Waterhouse N J, Sedelies K A, Sutton V R, Pinkoski M J, Thia K Y, Johnstone R, Bird P I, Green D R, Trapani J A
Cancer Cell Death, Peter MacCallum Cancer Centre, Locked Bag 1, A'Beckett Street, Melbourne, Victoria 8006, Australia.
Cell Death Differ. 2006 Apr;13(4):607-18. doi: 10.1038/sj.cdd.4401772.
Loss of Bid confers clonogenic survival to granzyme B-treated cells, however the exact role of Bid-induced mitochondrial damage--upstream or downstream of caspases--remains controversial. Here we show that direct cleavage of Bid by granzyme B, but not caspases, was required for granzyme B-induced apoptosis. Release of cytochrome c and SMAC, but not AIF or endonuclease G, occurred in the absence of caspase activity and correlated with the onset of apoptosis and loss of clonogenic potential. Loss of mitochondrial trans-membrane potential (DeltaPsim) was also caspase independent, however if caspase activity was blocked the mitochondria regenerated their DeltaPsim. Loss of DeltaPsim was not required for rapid granzyme B-induced apoptosis and regeneration of DeltaPsim following cytochrome c release did not confer clonogenic survival. This functional dissociation of cytochrome c and SMAC release from loss of DeltaPsim demonstrates the essential contribution of Bid upstream of caspase activation during granzyme B-induced apoptosis.
Bid缺失赋予颗粒酶B处理的细胞克隆形成存活能力，然而Bid诱导的线粒体损伤在半胱天冬酶上游还是下游的确切作用仍存在争议。我们在此表明，颗粒酶B诱导的凋亡需要颗粒酶B直接切割Bid，而非半胱天冬酶。在没有半胱天冬酶活性的情况下发生了细胞色素c和SMAC的释放，但AIF或核酸内切酶G未释放，且这与凋亡的开始及克隆形成潜能的丧失相关。线粒体跨膜电位（ΔΨm）的丧失也与半胱天冬酶无关，然而如果半胱天冬酶活性被阻断，线粒体可重新生成其ΔΨm。快速的颗粒酶B诱导的凋亡并不需要ΔΨm的丧失，且细胞色素c释放后ΔΨm的再生并未赋予克隆形成存活能力。细胞色素c和SMAC释放与ΔΨm丧失的这种功能解离表明，在颗粒酶B诱导的凋亡过程中，Bid在半胱天冬酶激活上游起重要作用。
