1887

Abstract

The high-risk Human Papillomavirus (HPV) E6 oncoprotein is known to contribute to human malignancy by targeting several of its cellular substrates through the ubiquitin-mediated degradation pathway. Previous studies have revealed that E6 interacts with the E6AP ubiquitin-protein ligase and directs its ubiquitylation activity toward several specific cellular proteins, one of the most important of which is p53. However, the role of E6AP in the degradation of many other E6 substrates is still ambiguous because loss of E6AP also induces a loss of E6 expression. To examine this further, we used CRISPR-edited E6AP knockout cells to perform E6 degradation assays in the presence of a catalytically inactive mutant form of E6AP, thus ensuring the stabilization of E6 but with the ligase itself being functionally inactive. Using this system, we found that E6 can mediate the degradation of several PDZ domain-containing proteins independently of E6AP ubiquitin ligase activity. This study thus opens up ways to investigate other possible components of the cellular ubiquitin proteasome pathway that E6 might utilize to target these substrates.

Keyword(s): HPV , ubiquitin , proteasome , E6 , DLG , PDZ , p53 , MAGI and E6AP
Loading

Article metrics loading...

/content/journal/jgv/10.1099/jgv.0.001331
2019-10-14
2019-11-12
Loading full text...

Full text loading...

References

  1. Parkin DM, Bray F. Chapter 2: the burden of HPV-related cancers. Vaccine 2006;24:S11–S25 [CrossRef]
    [Google Scholar]
  2. zur Hausen H. Papillomaviruses and cancer: from basic studies to clinical application. Nat Rev Cancer 2002;2:342–350 [CrossRef]
    [Google Scholar]
  3. Androphy EJ, Hubbert NL, Schiller JT, Lowy DR. Identification of the HPV-16 E6 protein from transformed mouse cells and human cervical carcinoma cell lines. Embo J 1987;6:989–992 [CrossRef]
    [Google Scholar]
  4. Gaglia MM, Munger K. More than just oncogenes: mechanisms of tumorigenesis by human viruses. Curr Opin Virol 2018;32:48–59 [CrossRef]
    [Google Scholar]
  5. Smotkin D, Wettstein FO. Transcription of human papillomavirus type 16 early genes in a cervical cancer and a cancer-derived cell line and identification of the E7 protein. Proc Natl Acad Sci USA 1986;83:4680–4684 [CrossRef]
    [Google Scholar]
  6. Thomas M, Banks L. Upsetting the balance: when viruses manipulate cell polarity control. J Mol Biol 2018;430:3481–3503 [CrossRef]
    [Google Scholar]
  7. Münger K, Basile JR, Duensing S, Eichten A, Gonzalez SL et al. Biological activities and molecular targets of the human papillomavirus E7 oncoprotein. Oncogene 2001;20:7888–7898 [CrossRef]
    [Google Scholar]
  8. Scheffner M, Werness BA, Huibregtse JM, Levine AJ, Howley PM. The E6 oncoprotein encoded by human papillomavirus types 16 and 18 promotes the degradation of p53. Cell 1990;63:1129–1136 [CrossRef]
    [Google Scholar]
  9. Hengstermann A, D'silva MA, Kuballa P, Butz K, Hoppe-Seyler F et al. Growth suppression induced by downregulation of E6-AP expression in human papillomavirus-positive cancer cell lines depends on p53. J Virol 2005;79:9296–9300 [CrossRef]
    [Google Scholar]
  10. Huibregtse JM, Scheffner M, Howley PM. Cloning and expression of the cDNA for E6-AP, a protein that mediates the interaction of the human papillomavirus E6 oncoprotein with p53. Mol Cell Biol 1993;13:775–784 [CrossRef]
    [Google Scholar]
  11. Huibregtse JM, Scheffner M, Howley PM. Localization of the E6-AP regions that direct human papillomavirus E6 binding, association with p53, and ubiquitination of associated proteins. Mol Cell Biol 1993;13:4918–4927 [CrossRef]
    [Google Scholar]
  12. Scheffner M, Huibregtse JM, Vierstra RD, Howley PM. The HPV-16 E6 and E6-AP complex functions as a ubiquitin-protein ligase in the ubiquitination of p53. Cell 1993;75:495–505 [CrossRef]
    [Google Scholar]
  13. Gardiol D, Kühne C, Glaunsinger B, Lee SS, Javier R et al. Oncogenic human papillomavirus E6 proteins target the discs large tumour suppressor for proteasome-mediated degradation. Oncogene 1999;18:5487–5496 [CrossRef]
    [Google Scholar]
  14. Kiyono T, Hiraiwa A, Fujita M, Hayashi Y, Akiyama T et al. Binding of high-risk human papillomavirus E6 oncoproteins to the human homologue of the Drosophila discs large tumor suppressor protein. Proc Natl Acad Sci U S A 1997;94:11612–11616 [CrossRef]
    [Google Scholar]
  15. Nakagawa S, Huibregtse JM. Human scribble (Vartul) is targeted for ubiquitin-mediated degradation by the high-risk papillomavirus E6 proteins and the E6AP ubiquitin-protein ligase. Mol Cell Biol 2000;20:8244–8253 [CrossRef]
    [Google Scholar]
  16. Thomas M, Laura R, Hepner K, Guccione E, Sawyers C et al. Oncogenic human papillomavirus E6 proteins target the MAGI-2 and MAGI-3 proteins for degradation. Oncogene 2002;21:5088–5096 [CrossRef]
    [Google Scholar]
  17. Thomas M, Massimi P, Navarro C, Borg JP, Banks L. The hScrib/Dlg apico-basal control complex is differentially targeted by HPV-16 and HPV-18 E6 proteins. Oncogene 2005;24:6222–6230 [CrossRef]
    [Google Scholar]
  18. Javier RT. Cell polarity proteins: common targets for tumorigenic human viruses. Oncogene 2008;27:7031–7046 [CrossRef]
    [Google Scholar]
  19. Lee C, Laimins LA. Role of the PDZ domain-binding motif of the oncoprotein E6 in the pathogenesis of human papillomavirus type 31. J Virol 2004;78:12366–12377 [CrossRef]
    [Google Scholar]
  20. Handa K, Yugawa T, Narisawa-Saito M, Ohno SI, Fujita M et al. E6AP-dependent degradation of DLG4/PSD95 by high-risk human papillomavirus type 18 E6 protein. J Virol 2007;81:1379–1389 [CrossRef]
    [Google Scholar]
  21. Ye F, Zhang M. Structures and target recognition modes of PDZ domains: recurring themes and emerging pictures. Biochem J 2013;455:1–14 [CrossRef]
    [Google Scholar]
  22. Pim D, Bergant M, Boon SS, Ganti K, Kranjec C et al. Human papillomaviruses and the specificity of PDZ domain targeting. Febs J 2012;279:3530–3537 [CrossRef]
    [Google Scholar]
  23. Watson RA, Thomas M, Banks L, Roberts S. Activity of the human papillomavirus E6 PDZ-binding motif correlates with an enhanced morphological transformation of immortalized human keratinocytes. J Cell Sci 2003;116:4925–4934 [CrossRef]
    [Google Scholar]
  24. Vande Pol SB, Klingelhutz AJ. Papillomavirus E6 oncoproteins. Virology 2013;445:115–137 [CrossRef]
    [Google Scholar]
  25. Tomaić V, Pim D, Banks L. The stability of the human papillomavirus E6 oncoprotein is E6AP dependent. Virology 2009;393:7–10 [CrossRef]
    [Google Scholar]
  26. Thatte J, Banks L. Human papillomavirus 16 (HPV-16), HPV-18, and HPV-31 E6 override the normal phosphoregulation of E6AP enzymatic activity. J Virol 2017;91: [CrossRef]
    [Google Scholar]
  27. Talis AL, Huibregtse JM, Howley PM. The role of E6AP in the regulation of p53 protein levels in human papillomavirus (HPV)-positive and HPV-negative cells. J Biol Chem 1998;273:6439–6445 [CrossRef]
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/jgv/10.1099/jgv.0.001331
Loading
/content/journal/jgv/10.1099/jgv.0.001331
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error