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)

It has been suggested that protein tyrosine phosphatase 1B (PTP1B) inhibitors might be a therapeutic target for the treatment of type 2 diabetes and obesity. A bioassay-guided phytochemical study of the EtOAc extract of the stem bark of Erythrina addisoniae (Leguminosae) resulted in the identification of a new PTP1B inhibitory compound, 5,2',4'-trihydroxy-6-(gamma,gamma-dimethylallyl)-2''',2'''-dimethyldihydropyrano[5''',6''']isoflavanone ( 6), along with five known prenylated isoflavonoids, orientanol E ( 1), senegalensin ( 2), warangalone ( 3), warangalone 4'-methyl ether ( 4) and 2,3-dihydroauriculatin ( 5). Compounds 1, 5 and 6 inhibited PTP1B with IC (50) values ranging from 2.6 +/- 0.5 to 10.1 +/- 0.3 microM. Our results indicate that hydroxylation at both 2'- and 4'-positions in the B-ring and cyclization between a hydroxy group at C-7 and one of the prenyl groups at C-6 or C-8 in the A-ring may be important for activity. Thus, compounds 5 and 6 could be a new class of natural PTP1B inhibitors.
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PMID:Inhibition of protein tyrosine phosphatase 1B by prenylated isoflavonoids isolated from the stem bark of Erythrina addisoniae. 1697 1

Lifestyle interventions including exercise programmes are cornerstones in the prevention of obesity-related diabetes. In this study, we demonstrate that a single bout of exercise inhibits high-fat diet-induced insulin resistance. Diet-induced obesity (DIO) increased the expression and activity of the protein tyrosine phosphatase 1B (PTP1B) and attenuated insulin signalling in gastrocnemius muscle of rats, a phenomenon which was reversed by a single session of exercise. In addition, DIO was observed to lead to serine phosphorylation of insulin receptor substrate 1 (IRS-1), which was also reversed by exercise in muscle in parallel with a reduction in c-Jun N-terminal kinase (JNK) activity. Thus, acute exercise increased the insulin sensitivity during high-fat feeding in obese rats. Overall, these results provide new insights into the mechanism by which exercise restores insulin sensitivity.
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PMID:Reversal of diet-induced insulin resistance with a single bout of exercise in the rat: the role of PTP1B and IRS-1 serine phosphorylation. 1700 71

Animals at advanced ages exhibit a reduction in central leptin sensitivity. However, changes in growth, metabolism, and obesity risk occur much earlier in life, particularly during the transition from youth to middle age. To determine when initial decreases in central leptin sensitivity occur, leptin-dependent suppression of food intake was tested in 8-, 12-, and 20-wk-old male, chow-fed Sprague Dawley rats. Intracerebroventricular leptin injection (3 microg) suppressed 24-h food intake in 8- and 12-wk-old rats (P < 0.05) but not 20-wk-old rats. To identify potential cellular mediators of this resistance, we focused on protein tyrosine phosphatase 1B (PTP1B), a recently described inhibitor of leptin signaling. PTP1B protein levels, as determined by Western blot, were significantly higher in mediobasal hypothalamic punches collected from 20-wk-old rats, compared with 8-wk-old rats (P < 0.05). When 20-wk-old rats were fasted for 24 h, levels of hypothalamic PTP1B decreased (P < 0.05), coincident with a restoration of leptin sensitivity. To directly test whether inhibition of PTP1B restores leptin sensitivity, 20-wk-old chow-fed rats were pretreated with a pharmacological PTP1B inhibitor 1 h before leptin, and 24-h food intake was recorded. As expected, leptin alone produced a small but nonsignificant reduction in food intake. However, pretreatment with the PTP1B inhibitor resulted in a marked improvement in leptin-dependent suppression of food intake (P < 0.05). These data are consistent with the hypothesis that increases in PTP1B contribute to hypothalamic leptin resistance as rats transition into middle age.
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PMID:Increased hypothalamic protein tyrosine phosphatase 1B contributes to leptin resistance with age. 1703 57

Protein tyrosine phosphatases (PTPs), a large family of signaling enzymes, play essential roles in intracellular signal transduction by regulating the cellular level of tyrosine phosphorylation to control cell growth and differentiation, metabolism, cell migration, gene transcription, ion-channel activity, immune response, cell apoptosis, and bone development. Among all PTPs, protein tyrosine phosphatase 1B (PTP1B) plays a seminal role in cellular signaling and in many human diseases, including cancer, diabetes, and obesity. Therefore, small molecular inhibitors of PTP1B can be promising drug candidates. Because of the structural homologies in many families of PTPs, it is a challenging task to find inhibitors specific to each PTP. Recent studies suggested that secondary binding pockets or peripheral binding sites around the conserved active site should be exploited to design novel potent and selective PTP1B inhibitors. In this review, we discuss the structural and biological features of small molecular PTP1B-specific inhibitors, with particular emphasis on small molecular inhibitors targeting PTP1B over the other PTPs that have been synthesized in the past 4 years.
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PMID:Recent development of small molecular specific inhibitor of protein tyrosine phosphatase 1B. 1703 61

Inhibition of protein tyrosine phosphatase 1B (PTP1B) has been proposed as a strategy for the treatment of type 2 diabetes and obesity. Bioassay-guided fractionation of MeOH extract of Selaginella tamariscina (Selaginellaceae) afforded a PTP1B inhibitory compound, amentoflavone. The compound inhibited PTP1B with an IC50 value of 7.3+/-0.5 microM. Kinetic study suggested that amentoflavone is a non-competitive inhibitor of PTP1B, with a Ki value of 5.2 microM. Treatment of 32D cells overexpressing the insulin receptor (IR) with amentoflavone resulted in a dose-dependent increase in tyrosine phosphorylation of IR. These results indicate that amentoflavone may enhance insulin-induced intracellular signaling possibly through inhibition of PTP1B activity.
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PMID:Protein tyrosine phosphatase 1B inhibitory activity of amentoflavone and its cellular effect on tyrosine phosphorylation of insulin receptors. 1726 85

Protein tyrosine phosphatase 1B (PTP1B) is an important drug target for the treatment of type II diabetes and obesity. There are strong indications that a novel class of allosteric inhibitors act by preventing the closure of the WPD-loop [C. Wiesmann, K.J. Barr, J. Kung, J. Zhu, D.A. Erlanson, W. Shen, B.J. Fahr, M. Zhong, L. Taylor, M. Randall, R.S. McDowell, S.K. Hansen, Allosteric inhibition of protein tyrosine phosphatase 1B, Nat. Struc. Mol. Biol. 11 (2004) 730-737.], which is absolutely essential for the catalytic activity of PTP1B. In this work, we develop force field parameters for one of these inhibitors (BB3), and subsequently utilise standard and targeted molecular dynamics simulations to perform a study of WPD-loop mobility in the presence of this inhibitor. We demonstrate that BB3 not only significantly reduces the flexibility of the WPD-loop compared to both the apo-enzyme or the closed conformation complexed with phosphotyrosine, but that this is accompanied by reduced flexibility in a related region, the S-loop, further emphasising the possibility of manipulating this region when designing novel inhibitors for PTP1B.
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PMID:A molecular dynamics study of WPD-loop flexibility in PTP1B. 1740 95

Emerging evidence suggests that increased dietary consumption of fructose in Western society may be a potentially important factor in the growing rates of obesity and the metabolic syndrome. This review will discuss fructose-induced perturbations in cell signaling and inflammatory cascades in insulin-sensitive tissues. In particular, the roles of cellular signaling molecules including nuclear factor kappa B (NFkB), tumor necrosis factor alpha (TNF-alpha), c-Jun amino terminal kinase 1 (JNK-1), protein tyrosine phosphatase 1B (PTP-1B), phosphatase and tensin homolog deleted on chromosome ten (PTEN), liver X receptor (LXR), farnesoid X receptor (FXR), and sterol regulatory element-binding protein-1c (SREBP-1c) will be addressed. Considering the prevalence and seriousness of the metabolic syndrome, further research on the underlying molecular mechanisms and preventative and curative strategies is warranted.
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PMID:Fructose and the metabolic syndrome: pathophysiology and molecular mechanisms. 1760 9

A three dimensional chemical feature based pharmacophore model was developed for the inhibitors of protein tyrosine phosphatase 1B (PTP1B) using the CATALYST software, which would provide useful knowledge for performing virtual screening to identify new inhibitors targeted toward type II diabetes and obesity. A dataset of 27 inhibitors, with diverse structural properties, and activities ranging from 0.026 to 600 microM, was selected as a training set. Hypol, the most reliable quantitative four featured pharmacophore hypothesis, was generated from a training set composed of compounds with two H-bond acceptors, one hydrophobic aromatic and one ring aromatic features. It has a correlation coefficient, RMSD and cost difference (null cost-total cost) of 0.946, 0.840 and 65.731, respectively. The best hypothesis (Hypol) was validated using four different methods. Firstly, a cross validation was performed by randomizing the data using the Cat-Scramble technique. The results confirmed that the pharmacophore models generated from the training set were valid. Secondly, a test set of 281 molecules was scored, with a correlation of 0.882 obtained between the experimental and predicted activities. Hypol performed well in correctly discriminating the active and inactive molecules. Thirdly, the model was investigated by mapping on two PTP1B inhibitors identified by different pharmaceutical companies. The Hypol model correctly predicted these compounds as being highly active. Finally, docking simulations were performed on few compounds to substantiate the role of the pharmacophore features at the binding site of the protein by analyzing their binding conformations. These multiple validation approaches provided confidence in the utility of this pharmacophore model as a 3D query for virtual screening to retrieve new chemical entities showing potential as potent PTP1B inhibitors.
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PMID:Pharmacophore modeling for protein tyrosine phosphatase 1B inhibitors. 1761 69

Allosteric inhibition of protein tyrosine phosphatase 1B (PTP1B), has paved a new path to design specific inhibitors for PTP1B, which is an important drug target for the treatment of type II diabetes and obesity. The PTP1B1-282-allosteric inhibitor complex crystal structure lacks alpha7 (287-298) and moreover there is no available 3D structure of PTP1B1-298 in open form. As the interaction between alpha7 and alpha6-alpha3 helices plays a crucial role in allosteric inhibition, alpha7 was modeled to the PTP1B1-282 in open form complexed with an allosteric inhibitor (compound-2) and a 5 ns MD simulation was performed to investigate the relative orientation of the alpha7-alpha6-alpha3 helices. The simulation conformational space was statistically sampled by clustering analyses. This approach was helpful to reveal certain clues on PTP1B allosteric inhibition. The simulation was also utilized in the generation of receptor based pharmacophore models to include the conformational flexibility of the protein-inhibitor complex. Three cluster representative structures of the highly populated clusters were selected for pharmacophore model generation. The three pharmacophore models were subsequently utilized for screening databases to retrieve molecules containing the features that complement the allosteric site. The retrieved hits were filtered based on certain drug-like properties and molecular docking simulations were performed in two different conformations of protein. Thus, performing MD simulation with alpha7 to investigate the changes at the allosteric site, then developing receptor based pharmacophore models and finally docking the retrieved hits into two distinct conformations will be a reliable methodology in identifying PTP1B allosteric inhibitors.
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PMID:Molecular dynamics simulation study of PTP1B with allosteric inhibitor and its application in receptor based pharmacophore modeling. 1868 9

Leptin is an important circulating signal for inhibiting food intake and body weight gain. In recent years, "leptin resistance" has been considered to be one of the main causes of obesity. However, the detailed mechanisms of leptin resistance are poorly understood. Increasing evidence has suggested that stress signals, which impair endoplasmic reticulum (ER) function, lead to an accumulation of unfolded proteins, which results in ER stress. In the present study, we hypothesized that ER stress is involved in leptin resistance. Tunicamycin, thapsigargin, or brefeldin A was used to induce ER stress. The activation status of leptin signals was measured by Western blotting analysis using a phospho-(Tyr705) signal transducer and activator of transcription 3 (STAT3) antibody. We observed that ER stress markedly inhibited leptin-induced STAT3 phosphorylation. In contrast, ER stress did not affect leptin-induced c-Jun NH(2)-terminal kinase activation. These results suggest that ER stress induces leptin resistance. ER stress-induced leptin resistance was mediated through protein tyrosine phosphatase 1B but not through suppressors of cytokine signaling 3. It is noteworthy that a chemical chaperone, which could improve the protein-folding capacity, reversed ER stress-induced leptin resistance. Moreover, homocysteine, which induces ER stress, caused leptin resistance both in vitro and in vivo. Together, these findings suggest that the pathological mechanism of leptin resistance is derived from ER stress.
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PMID:Endoplasmic reticulum stress induces leptin resistance. 1875 73


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