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)

Uncoupling protein (UCP) 3 and UCP2, mitochondrial carrier proteins dissipating electrochemical gradient across the mitochondrial inner membrane, have been implicated in the regulation of energy metabolism. The UCP3 gene is expressed abundantly in the skeletal muscle, while the UCP2 gene is detected in the white adipose tissue (WAT) with diffuse localization throughout the body. Uncoupling of electron transport and ATP synthesis has been reported to increase glucose uptake, suggesting that UCP may be involved in glucose metabolism. Thiazolidinediones (TZDs), which are insulin-sensitizing agents for NIDDM, have been reported to increase energy expenditure. To elucidate the pathophysiologic significance of UCP3 and UCP2 in the effect of TZDs on glucose metabolism and energy expenditure, we examined their basal mRNA levels in the WAT, brown adipose tissue (BAT), and skeletal muscle from Wistar fatty rats, a rat model of NIDDM and obesity with leptin receptor defect, and investigated expression of the genes encoding UCP3 and UCP2 in Wistar fatty rats and in Wistar lean rats with 2-week oral administration of 3 mg x kg(-1) x day(-1) pioglitazone, a TZD derivative. Basal UCP3 mRNA levels were significantly lower (38 +/- 8, 45 +/- 13, and 76 +/- 6%) in the retroperitoneal WAT, BAT, and skeletal muscle from Wistar fatty rats than in those from Wistar lean rats, while basal UCP2 mRNA levels were significantly higher by 2.1-, 1.8-, and 2.5-fold in the subcutaneous WAT, retroperitoneal WAT, and BAT from Wistar fatty rats, respectively, than in those from Wistar lean rats. In pioglitazone-treated Wistar fatty rats, UCP3 mRNA levels were significantly increased by 2.1-, 2.0-, and 1.6-fold in the epididymal WAT, retroperitoneal WAT, and BAT, respectively, as compared with those in nontreated fatty rats. In pioglitazone-treated lean rats, UCP3 mRNA levels were significantly increased by 1.3-fold in the BAT as compared with those in nontreated lean rats. No significant change of UCP2 mRNA levels was observed in pioglitazone-treated fatty and lean rats. In addition, to examine the direct effect of TZDs on adipocytes, we examined the regulation of UCP3 and UCP2 gene expression using the primary culture of rat mature adipocytes from Sprague-Dawley rats. In rat cultured mature adipocytes, UCP3 mRNA levels were increased in a dose-responsive manner by 10(-5) to 10(-4) mol/l pioglitazone, while there was no significant change of UCP2 mRNA levels. These results clearly demonstrate that UCP3 gene expression is upregulated by TZDs in the WAT and BAT in Wistar fatty rats, an obese model with leptin receptor defect, and that adipose UCP3 gene expression is increased in response to TZDs in vitro. The present study suggests the involvement of UCP3 in the effects of TZDs on energy and glucose metabolism.
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PMID:Increased adipose expression of the uncoupling protein-3 gene by thiazolidinediones in Wistar fatty rats and in cultured adipocytes. 979 55

To explore the potential role of the uncoupling protein (UCP) family in human obesity and diabetes, we have used the reverse transcription-polymerase chain reaction to quantify UCP mRNA expression in human skeletal muscle. Levels of mRNA for UCP2, and for both short (UCP3S) and long (UCP3L) forms of UCP3, were highly correlated in individuals, indicating that gene transcription of these UCPs may be coordinately regulated by common mechanisms. In normal glucose-tolerant individuals, muscle UCP2 mRNA levels were positively correlated with percentage of body fat and with BMI (r = 0.6 and P < 0.05 for both). UCP3S mRNA levels were also positively correlated with percentage of body fat (r = 0.52, P < 0.05), and UCP3L mRNA tended to increase as a function of obesity (0.05 < P < 0.1). UCP mRNA levels, however, were not correlated with resting metabolic rate. UCP3S and UCP3L mRNA levels (P < 0.05) and the UCP2 mRNA level (P = 0.09) were increased by 1.8- to 2.7-fold in type 2 diabetes, an effect that could not be explained by obesity. No significant difference was found for UCP2, UCP3S, or UCP3L mRNA levels between insulin-sensitive and insulin-resistant nondiabetic subgroups. We conclude that 1) skeletal muscle mRNA levels encoding UCP2 and UCP3 are correlated among individuals and may be coordinately regulated; 2) UCP3 expression is not regulated by differential effects on UCP3L and UCP3S forms of the mRNA; and 3) UCP mRNA expression tends to increase in muscle as a function of obesity but not of resting metabolic rate or insulin resistance, and is increased in patients with type 2 diabetes.
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PMID:Expression of mRNAs encoding uncoupling proteins in human skeletal muscle: effects of obesity and diabetes. 983 27

The recently identified uncoupling protein-3 (UCP-3) gene, predicted to encode a new member of the family of uncoupling proteins, is preferentially expressed in skeletal muscle and has been related to phenotypes of obesity and type 2 diabetes. We have established that during mouse ontogeny, the expression of the UCP-3 gene is switched on in skeletal muscle just after birth. The induction of UCP-3 gene expression is dependent on the initiation of suckling and particularly on lipid intake. Treatment of newborn mice with activators of peroxisome proliferator-activated receptors (PPARs), such as clofibrate, bezafibrate, or (4-chloro-6-(2,3-xylidine)-pirimidinylthio)acetic acid (WY 14,643), mimics the action of food intake on UCP-3 gene expression. The specific ligand of PPAR-alpha WY 14,643 induces UCP-3 gene expression in a time- and dose-dependent manner, whereas the thiazolidinedione BRL 49653, specific for PPAR-gamma, has no effect. These treatments act without altering circulating free fatty acids. During development, skeletal muscle expresses constitutive levels of PPAR-delta mRNA, whereas expression of the PPAR-gamma gene is undetectable. PPAR-alpha gene expression is developmentally regulated in muscle as it is first expressed at birth, just before UCP-3 gene induction occurs. The induction of UCP-3 gene expression by WY 14,643 is impaired in skeletal muscle of premature neonates, which do not express PPAR-alpha. It is proposed that the UCP-3 gene is predominantly regulated in neonatal muscle by PPAR-alpha activation.
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PMID:Activators of peroxisome proliferator-activated receptor-alpha induce the expression of the uncoupling protein-3 gene in skeletal muscle: a potential mechanism for the lipid intake-dependent activation of uncoupling protein-3 gene expression at birth. 1034 7

Uncoupling proteins are mitochondrial carrier proteins which are able to dissipate the proton gradient of the inner mitochondrial membrane. This uncoupling process reduces the amount of ATP generated through an oxidation of fuels. The hypothesis that uncoupling proteins (UCPs) are candidate genes for human obesity or Type II (non-insulin-dependent) diabetes mellitus is based on the finding that a chemical uncoupling of the mitochondrial membrane reduces body adiposity, and that lower metabolic rates predict weight gain. It is straightforward to hypothesize that common polymorphisms of UCP1, UCP2 and UCP3 genes lower metabolic rate by a more efficient energy coupling in the mitochondria. Furthermore, genetically engineered mice over expressing different UCP homologues are lean and resistant to diet-induced obesity. The three uncoupling protein homologue genes UCP1, UCP2, and UCP3 have been investigated for polymorphisms and mutations and their impact on Type II diabetes mellitus, obesity, and body weight gain or BMI. The main conclusion is that variation in the UCP1, UCP2 or UCP3 genes is not associated with major alterations of body weight gain. The contribution of UCP genes towards polygenic obesity and Type II diabetes is evaluated and discussed.
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PMID:Uncoupling proteins: functional characteristics and role in the pathogenesis of obesity and Type II diabetes. 1148 71

Recently, a role for uncoupling protein-3 (UCP3) in carbohydrate metabolism and in type 2 diabetes has been suggested. Mice overexpressing UCP3 in skeletal muscle showed reduced fasting plasma glucose levels, improved glucose tolerance after an oral glucose load, and reduced fasting plasma insulin levels. However, data regarding the expression of UCP3 in patients with type 2 diabetes is inconsistent, and so far, there have been no reports of UCP3 protein content. Here we compared, for the first time, the protein levels of UCP3 in vastus lateralis muscle in 14 male type 2 diabetic patients (age 49.8 +/- 2.1 years; BMI 27.2 +/- 1.2 kg/m(2); mean +/- SE) with 16 male control subjects (age 48.0 +/- 1.9 years; BMI 23.4 +/- 0.6 kg/m(2)). We found that UCP3 protein levels were twice as low in patients with type 2 diabetes compared with control subjects (117 +/- 16 vs. 58 +/- 12 AU; P = 0.007). There was no correlation between UCP3 content and BMI. In conclusion, UCP3 content is lower in type 2 diabetic patients compared with healthy control subjects. These results are consistent with a role for UCP3 in glucose homeostasis and suggest a role for UCP3 in type 2 diabetes.
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PMID:Uncoupling protein 3 content is decreased in skeletal muscle of patients with type 2 diabetes. 1172 73

Five mitochondrial uncoupling proteins exist in the human gemone: UCP2, expressed ubiquitously; UCP1, exclusively in brown adipose tissue (BAT); UCP3, predominantly in muscle; UCP4 and BMCP (UCP5), in brain. UCP4 is the ancestral prototype from which the other UCPn diverged. Findings on the level of organism and reconstituted recombinant proteins demonstrated that UCPn exhibit a protonophoric function, documented by overexpression in mice, L6 myotubes, INS1 cells, muscle, and yeast. In a few cases (yeast), this protonophoric function was correlated with elevated fatty acid (FA) levels. Reconstituted UCPn exhibited nucleotide-sensitive FA induced H(+) uniport. Two mechanisms, local buffering or FA cycling were suggested as an explanation. A basic UCPn role with mild uncoupling is to accelerate metabolism and reduce reactive oxygen species. UCP2 (UCP3) roles were inferred from transcriptional up-regulation mediated by FAs via peroxisome proliferator-activated receptors, cytokines, leptin signalling via hypothalamic pathway, and by thyroide and beta2 adrenergic stimulation. The latter indicated a role in catecholamine-induced thermogenesis in skeletal muscle. UCP2 (UCP3) may contribute to body weight regulation, although obesity was not induced in knockout (KO) mice. An obesity reduction in middle-aged humans was associated with the less common allele of -866 G/A polymorphism in the ucp2 gene promoter enhancing the exon 8 insertion: deletion transcript ratio. Up-regulated UCP2 transcription by pyrogenic cytokines (tumour necrosis factor alpha (TNFalpha)) suggested a role in fever. UCP2 could induce type 2 diabetes as developed from obesity due to up-regulated UCP2 transcription by FAs in pancreatic beta-cells. UCPn might be pro-apoptotic as well as anti-apoptotic, depending on transcriptional and biochemical regulation.
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PMID:Possible physiological roles of mitochondrial uncoupling proteins--UCPn. 1212 70

The "thrifty" genotype and phenotype that save energy are detrimental to the health of people living in affluent societies. Individual differences in energy metabolism are caused primarily by single nucleotide polymorphisms (SNPs), some of which promote the development of obesity/type 2 diabetes mellitus. In this review, four major questions are addressed: (1) Why did regional differences in energy metabolism develop during evolution? (2) How do genes respond to starvation and affluence? (3) Which SNPs correspond to the hypothetical "thrifty genes"? (4) How can we cope with disease susceptibility caused by the "thrifty" SNPs? We examined mtDNA and genes for energy metabolism in people who live in several parts of Asia and the Pacific islands. We included 14 genes, and the SNP frequencies of PPAR gamma 2, LEPR, and UCP3-p and some other genes differ significantly between Mongoloids and Caucasoids. These differences in SNPs may have been caused by natural selection depending on the types of agriculture practiced in different regions. Interventions to counteract the adverse effects of "thrifty" SNPs have been partially effective.
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PMID:Single nucleotide polymorphisms of thrifty genes for energy metabolism: evolutionary origins and prospects for intervention to prevent obesity-related diseases. 1215 Sep 34

The physiological function of human uncoupling protein-3 is still unknown. Uncoupling protein-3 is increased during fasting and high-fat feeding. In these situations the availability of fatty acids to the mitochondria exceeds the capacity to metabolize fatty acids, suggesting a role for uncoupling protein-3 in handling of non-metabolizable fatty acids. To test the hypothesis that uncoupling protein-3 acts as a mitochondrial exporter of non-metabolizable fatty acids from the mitochondrial matrix, we gave human subjects Etomoxir (which blocks mitochondrial entry of fatty acids) or placebo in a cross-over design during a 36-h stay in a respiration chamber. Etomoxir inhibited 24-h fat oxidation and fat oxidation during exercise by approximately 14-19%. Surprisingly, uncoupling protein-3 content in human vastus lateralis muscle was markedly up-regulated within 36 h of Etomoxir administration. Up-regulation of uncoupling protein-3 was accompanied by lowered fasting blood glucose and increased translocation of glucose transporter-4. These data support the hypothesis that the physiological function of uncoupling protein-3 is to facilitate the outward transport of non-metabolizable fatty acids from the mitochondrial matrix and thus prevents mitochondria from the potential deleterious effects of high fatty acid levels. In addition our data show that up-regulation of uncoupling protein-3 can be beneficial in the treatment of type 2 diabetes.
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PMID:Etomoxir-induced increase in UCP3 supports a role of uncoupling protein 3 as a mitochondrial fatty acid anion exporter. 1220 97

High-fat diet and intrauterine growth retardation may predispose to obesity, insulin resistance, and type 2 diabetes. Because prenatal ethanol (ETOH) exposure causes intrauterine growth retardation, we investigated its interactions with postnatal high-fat diet on glucose tolerance and adipocyte-derived hormones in the rat offspring. High-fat-fed offspring had increased adiposity, serum leptin, and muscle uncoupling protein-3, but decreased adiponectin mRNA, compared with corresponding chow-fed groups. ETOH-exposed offspring had normal adiponectin, but increased resistin mRNA and protein, compared with controls, regardless of postnatal diet. Skeletal muscle glucose transporter-4 content was decreased after both ETOH exposure and high-fat feeding. Glycemic and insulin responses to an ip glucose challenge were equally increased in non-ETOH-exposed high-fat-fed offspring and in ETOH-exposed chow-fed offspring, with additive effects of ETOH and high-fat diet. Pancreatic insulin content was elevated only in non-ETOH-exposed high-fat-fed offspring. The data suggest that high-fat diet worsens glucose intolerance in offspring of rats exposed to ETOH. Prenatal ETOH exposure and postnatal high-fat diet might cause insulin resistance through separate mechanisms, involving resistin and adiponectin, respectively.
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PMID:Glucose intolerance and resistin expression in rat offspring exposed to ethanol in utero: modulation by postnatal high-fat diet. 1253 10

In type 2 diabetes, glucose phosphorylation, a regulatory step in glucose utilization by skeletal muscle, is impaired. Since glucokinase expression in skeletal muscle of transgenic mice increases glucose phosphorylation, we examined whether such mice counteract the obesity and insulin resistance induced by 12 wk of a high-fat diet. When fed this diet, control mice became obese, whereas transgenic mice remained lean. Furthermore, high-fat fed control mice developed hyperglycemia and hyperinsulinemia (a 3-fold increase), indicating that they were insulin resistant. In contrast, transgenic mice were normoglycemic and showed only a mild increase in insulinemia (1.5-fold). They also showed improved whole body glucose tolerance and insulin sensitivity and increased intramuscular concentrations of glucose 6-phosphate and glycogen. A parallel increase in uncoupling protein 3 mRNA levels in skeletal muscle of glucokinase-expressing transgenic mice was also observed. These results suggest that the rise in glucose phosphorylation by glucokinase expression in skeletal muscle leads to increased glucose utilization and energy expenditure that counteracts weight gain and maintains insulin sensitivity.
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PMID:Prevention of obesity and insulin resistance by glucokinase expression in skeletal muscle of transgenic mice. 1450 May 48


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