Calpain-1 regulates Bax and subsequent Smac-dependent caspase-3 activation in neutrophil apoptosis
Calpain-1 regulates Bax and subsequent Smac-dependent caspase-3 activation in neutrophil apoptosis
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DOI：
10.1074/jbc.m308576200
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发表时间：
2004-02-13
影响因子：
4.8
通讯作者：
Simon, HU
中科院分区：
文献类型：
--
作者：
Altznauer, F;Conus, S;Simon, HU
在炎性反应消失和消退的情况下，中性粒细胞迅速发生自发的凋亡。在这里，我们报告了在这些细胞中的一条新的凋亡途径，它需要Calain-1的激活，并且对于关键效应因子caspase-3的酶激活是必不可少的。在中性粒细胞中，钙蛋白酶的高度特异的内在抑制物calastatin水平的降低导致了calain-1的激活，但不会导致calain-2的激活，这一过程可被特定的calain-1抑制剂或细胞内输送的calastatin多肽所阻断。通过分析囊性纤维化患者的中性粒细胞表现出延迟的凋亡，与对照组的中性粒细胞相比，与显著增加的calastatin和降低的calain-1蛋白水平相关，进一步支持了calastatin-calain系统的重要性。另外还设计了一些研究，将Calain-1放入导致中性粒细胞凋亡的生化事件的层次结构中。在自发和Fas受体诱导的中性粒细胞凋亡过程中，药理学上的Calain抑制阻止了Bax被切割成无法与Bclx相互作用的18 kDa片段(L)。此外，在有或没有激动型抗Fas受体抗体的情况下，Calain阻断都能阻止细胞色素c和Smac的释放，这是caspase-3加工和酶激活所必需的。综上所述，calastatin和calain-1是导致Bax、线粒体和caspase-3激活的一系列促凋亡事件的关键近端元件，它们的表达变化似乎在病理条件下影响了中性粒细胞的寿命。
In the absence and in the resolution of inflammatory responses, neutrophils rapidly undergo spontaneous apoptosis. Here we report about a new apoptosis pathway in these cells that requires calpain-1 activation and is essential for the enzymatic activation of the critical effector caspase-3. Decreased levels of calpastatin, a highly specific intrinsic inhibitor of calpain, resulted in activation of calpain-1, but not calpain-2, in neutrophils undergoing apoptosis, a process that was blocked by a specific calpain-1 inhibitor or by intracellular delivery of a calpastatin peptide. Further support for the importance of the calpastatin-calpain system was obtained by analyzing neutrophils from patients with cystic fibrosis that exhibited delayed apoptosis, associated with markedly increased calpastatin and decreased calpain-1 protein levels compared with neutrophils from control individuals. Additional studies were designed to place calpain-1 into the hierarchy of biochemical events leading to neutrophil apoptosis. Pharmacological calpain inhibition during spontaneous and Fas receptor-induced neutrophil apoptosis prevented cleavage of Bax into an 18-kDa fragment unable to interact with Bcl-x(L). Moreover, calpain blocking prevented the mitochondrial release of cytochrome c and Smac, which was indispensable for caspase-3 processing and enzymatic activation, both in the presence and absence of agonistic anti-Fas receptor antibodies. Taken together, calpastatin and calpain-1 represent critical proximal elements in a cascade of pro-apoptotic events leading to Bax, mitochondria, and caspase-3 activation, and their altered expression appears to influence the life span of neutrophils under pathologic conditions.