Capano Michela, Virji Sukaina, Crompton Martin
Department of Biochemistry and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
Biochem J. 2002 Apr 1;363(Pt 1):29-36. doi: 10.1042/bj3630029.
Glutamate and the NO donor, nitroprusside, synergistically induced the death of B50 cells from a rat CNS-derived neuroblastoma cell line. With low [nitroprusside] (10 microM) both nitroprusside and glutamate were required. Under these conditions, nuclei became pyknotic and caspases were activated. The activities of caspase-3 and caspase-6 (effector caspases) were higher than those of caspase-8 and caspase-9 (initiator caspases). The activation of all four caspases was inhibited by cyclosporin A, with the order of susceptibility caspase-8=caspase-9=caspase-6>caspase-3. To identify the possible locus of cyclosporin A action, we used an antisense oligodeoxynucleotide to suppress the level of cyclophilin-A to<5% of its control value. Cyclophilin-A suppression largely reproduced the inhibitory effects of cyclosporin A. These results provide the first indication that cyclophilin-A participates in the activation of the caspase cascade in neuronal cells, in particular in the form of cascade elicited by excitotoxic stimuli. It is concluded that neuroprotection by cyclosporin A against excitotoxin-induced apoptosis is, at least partly, due to inhibition of cyclophilin-A.
谷氨酸和一氧化氮供体硝普钠协同诱导大鼠中枢神经系统来源的神经母细胞瘤细胞系B50细胞死亡。在低浓度[硝普钠]（10微摩尔）时，硝普钠和谷氨酸都不可或缺。在此条件下，细胞核固缩，半胱天冬酶被激活。半胱天冬酶-3和半胱天冬酶-6（效应半胱天冬酶）的活性高于半胱天冬酶-8和半胱天冬酶-9（起始半胱天冬酶）。环孢素A抑制了所有这四种半胱天冬酶的激活，其敏感顺序为半胱天冬酶-8 = 半胱天冬酶-9 = 半胱天冬酶-6>半胱天冬酶-3。为了确定环孢素A作用的可能位点，我们使用反义寡脱氧核苷酸将亲环蛋白A的水平抑制至其对照值的<5%。亲环蛋白A的抑制在很大程度上重现了环孢素A的抑制作用。这些结果首次表明亲环蛋白A参与神经元细胞中半胱天冬酶级联反应的激活，特别是由兴奋性毒性刺激引发的级联反应形式。得出的结论是，环孢素A对兴奋性毒素诱导的细胞凋亡的神经保护作用至少部分归因于对亲环蛋白A的抑制。
