Gene expression of O-GlcNAc cycling enzymes in human breast cancers

O-GlcNAcylation is an abundant, dynamic, and inducible posttranslational modification in which single β-N-acetylglucosamine residues are attached by O-glycosidic linkage to serine or treonine residues. It is suggested that abnormally regulated O-GlcNAcylation may contribute to the pathology of cancer. Cycling of O-GlcNAc residues on intracellular proteins is controlled by two enzymes, O-GlcNAc transferease (OGT), which catalyses the addition of O-GlcNAc residues and nucleocytoplasmic β-N-acetylglucosaminidase (O-GlcNAcase; encoded by MGEA5 gene), an enzyme involved in the removal of O-GlcNAc. In this study, relationship between the mRNA expressions of genes coding O-GlcNAc cycling enzymes in breast ductal carcinomas and clinicopathological parameters were analyzed. The results showed that poorly differentiated tumors (grade II and III) had significantly higher OGT expression than grade I tumors. Contrary, MGEA5 transcript levels were significantly lower in grade II and III in comparison with grade I tumors. The Spearman rank correlation showed the expressions of OGT and MGEA5 in breast cancer was negatively correlated (r = −0.430, P = 0.0002). Lymph node metastasis status was significantly associated with decreased MGEA5 mRNA expression. This result suggests that elevation in O-GlcNAc modification of proteins may be implicated in breast tumor progression and metastasis

Isolation of a Glucosamine Binding Leguminous Lectin with Mitogenic Activity towards Splenocytes and Anti-Proliferative Activity towards Tumor Cells

A dimeric 64-kDa glucosamine-specific lectin was purified from seeds of Phaseolus vulgaris cv. “brown kidney bean.” The simple 2-step purification protocol involved affinity chromatography on Affi-gel blue gel and gel filtration by FPLC on Superdex 75. The lectin was absorbed on Affi-gel blue gel and desorbed using 1M NaCl in the starting buffer. Gel filtration on Superdex 75 yielded a major absorbance peak that gave a single 32-kDa band in SDS-PAGE. Hemagglutinating activity was completely preserved when the ambient temperature was in the range of 20°C–60°C. However, drastic reduction of the activity occurred at temperatures above 65°C. Full hemagglutinating activity of the lectin was observed at an ambient pH of 3 to 12. About 50% activity remained at pH 0–2, and only residual activity was observed at pH 13–14. Hemagglutinating activity of the lectin was inhibited by glucosamine. The brown kidney bean lectin elicited maximum mitogenic activity toward murine splenocytes at 2.5 µM. The mitogenic activity was nearly completely eliminated in the presence of 250 mM glucosamine. The lectin also increased mRNA expression of the cytokines IL-2, TNF-α and IFN-γ. The lectin exhibited antiproliferative activity toward human breast cancer (MCF7) cells, hepatoma (HepG2) cells and nasopharyngeal carcinoma (CNE1 and CNE2) cells with IC50 of 5.12 µM, 32.85 µM, 3.12 µM and 40.12 µM respectively after treatment for 24 hours. Flow cytometry with Annexin V and propidum iodide staining indicated apoptosis of MCF7 cells. Hoechst 33342 staining also indicated formation of apoptotic bodies in MCF7 cells after exposure to brown kidney bean lectin. Western blotting revealed that the lectin-induced apoptosis involved ER stress and unfolded protein response

FEASIBILITY STUDY OF A 10-GWh TOROIDAL SUPERCONDUCTIVE MAGNETIC ENERGY STORAGE SYSTEM1. SYSTEM DESIGN

Un système à aimant toroïdal est probablement preférable à celui d'un aimant solenoïda1 du point de vue des champs de fuite, de la fabrication, de l'entretien et des réparations. Au vu des propriétés non connues des roches et du niveau technologique actuel pour faire des excavations, il semble raisonnable d'adopter une structure en tranchée ouverte qui ne soutienne que la force électromagnétique centripète agissant sur l'aimant toroïdal.A toroidal coil system is probably preferable to a solenoid coil system in terms of stray magnetic field, fabrication, maintenance, and repair. Judging from the uncertain properties of rock masses and present level of excavation technology, it seems reasonable to choose an open trench structure that supports only the centering electromagnetic force of the toroidal coil

FEASIBILITY STUDY OF A 10-GWh TOROIDAL SUPERCONDUCTIVE MAGNETIC ENERGY STORAGE SYSTEM2. CONCEPTUAL DESIGN OF COIL SYSTEM

On présente le plan d'un système destiné à l'accumulation d'une énergie de 10 GWh par aimant supraconducteur. On prefère adopter un arrangement d'aimant toroïda1. Le principal avantage de ce système réside dans le fait que la fuite du champ magnétique est très faible, la réalisation et l'entretien plus simples. En conséquence, les charges pour le site de construction sont réduites.A conceptual design of a 10 GWh superconductive magnetic energy storage (SMES) for diurnal energy storage use is presented. A toroidal field coil arrangement is preferably adopted. The main advantage of this design is that the stray magnetic field is inherently quite small and manufacturability as well as maintainability is more feasible. Therefore, requirements for a construction site are rather small

FEASIBILITY STUDY OF A 10-GWh TOROIDAL SUPERCONDUCTIVE MAGNETIC ENERGY STORAGE SYSTEM3. CONCEPTUAL DESIGN OF ROCK MASS SUPPORT STRUCTURE

On examine d'abord les problèmes concernant le support rocheux de l'aimant. L'étude de la stabilité des fondations pour le système SMES de 10 GWh est menée à bien dans l'hypothèse d'une élasticité à symétrie axiale pour l e support. Selon nos calculs, on considère que la force magnétique agissant sur l'aimant toroïdal peut être contenue par la masse rocheuse des fondations.Problems concerning rock mass support system are examined and rock mass stability analysis for the conceptual design of the 10 GWH SMES system is carried out using F.E.M. under the condition of axi-symmetrical elasticity. From the results of calculations, it is considered that centering electromagnetic force of the toroidal coil type can be supported by the rock mass

Structure and mechanism of a bacterial beta-glucosaminidase having O-GlcNAcase activity

O-GlcNAc is an abundant post-translational modification of serine and threonine residues of nucleocytoplasmic proteins. This modification, found only within higher eukaryotes, is a dynamic modification that is often reciprocal to phosphorylation. In a manner analogous to phosphatases, a glycoside hydrolase termed O-GlcNAcase cleaves O-GlcNAc from modified proteins. Enzymes with high sequence similarity to human O-GlcNAcase are also found in human pathogens and symbionts. We report the three-dimensional structure of O-GlcNAcase from the human gut symbiont Bacteroides thetaiotaomicron both in its native form and in complex with a mimic of the reaction intermediate. Mutagenesis and kinetics studies show that the bacterial enzyme, very similarly to its human counterpart, operates via an unusual 'substrate-assisted' catalytic mechanism, which will inform the rational design of enzyme inhibitors