Cathepsin D triggers bax activation, resulting in selective apoptosis-inducing factor (AIF) relocation in T lymphocytes entering the early commitment phase to apoptosis
Cathepsin D triggers bax activation, resulting in selective apoptosis-inducing factor (AIF) relocation in T lymphocytes entering the early commitment phase to apoptosis
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DOI：
10.1074/jbc.m301911200
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发表时间：
2003-08-15
影响因子：
4.8
通讯作者：
Senik, A
中科院分区：
文献类型：
--
作者：
Bidère, N;Lorenzo, HK;Senik, A
活化的人 T 淋巴细胞暴露于针对线粒体的凋亡刺激（即十字孢菌素），进入早期、不依赖 caspase 的细胞凋亡阶段，其特征是细胞收缩和外周染色质浓缩。我们发现，在此阶段，AIF 选择性地从线粒体膜间隙释放，并且 Bax 以独立于 Bid 的方式经历构象变化、重新定位到线粒体并插入线粒体外膜。我们分析了组织蛋白酶 (Cat) B、D 和 L 的亚细胞分布，以寻找负责 Bax 激活和 AIF 释放的半胱天冬酶独立因子。所有这些都从溶酶体转移到胞质溶胶，与溶酶体的有限不稳定和以尺寸选择性方式释放溶酶体分子相关。然而，只有胃酶抑素 A 抑制 Cat D 活性才能抑制早期凋亡事件并延迟细胞死亡，即使存在巴弗洛霉素 A(1)（一种液泡型 H+-ATP 酶抑制剂，可抑制溶酶体酸化）也是如此。使用小干扰 RNA 介导的基因沉默来灭活 Cat D、Bax 和 AIF 基因表达。这使我们能够定义一个新的事件序列，其中 Cat D 触发 Bax 激活，Bax 诱导线粒体 AIF 的选择性释放，而后者负责早期凋亡表型。
Activated human T lymphocytes exposed to apoptotic stimuli targeting mitochondria (i.e. staurosporine), enter an early, caspase-independent phase of commitment to apoptosis characterized by cell shrinkage and peripheral chromatin condensation. We show that during this phase, AIF is selectively released from the intermembrane space of mitochondria, and that Bax undergo conformational change, relocation to mitochondria, and insertion into the outer mitochondrial membrane, in a Bid-independent manner. We analyzed the subcellular distribution of cathepsins (Cat) B, D, and L, in a search for caspase-independent factors responsible for Bax activation and AIF release. All were translocated from lysosomes to the cytosol, in correlation with limited destabilization of the lysosomes and release of lysosomal molecules in a size selective manner. However, only inhibition of Cat D activity by pepstatin A inhibited the early apoptotic events and delayed cell death, even in the presence of bafilomycin A(1), an inhibitor of vacuolar type H+-ATPase, which inhibits acidification in lysosomes. Small interfering RNA-mediated gene silencing was used to inactivate Cat D, Bax, and AIF gene expression. This allowed us to define a novel sequence of events in which Cat D triggers Bax activation, Bax induces the selective release of mitochondrial AIF, and the latter is responsible for the early apoptotic phenotype.