Signal transduction for apoptosis induction using apoptosis-inducing immunosuppressant

在我们以前的研究中，发现鞘氨醇样免疫抑制剂ISP-1通过抑制丝氨酸棕榈酰转移酶（其催化鞘脂生物合成的关键步骤）来抑制白细胞介素-2依赖性细胞毒性T细胞系CTLL-2的增殖。ISP-1诱导的生长抑制可被鞘氨醇拮抗。代替鞘氨醇，植物鞘氨醇在酿酒酵母中通过与哺乳动物细胞类似的途径合成。在这项研究中，观察到ISP-1对酿酒酵母增殖的抑制作用，并通过添加植物鞘氨醇消除。此外，通过流式细胞术在ISP-1处理的酵母细胞中检测到DNA的过度复制。我们已经确定了酿酒酵母基因，SLI 2，抵抗ISP-1的生长抑制。蛋白激酶催化结构域位于Sli 2 p的羧基末端部分。SLI 2的激酶死亡突变体没有对ISP-1产生任何抗性，这使我们预测Sli 2 p的激酶活性对于其抵抗ISP-1的功能是必不可少的。Sli 2 p过表达对丝氨酸棕榈酰转移酶活性和鞘脂代谢没有影响。这些结果表明，Sli 2 p可能在拯救ISP-1诱导的酵母鞘脂减少中发挥重要作用。

In our previous study, the sphingosine-like immunosuppressant, ISP-1, was found to suppress proliferation of an interleukin-2-depentent cytotoxic T cell line, CTLL-2, through the inhibition of serine palmitoyltransferase, which catalyzes the committed step of sphingolipid biosynthesis. The growth inhibition induced by ISP-1 was antagonized by the addition of sphingosine. Instead of sphingosine, phytosphingsine is synthesized in the Saccharomyces cerevisiae by the similar pathway of mammalian cells, In this study, the inhibition of proliferation by ISP-1 was observed with Saccharomyces cerevisiae, and was abolished by addition of phytosphingsine. In addition, overreplication of DNA was detected in the ISP-1 treated yeast cells by flow cytometry. And we have identified a Saccharomyces cerevisiae gene, SLI2, that resisted the growth inhibition of ISP-1. The protein kinase catalytic domain is located at the carboxy-terminal portion of Sli2p. Kinase-dead mutants of SLI2 did not give any resistance to ISP-1, leading us to predict that kinase activity of Sli2p should be essential for its function in resisting ISP-1. Sli2p overexpression had no effect on serine palmitoyltransferase activity and sphingolipids metabolism. These results indicated that Sli2p may play an important role in rescuing yeast from decrease of sphingolipids induced by ISP-1.