• Bulletin of the Korean Chemical Society
• /
• v.31 no.11
• /
• pp.3359-3365
• /
• 2010

The incorporation of microwave irradiation with the prevalent "click chemistry" is currently of considerable synthetic interest. We describe here the introduction of such laboratorial shortcut into carbohydrate-based drug discovery, resulting in the rapid formation of a series of triazole-linked salicylic $\beta$-D-O-glycosides with biological activities. All "clicked" products were achieved in excellent yields ($\approx$ 90%) within only a quarter. In addition, based on the structural characteristics of the afforded glycomimetics, their inhibitory activities were evaluated toward protein tyrosine phosphatases 1B (PTP1B) and a panel of homologous protein tyrosine phosphatases (PTPs). Docking simulation was also conducted to plausibly propose binding modes of this glycosyl salicylate series with the enzymatic target.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.2
• /
• pp.342-346
• /
• 2008

Aurintricarboxylic acid (ATA) prevents apoptosis in a wide range of cell types, including PC12 cells. ATA is known to increase the phosphorylation level of IGF-1 receptor (IGF-1R) and downstream signaling proteins. ATA can translocate across the plasma membrane of PC12 cells and inhibit protein tyrosine phosphatases (PTPs) and, therefore, it is not clear whether ATA exerted its antiapoptotic effect through activation of IGF-1R or by inhibition of cytosolic PTPs. When PC12 cells, deprived of serum, were treated with Fab fragment of anti-IGF-1R antibody to prevent the binding of ATA to the extracellular domain of IGF-1R, ATA was found to penetrate into the cytosolic space of the cells. Under these conditions, the survival-promoting effects of ATA were abolished, and the increase of phosphorylation and characteristic cleavage of IGF-1R were not observed. These results indicate that the antiapoptotic effect of ATA in PC12 cells is due to the binding of ATA to the extracellular domain of IGF-1R and subsequent activation of the IGF-1R, not inhibition of cytosolic PTP(s).

• The Korean Journal of Physiology and Pharmacology
• /
• v.3 no.3
• /
• pp.357-364
• /
• 1999

We investigated the role of $Ca^{2+}$ and protein kinases/phosphatases in the stimulatory effect of insulin on glucose transport. In isolated rat adipocytes, the simple omission of $CaCl_2$ from the incubation medium significantly reduced, but did not abolish, insulin-stimulated 2-deoxy glucose (2-DG) uptake. Pre-loading adipocytes with intracellular $Ca^{2+}$ chelator, 5,5'-dimethyl bis (o-aminophenoxy)ethane-N,N,N'N' tetraacetic acetoxymethyl ester (5,5'-dimethyl BAPTA/AM) completely blocked the stimulation. Insulin raised intracellular $Ca^{2+}$ concentration $([Ca^{2+}]_i)$ about 1.7 times the basal level of $72{\pm}5$ nM, and 5,5'-dimethyl BAPTA/AM kept it constant at the basal level. This correlation between insulin-induced increases in 2-DG uptake and $[Ca^{2+}]_i$ indicates that the elevation of $[Ca^{2+}]_i$ may be prerequisite for the stimulation of glucose transport. Studies with inhibitors (ML-9, KN-62, cyclosporin A) of $Ca^{2+}-calmodulin$ dependent protein kinases/phosphatases also indicate an involvement of intracellular $Ca^{2+}.$ Additional studies with okadaic acid and calyculin A, protein phosphatase-1 (PP-1) and 2A (PP-2A) inhibitors, indicate an involvement of PP-1 in insulin action on 2-DG uptake. These results indicate an involvement of $Ca^{2+}-dependent$ signaling pathway in insulin action on glucose transport.

• IMMUNE NETWORK
• /
• v.7 no.3
• /
• pp.141-148
• /
• 2007

Background: Anti-IgE mAb which binds circulating but not receptor-bound IgE has been shown to be effective in treatment for asthma and other allergic diseases. However, the mechanisms by which anti-IgE mAb influences the pathophysiological responses are remained to be illustrated. This study was undertaken to examine the therapeutic efficacy of non-anaphylactogenic anti-mouse IgE mAb using murine models of IgE-induced systemic fatal anaphylaxis. Methods: Active systemic anaphylaxis was induced by either penicillin V(Pen V) or OVA and passive systemic anaphylaxis was induced by either anaphylactogenic anti-mouse IgE or a mixture of anti-chicken gamma globulin (CGG) IgG1 mAb and CGG. The binding of the Fc portion of anti-IgE to CHO-stable cell line expressing mouse Fc ${\gamma}$ RIIb was examined using flow cytometry. Fc fragments of anti-IgE mAb were prepared using papain digestion. The expression of phosphatases in lungs were assessed by Western blotting and immunohistochemistry. Results: Anti-IgE mAb prevented IgE- and IgG-induced active and passive systemic fatal reactions. In both types of anaphylaxis, anti-IgE mAb suppressed antigen-specific IgE responses, but not those of IgG. Anti-IgE mAb neither prevented anaphylaxis nor suppressed the IgE response in Fc ${\gamma}$ RIIb-deficient mice. The Fc portion of anti-IgE mAb was bound to murine Fc ${\gamma}$ RIIb gene-transfected CHO cells and inhibited systemic anaphylaxis. Anti-IgE mAb blocked the anaphylaxis-induced downregulation of Fc ${\gamma}$ RIIb-associated phosphatases such as src homology 2 domain-containing inositol 5-phosphatase (SHIP) and phosphatase and tensin homologue deleted on chromosome ten (PTEN). Conclusion: Anti-IgE mAb prevented anaphylaxis by delivering nonspecific inhibitory signals through the inhibitory IgG receptor, Fc ${\gamma}$ RIIb, rather than targeting IgE.

• Molecules and Cells
• /
• v.42 no.2
• /
• pp.183-188
• /
• 2019

Osteoarthritis (OA) is a naturally occurring, irreversible disorder and a major health burden. The disease is multifactorial, involving both physiological and mechanical processes, but calcium crystals have been associated intimately with its pathogenesis. This study tested the hypothesis that these crystals have a detrimental effect on the differentiation of osteoclasts and bone homeostasis. This study employed an osteoblastosteoclast coculture system that resembles in vivo osteoblastdependent osteoclast differentiation along with $Ca^{2+}$-phosphate-coated culture dishes. The calcium-containing crystals upregulated the expression of RANKL and increased the differentiation of osteoclasts significantly as a result. On the other hand, osteoblast differentiation was unaffected. MicroRNA profiling showed that dual-specificity phosphatases 1 (DUSP1) was associated with the increased RANKL expression. DUSP1 belongs to a family of MAPK phosphatases and is known to inactivate all three groups of MAPKs, p38, JNK, and ERK. Furthermore, knockdown of DUSP1 gene expression suggested that RANKL expression increases significantly in the absence of DUSP1 regulation. Microarray analysis of the DUSP1 mRNA levels in patients with pathological bone diseases also showed that the downregulated DUSP1 expression leads to increased expression of RANKL and consequently to the destruction of the bone observed in these patients. These findings suggest that calcium-containing crystals may play a crucial role in promoting RANKL-induced osteoclastogenesis via DUSP1.

• Asian-Australasian Journal of Animal Sciences
• /
• v.5 no.4
• /
• pp.643-646
• /
• 1992

Role of low degradable protein in milk production of early lactating Murrah buffaloes has been studied in relation to energy status of test animals. Replacement of conventional concentrate mixture with low degradable cotton seed cake resulted in appreciable changes in circulatory transaminases and phosphatase levels. The enzymes viz. glutamate oxaloacetate and glutamate pyruvate transaminase and alkaline phosphatases increased with feeding of said cake indicating stress on hepatic tissue. Animals seemed to overcome stress by feeding enhanced levels of same protein along with improved feed intake, body weight and milk production.

• Journal of the Korean Chemical Society
• /
• v.46 no.3
• /
• pp.296-300
• /
• 2002

• Journal of Microbiology and Biotechnology
• /
• v.19 no.9
• /
• pp.918-921
• /
• 2009

In the present study, we examined the inhibitory effects of protein tyrosine phosphatase (PTPase) inhibitors, including sodium orthovanadate (SOV), ammonium molybdate (AM), and iodoacetamide (IA), on cell growth, accumulation of astaxanthin, and PTPase activity in the photosynthetic algae Haematococcus lacustris. PTPase activity was assayed spectrophotometrically and was found to be inhibited 60% to 90% after treatment with the inhibitors. SOY markedly abolished PTPase activity, significantly activating the accumulation of astaxanthin. These data suggest that the accumulation of astaxanthin in H. lacustris results from the concerted actions of several PTPases.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.243.2-244
• /
• 2002

Protein-tyrosine phosphatases (PTPs) constitute a family of receptor-like and cytoplasmic enzymes. which catalyze the dephosphorylation of phosphotyrosine residues in a variety of receptors and signaling molecules. Thirty subtypes of PTPs have been identified in human genomes. Among PTPs, PTP1 B has been suggested as a negative regulator of insulin signaling. Overexpression of this enzyme has been known as a cause of obesity and type II diabetes, so it is a target for drug discovery. (omitted)

• IMMUNE NETWORK
• /
• v.5 no.3
• /
• pp.144-149
• /
• 2005

Background: Fc receptor-mediated phagocytosis is a complex process involving the activation of kinases and phosphatases. FcgammaRIIB has been known to transduces inhibitory signals through an immunoreceptor tyrosine-based inhibitory motif (ITIM) in cytoplasmic domains. In this study, we examined the involvement of inositol-phosphatase in the Fc receptor-mediated phagocytosis. Methods: J774 cells were infected using vaccinia viral vector containing SH2 domain-containing inositol-phosphatase (SHIP) cDNA and stimulated with the sensitized sheep red blood cells. Results: Stimulation of J774 cells induced the tyrosine phosphorylation of SHIP which was maximal at 5 minutes. Phosphatidylinositol-3 (PI-3) kinase inhibitor (wortmannin) inhibits J774 cell phagocytosis of sensitized sheep red blood cells in a dose-dependent manner. Heterologious expression of SHIP in J774 cells inhibits phagocytosis of sensitized sheep red blood cells in a dose-dependency manner, but catalytically dead mutants of SHIP has no effect on phagocytosis. Conclusion: These results strongly suggest that the active signals mediated by PI-3 kinase are opposed by inhibitory signals through SHIP in the regulation of Fc receptor-mediated phagocytosis.