A novel NF-κB pathway involving IKKβ and p65/Re1A ser-536 phosphorylation results in p53 inhibition in the absence of 1NF-κB transcriptional activity
A novel NF-κB pathway involving IKKβ and p65/Re1A ser-536 phosphorylation results in p53 inhibition in the absence of 1NF-κB transcriptional activity
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DOI：
10.1074/jbc.m412643200
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发表时间：
2005-03-18
影响因子：
4.8
通讯作者：
Brady, JN
中科院分区：
文献类型：
--
作者：
Jeong, SJ;Pise-Masison, CA;Brady, JN
核因子 kappa B (NF-kappa B) 在调节细胞转化和凋亡中发挥重要作用。人类 T 细胞嗜淋巴细胞病毒 I 型蛋白 Tax 对病毒转化至关重要，它通过激活 NF-kappa B 来调节多个细胞基因的转录。我们之前已经证明，Tax 通过 NF-kappa B 的 p65/RelA 亚基抑制 p53 活性。我们现在提供的证据表明，上游激酶 IKK beta 通过 p65/RelA 的磷酸化在 Tax 诱导的 p53 抑制中发挥重要作用。 Ser-536。首先，小鼠胚胎成纤维细胞（MEF）IKK beta-/-细胞不支持Tax介导的p53抑制，而缺乏IKK alpha的MEF则允许Tax抑制p53。其次，将 IKK β 野生型 (WT)（而非激酶死亡突变体）转染至 IKK β-/- 细胞中，可通过 Tax 挽救 p53 抑制。第三，IKK β 特异性抑制剂 SC-514 降低了 Tax 抑制 p53 的能力。第四，我们使用转染 p65/RelA WT 或突变质粒的 MEF p65/RelA-/- 细胞表明，p65/RelA 在 Ser-536 处的磷酸化对于 p53 的 Tax 抑制非常重要。此外，Tax 在 WT 或 IKK α-/- 细胞中诱导 p65/RelA Ser-536 磷酸化，但未能在 IKK β-/- 细胞中诱导 p65/RelA Ser-536 磷酸化，表明 IKK β 和 p65/RelA 磷酸化之间存在联系。与这一观察结果一致，在人 T 细胞嗜淋巴细胞病毒 I 型转化细胞中存在 Tax 的情况下，通过 SC-514 阻断 IKK β 激酶活性会降低 p65/RelA Ser-536 的磷酸化。最后，Tax 抑制 p53 的能力与 NF-kappa B 转录激活途径不同。因此，我们的工作描述了一种新的 Tax-NF-kappa B p65/RelA 途径，其功能是抑制 p53，但不需要 NF-kappa B 转录活性。
Nuclear factor kappa B (NF-kappa B) plays an important role in regulating cellular transformation and apoptosis. The human T-cell lymphotropic virus type I protein, Tax, which is critical for viral transformation, modulates the transcription of several cellular genes through activation of NF-kappa B. We have demonstrated previously that Tax inhibits p53 activity through the p65/RelA subunit of NF-kappa B. We now present evidence that suggests that the upstream kinase IKK beta plays an important role in Tax-induced p53 inhibition through phosphorylation of p65/RelA at Ser-536. First, mouse embryo fibroblast (MEF) IKK beta-/- cells did not support Tax-mediated p53 inhibition, whereas MEFs lacking IKK alpha allowed Tax inhibition of p53. Second, transfection of IKK beta wild type (WT), but not a kinase-dead mutant, into IKK beta-/- cells rescued p53 inhibition by Tax. Third, the IKK beta-specific inhibitor SC-514 decreased the ability of Tax to inhibit p53. Fourth, we show that phosphorylation of p65/RelA at Ser-536 is important for Tax inhibition of p53 using MEF p65/RelA-/- cells transfected with p65/RelA WT or mutant plasmids. Moreover, Tax induced p65/RelA Ser536 phosphorylation in WT or IKK alpha-/- cells but failed to induce the phosphorylation of p65/RelA Ser-536 in IKK beta-/- cells, suggesting a link between IKK beta and p65/RelA phosphorylation. Consistent with this observation, blocking IKK beta kinase activity by SC-514 decreases the phosphorylation of p65/RelA at Ser-536 in the presence of Tax in human T-cell lymphotropic virus type I-transformed cells. Finally, the ability of Tax to inhibit p53 is distinguished from the NF-kappa B transcription activation pathway. Our work, therefore, describes a novel Tax-NF-kappa B p65/RelA pathway that functions to inhibit p53 but does not require NF-kappa B transcription activity.