Yohe H C, Ye S, Reinhold B B, Reinhold V N
Research Service, VA Medical and Regional Office Center, White River Junction, VT 05009-0001, USA.
Glycobiology. 1997 Dec;7(8):1215-27. doi: 10.1093/glycob/7.8.1215.
Sialoglycosphingolipids (gangliosides) have been increasingly implicated as regulators of membrane signaling events. Macrophage ganglioside patterns dramatically increase in complexity when murine peritoneal macrophages are stimulated in vivo with the appearance of the sialidase-sensitive monosialoganglioside GM1b (cisGM1) as a major component. Gangliosides from stimulated murine peritoneal macrophages were separated into monosialo and polysialo fractions and the polysialo fraction structurally characterized by enzymatic, chemical, and mass spectra methods. All detectable components of the polysialo fraction were determined to be disialogangliosides. Treatment of the polysialo fraction with Clostridium perfringens sialidase produced mostly the sialidase-resistant monosialoganglioside, GM1a, and a minor amount of asialoGM1. Periodate oxidation and mass spectrometry analyses demonstrated the lack of tandem disialo moieties which indicated the absence of GD1b or GD1c (GD1) entities. The combined data showed the major disialogangliosides consisted of GD1a entities comprising IV3-NeuAc,II3NeuAc-GgOse4Cer, IV3-NeuGc,II3NeuAc-GgOse4Cer, IV3NeuAc,II3NeuGc-GgOse4Cer, and IV3-NeuGc,II3NeuGc-GgOse4Cer. Minor components consisted of GD1alpha entities, IV3NeuAc, III6NeuAcGgOse4Cer, IV3NeuGc, III6NeuGc-GgOse4Cer, and also positional isomer(s) of GD1alpha(NeuAc, NeuGc). These isomeric components were identified by collision analysis and tandem mass spectrometry. Consistent with previous analyses, the ceramide portion of all polysialo (disialo) gangliosides contained solely C18 sphingosine with C16 and C24 fatty acid moieties. These results, combined with the previous characterization of macrophage monosialogangliosides, indicate normal murine macrophage ganglioside biosynthesis proceeds along the "a" ganglioside pathway, e.g., GM3-->GM2-->GM1a-->GD1a, and the proposed asialoganglioside or "alpha" pathway, asialoGM1-->GM1b-->GD1alpha. The presence of totally sialidase-sensitive gangliosides appears to be characteristic of functional murine peritoneal macrophages while they are reduced in genetically impaired cells.
唾液糖鞘脂（神经节苷脂）越来越多地被认为是膜信号事件的调节因子。当小鼠腹腔巨噬细胞在体内受到刺激时，其神经节苷脂模式的复杂性会显著增加，唾液酸酶敏感的单唾液酸神经节苷脂GM1b（顺式GM1）作为主要成分出现。将受刺激的小鼠腹腔巨噬细胞中的神经节苷脂分离为单唾液酸和多唾液酸部分，并通过酶促、化学和质谱方法对多唾液酸部分进行结构表征。确定多唾液酸部分的所有可检测成分均为双唾液酸神经节苷脂。用产气荚膜梭菌唾液酸酶处理多唾液酸部分，主要产生唾液酸酶抗性单唾液酸神经节苷脂GM1a和少量脱唾液酸GM1。高碘酸盐氧化和质谱分析表明缺乏串联双唾液酸部分，这表明不存在GD1b或GD1c（GD1）实体。综合数据表明，主要的双唾液酸神经节苷脂由包含IV3-NeuAc、II3NeuAc-GgOse4Cer、IV3-NeuGc、II3NeuAc-GgOse4Cer、IV3NeuAc、II3NeuGc-GgOse4Cer和IV3-NeuGc、II3NeuGc-GgOse4Cer的GD1a实体组成。次要成分由GD1α实体、IV3NeuAc、III6NeuAcGgOse4Cer、IV3NeuGc、III6NeuGc-GgOse4Cer以及GD1α（NeuAc，NeuGc）的位置异构体组成。这些异构体成分通过碰撞分析和串联质谱鉴定。与先前的分析一致，所有多唾液酸（双唾液酸）神经节苷脂的神经酰胺部分仅含有带有C16和C24脂肪酸部分的C18鞘氨醇。这些结果与先前对巨噬细胞单唾液酸神经节苷脂的表征相结合，表明正常小鼠巨噬细胞神经节苷脂生物合成沿着“a”神经节苷脂途径进行，例如GM3→GM2→GM1a→GD1a，以及提议的脱唾液酸神经节苷脂或“α”途径，脱唾液酸GM1→GM1b→GD1α。完全对唾液酸酶敏感的神经节苷脂的存在似乎是功能性小鼠腹腔巨噬细胞的特征，而在基因受损的细胞中它们会减少。
