The regulation of expression and function of glycoshingolipids on cell surfaces with an inhibitor of glucosylceramide synthesis.

1-Phenyl-2-decanoylamino-3-morpholino-1-propanol是一种有效的UDP-葡萄糖：神经酰胺葡萄糖基转移酶抑制剂，可抑制小鼠神经母细胞瘤细胞系的生长。在NS-20Y、Neuro2a和N1E-115细胞中，用[14C]半乳糖标记的神经节苷脂和中性神经鞘糖脂的代谢标记结果显示，当有苏氨酸-PDMP存在时，神经节苷脂和中性神经鞘糖脂的放射性掺入减少。用苏氨酸-PDMP处理NS-20Y细胞后，神经节苷脂和中性鞘糖脂的质量水平呈时间依赖性下降。在50muM苏氨酸-PDMP作用24小时后，中性鞘糖脂质量下降到32%，其中葡萄糖神经酰胺受到的影响最大(下降90%)。神经节苷脂质量减少到原始含量的57%。苏氨酸-PDMP可明显抑制神经母细胞瘤细胞在无血清条件下突起生长，并呈剂量依赖性。Threo-PDMP还可使在无血清培养中诱导的突起回缩。GM1可部分恢复NS-20Y细胞在含苏氨酸-PDMP的培养液中突起生长的能力。这些结果提示神经鞘糖脂可能在小鼠神经母细胞瘤细胞的轴突生长中起作用。经苏氨酸处理后，NS-20Y细胞中神经酰胺、鞘磷脂和鞘氨醇均有积聚。外源性鞘氨醇抑制轴突生长，引起轴突回缩。N，N-二甲基鞘氨醇(在-0.1um时抑制50%)、鞘氨醇(-0.8um)、N-己酰-鞘氨醇(-1um)和N-乙基鞘氨醇(-10um)可抑制NS-20Y细胞突起的生长。蛋白激酶抑制剂H-7不影响神经突起的生长，提示这些鞘磷脂的抑制作用不依赖于蛋白激酶C。

1-Phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), an effective inhibitor of UDP-glucose:ceramide glucosyltransferase, caused inhibition of cell growth in murine neuroblastoma cell lines. Metabolic labeling of glycosphingolipids with [14C]galactose in NS-20Y, Neuro2a, and N1E-115 cells showed reduced incorporation of radioactivity into gangliosides and neutral glycosphingolipids when threo-PDMP was present in the medium. Treatment of NS-20Y cells with threo-PDMP resulted in a time-dependent decrease in mass levels of gangliosides and neutral glycosphingolipids. After 24h in the presence of 50muM threo-PDMP, neutral glycosphingolipid mass was reduced to 32%, where glucosylceramide was the most affected (90% decrease). The ganglioside mass was reduced to 57% of the original content. Neurite outgrowth from neuroblastoma cells in serum-free medium was significantly inhibited by threo-PDMP in a dose-dependent manner. Threo-PDMP also caused retraction of neurites which had been induced to extend in serum-free medium. Pretreatment of cells with GM1 partially restored the ability of NS-20Y cells for neurite outgrowth in the medium containing threo-PDMP. These results suggest a possible role for glycosphingolilids in neurite outgrowth of murine neuroblastoma cells. Ceramide, sphingomyelin and sphingo-sine were found to accumulate in NS-20Y cells after treatment with threo-PDMP. Exogenous sphingosine inhibited neurite outgrowth and caused retraction of neurites. Neurite outgrowth from NS-20Y cells was inhibited by N,N-dimethyl-sphingosine (50% inhibition at -0.1 muM), sphingosine(-0.8 muM),N-hexanoyl-sphingosine (-1 muM), and N-acethylsphingosine(-10muM). A protein kinase inhibitor, H-7, did not affect the neurite outgrowth, suggesting the inhibitory effect of these sphingolipids is protein kinase C-independent.