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首页> 外文期刊>Molecular and Cellular Biology >Reduced Phosphorylation of p50 Is Responsible for Diminished NF-κB Binding to the Major Histocompatibility Complex Class I Enhancer in Adenovirus Type 12-Transformed Cells
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Reduced Phosphorylation of p50 Is Responsible for Diminished NF-κB Binding to the Major Histocompatibility Complex Class I Enhancer in Adenovirus Type 12-Transformed Cells

机译：p50磷酸化的减少是负责减少NF-κB与主要组织相容性复合体I类增强子在腺病毒12型转化细胞中的结合。

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Reduced cell surface levels of major histocompatibility complex class I antigens enable adenovirus type 12 (Ad12)-transformed cells to escape immunosurveillance by cytotoxic T lymphocytes (CTL), contributing to their tumorigenic potential. In contrast, nontumorigenic Ad5-transformed cells harbor significant cell surface levels of class I antigens and are susceptible to CTL lysis. Ad12 E1A mediates down-regulation of class I transcription by increasing COUP-TF repressor binding and decreasing NF-κB activator binding to the class I enhancer. The mechanism underlying the decreased binding of nuclear NF-κB in Ad12-transformed cells was investigated. Electrophoretic mobility shift assay analysis of hybrid NF-κB dimers reconstituted from denatured and renatured p50 and p65 subunits from Ad12- and Ad5-transformed cell nuclear extracts demonstrated that p50, and not p65, is responsible for the decreased ability of NF-κB to bind to DNA in Ad12-transformed cells. Hypophosphorylation of p50 was found to correlate with restricted binding of NF-κB to DNA in Ad12-transformed cells. The importance of phosphorylation of p50 for NF-κB binding was further demonstrated by showing that an NF-κB dimer composed of p65 and alkaline phosphatase-treated p50 from Ad5-transformed cell nuclear extracts could not bind to DNA. These results suggest that phosphorylation of p50 is a key step in the nuclear regulation of NF-κB in adenovirus-transformed cells.
机译：主要组织相容性复合物I类抗原的细胞表面水平降低，可使腺病毒12型（Ad12）转化细胞逃脱细胞毒性T淋巴细胞（CTL）的免疫监视，从而有助于其致瘤性。相反，非致瘤性Ad5转化的细胞具有明显的I类抗原细胞表面水平，并且易于CTL裂解。 Ad12 E1A通过增加COUP-TF阻遏物的结合并减少与Ⅰ类增强子的NF-κB激活剂结合来介导I类转录的下调。研究了Ad12转化细胞中核NF-κB结合力降低的潜在机制。从Ad12和Ad5转化的细胞核提取物中变性和复性的p50和p65亚基重构的杂合NF-κB二聚体的电泳迁移率迁移分析分析表明，p50而非p65导致NF-κB结合能力降低到Ad12转化细胞中的DNA。发现p50的低磷酸化与Ad12转化细胞中NF-κB与DNA的结合受限有关。 p50磷酸化对NF-κB结合的重要性进一步证明，由p65和经Ad5转化的细胞核提取物中碱性磷酸酶处理过的p50组成的NF-κB二聚体不能与DNA结合。这些结果表明，p50的磷酸化是腺病毒转化细胞中NF-κB核调节的关键步骤。

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