Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Failure to secrete adequate amounts of insulin in response to increasing concentrations of glucose is an important feature of type 2 diabetes. The mechanism for loss of glucose responsiveness is unknown. Uncoupling protein 2 (UCP2), by virtue of its mitochondrial proton leak activity and consequent negative effect on ATP production, impairs glucose-stimulated insulin secretion. Of interest, it has recently been shown that superoxide, when added to isolated mitochondria, activates UCP2-mediated proton leak. Since obesity and chronic hyperglycemia increase mitochondrial superoxide production, as well as UCP2 expression in pancreatic beta cells, a superoxide-UCP2 pathway could contribute importantly to obesity- and hyperglycemia-induced beta cell dysfunction. This study demonstrates that endogenously produced mitochondrial superoxide activates UCP2-mediated proton leak, thus lowering ATP levels and impairing glucose-stimulated insulin secretion. Furthermore, hyperglycemia- and obesity-induced loss of glucose responsiveness is prevented by reduction of mitochondrial superoxide production or gene knockout of UCP2. Importantly, reduction of superoxide has no beneficial effect in the absence of UCP2, and superoxide levels are increased further in the absence of UCP2, demonstrating that the adverse effects of superoxide on beta cell glucose sensing are caused by activation of UCP2. Therefore, superoxide-mediated activation of UCP2 could play an important role in the pathogenesis of beta cell dysfunction and type 2 diabetes.
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PMID:Superoxide-mediated activation of uncoupling protein 2 causes pancreatic beta cell dysfunction. 1467 73

BACKGROUND AND THERAPY: The metabolic syndrome comprises a virulent and lethal group of atherosclerotic risk factors, including dyslipidemia, obesity, systemic hypertension and insulin resistance. The prevalence of the metabolic syndrome has continuously grown in industrialized and developing countries during the last decades, and affects tens of millions of people in Germany and Europe. Particularly prominent as a risk factor for the development of insulin resistance is central obesity, which is causally involved in the pathogenesis of insulin resistance in addition to genetic predisposition. The metabolic syndrome can easily be diagnosed in clinical practice (guidelines of the WHO and ATP III panel), and immediate treatment of the metabolic syndrome is mandatory because those patients are at increased risk to develop overt diabetes mellitus, coronary artery disease and stroke. The high risk for cardiovascular diseases is supported by findings that the risk for myocardial infarction in patients with insulin resistance is as high as the risk of patients after their first myocardial infarction. Intentional weight reduction reduces abdominal obesity and beneficially modulates all features of the metabolic syndrome, while the benefits of aerobic exercise training are discussed controversially. Thus, weight reduction causally undoes essential features of the metabolic syndrome, but effects are often not enduring. Therefore, the treatment of cardiovascular risk factors such as hypertension and dislipidemia is essential. Of note, antihypertensive treatment is more effective than tight glucose control to reduce cardiovascular events. Diuretics, ACE-inhibitors and angiotensin II type 1 receptor antagonists are suggested as first line therapeutics. However, at least two antihypertensives are usually necessary to achieve the suggested goals of blood pressure reduction. In conclusion, the prevalence of the metabolic syndrome is continuously growing. Due to its adverse impact on cardiovascular disease, early detection and aggressive treatment is mandatory to ensure longlasting benefits for affected patients.
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PMID:[Arterial hypertension and metabolic syndrome]. 1468 1

Uncoupling protein (UCP) 2 is a member of the mitochondrial transporter superfamily that uncouples proton entry in the mitochondrial matrix from ATP synthesis. Although its physiological role remains to be established, UCP2 is considered a candidate gene for association with energy metabolism and obesity. A common promoter polymorphism, -866 G/A, has been associated with increased UCP2 gene expression and middle-aged adult obesity. In fact, our analysis of 296 juvenile obese and 568 nonobese control subjects revealed no difference in the prevalence of this polymorphism. Insulin and glucose response to oral glucose was comparable across the -866 genotypes. Metabolic studies in 147 of these juvenile obese subjects showed that homozygosity for the UCP2 promoter variant A was associated with important changes in energy metabolism compared with other genotypes, i.e., a 34% increase of carbohydrate oxidation (94 +/- 10 vs. 70 +/- 3 mg.min(-1).m(-2), P = 0.004) and a 23% decrease of lipid oxidation (26 +/- 3 vs. 34 +/- 1 mg.min(-1).m(-2), P = 0.03). Therefore, the juvenile obese subjects who are homozygous for the A variant have an increased ratio (3.6 +/- 1.2) of calories derived from carbohydrates to those from lipids compared with G/A or G/G obese children (1.4 +/- 0.2, P = 0.003), suggesting a role for UCP2 in the partitioning of metabolic fuels.
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PMID:The common -866 G/A polymorphism in the promoter of uncoupling protein 2 is associated with increased carbohydrate and decreased lipid oxidation in juvenile obesity. 1469 21

CBS domains are defined as sequence motifs that occur in several different proteins in all kingdoms of life. Although thought to be regulatory, their exact functions have been unknown. However, their importance was underlined by findings that mutations in conserved residues within them cause a variety of human hereditary diseases, including (with the gene mutated in parentheses): Wolff-Parkinson-White syndrome (gamma 2 subunit of AMP-activated protein kinase); retinitis pigmentosa (IMP dehydrogenase-1); congenital myotonia, idiopathic generalized epilepsy, hypercalciuric nephrolithiasis, and classic Bartter syndrome (CLC chloride channel family members); and homocystinuria (cystathionine beta-synthase). AMP-activated protein kinase is a sensor of cellular energy status that is activated by AMP and inhibited by ATP, but the location of the regulatory nucleotide-binding sites (which are prime targets for drugs to treat obesity and diabetes) was not characterized. We now show that tandem pairs of CBS domains from AMP-activated protein kinase, IMP dehydrogenase-2, the chloride channel CLC2, and cystathionine beta-synthase bind AMP, ATP, or S-adenosyl methionine,while mutations that cause hereditary diseases impair this binding. This shows that tandem pairs of CBS domains act, in most cases, as sensors of cellular energy status and, as such, represent a newly identified class of binding domain for adenosine derivatives.
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PMID:CBS domains form energy-sensing modules whose binding of adenosine ligands is disrupted by disease mutations. 1472 9

Acetyl-CoA carboxylase (ACC) catalyses the first step in fatty-acid biosynthesis. Owing to its role in primary metabolism, ACC has been exploited as a commercial herbicide target and identified as a chemically validated fungicide target. In animals, ACC is also a key regulator of fat metabolism. This function has made ACC a prime target for the development of anti-obesity and anti-Type II diabetes therapeutics. Despite its economic importance, there is a lack of published information on recombinant expression of ACC. We report here the expression of enzymically active fungal (Ustilago maydis ) ACC in Escherichia coli. The recombinant enzyme exhibited Km values of 0.14+/-0.013 mM and 0.19+/-0.041 mM for acetyl-CoA and ATP respectively, which are comparable with those reported for the endogenous enzyme. The polyketide natural product soraphen is a potent inhibitor of the BC (biotin carboxylase) domain of endogenous fungal ACC. Similarly, recombinant ACC activity was inhibited by soraphen with a K(i) of 2.1+/-0.9 nM. A truncated BC domain that included amino acids 2-560 of the full-length protein was also expressed in E. coli. The isolated BC domain was expressed to higher levels, and was more stable than full-length ACC. Although incapable of enzymic turnover, the BC domain exhibited high-affinity soraphen binding (Kd 1.1+/-0.3 nM), demonstrating a native conformation. Additional BC domains from the phytopathogenic fungi Magnaporthe grisea and Phytophthora infestans were also cloned and expressed, and were shown to exhibit high-affinity soraphen binding. Together, these reagents will be useful for structural studies and assay development.
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PMID:Expression and characterization of recombinant fungal acetyl-CoA carboxylase and isolation of a soraphen-binding domain. 1476 11

Epidemiological studies identified several risk factors as cardiovascular disease correlates, including smoking, obesity, hypertension, diabetes, and increased plasma lipids. High blood cholesterol, and in particular LDL cholesterol levels, represents a major determinant of coronary artery disease, in particular when included in the context of a comprehensive risk profile. The more recent guidelines (especially NCEP ATP III in the United States, and the European Joint Task Force) have suggested the opportunity to favor treatment of those subjects with higher global cardiovascular risk, first of all of those individuals with coronary artery disease or another cardiovascular manifestation or diabetes, then of subjects with clustered risk factors or with markedly raised levels of single risk factors, eventually of other subjects. In this perspective the treatment also of slight dyslipidemias has been shown capable of reducing cardiovascular event incidence and mortality. Recent investigations, aiming at evaluating the impact of these "clinical recommendations" in the treatment of dyslipidemias or other cardiovascular risk factors within a framework of high global cardiovascular risk (EURO-ASPIRE II, L-TAP, etc.), showed inadequate attention of community-based medicine, disclosed by the insufficient number of subjects investigated and by the large number of untreated or undertreated patients. Rosuvastatin, a recently marketed inhibitor of the 3-hydroxy-3-methylglutaryl coenzyme A reductase, is an effective drug which may normalize high plasma cholesterol among high-risk subjects more often than other similar molecules, thus permitting to reach stringent guideline lipid targets. It is hoped that coronary risk charts based on Italian data will be implemented, with the purpose of better finding and treating those subjects who may benefit, at a suitable level of cardiovascular risk.
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PMID:[Dyslipidemia and global cardiovascular risk: treatment guidelines]. 1498 42

Brown adipose tissue (BAT) is believed to function by dissipating excess energy in mammals. It is very important to understand the energy metabolism held in BAT since disorder of its energy-dissipating function may cause obesity or lifestyle-related diseases such as hypertension and diabetes. This function in BAT is mainly attributable to uncoupling protein (UCP), specifically expressed in its mitochondria. This protein consumes excess energy as heat by dissipating the H+ gradient across the inner mitochondrial membrane that is utilized as a driving force for ATP synthesis. In this review article, in addition to providing a brief introduction to the functional properties of BAT and UCP, we also describe and discuss properties of cultured brown adipocytes and the results of our exploratory studies on protein components involved in the energy-dissipating function in BAT.
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PMID:Identification of possible protein machinery involved in the thermogenic function of brown adipose tissue. 1500 Feb 52

Adipocyte dysfunction is strongly associated with the development of obesity and insulin resistance. It is accepted that the regulation of adipocytokine secretion or the adipocyte-specific gene expression is one of the most important targets for the prevention of obesity and amelioration of insulin sensitivity. In this study, we demonstrated that anthocyanins (cyanidin or cyanidin 3-glucoside) have the potency of a unique pharmacological function in isolated rat adipocytes. Treated adipocytes with anthocyanins enhanced adipocytokine (adiponectin and leptin) secretion and up-regulated the adipocyte specific gene expression without activation of PPARgamma in isolated rat adipocytes. The gene expression of adiponectin was also up-regulated in white adipose tissue in mice fed an anthocyanin supplemented diet. As one of the possible mechanisms, AMP-activated protein kinase activation would be associated with these changes, nevertheless, the AMP:ATP ratio was significantly decreased by administration of the anthocyanins. These data suggest that anthocyanins have a potency of unique therapeutic advantage and also have important implications for preventing obesity and diabetes.
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PMID:Anthocyanin enhances adipocytokine secretion and adipocyte-specific gene expression in isolated rat adipocytes. 1500 23

Insulin signaling is enhanced by moderate concentrations of reactive oxygen species (ROS) and suppressed by persistent exposure to ROS. Diabetic patients show abnormally high ROS levels and a decrease in insulin reactivity which is ameliorated by antioxidants, such as N-acetylcysteine (NAC). A similar effect of NAC has not been reported for non-diabetic subjects. We now show that the insulin receptor (IR) kinase is inhibited in cell culture by physiologic concentrations of cysteine. In two double-blind trials involving a total of 140 non-diabetic subjects we found furthermore that NAC increased the HOMA-R index (derived from the fasting insulin and glucose concentrations) in smokers and obese patients, but not in nonobese non-smokers. In obese patients NAC also caused a decrease in glucose tolerance and body fat mass. Simultaneous treatment with creatine, a metabolite utilized by skeletal muscle and brain for the interconversion of ADP and ATP, reversed the NAC-mediated increase in HOMA-R index and the decrease in glucose tolerance without preventing the decrease in body fat. As the obese and hyperlipidemic patients had lower plasma thiol concentrations than the normolipidemic subjects, our results suggest that low thiol levels facilitate the development of obesity. Supplementation of thiols plus creatine may reduce body fat without compromising glucose tolerance.
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PMID:Effect of thiol antioxidant on body fat and insulin reactivity. 1500 12

Two potential approaches for the treatment of obesity are presented, in which modulation of a target increases fatty acid oxidation. These two methods, which are here referred to as 'pull' and 'push' routes, involve creating a demand for fuel by uncoupling oxidation from ATP production ('pulling'), or shuttling fatty acyl CoA into the mitochondria by an afferent mechanism ('pushing'). Proof-of-principle studies in humans are required to assess the use of these approaches in weight loss maintenance.
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PMID:Fat oxidation in obesity: druggable or risky enterprise? 1501 Oct 98


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