Paris F, Grassmé H, Cremesti A, Zager J, Fong Y, Haimovitz-Friedman A, Fuks Z, Gulbins E, Kolesnick R
Laboratory of Signal Transduction, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
J Biol Chem. 2001 Mar 16;276(11):8297-305. doi: 10.1074/jbc.M008732200. Epub 2000 Nov 28.
The role of the second messenger ceramide in Fas-mediated death requires clarification. To address this issue, we generated hepatocytes from paired acid sphingomyelinase (ASMase; asmase)(+/+) and asmase(-/-) mice. asmase(-/-) hepatocytes, derived from 8-week-old mice, manifested normal sphingomyelin content and normal morphological, biochemical, and biologic features. Nonetheless, ASMase-deficient hepatocytes did not display rapid ceramide elevation or apoptosis in response to Jo2 anti-Fas antibody. asmase(-/-) hepatocytes were not inherently resistant to apoptosis because staurosporine, which did not induce early ceramide elevation, stimulated a normal apoptotic response. The addition of low nanomolar quantities of natural C16-ceramide, which by itself did not induce apoptosis, completely restored the apoptotic response to anti-Fas in asmase(-/-) hepatocytes. Other sphingolipids did not replace natural ceramide and restore Fas sensitivity. Overcoming resistance to Fas in asmase(-/-) hepatocytes by natural ceramide is evidence that it is the lack of ceramide and not ASMase which determines the apoptotic phenotype. The ability of natural ceramide to rescue the phenotype without reversing the genotype provides evidence that ceramide is obligate for Fas induction of apoptosis in hepatocytes.
第二信使神经酰胺在Fas介导的细胞死亡中的作用尚需阐明。为解决这一问题，我们从配对的酸性鞘磷脂酶（ASMase；asmase）（+/+）和asmase（-/-）小鼠中生成了肝细胞。源自8周龄小鼠的asmase（-/-）肝细胞表现出正常的鞘磷脂含量以及正常的形态、生化和生物学特征。尽管如此，ASMase缺陷型肝细胞在响应Jo2抗Fas抗体时并未表现出神经酰胺的快速升高或凋亡。asmase（-/-）肝细胞并非天生对凋亡具有抗性，因为本身不会诱导早期神经酰胺升高的星形孢菌素能刺激正常的凋亡反应。添加低纳摩尔量的天然C16-神经酰胺（其本身不会诱导凋亡）可完全恢复asmase（-/-）肝细胞对抗Fas的凋亡反应。其他鞘脂不能替代天然神经酰胺并恢复Fas敏感性。天然神经酰胺克服asmase（-/-）肝细胞对Fas的抗性这一事实证明，决定凋亡表型的是神经酰胺的缺乏而非ASMase。天然神经酰胺在不改变基因型的情况下挽救表型的能力证明，神经酰胺是Fas诱导肝细胞凋亡所必需的。
