Inhibition of human papillomavirus type 16 E7 phosphorylation by the S100 MRP-8/14 protein complex
Inhibition of human papillomavirus type 16 E7 phosphorylation by the S100 MRP-8/14 protein complex
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DOI：
10.1128/jvi.79.2.1099-1112.2005
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发表时间：
2005-01-01
影响因子：
5.4
通讯作者：
Palefsky, J
中科院分区：
文献类型：
--
作者：
Tugizov, S;Berline, J;Palefsky, J
人乳头瘤病毒16型(HPV16)E7是一种主要的病毒癌蛋白，被酪蛋白激酶11(CKII)磷酸化。两个S100家族钙结合蛋白，巨噬细胞抑制相关因子蛋白8(MRP-8)和MRP-14，形成了一个蛋白质复合体，MRP-8/14，可使CKII失活。MRP-8/14蛋白复合体可能抑制CKII介导的E7磷酸化，从而改变其与细胞配体的相互作用，从而降低E7的致癌活性。我们检测了MRP-8/14复合体对CKII活性和HPV16E7磷酸化的抑制作用。外源性MRP-8/14的摄取和内源性MRP-8/14的激活抑制了CKII活性和HPV16 E7的磷酸化。MRP-8/14介导的E7磷酸化抑制发生在细胞周期的G1期。对原代角质形成细胞以及HPV16和18转化的宫颈和包皮上皮细胞系中MRP表达的分析表明，MRP-8、MRP-14和MRP-8/14复合体仅在原代未转化的角质形成细胞中表达，而在HPV感染的永生化上皮细胞中不表达。HPV永生化角质形成细胞中的CKII活性大约是HPV阴性原代角质形成细胞的四倍。用外源性MRP-8/14处理HPV阳性永生化上皮细胞，在2周内可使E7蛋白去磷酸化并完全抑制细胞生长，而HPV阴性的原代和永生化HPV阴性的永生化上皮细胞的生长抑制率分别为25%和40%。这些结果表明，HPV感染的上皮细胞中的MRP-8/14蛋白复合体可能在调节CKII介导的E7磷酸化和抑制其致癌活性方面发挥重要作用。
The human papillomavirus type 16 (HPV16) E7 is a major viral oncoprotein that is phosphorylated by casein kinase 11 (CKII). Two S100 family calcium-binding proteins, macrophage inhibitory-related factor protein 8 (MRP-8) and MRP-14, form a protein complex, MRP-8/14, that inactivates CKII. The MRP-8/14 protein complex may inhibit CKII-mediated E7 phosphorylation and therefore may alter its interaction with cellular ligands and reduce E7 oncogenic activity. We examined the inhibitory effect of the MRP-8/14 complex on CKII activity and HPV16 E7 phosphorylation. We have shown that CKII activity and HPV16 E7 phosphorylation were inhibited by uptake of exogenous MRP-8/14 and activation of endogenous MRP-8/14. MRP-8/14-mediated inhibition of E7 phosphorylation occurred at the G, phase of the cell cycle. Analysis of MRP expression in primary keratinocytes and in HPV16- and 18-transformed cervical and foreskin epithelial cell lines showed that expression of MRP-8, MRP-14, and the MRP-8/14 complex was detected only in primary untransformed keratinocytes and not in the HPV-infected immortalized epithelial cells. CKII activity in HPV-immortalized keratinocytes was approximately fourfold higher than in HPV-negative primary keratinocytes. Treatment of HPV-positive immortalized epithelial cells with exogenous MRP-8/14 resulted in E7 hypophosphorylation and complete inhibition of cell growth within 2 weeks, compared with HPV-negative primary and immortalized HPV-negative cervical epithelial cells, which showed 25 and 40% growth inhibition, respectively. Together these results suggests that the MRP-8/14 protein complex in HPV-infected epithelial cells may play an important role in regulation of CKII-mediated E7 phosphorylation and inhibition of its oncogenic activity.