Cysteine cathepsins trigger caspase-dependent cell death through cleavage of Bid and antiapoptotic Bcl-2 homologues
Cysteine cathepsins trigger caspase-dependent cell death through cleavage of Bid and antiapoptotic Bcl-2 homologues
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DOI：
10.1074/jbc.m802513200
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发表时间：
2008-07-04
影响因子：
4.8
通讯作者：
Turk, Boris
中科院分区：
文献类型：
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作者：
Droga-Mazovec, Gabriela;Bojic, Lea;Turk, Boris
作为定义溶酶体组织蛋白酶在细胞凋亡中作用的模型，我们使用不同的细胞模型表征了溶酶体活性剂 LeuLeuOMe 的作用。 LeuLeuOMe 诱导溶酶体膜通透，导致溶酶体组织蛋白酶释放，裂解促凋亡 Bcl-2 家族成员 Bid 并降解抗凋亡成员 Bcl-2、Bcl-xL 或 Mcl-1。木瓜蛋白酶样半胱氨酸蛋白酶抑制剂 E-64d 在很大程度上阻止了细胞凋亡、Bid 裂解和 Bcl-2/Bcl-xL/Mcl-1 降解。 pancaspase 抑制剂 N-benzyloxycarbonyl-Val-Ala-Asp(OMe) 氟甲基酮未能阻止 Bid 裂解和抗凋亡 Bcl-2 同系物的降解，但显着减少了细胞死亡，表明这些细胞模型中组织蛋白酶介导的细胞凋亡大多遵循 caspase 依赖性途径。此外，体外实验表明，半胱氨酸组织蛋白酶 B、L、S、K 和 H 中的一种或多种可以裂解 Bcl-2、Bcl-xL、Mcl-1、Bak 和 BimEL，但未观察到 Bax 裂解。在抑制剂研究的基础上，我们证明 LeuLeuOMe 引发的溶酶体破坏发生在线粒体损伤之前。我们提出，溶酶体组织蛋白酶对抗凋亡 Bcl-2 家族成员的降解与组织蛋白酶介导的 Bid 激活协同作用，触发线粒体凋亡途径。此外，XIAP（X染色体连锁凋亡抑制剂）也被发现是半胱氨酸组织蛋白酶的靶标，表明组织蛋白酶也可以介导线粒体下游的半胱天冬酶依赖性细胞凋亡。
As a model for defining the role of lysosomal cathepsins in apoptosis, we characterized the action of the lysosomotropic agent LeuLeuOMe using distinct cellular models. LeuLeuOMe induces lysosomal membrane permeabilization, resulting in release of lysosomal cathepsins that cleave the proapoptotic Bcl-2 family member Bid and degrade the antiapoptotic member Bcl-2, Bcl-xL, or Mcl-1. The papain-like cysteine protease inhibitor E-64d largely prevented apoptosis, Bid cleavage, and Bcl-2/Bcl-xL/Mcl-1 degradation. The pancaspase inhibitor N-benzyloxycarbonyl-Val-Ala-Asp(OMe) fluoromethyl ketone failed to prevent Bid cleavage and degradation of anti-apoptotic Bcl-2 homologues but substantially decreased cell death, suggesting that cathepsin-mediated apoptosis in these cellular models mostly follows a caspase-dependent pathway. Moreover, in vitro experiments showed that one or more of the cysteine cathepsins B, L, S, K, and H could cleave Bcl-2, Bcl-xL, Mcl-1, Bak, and BimEL, whereas no Bax cleavage was observed. On the basis of inhibitor studies, we demonstrate that lysosomal disruption triggered by LeuLeuOMe occurs before mitochondrial damage. We propose that degradation of anti-apoptotic Bcl-2 family members by lysosomal cathepsins synergizes with cathepsin-mediated activation of Bid to trigger a mitochondrial pathway to apoptosis. Moreover, XIAP (X-chromosome-linked inhibitor of apoptosis) was also found to be a target of cysteine cathepsins, suggesting that cathepsins can mediate caspase-dependent apoptosis also downstream of mitochondria.