Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.9 (glucose-6-phosphatase)
 3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The development of the endoplasmic reticulum (ER) and the ultrastructural localization of glucose-6-phosphatase activity have been studied in the proximal jejunum and distal ileum during the postnatal period. One day after birth, the amount and the repartition of ER in the jejunal enterocytes are similar to that observed in postweaning period. In the following days an extensive proliferation of SER is noted in the supranuclear zone of the absorbing cells. From day 7 till postweaning period a gradual decrease of the amount of SER is observed and after weaning, the ultrastructure of the enterocytes is similar to that in the adult mouse enterocytes. At all time, a positive reaction for G-6-Pase activity is observed in the cisternae of the endoplasmic reticulum and in the nuclear envelope. In the distal ileum, the SER is poorly developed one day after birth. During the first two weeks, the ER increases but no extensive proliferation of SER can be noted as in the jejunum. The G-6-Pase activity can be visualized in the rough and smooth endoplasmic reticulum as well as in the nuclear envelope. It appears that the proliferation of SER could be interpreted as the morphologic expression of an increased G-6-Pase activity.
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PMID:Ultrastructural localization of intestinal glucose-6-phosphatase activity during the postnatal development of the mouse. 624 78

Glycogen storage diseases (GSD) are inborn errors of glycogen metabolism. Of the eight human GSD types in which the enzymatic deficiency has been identified, spontaneous animal counterparts have been reported for GSD I (glucose-6-phosphatase deficiency) in the mouse, for GSD II (acid alpha-glucosidase deficiency) in the dog, in cattle and in the quail, for GSD III (debrancher enzyme deficiency) in the dog and for GSD VIII (phosphorylase kinase deficiency) in the rat and the mouse. Experimentally induced GSD-like conditions have been described in the rat (Acarbose-induced GSD II-like conditions, iodoacetate-induced symptoms of myophosphorylase (GSD V) and myophosphofructokinase (GSD VII) deficiency) and the chicken (ochratoxin A-induced symptoms of cyclic AMP-dependent protein kinase deficiency). Enzymatic defects that are typical of the human GSD types have not been clearly identified in the induced animal conditions. The homology of animal and human GSD types is discussed. It is concluded that clinical, pathogenic and therapeutic studies of GSD may benefit from the use of animal models. For genetic studies of human GSD these models may prove to be of limited value, as the picture of several human GSD types is already obscured by genetic heterogeneity.
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PMID:Glycogen storage diseases in animals and their potential value as models of human disease. 640 5

The development of glucose-6-phosphatase (G-6-Pase-)-deficient hyperbasophilic foci was analyzed at 4-week intervals in the livers of CD-1 and C57BL/6J x C3H/HeJ F1 (hereafter called B6C3F1) mice given a single i.p. injection of diethylnitrosamine (DEN) (0.1, 0.2, or 0.4 mumol/g body weight) within 24 hr after birth. Transections of G-6-Pase-deficient foci of hepatocytes were readily discernible in liver sections of DEN-treated mice of either sex at 8 weeks of age. The size and number of these foci per liver increased with time. The occurrence of G-6-Pase-deficient focus transections with diameters as large as 1 mm coincided with the gross appearance of 1-mm gray-white nodules in the livers of male B6C3F1 mice at 16 weeks of age and in females at 32 weeks of age. Transections of all grossly visible hepatic nodules from male and female mice were G-6-Pase deficient and hyperbasophilic; the great majority were diagnosed as mouse hepatomas type A. After a single neonatal dose of DEN, the number and rate of growth of the G-6-Pase-deficient foci and the incidence and rate of appearance of gross hepatomas were greater in the liver of male than in those of female mice. In contrast, the average numbers of G-6-Pase-deficient foci in the livers of male and androgenized female B6C3F1 mice at 36 weeks of age were approximately equal and about twice that observed for the livers of DEN-treated female controls. Quantitation of carcinogen-induced histochemically detectable foci and hepatomas as a function of time provides a useful tool for the analysis of initiation and promotion in the mouse liver.
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PMID:Quantitative analysis of the time-dependent development of glucose-6-phosphatase-deficient foci in the livers of mice treated neonatally with diethylnitrosamine. 721 32

Glycogen storage disease type 1a (GSD 1a), an autosomal recessive disease, is caused by the inactivity of glucose-6-phosphatase, the gene of which has been recently cloned. We report on the missense mutation C-->T at nucleotide 326 of the G6Pase gene, causing the change of the Arg codon at position 83 into a Cys codon, as the single mutation detected in six Jewish patients. This finding suggests that this mutation might be prevalent among the Jewish population. A new missense mutation T-->G at nucleotide 576 resulting in V166G was found in an Arab Muslim patient. These families may benefit now from pre- and postnatal diagnosis by analysis of DNA from blood and amniotic fluid or chorionic villus cells rather than liver biopsy. No mutations in the G6Pase gene were detected in two GSD 1b patients.
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PMID:Characterization of the mutations in the glucose-6-phosphatase gene in Israeli patients with glycogen storage disease type 1a: R83C in six Jews and a novel V166G mutation in a Muslim Arab. 762 38

The glucose-6-phosphatase system comprises at least five different polypeptides and plays a key role in the metabolism of glucose. A defect in these proteins may cause glycogen storage disease type I (GSD I). We examined the ocular changes of two patients with GSD Ia and b. The patient with GSD Ib showed a delayed appearance of the choroidal flush on fluorescein angiography, a subnormal Arden ratio by electrooculography and atrophy of the retinal pigment epithelium and choriocapillaris. The patient with GSD type I a showed a gradual attenuation of the b-wave by electroretinography. These findings appeared similar to those observed with enzyme distribution among ocular tissue reported previously. To our knowledge, the findings described herein represent the first report of ocular changes associated with GSD I.
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PMID:Ocular changes of glycogen storage disease type I. 774 53

The regenerating liver after partial hepatectomy is one of the few physiologic models of cellular proliferation in the adult animal. During hepatic regeneration, the animal is able to maintain metabolic homeostasis despite the acute loss of two thirds of hepatic tissue. In examining the molecular mechanisms regulating hepatic regeneration, we isolated novel immediate-early genes that are rapidly induced as the remnant liver undergoes the transition from its normal quiescent state into the G1 phase of the cell cycle. One of the most rapidly and highly induced genes which we initially termed RL-1, encodes rat glucose-6-phosphatase (rG6Pase). G6Pase mRNA peaks at 30 min and 36-48 h after hepatectomy correlating with the first and second rounds of cell division. This finding is compatible with studies that showed that G6Pase enzyme activity increases during liver regeneration. However, the increase in G6Pase mRNA is much more dramatic, indicating that it is a more sensitive indicator of this regulation. G6Pase gene expression peaks in the perinatal time period in the liver and remains elevated during the first month of life. The expression of the G6Pase gene is also dramatically elevated in BB diabetic rats, again higher than the enzyme elevation, and its relative induction after partial hepatectomy is blunted in these animals. Insulin treatment of partially hepatectomized diabetic animals downregulates the expression of G6Pase mRNA. Using specific antibodies against G6Pase, we detect a 36-kD G6Pase protein, and its level is elevated in regenerating and diabetic livers. The pattern of G6Pase mRNA expression appears to reflect similar changes in insulin and glucagon levels which accompany diabetes and hepatic proliferation. The elevation of G6Pase expression in these conditions is indicative of its importance as a regulator of glucose homeostasis in normal and abnormal physiologic states.
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PMID:High levels of glucose-6-phosphatase gene and protein expression reflect an adaptive response in proliferating liver and diabetes. 786 Jul 67

Hepatic glycogen storage diseases (GSD) are a group of rare genetic disorders in which glycogen cannot be metabolized to glucose in the liver because of one of a number of possible enzyme deficiencies along the glycogenolytic pathway. Patients with GSD are usually diagnosed in infancy or early childhood with hypoglycemia, hepatomegaly, poor physical growth, and a deranged biochemical profile. Dietary therapies have been devised to use the available alternative metabolic pathways to compensate for disturbed glycogenolysis in GSD I (glucose-6-phosphatase deficiency), GSD III (debrancher enzyme deficiency), GSD VI (phosphorylase deficiency, which is less common), GSD IX (phosphorylase kinase deficiency), and GSD IV (brancher enzyme deficiency). In GSD I, glucose-6-phosphate cannot be dephosphorylated to free glucose. Managing this condition entails overnight continuous gastric high-carbohydrate feedings; frequent daytime feedings with energy distributed as 65% carbohydrate, 10% to 15% protein, and 25% fat; and supplements of uncooked cornstarch. In GSD III, though glycogenolysis is impeded, gluconeogenesis is enhanced to help maintain endogenous glucose production. In contrast to treatment for GSD I, advocated treatment for GSD III comprises frequent high-protein feedings during the day and a high-protein snack at night; energy is distributed as 45% carbohydrate, 25% protein, and 30% fat. Patients with GSD IV, VI, and IX have benefited from high-protein diets similar to that recommended for patients with GSD III.
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PMID:Nutrition therapy for hepatic glycogen storage diseases. 824 77

The crude membrane fraction of cardiomyocytes, which had been used as the antigen for the study of autoantibodies against beta-adrenergic receptors, was characterized using cytochemical methods: in a reaction for adenylate cyclase as an enzyme marker of the beta-receptors of plasma membrane and in a reaction for glucose-6-phosphatase as an enzyme marker of the sarcoplasmic reticulum. The specific precipitates of both enzyme reactions were localized on the membrane vesicles. In case of AC reaction the precipitate was observed on approximately 80% and in case of G-6-Pase on approximately 25% of the whole amount of the vesicles observed, indicating prevalence of vesicles of plasmalemmal origin. These results reveal that the used membrane fraction is appropriate for the study of autoantibodies against beta-receptors, but it can also contain other proteins (antigens) which can cross-react with autoantibodies against beta-adrenergic receptors.
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PMID:Characterization of the crude membrane fraction of cardiomyocytes using enzyme cytochemical markers. 826 66

Deficiency of the enzyme glucose-6-phosphatase is the biochemical defect in glycogen storage disease type I (GSD I). Normally this enzyme is present in the liver, intestine and kidneys. The lack of the enzyme in the kidney makes it obvious that glycogen storage will not be restricted to the liver but that also the kidneys will be involved, possibly resulting in renal damage. Glycogen storage in the kidney is most outspoken present in the proximal tubular cells. In case of insufficient metabolic control, a Fanconi-like syndrome can develop, disappearing with improved therapy. Although renal disease has not been considered a problem in GSD I, recent findings indicate that especially in adult patients chronic renal disease is a common complication. In the past gout nephropathy and renal stones were the complications mentioned. Recently it appears that in a considerable number of patients after a period of 'silent' hyperfiltration, renal damage develops with proteinuria, hypertension and renal dysfunction later on. In biopsies of such patients focal glomerulosclerosis is found.
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PMID:Renal complications in glycogen storage disease type I. 831 28

In the present report changes in the mRNA level of glucose-6-phosphatase (G6Pase; EC 3.1.39) in newborn and adult dogs in vivo were studied to further test the hypotheses that neonatal hyperglycemia may be due to unsuppressed gluconeogenesis by insulin and that the antidiabetic role of insulin-like growth factor-1 (IGF-1) may be intact in newborn dogs who have consistently demonstrated insulin resistance. Our results were the following: (i) Both renal and hepatic G6Pase mRNA were expressed at birth and increased with time during a 24-h period of fasting after birth. (ii) The renal G6Pase mRNA levels in newborn dogs did not respond to either insulin or epinephrine. (iii) Hyperinsulinemia lowered the liver G6Pase mRNA by only 16.3% in newborn dogs, but reduced the liver G6Pase mRNA to an undetectable level in adult dogs. (iv) Hyperglycemia decreased the hepatic G6Pase mRNA by 14.3% in newborn dogs under hyperinsulinemia. (v) Infused epinephrine did not elevate the hepatic G6Pase mRNA level in newborn dogs in the presence of hyperglycemia and hyperinsulinemia. (vi) In newborn dogs, hyper-IGF-1 rapidly reduced the hepatic G6Pase mRNA level by 50%, and hypoglycemia was unable to elevate the hepatic G6Pase mRNA level under the hyper-IGF-1. We concluded that the reduced rate of suppression of transcription of the liver G6Pase gene by insulin in newborn dogs may reflect the unsuppressed neonatal hepatic gluconeogenesis due to insulin resistance and that the physiological roles of IGF-1 seemed to be intact in newborn dogs and may be not responsible for neonatal hyperglycemia.
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PMID:Insulin resistance and the transcription of the glucose-6-phosphatase gene in newborn dogs. 916 94


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