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.
Oligosaccharides with biantennae and bisecting N-acetyl glucosamine (GlcNAc) residues attached to the mannose in the beta1-4 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.
Menon
Krishnakumar N
KN
Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Myodaiji, Okazaki, Aichi, Japan.
Ikeda
Takeshi
T
Fujimoto
Ichiro
I
Narimatsu
Hisashi
H
Nakakita
Shin-ichi
S
Hase
Sumihiro
S
Ikenaka
Kazuhiro
K
D000117:Acetylglucosamine / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry / Q000235:genetics; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D005700:Galactosyltransferases / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D009457:Neuroglia / Q000737:chemistry* / Q000201:enzymology; D009474:Neurons / Q000737:chemistry* / Q000201:enzymology; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D009844:Oligosaccharides; D005700:Galactosyltransferases; C063053:xylosylprotein 4-beta-galactosyltransferase; D000117:Acetylglucosamine