Uncoupling of Acetylation from Phosphorylation Regulates FoxO1 Function Independent of Its Subcellular Localization
Uncoupling of Acetylation from Phosphorylation Regulates FoxO1 Function Independent of Its Subcellular Localization
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DOI：
10.1074/jbc.m110.140228
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发表时间：
2010-08-27
影响因子：
4.8
通讯作者：
Accili, Domenico
中科院分区：
文献类型：
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作者：
Qiang, Li;Banks, Alexander S.;Accili, Domenico
转录因子FOXO1的活性受磷酸化依赖性的核排斥和脱乙酰化依赖性核保留调节。目前尚不清楚这两种翻译后修改如何相互影响。为了回答这个问题，我们表达了使用HEK-293细胞中磷酸化和乙酰化位点的突变的FOXO1 cDNA，并分析了其亚细胞定位模式。我们表明，模仿乙酰化态（KQ系列）的突变使FOXO1对Akt介导的磷酸化和核排斥更敏感，并且可以逆转磷酸化缺陷FOXO1的组成性核定位。相反，模仿脱乙酰化状态（KR系列）的突变促进了FOXO1核保留率。氧化应激和SIRT1激活剂白藜芦醇被认为可以促进FOXO1脱乙酰基化和核保留率，从而增加了其活性。因此，氧化应激（H2O2诱导）将FOXO1保留在核中需要FOXO1脱乙酰化。 H2O2还抑制了关键的胰岛素调节位点Ser-253和Thr-24上的FOXO1磷酸化，而与其乙酰化无关。相比之下，白藜芦醇的作用与FOXO1乙酰化及其磷酸化对SER-253和THR-24的磷酸化无关，这表明白藜芦醇以SIRT1-和AKT不依赖的方式作用于FoxO1。在H2O2处理的细胞中，脱乙酰化与去磷酸化的解离，表明这两种修饰可以彼此独立发生。可以预见，FOXO1以多种核形式存在，具体活动取决于乙酰化和磷酸化的平衡。
The activity of transcription factor FoxO1 is regulated by phosphorylation-dependent nuclear exclusion and deacetylation-dependent nuclear retention. It is unclear whether and how these two post-translational modifications affect each other. To answer this question, we expressed FoxO1 cDNAs with combined mutations of phosphorylation and acetylation sites in HEK-293 cells and analyzed their subcellular localization patterns. We show that mutations mimicking the acetylated state (KQ series) render FoxO1 more sensitive to Akt-mediated phosphorylation and nuclear exclusion and can reverse the constitutively nuclear localization of phosphorylation-defective FoxO1. Conversely, mutations mimicking the deacetylated state (KR series) promote FoxO1 nuclear retention. Oxidative stress and the Sirt1 activator resveratrol are thought to promote FoxO1 deacetylation and nuclear retention, thus increasing its activity. Accordingly, FoxO1 deacetylation was required for the effect of oxidative stress (induced by H2O2) to retain FoxO1 in the nucleus. H2O2 also inhibited FoxO1 phosphorylation on Ser-253 and Thr-24, the key insulin-regulated sites, irrespective of its acetylation. In contrast, the effect of resveratrol was independent of FoxO1 acetylation and its phosphorylation on Ser-253 and Thr-24, suggesting that resveratrol acts on FoxO1 in a Sirt1- and Akt-independent manner. The dissociation of deacetylation from dephosphorylation in H2O2-treated cells indicates that the two modifications can occur independently of each other. It can be envisaged that FoxO1 exists in multiple nuclear forms with distinct activities depending on the balance of acetylation and phosphorylation.