Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Plasminogen activator inhibitor-1 (PAI-1) is the major inhibitor of plasminogen activation and likely plays important roles in coronary thrombosis and arteriosclerosis. Tumor necrosis factor-alpha (TNFalpha) is one of many recognized physiological regulators of PAI-1 expression and may contribute to elevated plasma PAI-1 levels in sepsis and obesity. Although TNFalpha is a potent inducer of PAI-1 expression in vitro and in vivo, the precise location of the TNFalpha response site in the PAI-1 promoter has yet to be determined. Transient transfection studies using luciferase reporter constructs containing PAI-1 promoter sequence up to 6.4 kb failed to detect a response to TNFalpha. Moreover, TNFalpha failed to induce expression of enhanced green fluorescent protein under the control of a 2.9-kb human PAI-1 promoter in transgenic mice, although endogenous murine PAI-1 was strongly induced. These data suggested that the TNFalpha response element in the PAI-1 gene is remote from the proximal promoter region. In this study, seven candidate regulatory regions were identified using cross-species sequence homology analysis as well as DNase I-hypersensitive site analysis. We identified a 5' distal TNFalpha-responsive enhancer of the PAI-1 gene located 15 kb upstream of the transcription start site containing a conserved NFkappaB-binding site that mediates the response to TNFalpha. This newly recognized site is fully capable of binding NFkappaB subunits p50 and p65, whereas overexpression of the NFkappaB inhibitor IkappaB prevents TNFalpha-induced activation of this enhancer element.
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PMID:Tumor necrosis factor alpha activates the human plasminogen activator inhibitor-1 gene through a distal nuclear factor kappaB site. 1496 43

Obesity is an epidemic disease that threatens to inundate health care resources by increasing the incidence of diabetes, heart disease, hypertension, and cancer. These effects of obesity result from two factors: the increased mass of adipose tissue and the increased secretion of pathogenetic products from enlarged fat cells. This concept of the pathogenesis of obesity as a disease allows an easy division of disadvantages of obesity into those produced by the mass of fat and those produced by the metabolic effects of fat cells. In the former category are the social disabilities resulting from the stigma associated with obesity, sleep apnea that results in part from increased parapharyngeal fat deposits, and osteoarthritis resulting from the wear and tear on joints from carrying an increased mass of fat. The second category includes the metabolic factors associated with distant effects of products released from enlarged fat cells. The insulin-resistant state that is so common in obesity probably reflects the effects of increased release of fatty acids from fat cells that are then stored in the liver or muscle. When the secretory capacity of the pancreas is overwhelmed by battling insulin resistance, diabetes develops. The strong association of increased fat, especially visceral fat, with diabetes makes this consequence particularly ominous for health care costs. The release of cytokines, particularly IL-6, from the fat cell may stimulate the proinflammatory state that characterizes obesity. The increased secretion of prothrombin activator inhibitor-1 from fat cells may play a role in the procoagulant state of obesity and, along with changes in endothelial function, may be responsible for the increased risk of cardiovascular disease and hypertension. For cancer, the production of estrogens by the enlarged stromal mass plays a role in the risk for breast cancer. Increased cytokine release may play a role in other forms of proliferative growth. The combined effect of these pathogenetic consequences of increased fat stores is an increased risk of shortened life expectancy.
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PMID:Medical consequences of obesity. 1518 Oct 27

Obesity is the central promoter of the metabolic syndrome which also includes disturbed fibrinolysis in addition to hypertension, dyslipidaemia and impaired glucose tolerance/type 2 diabetes mellitus. Plasminogen activator inhibitor-1 (PAI-1) is the most important endogenous inhibitor of tissue plasminogen activator and uro-plasminogen activator, and is a main determinant of fibrinolytic activity. There is now compelling evidence that obesity and, in particular, an abdominal type of body fat distribution are associated with elevated PAI-1 antigen and activity levels. Recent studies established that PAI-1 is expressed in adipose tissue. The greater the fat cell size and the adipose tissue mass, the greater is the contribution of adipose production to circulating PAI-1. Experimental data show that visceral adipose tissue has a higher capacity to produce PAI-1 than subcutaneous adipose tissue. Studies in human adipocytes indicate that PAI-1 synthesis is upregulated by insulin, glucocorticoids, angiotensin II, some fatty acids and, most potently, by cytokines such as tumour necrosis factor-alpha and transforming growth factor-beta, whereas catecholamines reduce PAI-1 production. Interestingly, pharmacological agents such as thiazolidinediones, metformin and AT(1)-receptor antagonists were found to reduce adipose expression of PAI-1. In addition, weight loss by dietary restriction or comprehensive lifestyle modification is effective in lowering PAI-1 plasma levels. In conclusion, impaired fibrinolysis in obesity is probably also due to an increased expression of PAI-1 in adipose tissue. An altered function of the endocrine system and an impaired auto-/paracrine function at the fat cell levels may mediate this disturbance of the fibrinolytic system and thereby increase the risk for cardiovascular disease..
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PMID:Obesity and impaired fibrinolysis: role of adipose production of plasminogen activator inhibitor-1. 1535 68

Plasminogen activator inhibitor-1 (PAI-1) levels were found to be associated with obesity, indicating that adipocytes might influence PAI-1 plasma levels. In addition, the 4G/5G promoter polymorphism of the PAI-1 gene possibly modulates PAI-1 gene transcription and, as a consequence, PAI-1 plasma levels. Metabolic parameters, diabetes complications, PAI-1 plasma levels, and PAI-1 promoter genotypes were determined and were tested for correlation in 547 Caucasian patients with type 2 diabetes. Genotyping was performed by using allele-specific PCR, and PAI-1 plasma levels were measured in 547 well-characterized subjects with type 2 diabetes. The allelic frequencies of the polymorphism (0.56 for the 4G-genotype, 0.44 for the 5G-genotype) were not different from those observed in nondiabetic controls. The PAI-1 concentration was positively associated with MI, but not with the 4G/5G polymorphism. Statistical analysis of metabolic parameters, diabetic complications, and the 4G/5G polymorphism revealed that serum fibrinogen levels were significantly higher in the 4G/4G subgroup compared with the 4G/5G and 5G/5G subgroups. The correlation between serum fibrinogen and 4G allele remained significant, even when additional variables, such as gender, age, BMI, duration of diabetes, and HbA1c, were controlled. In patients with type 2 diabetes mellitus, the PAI-1 4G/5G promoter polymorphism does not predict PAI-1 plasma levels and is not associated with common metabolic parameters besides fibrinogen levels.
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PMID:Allelic frequency of the PAI-1 4G/5G promoter polymorphism in patients with type 2 diabetes mellitus and lack of association with PAI-1 plasma levels. 1555 60

Plasminogen activator inhibitor-1 (PAI-1) plays an important role in the pathogenesis of obesity-driven type 2 diabetes mellitus and associated cardiovascular complications. Here, we show that perturbation of caveolar microdomains leads to insulin resistance and concomitant up-regulation of PAI-1 in 3T3L1 adipocytes. We present several lines of evidence showing that the phosphatidylinositol 3-kinase (PI3K) pathway negatively regulates PAI-1 gene expression. Insulin-induced PAI-1 gene expression is up-regulated by a specific inhibitor of PI3K. In addition, serum PAI-1 level is elevated in protein kinase Balpha-deficient mice, whereas it is reduced in p70 ribosomal S6 kinase 1-deficient mice. The PI3K pathway phosphorylates retinoblastoma protein (pRB), known to release free E2 (adenoviral protein) factor (E2F), which we have previously demonstrated to be a transcriptional repressor of PAI-1 gene expression. Accordingly, cell-penetrating peptides that disrupt pRB-E2F interaction, and thereby release free E2F, are able to suppress PAI-1 levels that are elevated during insulin-resistant conditions. This study identifies a caveolar-dependent signal pathway that up-regulates PAI-1 in insulin-resistant adipocytes and proposes a previously undescribed pharmacological paradigm of disrupting pRB-E2F interaction to suppress PAI-1 levels.
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PMID:Identification and modulation of a caveolae-dependent signal pathway that regulates plasminogen activator inhibitor-1 in insulin-resistant adipocytes. 1556 40

Plasminogen activator inhibitor-1 (PAI-1), a 45-kDa serine proteinase inhibitor with reactive site peptide bond Arg345-Met346, is the main physiological plasminogen activator inhibitor. It occurs in human plasma at an antigen concentration of about 20 ng mL(-1). Besides the active inhibitory form of PAI-1 that spontaneously converts to a latent form, also a substrate form exists that is cleaved at the P1-P1' site by its target enzymes, but does not form stable complexes. Besides its role in regulating hemostasis, PAI-1 plays a role in several biological processes dependent on plasminogen activator or plasmin activity. Studies with transgenic mice have revealed a functional role for PAI-1 in wound healing, atherosclerosis, metabolic disturbances such as obesity and insulin resistance, tumor angiogenesis, chronic stress, bone remodeling, asthma, rheumatoid arthritis, fibrosis, glomerulonephritis and sepsis. It is not always clear if these functions depend on the antiproteolytic activity of PAI-1, on its binding to vitronectin or on its intereference with cellular migration or matrix binding.
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PMID:Pleiotropic functions of plasminogen activator inhibitor-1. 1563 64

Plasminogen activator inhibitor-1 (PAI-1) is the main physiological inhibitor of tissue-type (t-PA) and urokinase-type (u-PA) plasminogen activator. Recent studies in murine models have yielded apparently conflicting data on a potential role of PAI-1 in adipose tissue development and obesity. To reinvestigate this issue, we have rederived PAI-1 deficient (PAI-1(-/-)) and wild-type (WT) mice and generated true littermates in a 81.25% C57Bl/6: 18.75% 129 SV genetic background. Male 5-week-old PAI-1(-/-) and WT mice were kept on a high fat diet (20.1 kJ/g) for 15 weeks. Body weight gain was comparable for both genotypes, and at the time of sacrifice total body weights (39+/-1.1 versus 41 +/- 1.2 g) as well as the weights of subcutaneous (SC, 1,520 +/- 110 versus 1,480 +/- 110 mg) adipose tissue were not significantly different. In contrast, the gonadal (GON, 1,900 +/- 43 versus 1,510 +/- 86 mg, p < 0.005) tissue mass was larger in PAI-1(-/-) mice. Plasma levels of insulin, leptin, glucose, triglycerides, total, HDL and LDL cholesterol were comparable for both genotypes. Immunohistochemical analysis of SC and GON adipose tissues did not reveal differences in adipocyte size or number between both genotypes, whereas blood vessel density was also comparable for GON fat but lower in SC fat of WT mice. Thus, this study in littermate mice on high fat diet did not reveal an effect of PAI-1 deficiency on body weight, and a differential effect on SC and GON adipose tissue.
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PMID:Effect of plasminogen activator inhibitor-1 deficiency on nutritionally-induced obesity in mice. 1588 93

Adipose tissue secretes bioactive peptides, termed 'adipokines', which act locally and distally through autocrine, paracrine and endocrine effects. In obesity, increased production of most adipokines impacts on multiple functions such as appetite and energy balance, immunity, insulin sensitivity, angiogenesis, blood pressure, lipid metabolism and haemostasis, all of which are linked with cardiovascular disease. Enhanced activity of the tumour necrosis factor and interleukin 6 are involved in the development of obesity-related insulin resistance. Angiotensinogen has been implicated in hypertension and plasminogen activating inhibitor-1 (PAI-1) in impaired fibrinolysis. Other adipokines like adiponectin and leptin, at least in physiological concentrations, are insulin sparing as they stimulate beta oxidation of fatty acids in skeletal muscle. The role of resistin is less understood. It is implicated in insulin resistance in rats, but probably not in humans. Reducing adipose tissue mass, through weight loss in association with exercise, can lower TNF-alpha and IL-6 levels and increase adiponectin concentrations, whereas drugs such as thiazolinediones increase endogenous adiponectin production. In-depth understanding of the pathophysiology and molecular actions of adipokines may, in the coming years, lead to effective therapeutic strategies designed to protect against atherosclerosis in obese patients.
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PMID:The endocrine function of adipose tissue: an update. 1658 5

Metabolic syndrome is defined as a complex of hypertriglyceride, insulin resistance, hypertension, and accumulation of visceral fat. This syndrome is often accompanied by thrombotic diseases (e.g., myocardial infarction, cerebral infarction), but the mechanism (s) of thrombotic tendency has not yet been elucidated. Plasminogen activator inhibitor-1 (PAI-1), a principal regulator of fibrinolytic system, plays a pathological role in the development of thrombosis and cardiovascular diseases. PAI-1 is regarded to be one of adipocytokines because it is produced and secreted by adipocytes. The expression of PAI-1 in adipocytes is upregulated by insulin, TNF-alpha, and TGF-beta, suggesting that it is relevant to insulin resistance. PAI-1 antigen level in plasma is elevated in obese subjects and increases in parallel with their BMI and visceral fat. It was experimentally revealed that PAI-1 expression in adipose tissue was dramatically increased in genetically obese mice and abundant expression of PAI-1 was localized to adipocytes in vivo. PAI-1 deficient mice were resistant to high fat diet-induced body weight gain, adipose accumulation, and insulin resistance in association with lack of decreased expression of adiponectin. Taken together, PAI-1 may be a key molecule to develop obesity and insulin resistance as well as thrombotic diseases. It is possible to prevent thrombotic complications and cardiovascular diseases in obese patients by controlling PAI-1 expression and function. Each pathology included in metabolic syndrome could stimulate PAI-1 expression, and thus, PAI-1 would be a good marker of progression of metabolic syndrome itself and of risk for thrombotic cardiovascular diseases as well.
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PMID:[Thrombotic tendency and laboratory medicine in metabolic syndrome]. 1805 Jun 73

Obesity is a complex, multifactorial chronic disease frequently associated with cardiovascular risks, hypertriglyceridemia, low high-density lipoprotein-cholesterol, high blood pressure, and the insulin resistance that appears to be central to the pathogenesis of Type II diabetes. Plasminogen activator inhibitor-1 expression induced in differentiating adipose tissue, but its role in adipogenesis and obesity is poorly understood. Circulating plasminogen activator inhibitor-1 levels are elevated at an early stage of impaired glucose tolerance, resulting in diabetes and metabolic syndrome. Plasminogen activator inhibitor-1 levels are also significantly elevated in the plasma of obese individuals and in adipose tissues of obese mice and humans. Some investigators proposed that the -675 4G/5G polymorphism in plasminogen activator inhibitor-1 promoter caused overexpression of this gene and predisposed carriers to obesity. In this study, we investigated the role of -675 4G/5G polymorphism in plasminogen activator inhibitor-1 promoter in the expression of this gene and the contribution of plasminogen activator inhibitor-1 to adipogenesis. Using a dual-luciferase promoter assay, we determined that the -675 4G/5G polymorphism contributes significantly to overexpression of plasminogen activator inhibitor-1 in the course of adipogenesis. The antidiabetic agents troglitazone and ciglitazone inhibited reporter gene expression driven by wild-type and -675 4G/5G mutant promoter, as well as the expression of endogenous plasminogen activator inhibitor-1, indicating that suppression of plasminogen activator inhibitor-1 expression may contribute to antidiabetic effects of these agents. The results indicate that absence of plasminogen activator inhibitor-1 in adipocytes may protect the cells against insulin resistance by promoting glucose uptake and adipocyte differentiation via a decrease in the peroxisome proliferator activated receptor-gamma expression that modulates the adipocyte differentiation.
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PMID:The effect of plasminogen activator inhibitor-1 -675 4G/5G polymorphism on PAI-1 gene expression and adipocyte differentiation. 1816 May 87


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