Humanin binds and nullifies bid activity by blocking its activation of Bax and Bak
Humanin binds and nullifies bid activity by blocking its activation of Bax and Bak
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DOI：
10.1074/jbc.m411902200
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发表时间：
2005-04-22
影响因子：
4.8
通讯作者：
Reed, JC
中科院分区：
文献类型：
--
作者：
Zhai, DY;Luciano, F;Reed, JC
最近，我们发现人蛋白(Human in，HN)是一种由24个氨基酸组成的小分子内源性多肽，可与促凋亡蛋白Bax结合并抑制其活性。我们在这里表明，HN还与BH3-Only的Bcl2/Bax家族蛋白BID以及与蛋白酶介导的促凋亡蛋白激活相关的截短形式的BID相互作用。人工合成的HN多肽在体外能与纯化的Bid和TbID结合，并阻断TbID诱导的细胞色素c和Smac从分离的线粒体释放，而不能结合Bid或TbID的突变多肽缺乏这一活性。此外，HN肽还保留了对Bax-/-线粒体的保护活性，表明HN可以不依赖于Bax的方式阻断TBID诱导的这些细胞器中的促凋亡蛋白的释放。化学交联剂或凝胶过滤实验表明，HN肽可抑制TBID诱导的线粒体膜Bax和Bak的寡聚。基因转染实验表明，HN(但不是HN的失活突变体)也能保护完整细胞免受TBID过表达诱导的细胞凋亡。我们得出结论，BID代表了HN的一个额外的细胞靶点，我们认为HN介导的抑制BID参与了这种内源性多肽的抗凋亡活性。
Recently, we discovered that Humanin (HN), a small endogenous peptide of 24 amino acids, binds to and inhibits the proapoptotic protein Bax. We show here that HN also interacts with the BH3-only Bcl-2/Bax family protein, Bid, as well as a truncated form of Bid (tBid) associated with protease-mediated activation of this proapoptotic protein. Synthetic HN peptide binds purified Bid and tBid in vitro and blocks tBid-induced release of cytochrome c and SMAC from isolated mitochondria, whereas mutant peptides that fail to bind Bid or tBid lack this activity. Moreover, HN peptide also retained protective activity on bax-/- mitochondria, indicating that HN can block tBid-induced release of apoptogenic proteins from these organelles in a Bax-independent manner. HN peptide inhibits tBid-induced oligomerization of Bax and Bak in mitochondrial membranes, as shown by experiments with chemical crosslinkers or gel filtration. Gene transfection experiments showed that HN ( but not an inactive mutant of HN) also protects intact cells from apoptosis induced by overexpression of tBid. We conclude that Bid represents an additional cellular target of HN, and we propose that HN-mediated suppression of Bid contributes to the antiapoptotic activity of this endogenous peptide.