Molecular mechanisms involved in non-apoptotic programmed cell death regulation

我们使用Ras依赖的非凋亡程序性细胞死亡的体外模型系统，并解剖参与Ras诱导的非凋亡程序性细胞死亡的调节的分子机制。一般来说，半胱天冬酶非依赖性，非凋亡的程序性细胞死亡是已知的，是依赖于线粒体。因此，我们检查了线粒体是否参与Ras诱导的非凋亡的程序性细胞死亡。我们没有发现Ras诱导的细胞死亡过程中线粒体膜通透性增加的证据，Ras诱导的细胞死亡既不被Bcl-xL也不被vMIA抑制，这是已知的线粒体细胞死亡的有效抑制剂。这些结果表明，Ras诱导的细胞死亡属于一种新的类型的非凋亡的程序性细胞死亡，从来没有报道。利用Ras效应环突变体对Ras激活的细胞内信号通路进行了剖析，揭示了P13 K通路在死亡信号的转导中起着关键作用。筛选抑制或促进Ras诱导的细胞死亡的药理学试剂鉴定艰难梭菌毒素B为Ras诱导的细胞死亡的有效抑制剂，表明Rho蛋白家族可能在Ras诱导的细胞死亡的调节中起重要作用。使用显性负突变体的Rho家族蛋白揭示，Rac等可能有一个关键的作用，Ras诱导的非凋亡程序性细胞死亡。

We used the in vitro model system for Ras-dependent non-apoptotic programmed cell death and dissected the molecular mechanism involved in the regulation of Ras-induced non-apoptotic programmed cell death. In general, caspase-independent, non-apoptotic programmed cell deaths are known to be mitochondria-dependent We therefore examined whether mitochondria is involved in Ras-induced non-apoptotic programmed cell death. We found no evidence of increased permeability of mitochondrial membrane during Ras-induced cell death, and Ras-induced cell death was inhibited neither by Bcl-xL nor by vMIA, which are known to be potent inhitibors of mitochondrial cell death. These results indicated that Ras-induced cell death belongs to a novel type of non-apoptotic programmed cell death that has never been reported. Dissection of the intracellular signaling pathway activated by Ras using Ras effector loop mutant revealed that the Pl3K pathway plays a critical role in the transduction of the death signal. Screening of pharmacological agents that inhibit or promote Ras-induced cell death identified Toxin B of Clostridium difficile as a potent inhibitor of Ras-induced cell death, suggesting that the Rho family of proteins may play an important role in the regulation of Ras-induced cell death. Use of dominant-negative mutants of the Rho family proteins revealed that Rac among others may have a key role in Ras-induced non-apoptotic programmed cell death.