Alphaviruses induce apoptosis in Bcl-2-overexpressing cells: evidence for a caspase-mediated, proteolytic inactivation of Bcl-2
Alphaviruses induce apoptosis in Bcl-2-overexpressing cells: evidence for a caspase-mediated, proteolytic inactivation of Bcl-2
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DOI：
10.1093/emboj/17.5.1268
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发表时间：
1998-03-02
期刊：
影响因子：
11.4
通讯作者：
Michel, MR
中科院分区：
文献类型：
--
作者：
Grandgirard, D;Studer, E;Michel, MR
Bcl-2癌基因表达通过阻断病毒诱导的细胞凋亡在建立持续性病毒感染中起作用，这可能通过阻止病毒诱导的半胱天冬酶-3活化来实现，半胱天冬酶-3是一种IL-1 β转化酶（ICE）样半胱氨酸蛋白酶，其与细胞凋亡的死亡效应相有关。黑麦的结果表明，三种高度过表达功能性Bcl-2的细胞类型显示caspase-3激活，并经历了凋亡。在应答甲病毒Semliki Forest和Sindbis感染的细胞凋亡中，与载体对照对应物一样有效。在所有三种细胞类型中，过表达的26 kDa Bcl-2被切割成23 kDa蛋白质。抗体表位作图显示切割发生在氨基酸区域YEWD（31）向下箭头AGD（34）向下箭头A内的半胱天冬酶的一个或两个靶位点处，去除了已知对于Bcl-2的死亡保护活性至关重要的N-末端BH 4区域，用半胱天冬酶抑制剂Z-VAD预孵育细胞防止Bcl-2裂解并部分恢复Bcl-2对病毒诱导的细胞凋亡的保护活性。此外，被Glu取代的Asp 34和Asp 36在病毒感染后抵抗蛋白水解切割并消除细胞凋亡，这些发现表明，甲病毒可以触发半胱天冬酶介导的Bcl-2失活，以逃避这种生存因子施加的死亡保护。
Bcl-2 oncogene expression plays a role in the establishment of persistent viral infection by blocking virus-induced apoptosis, This might be achieved by preventing virus-induced activation of caspase-3, an IL-1 beta-converting enzyme (ICE)-like cysteine protease that has been implicated in the death effector phase of apoptosis, Contrary to this model, rye show that three cell types highly overexpressing functional Bcl-2 displayed caspase-3 activation and underwent. apoptosis in response to infection with alphaviruses Semliki Forest and Sindbis as efficiently as vector control counterparts. In all three cell types, overexpressed 26 kDa Bcl-2 was cleaved into a 23 kDa protein, Antibody epitope mapping revealed that cleavage occurred at one or two target sites for caspases within the amino acid region YEWD(31)down arrow AGD(34)down arrow A, removing the N-terminal BH4 region known to be essential for the death-protective activity of Bcl-2, Preincubation of cells with the caspase inhibitor Z-VAD prevented Bcl-2 cleavage and partially restored the protective activity of Bcl-2 against virus-induced apoptosis, Moreover, a murine Bcl-2 mutant having Asp31, Asp34 and Asp36 substituted by Glu was resistant to proteolytic cleavage and abrogated apoptosis following virus infection, These findings indicate that alphaviruses can trigger a caspase-mediated inactivation of Bcl-2 in order to evade the death protection imposed by this survival factor.