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:1.2.1.13 (glyceraldehyde-3-phosphate dehydrogenase)
6,511 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The thioredoxin peptide Trp-Cys-Gly-Pro-Cys-Lys, which contains the redox active dithiol, was found to be reduced by lipoamide in a coupled reaction with lipoamide dehydrogenase and NADH. The reduced peptide in turn was shown to reduce insulin, oxidized lens protein and glyceraldehyde-3-phosphate dehydrogenase. While the peptide is not as effective a catalyst for utilizing pyridine nucleotides to reduce protein disulfides as thioredoxin, it offers a system which may be developed to provide more efficient disulfide reduction. This is particularly relevant since no thioredoxin peptides have been found to be active with thioredoxin reductase.
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PMID:Thioredoxin fragment 31-36 is reduced by dihydrolipoamide and reduces oxidized protein. 312 52

Glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.2.12) (GAPDH) mRNA levels, protein, and enzymatic activity increase in 3T3-F442A adipocytes after exposure to physiological concentrations of insulin (Alexander, M., Curtis, G., Avruch, J., and Goodman, H. (1985) J. Biol. Chem. 260, 11978-11985). In order to understand the mechanism of this regulation, we have isolated and sequenced 5.4 kilobase pairs of a 12-kilobase pair human genomic clone encoding a functional GAPDH gene. The gene consists of 9 exons and 8 introns with eukaryotic signals necessary for the transcription and translation of GAPDH mRNA. The exon sequence confirms previously published cDNA sequences for human GAPDH in muscle, liver, and erythrocytes. The organization of the human and the unique chicken GAPDH genes is strikingly similar. Although chicken exons VIII-XI have been fused into human exon 8, introns which separate exons encoding the NAD binding, catalytic, and helical domains of the GAPDH protein have been retained. Stable transfection of rodent cells with the intact human GAPDH gene resulted in the expression of a correctly initiated human GAPDH mRNA and an enzymatically active human GAPDH polypeptide. Thus, the gene contains a functional promoter and intact coding sequences. Although many processed GAPDH pseudogenes and GAPDH-like sequences are present in the human genome, Southern blot analysis of human genomic DNA using a probe derived from the 3'-untranslated region of the GAPDH gene detected only two genes, a 10-copy processed pseudogene and a single copy of the isolated gene. In contrast, a probe derived from an intron segment of the isolated gene detected only a single copy of the GAPDH gene. Collectively, these findings strongly suggest that the human genome encodes a single functional GAPDH gene.
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PMID:Isolation and complete sequence of a functional human glyceraldehyde-3-phosphate dehydrogenase gene. 317 May 85

Human proinsulin (PI) has been expressed to a high level (100 mg/liter) as a human superoxide dismutase-PI fusion protein in the yeast, Saccharomyces cerevisiae. At the junction of the two proteins is a methionine residue, allowing PI to be released from the fusion by reaction with cyanogen bromide. The fusion is expressed using a regulated, hybrid promoter containing the regulatory region of the alcohol dehydrogenase II promoter and the 3' end of a glyceraldehyde-3-phosphate dehydrogenase promoter, allowing the recombinant yeast cells to be stably maintained. Production of the fusion protein is induced by growth in medium lacking a fermentable carbon source. The heterologous fusion protein is probably insoluble within the cell, since electron microscopy reveals the presence of 'inclusion bodies'. In a cell-free extract the fusion protein is also insoluble, but can be solubilized with sodium dodecyl sulfate, and cleaved with cyanogen bromide. The PI that is produced contains incorrect disulfide bonds. After sulfitolysis, the product can be easily purified, renatured, and processed to yield insulin.
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PMID:High level expression of proinsulin in the yeast, Saccharomyces cerevisiae. 332 32

Experimental type 1 diabetes mellitus is characterized by an early increase in kidney weight and glomerular volume, but changes in gene expression accompanying diabetic renal growth have not been elucidated. The early response genes, c-fos, c-jun, and c-myc encode proteins that regulate gene transcription, thus influencing the cellular responses to a stimulus. Accordingly, we studied c-fos, c-jun, and c-myc expression in glomeruli during the rapid phase of glomerular hypertrophy that follows the onset of hyperglycemia in diabetic rats. Total RNA was extracted by the method of Chomczynski from isolated glomeruli of streptozotocin (60 mg/kg i.v.) induced diabetic rats 24, 48, and 96 hours, and 1 week after the onset of hyperglycemia (blood glucose > 15 mmol/liter). A second group of rats, studied after streptozotocin administration, received twice daily insulin to maintain normoglycemia. A group of age-matched normal rats served as the control group. Northern blot analysis was performed with cDNA probes for c-fos, c-jun, and c-myc, and GAPDH. mRNA levels for c-fos increased fourfold 24 hours after the onset of hyperglycemia, but returned to baseline by 48 hours. mRNA levels for c-jun increased threefold 24 hours after the onset of hyperglycemia, in diabetic glomeruli, and the increase was sustained for one week. Intensive insulin treatment normalized blood glucose levels and abrogated the increases in c-fos and c-jun expression. There was no discernable increase in c-myc mRNA levels in the diabetic glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Expression of growth-related protooncogenes during diabetic renal hypertrophy. 775 77

The effects of high glucose on insulin-receptor tyrosine kinase activity and gene expression were investigated in 3T3-HIR cells. Cells incubated for 48 h in the presence of 25 mM glucose showed a 5-fold increase in the amount of insulin receptors per cell, receptor autophosphorylation and phosphorylation of the exogenous substrate poly(Glu/Tyr) compared with cells grown in the absence of glucose but in the presence of 25 mM fructose. These effects were associated with a 4-fold stimulation in steady-state levels of insulin-receptor mRNA. Significant cellular glucose utilization and lactate production were observed in the presence of high glucose in the culture medium, indicating a functional glycolytic pathway in glucose-treated cells, but not in cells treated with fructose. Such a differential response to hexoses favours the hypothesis of a carbohydrate regulation via a glycolytic intermediate. This was further supported by a similar glucose-induced increase in mRNA levels of the enzyme glyceraldehyde-3-phosphate dehydrogenase. To test the hypothesis that the stimulatory effect of glucose on amount of insulin receptors and phosphorylation state could result from post-transcriptional modifications, cells exposed to glucose were incubated with actinomycin D, a potent inhibitor of gene transcription. In cells challenged with high glucose plus inhibitor, insulin-receptor mRNA half-life was increased from 1 to 3 h, indicating that posttranscriptional mechanisms are involved in these processes of glucose regulation. Inhibition of protein synthesis by cycloheximide induced an overexpression of insulin-receptor mRNA levels in the presence of glucose, suggesting that labile repressor protein(s) could be implicated in the effects of glucose. We conclude that (1) long-term culture with high glucose increases the amount of insulin receptors and their tyrosine kinase activity and (2) the glucose-induced increase in insulin-receptor mRNA levels can be accounted for, at least in part, by posttranscriptional events.
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PMID:Glucose-induced stimulation of human insulin-receptor mRNA and tyrosine kinase activity in cultured cells. 782 18

Previous studies have shown that the adipose tissue of young genetically obese Zucker rats was characterized by a coordinate overtranscription of lipogenic genes, suggesting that the fa mutation triggers transcription factor(s) acting in common on the promoters of these genes. To test this hypothesis, we developed a system of transient transfection of rat adipocytes with constructs containing glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and fatty acid synthetase (FAS) promoters fused to gene reporter CAT. Those transfected cells expressed high levels of promoter-driven chloramphenicol acetyltransferase (CAT) activity through correctly initiated transcription as shown by primer extension analysis. Using this system we found a direct effect of insulin on GAPDH and FAS gene expression in rat adipocytes. In transfected adipocytes from obese compared to lean rats, activity of GAPDH and FAS promoters fused to CAT, was 2.6- and 8-fold increased, respectively. In contrast when reporter gene activity was driven by either phosphoenolpyruvate carboxykinase or beta-actin promoter, no difference could be observed between lean and obese, pointing out the promoter specificity of genotype effect. 5' deletion analysis of GAPDH promoter allowed us to narrow down the fa responsive region to nucleotide -488-329. As assessed by gel retardation and DNase I footprinting analysis, adipocyte nuclear protein interactions to this 159-bp fragment were found to be identical and to footprint the same 20-bp sequence. This study pointed out that overexpression of GAPDH and FAS genes in adipose tissue of genetically obese rats relies on promoter activation, through a 159-bp cis-acting region within the GAPDH promoter. The effects of the fa mutation on trans-acting factors binding to this region remain to be identified.
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PMID:Evidence of increased glyceraldehyde-3-phosphate dehydrogenase and fatty acid synthetase promoter activities in transiently transfected adipocytes from genetically obese rats. 783 67

Oral vanadate administration has been demonstrated to normalize blood glucose levels in ob/ob and db/db mice and streptozotocin (STZ) diabetic rats. The exact mechanism of this vanadate effect is uncertain, since there are no consistent effects on the insulin receptor tyrosine kinase activity or phosphotyrosine phosphatase activity. We have therefore studied the postreceptor actions of vanadate, focusing our attention on the steady-state levels of mRNA of enzymes involved in carbohydrate metabolism. When compared with their lean (ob/+) controls, the livers of ob/ob mice exhibited an approximately 90% reduction in the levels of phosphoenolpyruvate carboxykinase (PEPCK) mRNA and twofold to fivefold higher levels of the mRNAs for glyceraldehyde-3-phosphate dehydrogenase (GAPDH), the "liver beta-cell" glucose transporter (GLUT2), and the proto-oncogene c-myc. Administration of sodium vanadate (0.25 mg/mL) in the drinking water of ob/ob mice over a 45-day period resulted in a near normalization of blood glucose and increased PEPCK mRNA levels more than ninefold. Starvation of the ob/ob mice for 24 to 48 hours also increased PEPCK mRNA levels by fourfold to 15-fold. Vanadate treatment did not alter mRNA levels of any other proteins studied and had no effect on PEPCK mRNA in ob/+ mice. However, 1 to 100 mumol/L vanadate produced a concentration-dependent increase in PEPCK mRNA levels in an H35 hepatoma cell line, an effect opposite to the suppression of PEPCK mRNA produced by insulin. In summary, hyperglycemia in the ob/ob mouse is characterized by decreased expression of PEPCK and increased expression of GAPDH mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Vanadate normalizes hyperglycemia and phosphoenolpyruvate carboxykinase mRNA levels in ob/ob mice. 796 88

We have previously shown that the inflammatory mediator interleukin-1 suppressed transcription of CYP1A1 and CYP1A2 mRNAs (Barker, C.W., Fagan, J.B., and Pasco, D.S. (1992) J. Biol. Chem. 267, 8050-8055). Since many of the actions of inflammatory mediators are mimicked by oxidative stress, we treated isolated hepatocytes with 0.25-1.0 mM H2O2 to determine whether expression of these genes is also modulated by oxidative stress. Inducer-dependent accumulation of CYP1A1 and CYP1A2 mRNAs were maximally reduced approximately 50 and 70%, respectively, by 1.0 mM H2O2. Run-on transcription analysis suggested that the effect of H2O2 was mediated transcriptionally. The reduction in CYP1A mRNA levels was not due to a reduction in the levels of all mRNAs due to some general toxic effect since H2O2 did not reduce glyceraldehyde-3-phosphate dehydrogenase, alpha-tubulin, beta-fibrinogen, or albumin mRNA levels, and did not increase lactate dehydrogenase released into the medium. Insulin-mimicked H2O2 action, reducing the expression of both mRNAs, and N-acetylcysteine, which increases intracellular glutathione levels, completely reversed the insulin effect on both mRNAs and the H2O2 effect on CYP1A1 mRNA, but only partially reversed the H2O2 effect on CYP1A2 mRNA. This study indicates that the CYP1A1 and CYP1A2 genes are responsive to oxidative stress and that the majority of this responsiveness can be modified by cellular redox potential.
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PMID:Down-regulation of P4501A1 and P4501A2 mRNA expression in isolated hepatocytes by oxidative stress. 830 54

D-Glyceraldehyde irreversibly inhibited rat liver glucokinase in a concentration-dependent manner. The inactivation of glucokinase by glyceraldehyde was blocked by the presence of its substrates such as glucose and mannose. Glucokinase was highly sensitive to glyceraldehyde compared with some other glycolytic enzymes (from animal tissues) including hexokinase, glucose-6-phosphate isomerase, 6-phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase, and pyruvate kinase. The amino acid analysis of untreated and glyceraldehyde-treated glucokinase suggested that glyceraldehyde-induced inactivation of glucokinase is caused by glycation of Lys residues of the enzyme by the triose. Treatment of pancreatic islets with 6 mM glyceraldehyde for 1 h at 37 degrees C caused both inactivation of glucokinase and inhibition of glucose-induced insulin secretion. Another glucose-phosphorylating enzyme (hexokinase) in pancreatic islets, however, was little affected by glyceraldehyde. In addition, glyceraldehyde did not affect the insulin secretory responses of islets to nonglucose secretagogues such as glyceraldehyde and Leu. When pancreatic islets were cultured with a lower concentration (1 mM) of glyceraldehyde for a longer time (17 h) in the presence of 10 mM glucose to mimic the in vivo conditions, both glucokinase activity and glucose-induced insulin secretion were again decreased. This study demonstrates that glucose-induced insulin secretion is impaired by glyceraldehyde through the inactivation of glucokinase. The implication of this finding in the pathophysiology of type II diabetes is discussed.
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PMID:Inhibition of glucose-induced insulin secretion through inactivation of glucokinase by glyceraldehyde. 851 67

As demonstrated previously, liver acini draining the blood from intraportally transplanted pancreatic islets in streptozotocin-diabetic rats are altered in various respects. The hepatocytes in these acini store glycogen and/or fat, and they show an increase in proliferation as well as in apoptotic activity. Thus, they are phenotypically similar to carcinogen-induced preneoplastic liver foci (glycogen-storing foci and sometimes also mixed cell foci). By means of catalytic enzyme histochemistry or immunohistochemistry, we investigated the activity of key enzymes of alternative pathways of carbohydrate metabolism and some additional marker enzymes (well known from studies on preneoplastic hepatic foci) in the altered liver acini surrounding the islet isografts. In addition, the expression of glucose transporter proteins 1 and 2 (GLUT-1 and GLUT-2) were investigated immunohistochemically. The activities of hexokinase, pyruvate kinase, glyceraldehyde-3-phosphate dehydrogenase, and glucose-6-phosphate dehydrogenase were increased, whereas the activities of glycogen phosphorylase, adenylate cyclase, glucose-6-phosphatase, and membrane-bound adenosine triphosphatase were decreased in the altered liver acini. The expression of GLUT-2 was also decreased. GLUT-1 and glutathione S-transferase placental form were not expressed, and the activities of glycogen synthase and gamma-glutamyl-transferase remained unchanged. All changes of the enzyme activities were in line with the well known effects of insulin and resembled alterations characteristic of preneoplastic liver foci observed in different models of hepatocarcinogenesis. It remains to be clarified in long-term experiments whether or not these foci represent preneoplastic lesions and may proceed to neoplasia.
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PMID:Altered liver acini induced in diabetic rats by portal vein islet isografts resemble preneoplastic hepatic foci in their enzymic pattern. 864 65


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