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

Disturbances in energy homeostasis can result in obesity and other metabolic diseases. Here we report a metabolic pathway present in normal human skeletal muscle myoblasts that is activated by the small polyphenolic molecule kaempferol (KPF). Treatment with KPF leads to an approximately 30% increase in skeletal myocyte oxygen consumption. The mechanism involves a several-fold increase in cyclic AMP (cAMP) generation and protein kinase A activation, and the effect of KPF can be mimicked via treatment with dibutyryl cAMP. Microarray and real-time PCR studies identified a set of metabolically relevant genes influenced by KPF including peroxisome proliferator-activated receptor gamma coactivator-1alpha, carnitine palmitoyl transferase-1, mitochondrial transcription factor 1, citrate synthase, and uncoupling protein-3, although KPF itself is not a direct mitochondrial uncoupler. The cAMP-responsive gene for type 2 iodothyronine deiodinase (D2), an intracellular enzyme that activates thyroid hormone (T3) for the nucleus, is approximately threefold upregulated by KPF; furthermore, the activity half-life for D2 is dramatically and selectively increased as well. The net effect is an approximately 10-fold stimulation of D2 activity as measured in cell sonicates, with a concurrent increase of approximately 2.6-fold in the rate of T3 production, which persists even 24 h after KPF has been removed from the system. The effects of KPF on D2 are independent of sirtuin activation and only weakly reproduced by other small polyphenolic molecules such as quercetin and fisetin. These data document a novel mechanism by which a xenobiotic-activated pathway can regulate metabolically important genes as well as thyroid hormone activation and thus may influence metabolic control in humans.
 ...
PMID:The small polyphenolic molecule kaempferol increases cellular energy expenditure and thyroid hormone activation. 1732 47

Reactive oxygen species (ROS) production has recently been established as an essential contributor in the pathogenesis of obesity-associated insulin resistance. The FoxO1 pathway plays a role not only in nutrient sensing but also in regulating ROS production. We exposed adipocytes to free fatty acids (FFA) and demonstrated that FoxO1 protein levels decrease in a dose-dependent manner. The FoxO1 downregulation correlated with an increase in the production of ROS and a proinflammatory adipokine pattern characterized by a decrease in adiponectin and an increase in IL-6, plasminogen activator inhibitor-1, and monocyte chemotactic protein-1 mRNA expression levels. Similarly, a decrease in FoxO1 protein levels was seen in adipocytes of db/db mice compared with controls. Treatment with the sirtuin agonist resveratrol, which translocates FoxO1 to the nucleus, increased FoxO1 protein levels in adipocytes exposed to FFA. This correlated with a decrease in the generation of ROS and a partial reversal of the proinflammatory adipokine pattern. Together these results indicate that the insulin-resistant adipocyte produced by the exposure to a high concentration of fatty acids is characterized by decreased levels of FoxO1. These data also suggest that modulation of the Sirt1/FoxO1 pathway is a potentially useful therapeutic target for the obesity-induced dysfunctional adipocyte.
 ...
PMID:Role of FoxO1 in FFA-induced oxidative stress in adipocytes. 1737 93

Sir2 protein deacetylases (or sirtuins) catalyze NAD+-dependent conversion of epsilon-amino-acetylated lysine residues to deacetylated lysine, nicotinamide, and 2'-O-acetyl-ADP-ribose. Small-molecule modulation of sirtuin activity might treat age-associated diseases, such as type II diabetes, obesity, and neurodegenerative disorders. Here, we have evaluated the mechanisms of sirtuin inhibition of histone peptides containing thioacetyl or mono-, di-, and trifluoroacetyl groups at the epsilon-amino of lysine. Although all substituted peptides yielded inhibition of the deacetylation reaction, the thioacetyl-lysine peptide exhibited exceptionally potent inhibition of sirtuins Sirt1, Sirt2, Sirt3, and Hst2. Using Hst2 as a representative sirtuin, the trifluoroacetyl-lysine peptide displayed competitive inhibition with acetyl-lysine substrate and yielded an inhibition constant (Kis) of 4.8 microM, similar to its Kd value of 3.3 microM. In contrast, inhibition by thioacetyl-lysine peptide yielded an inhibition constant (Kis) of 0.017 microM, 280-fold lower than its Kd value of 4.7 microM. Examination of thioacetyl-lysine peptide as an alternative sirtuin substrate revealed conserved production of deacetylated peptide and 1'-SH-2'-O-acetyl-ADP-ribose. Pre-steady-state and steady-state analysis of the thioacetyl-lysine peptide showed rapid nicotinamide formation (4.5 s-1) but slow overall turnover (0.0024 s-1), indicating that the reaction stalled at an intermediate after nicotinamide formation. Mass spectral analysis yielded a novel species (m/z 1754.3) that is consistent with an ADP-ribose-peptidyl adduct (1'-S-alkylamidate) as the stalled intermediate. Additional experiments involving solvent isotope effects, general base mutational analysis, and density functional calculations are consistent with impaired 2'-hydroxyl attack on the ADP-ribose-peptidyl intermediate. These results have implications for the development of mechanism-based inhibitors of Sir2 deacetylases.
 ...
PMID:Mechanism-based inhibition of Sir2 deacetylases by thioacetyl-lysine peptide. 1802 80

Although the progressive metabolic changes associated with obesity are complex, it is well-recognized that obesity is a risk factor for the development of insulin resistance and type 2 diabetes. Because both obesity and type 2 diabetes are associated with insulin resistance, there is significant interest in defining the mechanistic basis for insulin resistance. Recent studies involving SIRT1, the most intensely studied sirtuin family member, have shown that it regulates many metabolic adaptations linked with obesity. SIRT1 has been shown to regulate the expression of adipokines, repress the activity of factors required for maturation of fat cells, regulate insulin secretion, modulate plasma glucose levels and insulin sensitivity and alter mitochondrial capacity. Moreover, some investigators have suggested that altering SIRT1 activity may be a promising new therapy for type 2 diabetes. In this review we focus on the role of sirtuins in obesity with particular emphasis on the contribution of SIRT1.
 ...
PMID:The role of sirtuin proteins in obesity. 1859 74

Resveratrol, a phytoallexin, has recently been reported to slow aging by acting as a sirtuin activator. Resveratrol also has a wide range of pharmacological effects on adipocytes. In this study, we investigated the effects of resveratrol on adipogenesis and apoptosis using 3T3-L1 cells. In mature adipocytes, 100 and 200 microM resveratrol decreased cell viability dose-dependently by 23 +/- 2.7%, and 75.3 +/- 2.8% (p < 0.0001), respectively, after 48 h treatment, and 100 microM resveratrol increased apoptosis by 76 +/- 8.7% (p < 0.0001). Resveratrol at 25 and 50 microM decreased lipid accumulation in maturing preadipocytes significantly by 43 +/- 1.27% and 94.3 +/- 0.3% (p < 0.0001) and decreased cell viability by 25 +/- 1.3% and 70.4 +/- 1.6% (p < 0.0001), respectively. In order to understand the anti-adipogenic effects of resveratrol, maturing 3T3-L1 preadipocytes were treated with 25 microM resveratrol and the change in the expression of several adipogenic transcription factors and enzymes was investigated using real-time RT-PCR. Resveratrol down-regulated the expression of PPAR gamma, C/EBP alpha, SREBP-1c, FAS, HSL, LPL and up-regulated the expression of genes regulating mitochondrial activity (SIRT3, UCP1 and Mfn2). These results indicate that resveratrol may alter fat mass by directly affecting cell viability and adipogenesis in maturing preadipocytes and inducing apoptosis in adipocytes and thus may have applications for the treatment of obesity.
 ...
PMID:Resveratrol induces apoptosis and inhibits adipogenesis in 3T3-L1 adipocytes. 1868 88

The sirtuin SIRT1 is an important regulator of energy metabolism through its impact on glucose and lipid metabolism and therefore we tested the hypothesis that genetic variation in SIRT1 may have an effect on adiposity in a Belgian case/control association study. This study included 1,068 obese patients (BMI > or = 30 kg/m(2)) from the outpatient obesity clinic and 313 lean controls (BMI between 18.5 and 25 kg/m(2)). Anthropometrics were assessed by classical methods and visceral (VFA), subcutaneous (SFA) and total abdominal (TFA) fat areas were determined by a CT scan. The extent of linkage disequilibrium in SIRT1 allowed us to reduce the number of SNPs to two, sufficient to cover the entire gene. The two tagSNPs (rs7069102 and rs3818292) were analyzed by LightSNiP assays in all subjects. Rs3818292 genotypes were similarly distributed in cases and controls, whereas rs7069102 was different for the additive (P = 0.007) and dominant (P = 0.01) model. The variant C-allele of rs7069102 reduced obesity risk with an OR of 0.74 (P = 0.025; 95% CI 0.57-0.96) under a dominant model. In obese male subjects, this variant allele was associated with increased waist circumference (P = 0.04), WHR (P = 0.02), TFA (P = 0.03) and VFA (P = 0.005) (dominant model; adjusted for age and BMI). Rs3818292 was related to VFA (P = 0.005; adjusted for age and BMI) in obese males while in obese women, no significant associations were detected. Our data suggest that genetic variation in SIRT1 increases the risk for obesity, and that SIRT1 genotype correlates with visceral obesity parameters in obese men.
 ...
PMID:Association of SIRT1 gene variation with visceral obesity. 1882 Sep 48

Sirtuins are critical regulators of many cellular processes, including insulin secretion, the cell cycle, and apoptosis. Sirtuins are associated with a variety of age-associated diseases such as type II diabetes, obesity, and Alzheimer's disease. A thorough understanding of sirtuin chemical mechanisms will aid toward developing novel therapeutics that regulate metabolic disorders and combat associated diseases. In this review, we discuss the unique deacetylase mechanism of sirtuins and how this information might be employed to develop inhibitors and other molecular probes for therapeutic and basic research applications. We also cover physiological regulation of sirtuin activity and how these modes of regulation may be exploited to manipulate sirtuin activity in live cells. Development of molecular probes and drugs that specifically target sirtuins will further understanding of sirtuin biology and potentially afford new treatments of several human diseases.
 ...
PMID:Mechanisms and molecular probes of sirtuins. 1894 Jun 61

Cardiovascular disease (CVD) is the most prevalent disease worldwide and there is intense interest in pharmaceutical approaches to reduce the burden of this chronic, aging-related condition. The sirtuin (SIRT) family of NAD(+)-dependent protein deacetylases and ADP-ribosyltransferases have emerged as exciting targets for CVD management that can impact the cardiovascular system both directly and indirectly, the latter by modulating whole body metabolism. SIRT1-4 regulate the activities of a variety of transcription factors, coregulators, and enzymes that improve metabolic control in adipose tissue, liver, skeletal muscle, and pancreas, particularly during obesity and aging. SIRT1 and 7 can control myocardial development and resist stress- and aging-associated myocardial dysfunction through the deacetylation of p53 and forkhead box O1 (FoxO1). By modulating the activity of endothelial nitric oxide synthase (eNOS), FoxO1, and p53, and the expression of angiotensin II type 1 receptor (AT1R), SIRT1 also promotes vasodilatory and regenerative functions in endothelial and smooth muscle cells of the vascular wall. Given the array of potentially beneficial effects of SIRT activation on cardiovascular health, interest in developing specific SIRT agonists is well-substantiated. Because SIRT activity depends on cellular NAD+ availability, enzymes involved in NAD+ biosynthesis, including nicotinamide phosphoribosyltransferase (Nampt), may also be valuable pharmaceutical targets for managing CVD. Herein we review the actions of the SIRT proteins on the cardiovascular system and consider the potential of modulating SIRT activity and NAD+ availability to control CVD.
 ...
PMID:NAD(+), sirtuins, and cardiovascular disease. 1914 6

Sirtuins are protein deacetylases, which are dependent on nicotine adenine dinucleotide. They are phylogenetically conserved from bacteria to humans. Seven sirtuin proteins localized in a wide variety of subcellular locations have been identified in the human genome. The most important known function of sirtuins is their regulation of transcriptional repression, mediated through binding of a complex containing sirtuins and other proteins. Studies have shown that sirtuins have pathophysiological relevance to neurodegeneration, muscle differentiation, inflammation, obesity, and cancer. In addition, sirtuin activity extends the lifespan of several organisms. In this review, we discuss the mode(s) of action of sirtuins, and their biological role(s) in health and disease.
 ...
PMID:Function of sirtuins in biological tissues. 1930 Dec 79

Nonalcoholic fatty liver disease (NAFLD) is an abnormal liver metabolism often observed with insulin resistance and metabolic syndrome. Calorie restriction is a useful treatment for NAFLD and reportedly prolongs the life spans of several species in which sirtuin plays an important role. In this study, we examined whether the activation of SIRT1, a mammalian ortholog of sirtuin, may ameliorate the development of NAFLD. Monosodium glutamate (MSG) mice, which exhibited obesity and insulin resistance, were treated with SRT1720, a specific SIRT1 activator from the age of 6-16 wk. Sixteen-week-old MSG mice exhibited increased liver triglyceride content and elevated levels of aminotransferase. SRT1720 treatment significantly reduced these levels without affecting body weight or food intake. These results suggested that the administration of SRT1720 ameliorated the development of NAFLD in MSG mice. The expressions of lipogenic genes, such as sterol regulatory element-binding protein-1c, acetyl-CoA carboxylase, and fatty acid synthase, and the serum lipid profiles, including free fatty acids, were elevated in MSG mice and were reduced by SRT1720 treatment. SRT1720 treatment also reduced the expressions of lipogenic genes in cultured HepG2 cells. Furthermore, SRT1720 treatment decreased the expressions of marker genes for oxidative stress and inflammatory cytokines in the liver of MSG mice. Taken together, SRT1720 treatment may reduce liver lipid accumulation, at least in part, by directly reducing the expressions of lipogenic genes. The reduction of oxidative stress and inflammation may also be involved in the amelioration of NAFLD.
 ...
PMID:Treatment with SRT1720, a SIRT1 activator, ameliorates fatty liver with reduced expression of lipogenic enzymes in MSG mice. 1972 16


1 2 3 4 5 6 7 8 9 10 Next >>