) and grafted (85%) animals. Grafts had lower pre- and poststimulation glycogen, diminished citrate synthase activity, and greater hexokinase activity. No differences were observed in phosphofructokinase activity, glucose transporter GLUT-4 content, fiber type, beta-adrenergic-receptor (beta-AR) density, or binding affinity. Isoproterenol-stimulated adenylyl cyclase activity was lower in grafted vs. control muscle, suggesting an uncoupling of the beta-AR-effector complex. Thus the diminished ability of the grafted muscle to sustain power may be explained, in part, by a decrease in energy available from glycogen stores and/or a decrease in oxidative capacity.
...
PMID:Functional deficits in medial gastrocnemius grafts in rats: relation to muscle metabolism and beta-AR regulation. 921 46

Twenty-six different hepatoma cell lines established from cancer-prone transgenic mice exhibited a close correlation between expression of the GLUT 2 glucose transporter and activation of the L-type pyruvate kinase (L-PK) gene by glucose, as judged by Northern blot analyses and transient transfection assays. The L-PK gene and a transfected L-PK construct were silent in GLUT 2(+) cells and active in GLUT 2(-) cells cultured in glucose-free medium. Transfection of GLUT 2(-) cells with a GLUT 2 expression vector restored the inducibility of the L-PK promoter by glucose, mainly by suppressing the glucose-independent activity of this promoter. Culture of GLUT 2(-) cells, in which the L-PK gene is constitutively expressed, in a culture medium using fructose as fuel selected GLUT 2(+) clones in which the L-PK gene responded to glucose. The expression of the L-PK gene in GLUT 2(-) cells cultured in the absence of glucose was correlated with a high intracellular glucose 6-phosphate (Glu-6-P) concentration while under similar culture conditions Glu-6-P concentration was very low in GLUT 2(+) cells. Consequently, a role of GLUT 2 in the glucose responsiveness of glucose-sensitive genes in cultured hepatoma cells could be to allow for Glu-6-P depletion under gluconeogenic culture conditions. In the absence of GLUT 2, glucose endogeneously produced might be unable to be exported from the cells and would be phosphorylated again to Glu-6-P by constitutively expressed hexokinase isoforms, continuously generating the glycolytic intermediates active on the L-PK gene transcription.
...
PMID:Role of the GLUT 2 glucose transporter in the response of the L-type pyruvate kinase gene to glucose in liver-derived cells. 921 18

We have reported previously that a high glycolytic capacity develops soon after birth in enterocytes isolated from suckling newborn pigs. In the present work, we investigated whether such metabolic changes could affect intestinal glucose utilization in vivo and examined possible variations in glucose metabolism along the small intestine. Glucose utilization by individual tissues was assessed using the 2-deoxyglucose technique. The overall glucose utilization rate was doubled in suckling vs. fasting 2-day-old pigs because of significantly higher rates in all tissues studied, except for the brain. In parallel, enterocytes were isolated from the proximal, medium, or distal jejunoileum of newborn vs. 2-day-old pigs and assessed for their capacity to utilize, transport, and phosphorylate glucose. Intestinal glucose consumption accounted for approximately 15% of glucose turnover rate in suckling vs. 8% in fasting pigs. Moreover, there was a proximal-to-distal gradient of glucose utilization in the intestinal mucosa of suckling pigs. Such a gradient was also evidenced on isolated enterocytes. The stimulation of both hexokinase activity (HK2 isoform) and basolateral glucose transporter (GLUT2), as observed in the proximal jejunum, could account for such a site-specific effect of suckling.
...
PMID:GLUT2 and hexokinase control proximodistal gradient of intestinal glucose metabolism in the newborn pig. 922 91

To determine the influence of tumor cell proliferation and changes in the genetic program in malignant cells on the fluorodeoxyglucose (FDG) uptake we performed PET studies in several animal tumors: spontaneous mammary fibroadenoma, chemically-induced mammary adenocarcinoma and Dunning prostate adenocarcinoma. The expression of the glucose transporter (GLUT1) and of hexokinase (Hk) was measured using 32P-labeled cDNA probes and densitometry. Furthermore the proliferative activity was determined with one-dimensional flow cytometry. The FDG uptake and the proliferation parameters were not correlated. The normalized amounts of GLUT and Hk mRNA were lower in spontaneous fibroadenomas and prostate tumors than in chemically induced mammary. The FDG uptake was correlated to GLUT1 expression with r = 0.83 and to Hk expression with r = 0.77. Multiple regression analysis revealed a relation of FDG uptake to GLUT1 and HK with r = 0.87. Our results show that the FDG uptake in our study was related not to differences in proliferation, but rather to differences in the transcription of glycolysis associated genes.
...
PMID:FDG uptake, tumor proliferation and expression of glycolysis associated genes in animal tumor models. 923 32


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---