The role of TNF-alpha and its receptors in the production of beta-1,4 galactosyltransferase I and V mRNAs by rat primary astrocytes.

Glycosylation is one of the most important post-translational modifications. It is clear that the single step of beta-1,4-galactosylation is performed by a family of beta-1, 4-galactosyltransferases (beta-1,4-GalTs), and that each member of this family may play a distinct role in different tissues and cells. beta-1,4-GalT I and V are involved in the biosynthesis of N-linked oligosaccharides. beta-1,4-GalT I and V mRNAs are present in control astrocytes and affected by TNF-alpha and lipopolysaccharide (LPS) stimuli. In this study, we examined the regulatory mechanisms of tumor necrosis factor-alpha (TNF-alpha)-affected production of beta-1,4-GalT I and V mRNAs. We show here that cultured astrocytes express TNF-alpha receptor 1 (TNFR1) and increased slightly after exposure to LPS. TNF-alpha and TNFR2 are not detected in control astrocytes and upregulated significantly with LPS stimulation and that activation of these receptors by TNF-alpha affects expressions of beta-1,4-GalT I and V mRNAs. In addition, we observed that not only exogenous TNF-alpha but also TNF-alpha produced by astrocytes affected beta-1,4-GalT I and V mRNAs production in astrocytes. These results suggest that an autocrine loop involving TNF-alpha contributes to the production of beta-1,4-GalT I and V mRNA in response to inflammation.