A mutation of Keap1 found in breast cancer impairs its ability to repress Nrf2 activity
A mutation of Keap1 found in breast cancer impairs its ability to repress Nrf2 activity
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DOI：
10.1016/j.bbrc.2007.08.051
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发表时间：
2007-11-03
影响因子：
3.1
通讯作者：
Nguyen, Truyen
中科院分区：
文献类型：
--
作者：
Nioi, Paul;Nguyen, Truyen
Keapl是基于Cullin 3的E3泛素连接酶的底物识别模块。其主要作用是催化Nrf 2转录因子的泛素化。氧化应激阻断Keapl的E3连接酶活性，其稳定Nrf 2，允许其驱动某些抗氧化剂和药物代谢酶的表达。最近的一项研究发现了乳腺癌中存在的Keapl基因突变（Keap 1C 23 Y）。使用报告基因测定，我们表明，Keap 1C 23 Y是受损的抑制Nrf 2依赖性转录的能力。与野生型Keapl不同，我们发现Keap 1C 23 Y未能刺激Nrf 2的降解。免疫共沉淀实验表明，Keap 1C 23 Y保留了与Nrf 2和Cullin 3相互作用的能力。相反，我们发现Keap 1C 23 Y不能有效地促进Nrf 2的泛素化，这表明其内在的生物活性可能已经受到损害。这些结果揭示了Keapl的N-末端区域在调节其E3连接酶活性中的意想不到的作用。重要的是，我们的研究结果表明存在一个悖论，即Nrf 2活性在非恶性细胞中是有益的，但在癌细胞中，它可能为克隆扩增提供选择性优势。(c)2007爱思唯尔公司All rights reserved.
Keapl is the substrate recognition module of a Cullin 3-based E3 ubiquitin ligase. Its primary role is to catalyze the ubiquitylation of the Nrf2 transcription factor. Oxidative stress blocks the E3 ligase activity of Keapl which stabilizes Nrf2 allowing it to drive the expression of certain antioxidant and drug metabolizing enzymes. A recent study identified a mutation in the Keapl gene (Keap1C23Y) that is present in breast cancer. Using reporter gene assays we show that Keap1C23Y is impaired in its ability to repress Nrf2 dependent transcription. Unlike wild-type Keapl, we found that Keap1C23Y failed to stimulate the degradation of Nrf2. Co-immunopreciptation experiments showed that Keap1C23Y retains its ability to interact with Nrf2 and Cullin 3. In contrast, we found that Keap1C23Y could not efficiently promote the ubiquitylation of Nrf2, suggesting that its intrinsic biological activity might have been compromised. These results revealed an unexpected role for the N-terminal region of Keapl in regulating its E3 ligase activity. Importantly, our findings suggest that a paradox exists whereby Nrf2 activity is beneficial in non-malignant cells but in cancer cells it may provide a selective advantage for clonal expansion. (c) 2007 Elsevier Inc. All rights reserved.