Acetylation of Foxo1 alters its DNA-binding ability and sensitivity to phosphorylation
Acetylation of Foxo1 alters its DNA-binding ability and sensitivity to phosphorylation
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DOI：
10.1073/pnas.0502738102
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发表时间：
2005-08-09
影响因子：
11.1
通讯作者：
Fukamizu, A
中科院分区：
文献类型：
--
作者：
Matsuzaki, H;Daitoku, H;Fukamizu, A
FOXO转录因子家族在新陈代谢、细胞增殖和氧化应激反应等多种生物学过程中发挥着关键作用。我们先前报道，FOXO家族成员Foxo1是通过组蛋白乙酰化转移酶cAMP反应元件结合蛋白(CREB)结合蛋白(CBP)和NAD依赖的组蛋白去乙酰化沉默信息调节器2催化可逆乙酰化来调节Foxo1的转录活性，并且Foxo1的Lys-242、Lys-245和Lys-262位的乙酰化减弱了其转录活性。然而，乙酰化调控Foxo1活性的分子机制仍不清楚。在这里，我们证明了Foxo1中这些赖氨酸的正电荷有助于它与DNA的结合，而CBP在这些残基上的乙酰化减弱了它与同源DNA序列的结合能力。值得注意的是，我们还发现，Foxo1的乙酰化通过磷脂酰肌醇3-激酶-蛋白激酶B信号通路增加了其在Ser-253的磷酸化水平，并且这种作用在乙酰化缺陷的Foxo1突变体中被覆盖。此外，在体外的激酶反应中，野生型Foxo1与其靶DNA序列的结合抑制了依赖于蛋白激酶B的Foxo1的磷酸化，而模拟组成乙酰化状态的突变的Foxo1蛋白即使在DNA存在的情况下也能有效地磷酸化。这些结果表明，乙酰化通过改变与靶DNA的亲和力和对磷酸化的敏感性来调节Foxo1的功能。
The FOXO family of forkhead transcription factors plays a key role in a variety of biological processes, including metabolism, cell proliferation, and oxidative stress response. We previously reported that Foxo1, a member of the FOXO family, is regulated through reversible acetylation catalyzed by histone acetyltransferase cAMP-response element-binding protein (CREB)-binding protein (CBP) and NAD-dependent histone deacetylase silent information regulator 2, and that the acetylation at Lys-242, Lys-245, and Lys-262 of Foxo1 attenuates its transcriptional activity. However, the molecular mechanism by which acetylation modulates Foxo1 activity remains unknown. Here, we show that the positive charge of these lysines in Foxo1 contributes to its DNA-binding, and acetylation at these residues by CBP attenuates its ability to bind cognate DNA sequence. Remarkably, we also show that acetylation of Foxo1 increases the levels of its phosphorylation at Ser-253 through the phosphatidylinositol 3-kinase-protein kinase B signaling pathway, and this effect was overridden on the acetylation-deficient Foxo1 mutant. Furthermore, in in vitro kinase reactions, the association of wild-type Foxo1 and its target DNA sequence inhibits the protein kinase B-dependent phosphorylation of Foxo1, whereas mutated Foxo1 proteins, which mimic constitutively acetylated states, are efficiently phosphorylated even in the presence of the DNA. These results suggest that acetylation regulates the function of Foxo1 through altering the affinity with the target DNA and the sensitivity for phosphorylation.