Apoptotic signaling through CD95 (Fas/Apo-1) activates an acidic sphingomyelinase.
Apoptotic signaling through CD95 (Fas/Apo-1) activates an acidic sphingomyelinase.
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DOI：
10.1084/jem.180.4.1547
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发表时间：
1994-10-01
期刊：
影响因子：
--
通讯作者：
Testi R
中科院分区：
文献类型：
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作者：
Cifone MG;De Maria R;Roncaioli P;Rippo MR;Azuma M;Lanier LL;Santoni A;Testi R
从膜受体结合到凋亡性细胞死亡的细胞内途径仍然缺乏特征。我们研究了CD 95（Fas/Apo-1抗原）交联后产生的细胞内信号传导，CD 95是一种广泛表达的细胞表面受体，其参与导致触发细胞凋亡程序。用转染人CD 95的L细胞免疫小鼠，制备了一种新的抗人CD 95单克隆抗体DX 2。CD 95与DX 2的交联导致早幼粒细胞U937细胞以及其他人肿瘤细胞系和CD 95转染的鼠细胞中鞘磷脂酶（SMase）的活化，如通过诱导体内鞘磷脂（SM）水解和神经酰胺生成所证明的。直接在体外测量的酶活性内CD 95刺激的U937细胞提取物，使用标记的SM囊泡作为底物，表现出较强的SMase活性，需要pH 5.0的最佳底物水解。最后，所有测试的CD 95敏感性细胞系在暴露于细胞渗透性C2-神经酰胺后可被诱导进行凋亡。这些数据表明，CD 95交联诱导SM的分解和神经酰胺的生产，通过酸性SMase，从而提供了第一个信息，从CD 95的早期信号产生，并可能是相关的，在定义的生化性质的细胞内信使，导致细胞凋亡性细胞死亡。
Intracellular pathways leading from membrane receptor engagement to apoptotic cell death are still poorly characterized. We investigated the intracellular signaling generated after cross-linking of CD95 (Fas/Apo-1 antigen), a broadly expressed cell surface receptor whose engagement results in triggering of cellular apoptotic programs. DX2, a new functional anti-CD95 monoclonal antibody was produced by immunizing mice with human CD95-transfected L cells. Crosslinking of CD95 with DX2 resulted in the activation of a sphingomyelinase (SMase) in promyelocytic U937 cells, as well as in other human tumor cell lines and in CD95-transfected murine cells, as demonstrated by induction of in vivo sphingomyelin (SM) hydrolysis and generation of ceramide. Direct in vitro measurement of enzymatic activity within CD95- stimulated U937 cell extracts, using labeled SM vesicles as substrates, showed strong SMase activity, which required pH 5.0 for optimal substrate hydrolysis. Finally, all CD95-sensitive cell lines tested could be induced to undergo apoptosis after exposure to cell-permeant C2-ceramide. These data indicate that CD95 cross-linking induces SM breakdown and ceramide production through an acidic SMase, thus providing the first information regarding early signal generation from CD95, and may be relevant in defining the biochemical nature of intracellular messengers leading to apoptotic cell death.