Yamaji T, Nakamura S, Takematsu H, Kawasaki T, Kozutsumi Y
Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, and Laboratory of Membrane Biochemistry and Biophysics, Graduate School of Biostudies, Kyoto University, Kyoto 606-8501, Japan.
J Biochem. 2001 Apr;129(4):521-7. doi: 10.1093/oxfordjournals.jbchem.a002886.
In our previous study, the sphingosine-like immunosuppressant ISP-1 was shown to induce apoptosis in the mouse cytotoxic T cell line CTLL-2. In this study, we characterized the ISP-1-induced apoptotic pathway. Although caspase-3-like protease activity increases concomitantly with ISP-1-induced apoptosis in CTLL-2 cells, the apoptosis is not inhibited by caspase-3-like protease inhibitors, i.e. DEVD-cho and z-DEVD-fmk. In contrast, sphingosine-induced apoptosis in CTLL-2 cells is caspase-3-like protease-dependent. A caspase inhibitor with broad specificity, z-VAD-fmk, protects cells from apoptosis induced by ISP-1, indicating that ISP-1-induced apoptosis is dependent on caspase(s) other than caspase-3. Overexpression of Bcl-2 or Bcl-xL suppresses the apoptosis induced by ISP-1, although sphingosine-induced apoptosis is not efficiently inhibited by Bcl-2. Finally, ISP-1-induced mitochondrial depolarization, which is thought to be a checkpoint dividing the apoptotic pathway into upstream and downstream stages, is not inhibited by DEVD-cho, but is inhibited by z-VAD-fmk. These data suggest that a pathway dependent on caspase(s) other than caspase-3 is involved upstream of mitochondrial depolarization in ISP-1-induced apoptosis.
在我们之前的研究中，鞘氨醇样免疫抑制剂ISP-1被证明可诱导小鼠细胞毒性T细胞系CTLL-2凋亡。在本研究中，我们对ISP-1诱导的凋亡途径进行了表征。尽管在CTLL-2细胞中，类半胱天冬酶-3蛋白酶活性随ISP-1诱导的凋亡而同步增加，但该凋亡不受类半胱天冬酶-3蛋白酶抑制剂（即DEVD-cho和z-DEVD-fmk）的抑制。相反，鞘氨醇诱导的CTLL-2细胞凋亡是类半胱天冬酶-3蛋白酶依赖性的。具有广泛特异性的半胱天冬酶抑制剂z-VAD-fmk可保护细胞免受ISP-1诱导的凋亡，这表明ISP-1诱导的凋亡依赖于除半胱天冬酶-3之外的其他半胱天冬酶。Bcl-2或Bcl-xL的过表达可抑制ISP-1诱导的凋亡，尽管鞘氨醇诱导的凋亡不能被Bcl-2有效抑制。最后，ISP-1诱导的线粒体去极化被认为是将凋亡途径分为上游和下游阶段的一个检查点，它不受DEVD-cho的抑制，但受z-VAD-fmk的抑制。这些数据表明，在ISP-1诱导的凋亡中，线粒体去极化上游涉及一条依赖于除半胱天冬酶-3之外的其他半胱天冬酶的途径。
