A possible involvement of endogenous polyamines in the TNF-α cellular sensitivity

AbstractA critical step in the cytotoxic action mechanism of tumor necrosis factor-α (TNF-α) involves, among mitochondrial dysfunctions, an early change of the inner membrane permeability displaying the characteristics of permeability transition. Cytosolic polyamines, especially spermine, are known to inhibit it. Our results show that spermine is only detectable in the TNF-α resistant C6 cells while N1-acetylspermidine is present in the TNF-α sensitive WEHI-164 cells, and putrescine and spermidine are found in both. TNF-α treatment does not change this distribution but only induces a quantitative alteration in TNF-α sensitive cells. Omission of glutamine (energetic substrate) from the culture media alters neither the TNF-α responsiveness of both cell lines nor their polyamine distributions, only their quantitative polyamine contents

REGULATION DE LA GLYCOSYLATION DES GLYCOPROTEINES INTESTINALES AU COURS DU DEVELOPPEMENT POSTNATAL (ROLE DES POLYAMINES)

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Effect of retinoic acid on two glycosyltransferase activities in c6 cultured glioma cells

International audience1. Activity of two glycosyltransferases was studied in retinoic acid-treated C6 cultured glioma cells. 2. The beta-galactoside alpha 2,3-sialyltransferase transferring N-acetylneuramin onto the O-glycans residues of glycoproteins was activated up to twice after chronic treatment (from 24 to 96 hr) with all-trans retinoic acid. 3. No effect was observed for shorter treatments. 4. On the opposite, the N-glycan galactosyltransferase activity remained unchanged whatever the length of retinoic acid treatment was. 5. The activatory effect was not dependent on isomery, as all-trans and 13-cis retinoic acid isomers were both activators of the C6 glioma cell sialyltransferase. 6. Measurement of adhesion of retinoic acid-treated cells using labelled plasma membranes showed an enhancement of adhesion in correlation with enhancement of sialyltransferase activity

Study of o-glycan sialylation in c6 cultured glioma cells: Regulation of a β-galactoside α2,3 sialyltransferase activity by ca2+/calmodulin antagonists and phosphatase inhibitors

International audienc

Study ofO-sialylation of glycoproteins in C6 glioma cells treated with retinoic acid

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Study of O-glycan sialylation in C6 cultured glioma cells: Evidence for post-translational regulation of Aβ-galactoside α2,3 sialyltransferase activity by N-glycosylation

International audienceWe have studied the Gal beta 1-3GalNAc-R alpha 2,3 sialyltransferase from C6 glioma cells transferring Neu5Ac from CMP-Neu5Ac onto O-glycans of glycoproteins. Using synchronized C6 glioma cells, we showed that the alpha 2,3 sialyltransferase activity was inhibited by tunicamycin to a greater extend than DNA and protein biosynthesis suggesting inhibition of N-glycosylation of this enzyme. Additional demonstration of N-glycosylation of the alpha 2,3 sialytransferase was provided through ConA-Sepharose binding. Treatment of partially purified alpha 2,3 sialytransferase by peptide-N-glycosidase F showed a significative inhibition demonstrating that N-glycan moiety is required for complete activity of the C6 glioma cell alpha 2,3 sialyltransferase