Uncommon membrane distribution of Shiga toxin glycosphingolipid receptors in toxin-sensitive human glomerular microvascular endothelial cells
Uncommon membrane distribution of Shiga toxin glycosphingolipid receptors in toxin-sensitive human glomerular microvascular endothelial cells
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DOI：
10.1515/hsz-2011-0288
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发表时间：
2012-03-01
影响因子：
3.7
通讯作者：
Muething, Johannes
中科院分区：
文献类型：
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作者：
Betz, Josefine;Bauwens, Andreas;Muething, Johannes
鞘糖脂（GSL）神经酰胺三己糖基（Gb 3 Cer）和神经酰胺四己糖基（Gb 4 Cer）的膜微区结合，分别是滋贺毒素（Stx）的高效和低效受体，被认为是Stx介导的细胞毒性的功能要求。在以前的研究中，我们证明了主要的本地化的Stx受体的胆固醇富集膜微区的中度Stx敏感的人脑微血管内皮细胞（HBMEC）的耐洗涤剂膜（DRM）的装置。在这里，我们报告了一个不同的优先分布的Stx受体在非DRM部分的人肾小球微血管内皮细胞（GMVECs），在人类肾脏的主要目标的Stx。使用电喷雾电离（ESI）质谱法对Stx受体进行的完整结构表征显示，GMVEC中的Gb 3Cer和Gb 4Cer脂质体具有主要由C24：0/C24：1或C16：0脂肪酸和鞘氨醇（d18：1）组成的神经酰胺部分，与先前在HBMEC中发现的那些相当。薄层层析免疫染色显示，GMVECs中Gb 3Cer的含量比HBMEC中高约2倍，Gb 4Cer的含量高约1.4倍。然而，这并不能解释与HBMEC相比Stx 1和Stx 2对GMVEC的显著更高的细胞毒性作用。我们的发现打开了新的问题，在GMVECs的膜组装的Stx受体的微区协会和GSL的功能作用。
Membrane microdomain association of the glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), the highly and less effective receptors, respectively, for Shiga toxins (Stxs), is assumed as a functional requirement for Stx-mediated cytotoxicity. In a previous study, we demonstrated predominant localization of Stx receptors in cholesterol-enriched membrane microdomains of moderately Stx-sensitive human brain microvascular endothelial cells (HBMECs) by means of detergent-resistant membranes (DRMs). Here we report a different preferential distribution of Stx receptors in non-DRM fractions of human glomerular microvascular endothelial cells (GMVECs), the major targets of Stxs in the human kidney. Full structural characterization of Stx receptors using electrospray ionization (ESI) mass spectrometry revealed Gb3Cer and Gb4Cer lipoforms with ceramide moieties mainly composed of C24:0/C24:1 or C16:0 fatty acid and sphingosine (d18:1) in GMVECs comparable to those previously found in HBMECs. Thin-layer chromatography immunostaining demonstrated an approximately 2-fold higher content of Gb3Cer and a 1.4-fold higher content of Gb4Cer in GMVECs than in HBMECs. However, this does not explain the remarkable higher cytotoxic action of Stx1 and Stx2 toward GMVECs as compared with HBMECs. Our finding opens new questions on the microdomain association of Stx receptors and the functional role of GSLs in the membrane assembly of GMVECs.