Stefanis L, Troy C M, Qi H, Shelanski M L, Greene L A
Department of Pathology, Taub Center for Alzheimer's Disease Research and Center for Neurobiology and Behavior, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
J Neurosci. 1998 Nov 15;18(22):9204-15. doi: 10.1523/JNEUROSCI.18-22-09204.1998.
We have previously shown that caspase-2 (Nedd-2) is required for apoptosis induced by withdrawal of trophic support from PC12 cells and sympathetic neurons. Here, we examine the relationship of caspase-2 processing and cell death to induction of caspase-3 (CPP32)-like activity in PC12 cells. Caspase-2 processing, at a site tentatively identified as D333, led to the formation of an N-terminal 37 kDa product. This processing correlated temporally with induction of caspase-3-like activity. Agents previously shown to inhibit caspase-3-like activation, such as bcl-2 and the Cdk inhibitor flavopiridol, also acted upstream of caspase-2 processing. The general caspase inhibitors BAF and zVAD-FMK inhibited N-terminal caspase-2 processing. In contrast, the more selective caspase inhibitor DEVD-FMK inhibited the induction of caspase-3-like activity but did not affect caspase-2 processing or significantly suppress death in PC12 cells or sympathetic neurons. This indicates that caspase-3-like activity is not required for either caspase-2 processing or apoptosis in this paradigm. An antisense oligonucleotide to caspase-2 inhibited cell death but did not affect caspase-3-like activity, indicating that caspase-2 is not upstream of this activity and that activation of caspase-3-like caspases is not sufficient for death. Thus, in our paradigm, caspase-2 processing and caspase-3-like activity are induced independently of each other. Moreover, although death requires caspase-2, caspase-3-like activity is neither necessary nor sufficient for death.
我们之前已经表明，半胱天冬酶-2（Nedd-2）是PC12细胞和交感神经元因营养支持撤除所诱导的细胞凋亡所必需的。在此，我们研究半胱天冬酶-2的加工过程及细胞死亡与PC12细胞中半胱天冬酶-3（CPP32）样活性诱导之间的关系。半胱天冬酶-2在一个初步确定为D333的位点进行加工，导致形成一个N端37 kDa的产物。这种加工过程在时间上与半胱天冬酶-3样活性的诱导相关。先前显示可抑制半胱天冬酶-3样激活的因子，如bcl-2和细胞周期蛋白依赖性激酶抑制剂黄酮哌啶醇，也作用于半胱天冬酶-2加工的上游。通用的半胱天冬酶抑制剂BAF和zVAD-FMK抑制N端半胱天冬酶-2的加工。相反，更具选择性的半胱天冬酶抑制剂DEVD-FMK抑制半胱天冬酶-3样活性的诱导，但不影响半胱天冬酶-2的加工，也不能显著抑制PC12细胞或交感神经元的死亡。这表明在这种模式下，半胱天冬酶-3样活性对于半胱天冬酶-2的加工或细胞凋亡都不是必需的。针对半胱天冬酶-2的反义寡核苷酸抑制细胞死亡，但不影响半胱天冬酶-3样活性，这表明半胱天冬酶-2不在该活性的上游，且半胱天冬酶-3样半胱天冬酶的激活不足以导致细胞死亡。因此，在我们的模式中，半胱天冬酶-2的加工和半胱天冬酶-3样活性是相互独立诱导的。此外，虽然细胞死亡需要半胱天冬酶-2，但半胱天冬酶-3样活性对于细胞死亡既非必要条件也非充分条件。
