Changes in N-linked sugar chain patterns induced by moderate-to-high expression of the galactosyltransferase I gene in a brain-derived cell line, CG4

• Published in: Journal of neuroscience research Vol. 80; no. 1; pp. 29 - 36
• Main Authors: Menon, Krishnakumar N., Ikeda, Takeshi, Fujimoto, Ichiro, Narimatsu, Hisashi, Nakakita, Shin-ichi, Hase, Sumihiro, Ikenaka, Kazuhiro
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.04.2005
• Subjects: Acetylglucosamine - chemistry; Acetylglucosamine - metabolism; Animals; BA2; Brain Chemistry - genetics; Cell Line; cell morphology; CG4 cells; Chromatography, High Pressure Liquid; galactosyltransferase I; Galactosyltransferases - genetics; Galactosyltransferases - metabolism; Gene Expression; Humans; Neuroglia - chemistry; Neuroglia - enzymology; Neurons - chemistry; Neurons - enzymology; Oligosaccharides - chemistry; Oligosaccharides - metabolism; Reverse Transcriptase Polymerase Chain Reaction; sugar chain pattern; Transfection
• ISSN: 0360-4012; 1097-4547
• DOI: 10.1002/jnr.20416

Oligosaccharides with biantennae and bisecting N‐acetyl glucosamine (GlcNAc) residues attached to the mannose in the β1‐4 trimannosyl core (BA2) are enriched in the brain and considered brain‐type sugar chains. We investigated the significance of the interplay between galactosyltransferase I (GalTase I) and BA2 formation in a brain‐derived cell line, CG4. Increased GalTase expression in different glial‐ and neuronal‐derived cell lines was accompanied by decreased or undetectable levels of BA2, depending on the level of GalTase expression. Forceful expression of GalTase I in CG4 cells expressing high levels of BA2 and low GalTase activity significantly reduced BA2 levels. In addition, a sixfold increase in an abnormal sugar chain A1(6)G1Fo and a moderate increase in A2G2Fo(6)F were evident. The increased levels of A1(6)G1Fo indicate a diversion or abrogation of the N‐linked sugar chain biosynthetic pathway from normal. The accumulation of A1(6)G1Fo and increased A2G2Fo(6)F levels were accompanied by decreased levels of the high mannose‐type sugar chains, M5A, M6B, M8A, and M9A. Increased GalTase I expression also led to stunted growth and abnormal morphology of CG4 cells, with increased mortality. Even moderate overexpression of GalTase I thus disrupts the normal biosynthetic pathway of N‐linked sugar chains, and high overexpression is fatal to CG4 cells. © 2005 Wiley‐Liss, Inc.