engleski

HPV-16 E7 phoshorylation as a signature of malignancy

Among 200 Human papillomavirus (HPV) types which infect human epithelial cells only a small number of these are associated with human cancers at various anatomical sites, and they are referred as the high-risk types. Of these, cervical cancer is the most important disease which affects women predominantly in developing countries, causing more than 600, 000 cancers annually. The malignant development results from a joint action of the two main viral oncoproteins E6 and E7. They target various host proteins which are involved in the regulation of apoptosis, cell cycle control and cell polarity. E7 was shown to interact with many cellular proteins amongst which targeting of the retinoblastoma tumor suppressor (pRb) being the most relevant. Interestingly, it has been also shown that some of the other interactions were specifically modified by posttranslational modifications of E7. A good example of that is the phosphorylation of Ser31 and Ser32 by casein kinase II (CKII) which was demonstrated to play the pivotal role in modulating E7 interactions with cellular substrates. Older data have demonstrated that CKII phosphorylation plays a crucial role in E7s transformational capacity and that it is required for its interactions with TBP, while our more recent studies indicate that the upregulation in the phosphorylation of a variant of E7 leads to an increased capacity of E7 to target pRb and p130 for proteasome mediated degradation. In addition, our recent NMR analyses of CKII phosphorylated E7 reveal critical changes in the local conformation of the protein, thereby beginning to explain how phosphorylation might modulate E7 function.

HPV E7 ; phoshphorylation ; CKII

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