Roles of sphingolipids and glycosphingolipids in neurite extension, adhesion and growth of neuronal cells.

(1)糖基神经酰胺合成酶抑制剂PDMP （1-phenyl-2-decanoylamino-3morpholino-1-propanol）影响小鼠神经母细胞瘤NS-20Y细胞的细胞周期进展：S期细胞比例减少，GO/G1期细胞比例显著增加。添加NS-20Y细胞的主要鞘糖脂、乳糖神经酰胺、球四糖神经酰胺、GM1或GD1a后，细胞生长均未恢复。GM1本身表现出对细胞周期进程的抑制作用。流式细胞术分析显示，NS-20Y细胞在细胞周期进程中，GM1在细胞表面的表达没有变化。(2) PDMP、n -丁基脱氧半乳糖吉里霉素、福马菌素b1、l -环丝氨酸和β -氯- l -丙氨酸抑制鞘脂的生物合成和循环途径，并研究其对细胞生长和GM1表达的影响。在NS20Y细胞中，糖鞘脂主要由鞘氨醇和鞘氨脂合成，鞘脂水解产生更多的糖鞘脂；（ii）鞘氨氨酸的新生生物合成部分用于鞘脂糖的合成；（iii）部分天然或部分水解的GM1通过高尔基体从内体途径再循环。(3)在小鼠神经母细胞瘤细胞系和大鼠PC12细胞中检测细胞表面糖缀合物与一系列凝集素的反应性。LFuc特异性凝集素只与每个细胞的一小部分发生反应。大多数Gal GalNAc特异性凝集素和Man Glc特异性凝集素在不同强度下反应良好。Maackia amurensis （MAM）凝集素与小鼠神经母细胞瘤细胞（NS-20Y, Neuro2a, NIE-115）和大鼠PC12细胞反应良好，表明存在Sia α2-3Gal糖链。(4) MAM凝集素浓度在1μ g/ml以上时，能强烈抑制NS-20Y神经母细胞瘤细胞的神经突生长，细胞形态发生特征性变化。其他不同特异性结合NS-20Y细胞的凝集素没有表现出这些作用。MAMlectins与细胞表面唾液酸结合导致神经突延伸抑制和形态改变的机制非常有趣。少

( 1 ) An inhibitor of glucosylceramide synthase, PDMP ( 1-phenyl-2-decanoylamino-3morpholino-1-propanol ), affected the cell cycle progression of murine neuroblastoma NS-20Y cells: the proportion of cells in the S phase was reduced, and that in the GO/G1 phase significantly increased. The recovery of cell growth was not found after the addition of major glycosphingolipids of NS-20Y cells, lactosylceramide, globotetraosylceramide, GM1, or GD1a. GM1 itself showed an inhibition of cell cycle progression. A flow cytometric analysis showed that the expression of GM1 on the cell surface did not change during the cell cycle progression of NS-20Y cells.( 2 ) Pathways for the biosynthesis and recycling of sphingolipids were inhibited by PDMP, N-butyldeoxygalactonojirimycin, fumonisin B l , L-cycloserine, or β -chloro-L-alanine and the effects on cell growth and GM1 expression were investigated. In NS20Y cells, ( i ) glycoshingolipids were synthesized predominantly from sphingosine and sphingani … More ne produced by hydrolysis of sphingolipids; ( ii ) de novo biosynthesis of sphinganine was used for a part of glycosphingolipid synthesis; and ( iii ) a part of native or partially hydrolyzed GM1 was recycled from the endosomal pathway through the Golgi apparatus.( 3 ) The cell surface glycoconjugates were examined for their reactivity with a series of lectins in mouse neuroblastoma cell lines and rat PC12 cell. Lectins specific for LFuc reacted only with a minor population of each cells. Most of the lectins specific for Gal GalNAc and those specific for Man Glc GlcNAc reacted well with varying intensities. Maackia amurensis ( MAM ) lectin reacted well with mouse neuroblastoma cells ( NS-20Y, Neuro2a, NIE-115 ) and rat PC12 cell, indicating the presence of Sia α2-3Gal sugar chains.( 4 ) Neurite outgrowth in tnurine neuroblastoma NS-20Y cells induced by serum deprivation was strongly inhibited by MAM lectin at the concentration above 1μ g/ml, and a characteristic change in cell morphology Was observed. Other lectins which bound to NS-20Y cells with different specificities did not show these effects. The mechanisms by which the binding of MAMlectins to cell surface sialic acids caused the inhibition of neurite extension and the morphology change are very intriguing. Less