Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011860 (type 2 diabetes)
 57,723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The beta-cell/liver glucose transporter (GLUT2) gene was screened for mutations using single-strand conformation polymorphism analysis (SSCP) in 30 Japanese subjects with non-insulin dependent diabetes mellitus (NIDDM). Analysis of all exons and adjacent intron regions identified six SSCP polymorphisms, three of which resulted in amino acid substitutions: V101I, T110I and G519E. The V101I and G519E, substitutions represent new polymorphisms in this gene. The six polymorphisms were observed in both NIDDM and control groups and there were no significant differences in allele frequencies between groups. A portion of the insulin receptor substrate 1 gene in 30 NIDDM subjects and in normal control subjects was also screened for mutations. Two SSCP variants that change the sequence of the protein, delta S686/687 (deletion of the codons for serine-686 and 687) and G972R, were identified in two different NIDDM subjects, both whom were also heterozygous for the V101I polymorphisms in GLUT2. The GLUT2 and IRS1 amino acid polymorphisms did not show a simple pattern of co-inheritance with NIDDM in the families of these subjects suggesting that neither polymorphism is sufficient to cause NIDDM but may increase diabetes-susceptibility through their interaction with other loci and environmental factors.
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PMID:Identification of two novel amino acid polymorphisms in beta-cell/liver (GLUT2) glucose transporter in Japanese subjects. 771 16

High-fat intake leading to obesity contributes to the development of non-insulin-dependent diabetes mellitus (NIDDM, type 2). Similarly, mice fed a high-fat (safflower oil) diet develop defective glycemic control, hyperglycemia, and obesity. To assess the effect of a modest increase in the expression of GLUT4 (the insulin-responsive glucose transporter) on impaired glycemic control caused by fat feeding, transgenic mice harboring a GLUT4 minigene were fed a high-fat diet. Low-level tissue-specific (heart, skeletal muscle, and adipose tissue) expression of the GLUT4 minigene in transgenic mice prevented the impairment of glycemic control and accompanying hyperglycemia, but not obesity, caused by fat feeding. Thus, a small increase (< or = 2-fold) in the tissue level of GLUT4 prevents a primary symptom of the diabetic state in a mouse model, suggesting a possible target for intervention in the treatment of NIDDM.
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PMID:High fat diet-induced hyperglycemia: prevention by low level expression of a glucose transporter (GLUT4) minigene in transgenic mice. 772 22

Insulin receptor (IR) and insulin-responsive glucose transporter (Glut4) represent two candidate genes involved in the development of non-insulin dependent diabetes mellitus (NIDDM); detection of molecular alterations in these genes might explain their possible contribution to NIDDM. Recently, mutations within the coding region of IR and Glut4 have identified: they include the Glut4Ile383 and IRGln1152 variants which were found at low frequencies in diabetic Caucasian populations. In this study Italian NIDDM patients and control subjects were analysed and mutated alleles were not found. Therefore in our population these variants appear to have little relevance to the genetic susceptibility to NIDDM.
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PMID:Failure to detect Glut4-Ile383 and IR-Gln1152 variants in NIDDM (non-insulin dependent diabetes mellitus) and control subjects in an Italian population. 781 14

This article reviews the effects of diet and exercise on insulin sensitivity in patients with type II diabetes (non-insulin-dependent diabetes mellitus, NIDDM). Dietary caloric restriction operative through weight loss decrease the insulin resistance characteristic of the disease by increased glucose transport. The precise localization of this effect is unknown, as is the defect in the insulin signalling pathway in type II diabetes. Inherent problems are the inability to clearly separate obesity and type II diabetes and methodological difficulties in the distinction of dietary effects from exercise-induced effects. The mechanism of exercise-induced insulin sensitivity has gained considerable understanding through the detection of the glucose transporter molecule GLUT-4 in muscle. It is now clear that the presence of insulin is not mandatory and mere electrical stimulation of the muscle produces similar effects through distinct signalling pathways. Exercise-induced increased blood flow and decreased vascular resistance may also play an important role. In contrast to these newer experimental data, clinical studies and feasibility studies aimed to implement exercise as a valuable therapeutic measure in type II diabetes have failed to delineate promising long-lasting effects and can therefore not be generally recommended. Encouraging epidemiological data have recently been found with respect to the prevention of type II diabetes by increased physical activity in patients at risk.
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PMID:The influence of diet and physical activity on insulin sensitivity. 784 96

Glucokinase is a key enzyme of glucose metabolism that phosphorylates glucose to glucose-6-phosphate (G-6-P). This is the first step of glucose metabolism after the uptake of glucose by glucose transporter 2 (GLUT 2). Glucokinase is one of the hexo-kinases and is expressed only in pancreatic beta cells and hepatocytes. Recently it was reported that glucokinase gene is associated with some families with MODY (maturity-onset diabetes of the young). As MODY is a subtype of diabetes which is inherited autosomal dominantly, the correlation of diabetes with glucokinase gene was vigorously studied in many laboratories. The first mutation in exon 7 of the glucokinase gene was reported in 1992. Since the first report of the glucokinase gene mutation in exon 7, a number of mutations and a deletion were reported to be associated with MODY or late-onset NIDDM. But investigations by many groups revealed that glucokinase gene abnormalities are responsible for less than one per cent of NIDDM which is relatively small compared with diabetes with mitochondrial gene alterations.
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PMID:[Glucokinase gene abnormalities in maturity-onset diabetes of the young (MODY) and late-onset NIDDM]. 798 82

The purpose of these experiments was to test the hypothesis that impaired glucose-stimulated insulin secretion in NIDDM is due to mutations in the islet beta cell/liver glucose transporter (GLUT 2) gene. Using oligonucleotide primers flanking each of the 11 exons, the structural portion of the gene was studied by PCR-SSCP analysis. DNA from African-American females (n = 48), who had gestational diabetes but developed overt NIDDM after delivery, was studied. Each SSCP variant was sequenced directly from genomic DNA. Two amino acid substitutions from the previously reported sequence were found, one in exon 3 and the other in exon 4B. Four additional silent mutations in the coding region, and six intron mutations outside the splice junction consensus sequences, were also identified. The mutation GTC x ATC in exon 4B substituted Val197 to Ile197. This amino acid substitution was found in only one NIDDM patient in a single allele, and was not found in 52 control subjects. This residue exists in the fifth membrane spanning domain, and Val at this position is conserved in mouse and rat GLUT 2, and human GLUT 1 to GLUT 4. The other codon change in exon 3, ACT x ATT, substituted Thr110 to Ile110 in the second membrane spanning domain. To determine the frequency of this non-conservative amino acid substitution, a PCR-LCR assay was developed. This assay was simple and highly specific for detection of this single nucleotide substitution. The allelic frequency of the ATT (Ile110) in NIDDM patients (39.6%, n = 48) and that in controls (47.1%, n = 52) did not differ (p = 0.32, Fisher's exact test).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Variability of the pancreatic islet beta cell/liver (GLUT 2) glucose transporter gene in NIDDM patients. 806 45

Metformin (dimethylbiguanide) is an antihyperglycaemic drug used to treat non-insulin dependent diabetes mellitus. It acts in the presence of insulin to increase glucose utilization and reduce glucose production, thereby countering insulin resistance. The effects of metformin include increased glucose uptake, oxidation and glycogenesis by muscle, increased glucose metabolism to lactate by the intestine, reduced hepatic gluconeogenesis and possibly a reduced rate of intestinal glucose absorption. Metformin appears to facilitate steps in the postreceptor pathways of insulin action, and may exert effects that are independent of insulin. In muscle, metformin increases translocation into the plasma membrane of certain isoforms of the glucose transporter. The effects of metformin are generally moderate, and do not cause clinical hypoglycaemia or increased weight gain. Metformin has an antihypertriglyceridaemic effect and exerts various potentially useful effects on haemostasis. A risk of lactic acidosis is negligible provided that the contraindications, particularly renal incompetence are respected.
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PMID:Metformin--an update. 811 99

Mechanisms causing cellular insulin resistance in gestational diabetes mellitus are not known. We, therefore, studied isolated omental adipocytes obtained during elective cesarean sections in nondiabetic (control) and GDM gravidas. Cellular insulin resistance was attributed to impaired stimulation of glucose transport; compared with control subjects, basal and maximally insulin-stimulated transport rates (per surface area) were reduced 38 and 60% in GDM patients, respectively. To determine underlying mechanisms, we assessed the number, subcellular distribution, and translocation of GLUT4, the predominant insulin-responsive glucose transporter isoform. The cellular content of GLUT4 was decreased by 44% in GDM patients as assessed by immunoblot analysis of total postnuclear membranes. However, GDM patients segregated into two subgroups; half expected profound (76%) cellular depletion of GLUT4 and half had GLUT4 levels in the normal range. Cellular GLUT4 was negatively correlated with adipocyte size in the control subjects and GDM patients with normal GLUT4 (r = 0.60), but fell way below this continuum in GDM patients with low GLUT4, indicating that heterogeneity was not caused by differences in obesity. All GDM. distribution. In basal cells, increased amounts of GLUT4 were detected in membranes fractionating with (such that the plasma membrane GLUT4 level in GDM (such that the plasma membrane GLUT4 level in GDM patients was equal to that observed in insulin-stimulated cells from control subjects). Furthermore, insulin stimulation induced translocation of GLUT4 from low-density microsomes to plasma membranes in control subjects but did not alter subcellular distribution in GDM patients. In other experiments, cellular content of GLUT1 was normal in GDM patients, and GLUT1 did not undergo insulin-mediated recruitment to plasma membranes in either control subjects or GDM patients. A faint signal was detected for GLUT3 only in low-density microsomes and only with one of two different antibodies. In GDM, we conclude that insulin resistance in adipocytes involves impaired stimulation of glucose transport and arises from a heterogeneity of defects intrinsic to the glucose transport effector system. GLUT4 content in adipocytes is profoundly depleted in approximately 50% of GDM patients, whereas all patients are found to exhibit a novel abnormality in GLUT4 subcellular distribution. This latter defect is characterized by accumulation of GLUT4 in membranes cofractionating with plasma membranes and high-density microsomes in basal cells and absence of translocation in response to insulin. The data suggest that abnormalities in cellular traffic or targeting relegate GLUT4 to a membrane compartment from which insulin cannot recruit transporters to the cell surface and have important implications regarding skeletal muscle insulin resistance in GDM and NIDDM.
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PMID:Multiple defects in the adipocyte glucose transport system cause cellular insulin resistance in gestational diabetes. Heterogeneity in the number and a novel abnormality in subcellular localization of GLUT4 glucose transporters. 824 23

Sulfonylurea drugs are widely used in the therapy of NIDDM. The improvement of glucose tolerance after long-term treatment of NIDDM patients with the drug can be explained by stimulation of glucose utilization in peripheral tissues that are characterized by insulin resistance in these patients. We studied whether the novel sulfonylurea drug, glimepiride, stimulates glucose transport into isolated insulin-resistant rat adipocytes. After long-term incubation of the cells in primary culture with high concentrations of glucose, glutamine, and insulin, stimulation of glucose transport by insulin was significantly reduced both with respect to maximal responsiveness (65% decrease of Vmax) and sensitivity (2.6-fold increase of ED50) compared with adipocytes cultured in medium containing a low concentration of glucose and no insulin. This reflects insulin resistance of glucose transport. In contrast, both responsiveness and sensitivity of glucose transport toward stimulation by glimepiride were only marginally reduced in insulin-resistant adipocytes (15% decrease of Vmax; 1.2-fold increase of ED50) versus control cells. Glimepiride, in combination with glucose and glutamine during the primary culture, caused desensitization of the glucose transport system toward stimulation by insulin, but to a lesser degree than insulin itself (50% reduction of Vmax; ninefold increase of ED50). Again, the maximal responsiveness and sensitivity of glucose transport toward stimulation by glimepiride were only slightly diminished. The presence of glimepiride during primary culture did not antagonize the induction of insulin resistance of glucose transport. The stimulation of glucose transport in insulin-resistant adipocytes by glimepiride is caused by translocation of glucose transporters from low-density microsomes to plasma membranes as demonstrated by subcellular fractionation and immunoblotting with anti-GLUT1 and anti-GLUT4 antibodies. Immunoprecipitation of GLUT4 from 32Pi- and [35S]methionine-labeled adipocytes revealed that the insulin resistance of GLUT4 translocation is accompanied by increased (three- to fourfold) phosphorylation of GLUT4 in both low-density microsomes and plasma membranes. Short-term treatment of desensitized adipocytes with glimepiride or insulin reduced GLUT4 phosphorylation by approximately 70 and 25%, respectively, in both fractions. We conclude that glimepiride activates glucose transport by stimulation of GLUT1 and GLUT4 translocation in rat adipocytes via interference at a site downstream of the putative molecular defect in the signaling cascade between the insulin receptor and the glucose transport system induced by high concentrations of glucose and insulin. The molecular site of glimepiride action is related to GLUT4 phosphorylation/dephosphorylation, which may regulate glucose transporter activity and translocation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The sulfonylurea drug, glimepiride, stimulates glucose transport, glucose transporter translocation, and dephosphorylation in insulin-resistant rat adipocytes in vitro. 824 32

The development of both type II diabetes and gestational diabetes is probably governed by a complex and variable interaction of genes and environment. Molecular genetics has so far failed to identify discrete gene mutations accounting for metabolic changes in NIDDM. Both beta cell dysfunction and insulin resistance are operative in the manifestation of these disorders. Specific and sensitive immunoradiometric assays found fasting hyperproinsulinemia and first-phase hypoinsulinemia early in the natural history of the disorder. A lack of specificity of early radioimmunoassays for insulin resulted in measuring not only insulin but also proinsulins, leading to overestimation of insulin and misleading conclusions about its role in diabetes. The major causes of insulin resistance are the genetic deficiency of glycogen synthase activation, compounded by additional defects due to metabolic disorders, receptor downregulation, and glucose transporter abnormalities, all contributing to the impairment in muscle glucose uptake. The liver is also resistant to insulin in NIDDM, reflected in persistent hepatic glucose production despite hyperglycemia. Insulin resistance is present in many nondiabetics, but in itself is insufficient to cause type II diabetes. Gestational diabetes is closely related to NIDDM, and the combination of insulin resistance and impaired insulin secretion is of importance in its pathogenesis.
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PMID:The genetics and pathophysiology of type II and gestational diabetes. 856 92


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