Ceramide enables Fas to cap and kill
Ceramide enables Fas to cap and kill
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DOI：
10.1074/jbc.m101866200
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发表时间：
2001-06-29
影响因子：
4.8
通讯作者：
Kolesnick, R
中科院分区：
文献类型：
--
作者：
Cremesti, A;Paris, F;Kolesnick, R
最近的研究表明，Fas的三聚化不足以诱导细胞凋亡，三聚化Fas的超聚集可能是诱导细胞凋亡的先决条件。对于许多细胞表面受体来说，通过多价配体或抗体的交联可诱导它们在质膜内的横向分离，并在细胞的一端共定位为“帽”。在这项研究中，我们证明了Fas的封盖对于最佳功能是必不可少的，并且封盖是神经酰胺依赖的。在Jurkat T淋巴细胞和肝细胞原代培养中，CH-11和Jo2抗fas抗体分别在15-30 s和1 min时检测到神经酰胺升高，并在1 min达到峰值。两种细胞类型在Fas结扎后30 s检测到Capping，在2 min达到峰值，并维持在较低水平长达30 min，神经酰胺的产生对Capping至关重要。酸性鞘磷脂酶（-/-）肝细胞在jo2诱导的神经酰胺生成、覆盖和凋亡中存在缺陷，而纳米摩尔浓度的c -16神经酰胺可以恢复这些事件。为了进一步探索神经酰胺在Fas capping中的作用，我们使用了flag标记的可溶性Fas配体（sFasL），它与三聚体Fas结合，但不能诱导Jurkat细胞的capping或凋亡，sFasL与M2抗flag抗体交联可诱导这两种事件。用天然c -16神经酰胺预处理细胞绕过了强制抗体交联的必要性，使sFasL能够帽化和杀伤。完整的鞘脂富集膜结构域的存在可能是Fas封盖所必需的，因为它们被胆固醇消耗剂破坏，取消了封盖并阻止了细胞凋亡。这些数据表明，在一些细胞中，封盖是一种神经酰胺依赖事件，需要最佳的Fas信号传导。
Recent studies suggest that trimerization of Fas is insufficient for apoptosis induction and indicate that super-aggregation of trimerized Fas might be prerequisite. For many cell surface receptors, cross-linking by multivalent ligands or antibodies induces their lateral segregation within the plasma membrane and co-localization into "caps" on one pole of the cell. In this study, we show that capping of Fas is essential for optimal function and that capping is ceramide-dependent. in Jurkat T lymphocytes and in primary cultures of hepatocytes, ceramide elevation was detected as early as 15-30 s and peaked at 1 min after CH-11 and Jo2 anti-Fas antibody treatment, respectively. Capping was detected 30 s after Fas ligation, peaked at 2 min, and was maintained at a lower level for as long as 30 min in both cell types, Ceramide generation appeared essential for capping. Acid sphingomyelinase(-/-) hepatocytes were defective in Jo2-induced ceramide generation, capping, and apoptosis, and nanomolar concentrations of C-16-ceramide restored these events. To further explore the role of ceramide in capping of Fas, we employed FLAG-tagged soluble Fas ligand (sFasL), which binds trimerized Fas but is unable to induce capping or apoptosis in Jurkat cells, Cross-linking of sFasL with M2 anti-FLAG antibody induced both events. Pretreatment of cells with natural C-16-ceramide bypassed the necessity for forced antibody cross-linking and enabled sFasL to cap and kill. The presence of intact sphingolipid-enriched membrane domains may be essential for Fas capping since their disruption with cholesterol-depleting agents abrogated capping and prevented apoptosis, These data suggest, that capping is a ceramide-dependent event required for optimal Fas signaling in some cells.