A Systematic Analysis of Human Papillomavirus (HPV) E6 PDZ Substrates Identifies MAGI-1 as a Major Target of HPV Type 16 (HPV-16) and HPV-18 Whose Loss Accompanies Disruption of Tight Junctions
A Systematic Analysis of Human Papillomavirus (HPV) E6 PDZ Substrates Identifies MAGI-1 as a Major Target of HPV Type 16 (HPV-16) and HPV-18 Whose Loss Accompanies Disruption of Tight Junctions
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DOI：
10.1128/jvi.01756-10
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发表时间：
2011-02-01
影响因子：
5.4
通讯作者：
Banks, Lawrence
中科院分区：
文献类型：
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作者：
Kranjec, Christian;Banks, Lawrence
来自高风险、致癌类型人乳头瘤病毒 (HPV) 的 E6 蛋白的特征是在其末端羧基末端存在 PDZ (PSD95/Dlg/ZO-1) 结合基序，通过该基序它们与许多含有 PDZ 结构域的细胞底物相互作用。为了确定其中有多少在体内被 E6 降解，我们对 E6 消融对许多先前报道的 E6 PDZ 底物表达水平的影响进行了广泛的分析。使用 HPV 16 型 (HPV-16) 阳性 CaSKi 细胞和 HPV-18 阳性 HeLa 细胞，我们发现 MAGI-1 是 HPV-16 和 HPV-18 E6 的主要降解目标。相比之下，hDlg、hScrib、PTPN3、TIP2、FAP1 和 PSD95 都对 E6 诱导的降解表现出不同程度的敏感性，并且对某些底物观察到高度的 HPV 类型特异性。我们还表明，E6 优先靶向细胞核内和膜位点的 MAGI-1。 MAGI-1 降解的直接后果之一是紧密连接完整性的丧失，这是由紧密连接蛋白 ZO-1 的错误定位决定的。 E6 表达的消除可恢复紧密连接，而这种恢复依赖于 MAGI-1 的存在。这些结果表明，致癌性 HPV E6 蛋白通过降解 MAGI-1 破坏细胞紧密连接，并进一步证明 E6 的 PDZ 结合潜力如何导致 HPV 诱导的恶性肿瘤。
The E6 proteins from high-risk, cancer-causing types of human papillomavirus (HPV) are characterized by the presence of a PDZ (PSD95/Dlg/ZO-1) binding motif in their extreme carboxy termini, through which they interact with a number of cellular PDZ domain-containing substrates. In order to ascertain how many of these are degraded by E6 in vivo, we performed an extensive analysis of the effects of E6 ablation on the expression levels of a number of previously reported E6 PDZ substrates. Using HPV type 16 (HPV-16)-positive CaSKi cells and HPV-18-positive HeLa cells, we have found that MAGI-1 is a major degradation target of both HPV-16 and HPV-18 E6. In contrast, hDlg, hScrib, PTPN3, TIP2, FAP1, and PSD95 all exhibit various degrees of susceptibility to E6-induced degradation, and a high degree of HPV type specificity is observed for certain substrates. We also show that E6 preferentially targets MAGI-1 within the nucleus and at membrane sites. One of the direct consequences of MAGI-1 degradation is a loss of tight-junction integrity, as determined by mislocalization of the tight-junction protein ZO-1. Ablation of E6 expression restores tight junctions, and this restoration is dependent on the presence of MAGI-1. These results demonstrate that oncogenic HPV E6 proteins disrupt cellular tight junctions through the degradation of MAGI-1, and they provide further evidence of how the PDZ binding potential of E6 can contribute to HPV-induced malignancy.