Endosomes and lysosomes play distinct roles in sulfatide-induced neuroblastoma apoptosis: potential mechanisms contributing to abnormal sulfatide metabolism in related neuronal diseases.
Endosomes and lysosomes play distinct roles in sulfatide-induced neuroblastoma apoptosis: potential mechanisms contributing to abnormal sulfatide metabolism in related neuronal diseases.
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内体和溶酶体在硫苷脂诱导的神经母细胞瘤细胞凋亡中发挥着不同的作用：导致相关神经元疾病中硫苷脂代谢异常的潜在机制。
DOI：
10.1042/bj20070976
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
Han,Xianlin
中科院分区：
文献类型：
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作者：
Zeng,Youchun;Cheng,Hua;Jiang,Xuntian;Han,Xianlin
脑硫脂代谢、运输和稳态的改变出现在阿尔茨海默氏病的最早临床可识别阶段，并且与异染性脑白质营养不良相关。然而，硫苷脂在这些疾病状态中的作用仍然未知。在本研究中，我们研究了补充硫苷脂后NB（神经母细胞瘤）细胞的后遗症以及导致硫苷脂诱导变化的生化机制。通过使用鸟枪脂质组学，我们发现硫苷脂、神经酰胺和鞘氨醇在 NB 细胞中以时间和剂量依赖性方式急剧积累。利用亚细胞分级分离和鸟枪脂质组学分析的进一步研究表明，大部分增加的神经酰胺含量是在内体隔室中产生的，而硫苷脂主要在溶酶体中积累。此外，我们确定硫苷脂介导的内体神经酰胺含量增加主要是由于β-半乳糖苷酶活性，其直接将硫苷脂水解为神经酰胺，而无需事先脱硫步骤。线粒体膜去极化、磷脂酰丝氨酸易位和 TUNEL（末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记）测定表明，大量细胞凋亡与硫苷脂和神经酰胺的积累同时发生。这些发现也在原代神经元培养中得到了证实。总的来说，我们的结果表明，由于内体介导的神经酰胺生成和溶酶体中硫苷脂细胞毒性水平的积累，异常的硫苷脂代谢可诱导细胞凋亡。
Alterations in sulfatide metabolism, trafficking and homoeostasis are present at the earliest clinically recognizable stages of Alzheimer's disease and are associated with metachromatic leukodystrophy. However, the role of sulfatide in these disease states remains unknown. In the present study, we investigated the sequelae of NB (neuroblastoma) cells upon sulfatide supplementation and the biochemical mechanisms contributing to the sulfatide-induced changes. By using shotgun lipidomics, we showed dramatic accumulations of sulfatide, ceramide and sphingosine in NB cells in a time- and dose-dependent manner. Further studies utilizing subcellular fractionation and shotgun lipidomics analyses demonstrated that most of the increased ceramide content was generated in the endosomal compartment, whereas sulfatides predominantly accumulated in lysosomes. In addition, we determined that the sulfatide-mediated increase in endosomal ceramide content mainly resulted from β-galactosidase activity, which directly hydrolyses sulfatide to ceramide without a prior desulfation step. Substantial cell apoptosis occurred in parallel with the accumulation of sulfatides and ceramides, as revealed by mitochondrial membrane depolarization, by phosphatidylserine translocation and by the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling) assay. These findings were also demonstrated with primary neuron cultures. Collectively, our results demonstrate that abnormal sulfatide metabolism can induce cell apoptosis due to endosome-mediated ceramide generation and the accumulation of cytotoxic levels of sulfatides in lysosomes.