Loss of p53 enhances catalytic activity of IKKβ through O-linked β-N-acetyl glucosamine modification
Loss of p53 enhances catalytic activity of IKKβ through O-linked β-N-acetyl glucosamine modification
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DOI：
10.1073/pnas.0813210106
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发表时间：
2009-03-03
影响因子：
11.1
通讯作者：
Tanaka, Nobuyuki
中科院分区：
文献类型：
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作者：
Kawauchi, Keiko;Araki, Keigo;Tanaka, Nobuyuki
I kappa B 激酶 (IKK)-NF-kappa B 通路在肿瘤发生中发挥着关键作用。最近，我们发现 p53 通过 IKK-NF-kappa B 途径调节葡萄糖代谢，并且在缺乏 p53 的情况下，IKK-NF-kappa B 和糖酵解之间的正反馈环在癌基因诱导的细胞转化中发挥着不可或缺的作用。在这里，我们证明，在 p53 缺陷的小鼠胚胎成纤维细胞 (MEF) 和转化的人成纤维细胞中，IKK β（IKK 复合物的一个组成部分）被 O-连接的 β-N-乙酰氨基葡萄糖 (O-GlcNAc) 组成型修饰。在 p53 缺陷细胞中，O-GlcNA 酰化的 IKK β 和 IKK 的激活磷酸化因 p65/NF-κ B 敲低或葡萄糖消耗而减少。我们还发现高葡萄糖诱导 IKK β 的 O-GlcNAc 酰化并维持 TNF α 依赖性的 IKK β 活性。此外，O-GlcNAcase 抑制剂链脲佐菌素增强了 O-GlcNAc 酰化并同时激活 IKK β 的磷酸化。突变分析显示，IKK beta 的 O-GlcNAcNA 酰化发生在 C 端结构域的 Ser 733 处，该位点被确定为失活磷酸化位点，表明 IKK beta O-GlcNAcNAc 酰化调节其催化活性。综上所述，我们提出了一种通过 p53 缺失增强 NF-kappa B 活性的新机制，该机制在肿瘤发生过程中引起从增强的葡萄糖代谢到 IKK 的正反馈调节。
The I kappa B kinase (IKK)-NF-kappa B pathway plays a critical role in oncogenesis. Recently, we have shown that p53 regulates glucose metabolism through the IKK-NF-kappa B pathway and that, in the absence of p53, the positive feedback loop between IKK-NF-kappa B and glycolysis has an integral role in oncogene-induced cell transformation. Here, we demonstrate that IKK beta, a component of the IKK complex, was constitutively modified with O-linked beta-N-acetyl glucosamine (O-GlcNAc) in both p53-deficient mouse embryonic fibroblasts (MEFs) and transformed human fibroblasts. In p53deficient cells, the O-GlcNAcylated IKK beta and the activating phosphorylation of IKK were decreased by p65/NF-kappa B knockdown or glucose depletion. We also found that high glucose induced the O-GlcNAcylation of IKK beta and sustained the TNF alpha-dependent IKK beta activity. Moreover, the O-GlcNAcase inhibitor streptozotocin intensified O-GlcNAcylation and concomitant activating phosphorylation of IKK beta. Mutational analysis revealed that O-GlcNAcylation of IKK beta occurred at Ser 733 in the C-terminal domain, which was identified as an inactivating phosphorylation site, suggesting that IKK beta O-GlcNAcylation regulates its catalytic activity. Taken together, we propose a novel mechanism for the enhancement of NF-kappa B activity by loss of p53, which evokes positive feedback regulation from enhanced glucose metabolism to IKK in oncogenesis.