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1.
Experimental & Molecular Medicine ; : 353-360, 2002.
Article Dans Anglais | WPRIM | ID: wpr-203701

Résumé

The present study was undertaken to explore whether retinoids, which are known to have immunomodulatory actions, could attenuate tumor necrosis factor-alpha (TNF)-stimulated inducible nitric oxide synthase (iNOS) expression in 3T3-L1 adipocytes. Adipocytes incubated with TNF induced dose- and time-dependent accumulation of nitrite in the culture medium through the iNOS induction as confirmed by Western blotting. Treatment of cells with TNF in the presence of all-trans-retinoic acid (RA) significantly decreased their ability to produce nitrite and iNOS induction. Both 13-cis- and all- trans-RA-induced suppression was dose-dependent, and all-trans-RA was somewhat potent than 13-cis-RA. The inhibitory effect of RA on TNF-induced iNOS induction was reversible, completely recovered after 2 days, and was exerted through the inhibition of NF-kappaB activation. TNF also suppressed the lipoprotein lipase (LPL) activity of 3T3-L1 adipocytes. RA could not reverse the TNF- induced LPL suppression at RA levels causing near complete inhibition of the TNF-induced NO production. These results indicate that RAs attenuate iNOS expression reversibly in TNF-stimulated 3T3-L1 adipocytes, and that the TNF- induced LPL suppression is not the result of NO overproduction.


Sujets)
Animaux , Souris , Cellules 3T3 , Adipocytes/effets des médicaments et des substances chimiques , Cellules cultivées , Induction enzymatique/effets des médicaments et des substances chimiques , Antienzymes/pharmacologie , Lipoprotein lipase/effets des médicaments et des substances chimiques , Facteur de transcription NF-kappa B/antagonistes et inhibiteurs , Monoxyde d'azote/métabolisme , Nitric oxide synthase/antagonistes et inhibiteurs , Trétinoïne/pharmacologie , Facteur de nécrose tumorale alpha/pharmacologie
2.
Experimental & Molecular Medicine ; : 12-17, 2000.
Article Dans Anglais | WPRIM | ID: wpr-16701

Résumé

Glucose prevents the development of diabetes induced by alloxan. In the present study, the protective mechanism of glucose against alloxan-induced beta-cell damage was investigated using HIT-T 15 cell, a Syrian hamster transformed beta-cell line. Alloxan caused beta-cell damages with DNA fragmentation, inhibition of glucose-stimulated insulin release, and decrease of cellular ATP level, but all of these beta-cell damages by alloxan were prevented by the presence of 20 mM glucose. Oligomycin, a specific inhibitor of ATP synthase, completely abolished the protective effects of glucose against alloxan-induced cell damage. Furthermore, treatment of nuclei isolated from HIT-T15 cells with ATP significantly prevented the DNA fragmentation induced by Ca2+. The results indicate that ATP produced during glucose metabolism plays a pivotal role in the protection of glucose against alloxan-induced beta-cell damage.


Sujets)
Adénosine triphosphate/pharmacologie , Adénosine triphosphate/métabolisme , Alloxane/pharmacologie , Animaux , Lymphocytes B/métabolisme , Lymphocytes B/effets des médicaments et des substances chimiques , Lymphocytes B/cytologie , Calcium/pharmacologie , Lignée cellulaire , Noyau de la cellule/génétique , Noyau de la cellule/effets des médicaments et des substances chimiques , Survie cellulaire , ADN/métabolisme , ADN/génétique , ADN/effets des médicaments et des substances chimiques , Fragmentation de l'ADN , Relation dose-effet des médicaments , Acide egtazique/pharmacologie , Glucose/pharmacologie , Insuline/métabolisme , Oligomycines/pharmacologie
3.
Experimental & Molecular Medicine ; : 131-135, 1998.
Article Dans Anglais | WPRIM | ID: wpr-35393

Résumé

The ornithine aminotransferase (OAT) activity of mouse was found to be highest in the small intestine. The mitochondrial OAT from mouse small intestine was purified to homogeneity by the procedures including heart treatment, ammonium sulfate fractionation, octyl-Sepharose chromatography, and Sephadex G-150 gel filtration. Comparing to the amino acid sequence of mouse hepatic OAT, six N-terminal amino acid residues have been deleted in intestinal OAT. However, the subsequent sequence was identical with that of hepatic OAT. The molecular weights of both intestinal and hepatic OAT were estimated as 46 kDa by SDS-gel electrophoresis and as 92 kDa by gel filtration, indicating that both native OATs are dimeric. Biochemical properties of intestinal OAT, such as molecular weight, pH optimum and K(m) values for L-ornithine and alpha-ketoglutarate, were similar to those of hepatic OAT. However, intestinal OAT was more labile than hepatic OAT to tryptic digestion.


Sujets)
Mâle , Souris , Séquence d'acides aminés , Animaux , Intestin grêle/enzymologie , Foie/enzymologie , Souris de lignée ICR , Données de séquences moléculaires , Masse moléculaire , Ornithine-oxo-acid transaminase/métabolisme , Ornithine-oxo-acid transaminase/isolement et purification , Ornithine-oxo-acid transaminase/génétique , Distribution tissulaire
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