Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The application of molecular scanning techniques to the detection of potentially pathogenic mutations in candidate genes in patients with non-insulin-dependent diabetes has revealed a number of molecular variants of uncertain pathophysiologic significance. The determination of the significance of such variants requires large-scale population studies of the prevalence of the mutant in affected and control groups. Herein, we describe two adaptations of the technique of single nucleotide primer extension (SNuPE) which allow the simultaneous examination of large numbers of alleles at multiple loci. The usefulness of these adaptations is illustrated by their application to the simultaneous detection of three point mutations, two in the tyrosine kinase domain of the insulin receptor and one in the insulin-responsive glucose transporter (GLUT4) in a highly insulin-resistant NIDDM population. By pooling genomic or amplified DNA and performing the SNuPE reactions with three primers of different length we could readily examine 300 alleles on a single 20 lane gel. Using pooled SNuPE, we also examined a large British Caucasian control population for the prevalence of GLUT4 Ile383, a variant which has previously been reported only in NIDDM. GLUT4 Ile383 was detected in 2/42 of the highly insulin-resistant NIDDM subjects and 4/240 middle-aged blood donors. Family studies and examination of the expressed mutant transporter will be necessary to establish whether this mutation is of functional significance. Pooled and multiplex SNuPE are powerful techniques with wide applicability to population genetic studies of specific mutations.
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PMID:Rapid and simultaneous detection of multiple mutations by pooled and multiplex single nucleotide primer extension: application to the study of insulin-responsive glucose transporter and insulin receptor mutations in non-insulin-dependent diabetes. 130 12

The recent application of recombinant DNA technology to clinical investigation now allows the identification of the molecular alterations responsible for insulin resistance. In this review, the recent knowledge concerning these investigations is reported. Genetic mutations of the insulin gene as the source of insulin resistance have been reported for a long time. More recently a series of mutations of the insulin receptor gene have been identified as the cause of the extreme insulin resistance, observed in rare syndromes, such as type A insulin resistance or leprechaunism. However, it is probable that the majority of the molecular defects causing insulin resistance occur at the postreceptor level. The key proteins involved in the different intracellular signalling pathways of insulin are only partly identified. A better understanding of the mechanisms of insulin action is essential for the identification of corresponding genetic alterations. The investigations concerning the glucose transporter GLUT4 and glucokinase genes are good examples of complex but promising research, which has recently started. Elucidation of the genetic and molecular basis of diseases such as type II diabetes or other states associated with insulin resistance, is the long-term goal.
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PMID:Molecular basis of insulin resistance. 130 16

Insulin resistance syndromes are heterogeneous in either severity or mechanism. Many drugs have been shown to counteract various elements of insulin resistance. Some of them, by normalization of metabolic parameters, decrease insulin resistance induced by chronic hyperglycemia in diabetes. Insulin and, to some extent, sulfonylureas are in this group, but these drugs are not stricto sensu medication of insulin resistance. Some drugs sensitize peripheral tissues to the action of insulin. For instance, biguanides and thiazolidine-dione facilitate translocation to the membrane of glucose transporter in presence of insulin. Other compounds as vanadate or IGF-1 mimic some peripheral action of insulin. Finally, blockade of FFA oxidation by specific inhibitors (methylpalmoxyrate) can limit insulin resistance. In 1992, among these compounds, specific of insulin resistance, biguanides are mostly used. However, the efficacy of these drugs is moderate and limited to type 2 diabetes.
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PMID:Pharmacological approach in the treatment of insulin resistance. 130 17

Insulin resistance of the skeletal muscle is a key feature of Type 2 (non-insulin-dependent) diabetes mellitus. To determine whether a decrease of glucose carrier proteins or an altered subcellular distribution of glucose transporters might contribute to the pathogenesis of the insulin resistant state, we measured glucose transporter numbers in membrane fractions of gastrocnemius muscle of 14 Type 2 diabetic patients and 16 non-diabetic control subjects under basal conditions. Cytochalasin-B binding and immunoblotting with antibodies against transporter-subtypes GLUT 1 and GLUT 4 were applied. The cytochalasin-B binding values (pmol binding sites/g muscle) found in a plasma membrane enriched fraction, high and low density membranes of both groups (diabetic patients and non-diabetic control subjects) suggested a reduced number of glucose transporters in the plasma membranes of the diabetic patients compared to the control subjects (diabetic patients: 1.47 +/- 1.01, control subjects: 3.61 +/- 2.29, p less than or equal to 0.003). There was no clear difference in cytochalasin-B binding sites in high and low density membranes of both groups (diabetic patients: high density membranes 3.76 +/- 1.82, low density membranes: 1.67 +/- 0.81; control subjects: high density membranes 5.09 +/- 1.68, low density membranes 1.45 +/- 0.90). By Western blotting analysis we determined the distribution of the glucose transporter subtypes GLUT 1 and GLUT 4 in the plasma membrane enriched fraction and low density membranes of seven patients of each group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Subcellular distribution of GLUT 4 in the skeletal muscle of lean type 2 (non-insulin-dependent) diabetic patients in the basal state. 132 31

In order to determine the possible contribution of the GLUT1 (HepG2) glucose transporter gene to the inheritance of non-insulin-dependent diabetes mellitus (NIDDM), two restriction fragment length polymorphisms (RFLPs) and the related haplotypes at this locus were studied in 48 Italian diabetic patients and 58 normal subjects. Genotype frequencies for the XbaI polymorphism were significantly different between patients and controls (XbaI: chi 2 = 9.80, df = 2, P less than 0.0079). A significant difference was also found in the allele frequencies between NIDDM patients and controls (chi 2 = 9.39, df = 1, P less than 0.0022), whereas no differences were found for the StuI RFLP. No linkage disequilibrium was detected between the XbaI and StuI RFLPs in this sample. The analysis of the four haplotype frequencies (X1S1, X1S2, X2S1, X2S2) revealed a significant difference between diabetic patients and controls (chi 2 = 14.26, df = 3, P less than 0.002). By comparing single haplotype frequencies, a significant difference between the two groups was found for the X1S1 and X2S2 haplotypes. A two-allele RFLP at the GLUT4 (muscle/adipocyte) glucose transporter gene, detected with the restriction enzyme KpnI, was also examined; no differences were found between patients and controls for this RFLP. The finding of an association between polymorphic markers at the GLUT1 transporter and NIDDM suggests that this locus may contribute to the inherited susceptibility to the disease in this Italian population.
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PMID:Polymorphisms at the GLUT1 (HepG2) and GLUT4 (muscle/adipocyte) glucose transporter genes and non-insulin-dependent diabetes mellitus (NIDDM). 134 45

Glucose is reabsorbed from the glomerular filtrate in the proximal segment of the renal tubule in two stages. The first stage is uphill transport across the brush border membrane by Na(+)-glucose cotransport and the second stage is downhill transport across the basolateral membrane by facilitated diffusion. Genes for both a renal Na(+)-glucose cotransporter (SGLT1) and a renal facilitated glucose transporter (GLUT2) have been cloned and sequenced. To examine whether SGLT1 and GLUT2 colocalize to the same tubular epithelial cells in rat kidney, double-immunoperoxidase studies with dual chromogens and paraformaldehyde perfusion-fixed frozen sections of rat kidney were performed. Antipeptide antisera were prepared against rat GLUT2 (amino acids 510-522) and rabbit SGLT1 (amino acids 402-420). Proximal tubules were identified immunocytochemically with an antiserum raised against a synthetic peptide corresponding to the 21 amino acids at the COOH-terminal of the heavy chain of rat gamma-glutamyl transpeptidase, which is a proximal tubule-specific enzyme. The anti-GLUT2 antiserum strongly stained the basolateral membrane of 46% of cortical tubules, whereas the SGLT1 antiserum stained the brush border of 56% of the cortical tubules. The gamma-glutamyl transpeptidase antiserum also stained the brush border of 51% of the cortical tubules. GLUT2 and SGLT1 colocalized to 40% of cortical epithelium, but 16% of cortical epithelial cells were immunopositive for brush border SGLT1 and immunonegative for basolateral GLUT2. These gamma-glutamyl transpeptidase staining results suggest that at least 50% of the tubules in the cortex are proximal tubules and that SGLT1 and GLUT2 colocalize to most proximal tubules. The fact that SGLT1 antiserum immunoreacted with tubules unreactive to the GLUT2 antiserum suggests that either the SGLT1 epitope is conserved on a related brush border protein or that there is another GLUT transporter responsible for the exit of sugar from these proximal tubule cells.
Diabetes 1992 Jun
PMID:Colocalization of GLUT2 glucose transporter, sodium/glucose cotransporter, and gamma-glutamyl transpeptidase in rat kidney with double-peroxidase immunocytochemistry. 135 Feb 59

The precise genetic defects underlying the etiology of non-insulin-dependent diabetes mellitus (NIDDM) have yet to be identified. The beta-cell/liver glucose transporter gene GLUT2 represents a good candidate for the etiology of the disease, being involved in the glucose signalling for beta-cell insulin release. Population association studies of the GLUT2 gene in NIDDM have so far yielded controversial results. In order to determine the possible contribution of this gene to the inheritance of NIDDM, we have employed a new approach, where two polymorphic markers of the GLUT2 locus, detected with the restriction enzyme Taq-1, were examined for linkage with the disease in a group of 22 Italian pedigrees with affected members (n = 50). Departure from independent segregation between markers and disease was analyzed by the Affected-Pedigree-Members (APM) statistical method. Furthermore, association analysis between the Taq-1 RFLPs at the GLUT2 locus and NIDDM was performed in a group of diabetics with a strong family history, comprising the 22 probands and 23 other diabetics with an affected first-degree relative. The results indicate that there was no segregation distortion between the Taq-1 markers of the GLUT2 gene and the disease in the pedigrees examined. Also, no significant difference in genotype distribution, haplotype and allele frequencies was found between diabetics and controls for the two Taq-1 RFLPs. We conclude that genetic variation at the GLUT2 transporter gene is unlikely to contribute in a major way to the inheritance for NIDDM in this Italian population.
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PMID:Polymorphisms at the GLUT2 (beta-cell/liver) glucose transporter gene and non-insulin-dependent diabetes mellitus (NIDDM): analysis in affected pedigree members. 135 29

Familial NIDDM probably results from combined inherited defects of insulin secretion and action. Members of the facilitative glucose transporter family are strong candidates for both defects, and RFLPs for both GLUT1 (erythrocyte) and GLUT2 (liver/islet) genes have been associated with NIDDM in some populations. To test the hypothesis that GLUT1 and GLUT2 mutations contribute to the inherited predisposition to NIDDM, we examined linkage of these loci with NIDDM in 18 large Utah white pedigrees (two and three generation) ascertained for > or = 2 NIDDM siblings. We used two RFLPs detected with Xba1 and Stu1 for the GLUT1 transporter. For the GLUT2 (liver/beta-cell) transporter gene, we used an RFLP detected with EcoR1 and a highly polymorphic (6-allele) dinucleotide (microsatellite) repeat. Analysis was performed with the MLINK program of the LINKAGE package. We tested four models for each locus: dominant and recessive, with IGT alternately considered as unknown affection status, or affected if IGT was diagnosed < or = 45 yr of age and unknown if > 45 yr. Disease gene frequencies were chosen to give approximate disease prevalence in American whites (q = 0.03, dominant; q = 0.25, recessive). Linkage of GLUT1 and NIDDM was strongly and significantly rejected under all models, with total (pooled) LOD scores of -5.7 to -8.9, indicating > 500,000:1 odds against linkage. Pooled LOD scores were significantly negative (< -2.0, or 100:1 odds against linkage) to a recombination fraction of > 5%. No heterogeneity was apparent. Analysis of GLUT2 gave similar results, with LOD scores of < -4.0 under each model, indicating at least 10,000:1 odds against linkage.(ABSTRACT TRUNCATED AT 250 WORDS)
Diabetes 1992 Dec
PMID:Linkage analysis of GLUT1 (HepG2) and GLUT2 (liver/islet) genes in familial NIDDM. 135 87

Previous studies revealed that rat islets express the GLUT2-liver facilitative glucose transporter isoform, a glucose carrier with a low affinity for glucose but a high capacity for glucose transport. These studies indicated the presence of a second glucose transporter in rat islets; however, they did not indicate to which of the five known facilitative glucose transporters it corresponded. In this study, we isolated RNA from rat islets of Langerhans and confirmed the presence of GLUT2 mRNA. In addition, we present data indicating that the second isoform expressed in islets is the GLUT1-erythrocyte isoform. The effect of culturing islets in 5.5, 8.3, or 11.1 mM glucose on the levels of GLUT1 and GLUT2 mRNA also was examined. The levels of GLUT1 and GLUT2 mRNA were two- and threefold higher, respectively, in islets cultured for 24 h in 11.1 mM glucose compared with those incubated in the presence of 5.5 mM glucose. Therefore, the previously observed increase in GLUT2 mRNA levels in the islets of rats made hyperglycemic by chronic infusion of glucose can be mimicked in vitro, implying that glucose regulates GLUT2 mRNA expression.
Diabetes 1992 Jan
PMID:Expression of GLUT1 and GLUT2 glucose transporter isoforms in rat islets of Langerhans and their regulation by glucose. 137 Jan 54

We previously reported that, in primary cultured adipocytes, chronic exposure to glucose plus insulin impairs the insulin-responsive glucose transport system. In this study, we examined regulation of glucose transport in BC3H1 myocytes as a model for muscle and found important differences between BC3H1 cells and adipocytes. In myocytes, chronic glucose exposure per se (25 mM) decreased basal glucose transport activity by 78% and insulin's acute ability to maximally stimulate transport by 68% (ED50 approximately 2.5 mM; T1/2 approximately 4 h). D-Mannose and 3-O-methyl-glucose diminished transport rates with approximately 100 and 50% of the potency of D-glucose, respectively, whereas L-glucose, D-fructose, and D-galactose were inactive. Chronic glucose exposure also reduced cell surface insulin binding by 30% via an apparent decrease in receptor affinity, and this effect was associated with a comparable rightward shift in the insulin-glucose transport dose-response curve. In other studies, persistent stimulation with 15 nM insulin also decreased maximally stimulated glucose transport activity, which was independent and additive to the regulatory effect of glucose. Moreover, glucose and insulin-induced insulin resistance via different mechanisms. Glucose (25 mM) reduced the number of cellular glucose transporter proteins by 84% and levels of GLUT1 transporter mRNA by 50% (whether normalized to total RNA or CHO-B mRNA). In contrast, chronic insulin exposure led to a 2.1-fold increase in GLUT1 mRNA but did not alter cellular levels of transporter protein. Cotreatment with glucose prevented the insulin-induced rise in GLUT1 mRNA. BC3H1 cells did not express GLUT4 mRNA that encodes the major transporter isoform in skeletal muscle. In conclusion, in BC3H1 myocytes 1) glucose diminished insulin sensitivity by decreasing insulin receptor binding affinity and decreased basal and maximally insulin-stimulated glucose transport rates via cellular depletion of glucose transporters and suppression of GLUT1 mRNA; 2) chronic insulin exposure exerted an independent and additive effect to reduce maximal transport activity; however, insulin increased levels of GLUT1 mRNA and did not alter the cellular content of glucose transporters; and 3) although BC3H1 cells are commonly used as a model for skeletal muscle, studies examining glucose transport should be interpreted cautiously due to the absence of GLUT4 expression. Nevertheless, the data generally support the idea that, in non-insulin-dependent diabetes mellitus, hyperglycemia and hyperinsulinemia can induce or exacerbate insulin resistance in target tissues.
Diabetes 1992 Mar
PMID:Glucose and insulin chronically regulate insulin action via different mechanisms in BC3H1 myocytes. Effects on glucose transporter gene expression. 137 73


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