Differentiation-dependent sensitivity to apoptogenic factors in PC12 cells
Differentiation-dependent sensitivity to apoptogenic factors in PC12 cells
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DOI：
10.1074/jbc.m400692200
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发表时间：
2004-07-23
影响因子：
4.8
通讯作者：
Evan, G
中科院分区：
文献类型：
--
作者：
Vyas, S;Juin, P;Evan, G
在未分化或NGF/BT(2)cAMP分化的PC12细胞中，我们分别研究了血清和神经生长因子(NGF)/二丁酰环腺苷(BT(2)cAMP)停用后线粒体途径在细胞死亡中的作用。在PC12细胞中，全细胞色素c、Smac/Diablo和Omi/HtrA2在营养因子剥夺后迅速释放。BCL-2和Akt抑制这种释放。然而，这种保护在分化的PC12细胞中持续的时间更长。在分化的细胞中，但不是未分化的细胞中，Bcl2和Akt也抑制了全细胞色素c释放的下游的细胞凋亡。因此，即使在NGF、Bcl2或Akt存在的情况下，未分化的PC12细胞对显微注射细胞色素c诱导的细胞凋亡也表现出显著的敏感性。相反，在分化的细胞中，这些因素抑制了细胞死亡。与这些观察一致的是，在表达Akt或Bcl2的未分化但未分化的细胞提取液中观察到细胞色素c对原天冬氨酸氨基转移酶9的反应。内源性caspase 9在细胞死亡过程中被切割，而显性阴性caspase 9则抑制细胞死亡。确定凋亡抑制物(IAPs)作用的结果表明，IAPs获得抑制是分化程序的一部分。泛素-Deltan-AVPI Smac/Diablo仅诱导分化细胞死亡。C-IAP-2在分化的细胞中不受调控，而X-连锁的IAP水平在这些细胞中下降，与细胞死亡一致。此外，表达X-连锁IAP使未分化的细胞对显微注射细胞色素c产生抵抗。总体而言，在分化的PC12细胞中，在线粒体凋亡因子释放水平和线粒体后激活caspase 9观察到的细胞死亡的抑制调节在未分化的PC12细胞中减少或不存在。
We have investigated the role of the mitochondrial pathway during cell death following serum and nerve growth factor (NGF)/dibutyryl cyclic AMP (Bt(2)cAMP) withdrawal in undifferentiated or NGF/Bt(2)cAMP-differentiated PC12 cells, respectively. Holocytochrome c, Smac/DIABLO, and Omi/ HtrA2 are released rapidly following trophic factor deprivation in PC12 cells. Bcl-2 and Akt inhibited this release. The protection, however, persisted longer in differentiated PC12 cells. In differentiated, but not undifferentiated cells, Bcl-2 and Akt also inhibited apoptosis downstream of holocytochrome c release. Thus, undifferentiated PC12 cells showed marked sensitivity to induction of apoptosis by microinjected cytochrome c even in the presence of NGF, Bcl-2, or Akt. In contrast, in differentiated cells these factors suppressed cell death. Consistent with these observations, in vitro processing of procaspase 9 in response to cytochrome c was observed in extracts from undifferentiated but not differentiated cells expressing Akt or Bcl-2. Endogenous caspase 9 was cleaved during cell death, whereas dominant negative caspase 9 inhibited cell death. The results from determining the role of inhibitors of apoptosis (IAPs) suggest that acquisition of inhibition by IAPs is part of the differentiation program. Ubiquitin-DeltaN-AVPI Smac/DIABLO induced cell death in differentiated cells only. c-IAP-2 is unregulated in differentiated cells, whereas X-linked IAP levels decreased in these cells coincident with cell death. Moreover, expressing X-linked IAP rendered undifferentiated cells resistant to microinjected cytochrome c. Overall, the inhibitory regulation, of cell death at the level of release of mitochondrial apoptogenic factors and at post-mitochondrial activation of caspase 9 observed in differentiated PC12 cells, is reduced or absent in the undifferentiated counterparts.