Fbxo45-mediated degradation of the tumor-suppressor Par-4 regulates cancer cell survival
Fbxo45-mediated degradation of the tumor-suppressor Par-4 regulates cancer cell survival
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DOI：
10.1038/cdd.2014.92
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发表时间：
2014-10-01
影响因子：
12.4
通讯作者：
Elenitoba-Johnson, K. S. J.
中科院分区：
文献类型：
--
作者：
Chen, X.;Sahasrabuddhe, A. A.;Elenitoba-Johnson, K. S. J.
前列腺凋亡反应蛋白4（Par-4）也称为PRKC凋亡WT 1调节剂，是一种选择性诱导癌细胞凋亡的肿瘤抑制因子。然而，它的翻译后调节泛素介导的蛋白水解和细胞机制，是负责其蛋白酶体降解是未知的。使用免疫纯化和无偏质谱法为基础的方法，我们表明，Par-4通过一个短的共识序列基序与SPRY-域包含E3泛素连接酶Fbxo 45相互作用。Fbxo 45在细胞质中与Par-4相互作用并介导其泛素化和蛋白酶体降解。Fbxo 45沉默导致Par-4的稳定，同时细胞凋亡增加。重要的是，不能结合Fbxo 45的Par-4突变体是稳定的，并进一步增强星形孢菌素诱导的细胞凋亡。Fbxo 45与Par-4的共表达保护癌细胞免受Par-4诱导的凋亡。我们的研究表明，Fbxo 45是Par-4的功能性E3连接酶的底物受体亚基，在癌细胞存活中起关键作用。
Prostate apoptosis response protein 4 (Par-4) also known as PRKC apoptosis WT1 regulator is a tumor suppressor that selectively induces apoptosis in cancer cells. However, its post-translational regulation by ubiquitin-mediated proteolysis and the cellular machinery that is responsible for its proteasomal degradation are unknown. Using immunopurification and an unbiased mass spectrometry-based approach, we show that Par-4 interacts with the SPRY-domain containing E3 ubiquitin ligase Fbxo45 through a short consensus sequence motif. Fbxo45 interacts with Par-4 in the cytoplasm and mediates its ubiquitylation and proteasomal degradation. Fbxo45 silencing results in stabilization of Par-4 with increased apoptosis. Importantly, a Par-4 mutant that is unable to bind Fbxo45 is stabilized and further enhances staurosporine-induced apoptosis. Co-expression of Fbxo45 with Par-4 protects cancer cells against Par-4-induced apoptosis. Our studies reveal that Fbxo45 is the substrate-receptor subunit of a functional E3 ligase for Par-4 that has a critical role in cancer cell survival.