Mcl-1 interacts with truncated bid and inhibits its induction of cytochrome c release and its role in receptor-mediated apoptosis
Mcl-1 interacts with truncated bid and inhibits its induction of cytochrome c release and its role in receptor-mediated apoptosis
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DOI：
10.1074/jbc.m505688200
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发表时间：
2006-03-03
影响因子：
4.8
通讯作者：
Brady, HJM
中科院分区：
文献类型：
--
作者：
Clohessy, JG;Zhuang, JG;Brady, HJM
死亡受体如肿瘤坏死因子-R1和Fas的参与导致胞质Bid裂解为截短的Bid（tBid），其易位到线粒体以激活Bax/巴克，导致细胞色素c的释放。然而，激活的机制还没有完全理解。在这里，我们已经确定了抗凋亡Bcl-2家族成员Mcl-1作为一个有效的TBID结合伙伴。定点突变显示tBid的Bcl-2同源（BH）3结构域是与Mcl-1结合所必需的，而Mcl-1的所有三个BH结构域（BH 1、BH 2和BH 3）是与tBid相互作用所必需的。使用分离的线粒体和重组蛋白的体外研究表明，Mcl-1强烈抑制TBID诱导的细胞色素c释放。除了其与Bax和巴克直接相互作用的能力之外，tBid还结合Mcl-1并从Mcl-1-巴克复合物中置换巴克。重要的是，Mcl-1的过表达赋予HeLa细胞对TRAIL和肿瘤坏死因子-α诱导的细胞凋亡的抗性，而通过RNA干扰靶向Mcl-1使HeLa细胞对TRAIL诱导的细胞凋亡敏感。因此，我们的研究证明了一种新的调节tBid的Mcl-1通过蛋白质-蛋白质相互作用的凋亡信号从死亡受体线粒体。
Engagement of death receptors such as tumor necrosis factor-R1 and Fas brings about the cleavage of cytosolic Bid to truncated Bid (tBid), which translocates to mitochondria to activate Bax/Bak, resulting in the release of cytochrome c. The mechanism underlying the activation, however, is not fully understood. Here, we have identified the anti-apoptotic Bcl-2 family member Mcl-1 as a potent tBid-binding partner. Site-directed mutagenesis reveals that the Bcl-2 homology (BH) 3 domain of tBid is essential for binding to Mcl-1, whereas all threeBHdomains (BH1, BH2, and BH3) of Mcl-1 are required for interaction with tBid. In vitro studies using isolated mitochondria and recombinant proteins demonstrate that Mcl-1 strongly inhibits tBid-induced cytochrome c release. In addition to its ability to interact directly with Bax and Bak, tBid also binds Mcl-1 and displaces Bak from the Mcl-1-Bak complex. Importantly, overexpression of Mcl-1 confers resistance to the induction of apoptosis by both TRAIL and tumor necrosis factor-alpha in HeLa cells, whereas targeting Mcl-1 by RNA interference sensitizes HeLa cells to TRAIL-induced apoptosis. Therefore, our study demonstrates a novel regulation of tBid by Mcl-1 through protein-protein interaction in apoptotic signaling from death receptors to mitochondria.