14-3-3 interacts directly with and negatively regulates pro-apoptotic bax
14-3-3 interacts directly with and negatively regulates pro-apoptotic bax
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DOI：
10.1074/jbc.m207880200
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发表时间：
2003-01-17
影响因子：
4.8
通讯作者：
Tsujimoto, Y
中科院分区：
文献类型：
--
作者：
Nomura, M;Shimizu, S;Tsujimoto, Y
Bcl2蛋白家族由抗凋亡成员和促凋亡成员组成，具有良好的细胞凋亡调控功能。具有BH1、BH2和BH3结构域的促凋亡成员(如BAX和BAK)是多种细胞凋亡信号的通道。Bax通常以不活跃的形式定位于细胞质。Bax在细胞凋亡刺激下移位到线粒体，发生寡聚化，诱导细胞色素c等促凋亡因子的释放，但Bax的线粒体易位和促凋亡活性是如何调控的，目前还不清楚。在这里，我们报道了细胞质蛋白14-3-3theta与Bax结合，并在凋亡刺激下，通过caspase不依赖的机制以及通过caspase直接切割14-3-3theta来释放Bax。与Bad不同的是，与14-3-3theta的相互作用不依赖于Bax的磷酸化。在分离的线粒体中，我们发现14-3-3theta抑制Bax的整合和Bax诱导的细胞色素c的释放。过表达14-3-3theta或其突变体(缺乏与各种磷酸化靶点结合但仍与Bax结合的能力)可抑制Bax诱导的细胞凋亡，而过表达14-3-3theta不能抑制不与14-3-3theta结合的Bax突变体诱导的细胞凋亡。这些发现表明，14-3-3theta在负性调节Bax的活性中起着关键作用。
The Bcl-2 family of proteins comprises well characterized regulators of apoptosis, consisting of anti-apoptotic members and pro-apoptotic members. Pro-apoptotic members possessing BH1, BH2, and BH3 domains (such as Bax and Bak) act as a gateway for a variety of apoptotic signals. Bax is normally localized to the cytoplasm in an inactive form. In response to apoptotic stimuli, Bax translocates to the mitochondria and undergoes oligomerization to induce the release of apoptogenic factors such as cytochrome c, but it is still largely unknown how the mitochondrial translocation and proapoptotic activity of Bax is regulated. Here we report that cytoplasmic protein 14-3-3theta binds to Bax and, upon apoptotic stimulation, releases Bax by a caspase-independent mechanism, as well as through direct cleavage of 14-3-3theta by caspases. Unlike Bad, the interaction with 14-3-3theta is not dependent on the phosphorylation of Bax. In isolated mitochondria, we found that 14-3-3theta inhibited the integration of Bax and Bax-induced cytochrome c release. Bax-induced apoptosis was inhibited by overexpression of either 14-3-3theta or its mutant (which lacked the ability to bind to various phosphorylated targets but still bound to Bax), whereas overexpression of 14-3-3theta was unable to inhibit apoptosis induced by a Bax mutant that did not bind to 14-3-3theta. These findings indicate that 14-3-3theta plays a crucial role in negatively regulating the activity of Bax.