Institute of Glycotechnology, Future Science and Technology Joint Research Center, Tokai University, Kanagawa, Japan .
INSERM U 499, RTH Laënnec School of Medicine, and Fondation Gillet-Mérieux, Lyon-Sud Hospital, Lyon, France .
Proc Jpn Acad Ser B Phys Biol Sci. 2006 Sep;82(6):189-96. doi: 10.2183/pjab.82.189. Epub 2006 Sep 21.
Gangliosides in the brain of the knockout mouse deficient in the activity of β1,4 N-acetylgalactosaminyl transferase (β1,4 GalNAc-T)(GM2 synthase) consisted of nearly exclusively of GM3- and GD3-gangliosides as expected from the known substrate specificity of the enzyme and in confirmation of the initial reports from two laboratories that generated the mutant mouse experimentally. The total molar amount of gangliosides was approximately 30% higher in the mutant mouse brain than that in the wild-type brain. However, contrary to the initial reports, one-fourth of total GD3-ganglioside was O-acetylated. It reacted positively with an anti-O-acetylated GD3 monoclonal antibody and disappeared with a corresponding increase in GD3-ganglioside after mild alkaline treatment. The absence of O-acetylated GD3 in the initial reports can be explained by the saponification step included in their analytical procedures. Although quantitatively much less and identification tentative, we also detected GT3 and O-acetylated GT3. Anti-GD3 and anti-O-acetylated GD3 monoclonal antibodies gave positive reactions in the brain of mutant mouse as expected from the analytical results. Either antibody barely stained wild-type brain except for immunoreactivity of GD3 in the cerebellar Purkinje cells. The distributions of GD3 and O-acetylated GD3 in the brain of mutant mouse were similar but differential localization was noted in the cerebellar Purkinje cells and cerebral cortex.
在缺乏β1,4 N-乙酰半乳糖胺基转移酶（β1,4 GalNAc-T）（GM2 合酶）活性的敲除小鼠脑中，神经节苷脂几乎完全由 GM3-和 GD3-神经节苷脂组成，这与酶的已知底物特异性相符，并证实了最初从两个实验室生成突变鼠的报告，这两个实验室从实验上生成了该突变鼠。突变鼠脑中神经节苷脂的总摩尔量比野生型鼠脑中高约 30%。然而，与最初的报告相反，四分之一的总 GD3-神经节苷脂发生了 O-乙酰化。它与抗 O-乙酰化 GD3 单克隆抗体反应阳性，并在温和碱性处理后随着 GD3-神经节苷脂的相应增加而消失。最初的报告中没有 O-乙酰化 GD3，可以用其分析程序中包括的皂化步骤来解释。尽管数量较少且鉴定不明确，但我们还检测到 GT3 和 O-乙酰化 GT3。抗 GD3 和抗 O-乙酰化 GD3 单克隆抗体在突变鼠脑中产生阳性反应，这与分析结果相符。两种抗体除了小脑浦肯野细胞中的 GD3 免疫反应性外，几乎都不染色野生型脑。突变鼠脑中 GD3 和 O-乙酰化 GD3 的分布相似，但在小脑浦肯野细胞和大脑皮层中注意到了差异定位。
