Evidence for a novel antioxidant function and isoform-specific regulation of the human p66Shc gene.
Evidence for a novel antioxidant function and isoform-specific regulation of the human p66Shc gene.
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DOI：
10.1091/mbc.e13-11-0666
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发表时间：
2014-07-01
影响因子：
3.3
通讯作者：
Tsuji Y
中科院分区：
文献类型：
--
作者：
Miyazawa M;Tsuji Y
p66Shc（而非 p52Shc 或 p46Shc）受 Nrf2-ARE 系统调节，表明 p66Shc 作为抗氧化基因。 p66Shc 作为细胞质中的抗氧化蛋白，保护细胞免受 ROS 毒性并维持其他 ARE 调节基因的表达。最后，p66Shc 对于红细胞分化至关重要。哺乳动物 Shc 家族由 p46、p52 和 p66 亚型组成，在细胞生长和应激反应中充当衔接蛋白。 p66Shc 通过在线粒体中充当促氧化蛋白而被证明是一种负寿命调节因子；然而，p66Shc 表达和功能的调节机制尚不完全清楚。这项研究为 p66Shc 作为抗氧化剂和细胞分化中的关键蛋白的新功能提供了证据。在 Shc 家族中，p66Shc 的转录是独一无二的，在 K562 人红白血病和其他细胞类型中，经过氯化血红素（一种含铁卟啉）处理后，p66Shc 的转录通过抗氧化反应元件 (ARE) - 核因子红细胞 2 相关因子 2 (Nrf2) 通路被激活。磷酸化的 p66Shc Ser-36 先前报道易于定位于线粒体，通过氯高铁血红素处理会增加 p66Shc 的磷酸化，但 p66Shc 仍完全存在于细胞质中。 p66Shc 敲低可抑制氯高铁血红素诱导的红系分化，其中活性氧的产生和细胞凋亡与其他 ARE 依赖性抗氧化基因的抑制相结合显着增强。相反，p66Shc 过度表达足以诱导红系分化。总的来说，这些结果证明了 Nrf2-ARE 途径对 Shc 基因的亚型特异性调节以及 p66Shc 在细胞质中的新抗氧化作用。因此，p66Shc 是一种参与细胞氧化应激反应和分化的双功能蛋白。
p66Shc, but not p52Shc or p46Shc, is regulated by the Nrf2-ARE system, indicative of p66Shc as an antioxidant gene. p66Shc serves as an antioxidant protein in the cytoplasm, protecting cells from ROS toxicity and maintaining expression of other ARE-regulated genes. Finally, p66Shc is essential for erythroid differentiation. The mammalian Shc family, composed of p46, p52, and p66 isoforms, serves as an adaptor protein in cell growth and stress response. p66Shc was shown to be a negative lifespan regulator by acting as a prooxidant protein in mitochondria; however, the regulatory mechanisms of p66Shc expression and function are incompletely understood. This study provides evidence for new features of p66Shc serving as an antioxidant and critical protein in cell differentiation. Unique among the Shc family, transcription of p66Shc is activated through the antioxidant response element (ARE)–nuclear factor erythroid 2–related factor 2 (Nrf2) pathway in K562 human erythroleukemia and other cell types after treatment with hemin, an iron-containing porphyrin. Phosphorylated p66Shc at Ser-36, previously reported to be prone to mitochondrial localization, is increased by hemin treatment, but p66Shc remains exclusively in the cytoplasm. p66Shc knockdown inhibits hemin-induced erythroid differentiation, in which reactive oxygen species production and apoptosis are significantly enhanced in conjunction with suppression of other ARE-dependent antioxidant genes. Conversely, p66Shc overexpression is sufficient for inducing erythroid differentiation. Collectively these results demonstrate the isoform-specific regulation of the Shc gene by the Nrf2-ARE pathway and a new antioxidant role of p66Shc in the cytoplasm. Thus p66Shc is a bifunctional protein involved in cellular oxidative stress response and differentiation.