title: The Subcellular Localisation of the Human Papillomavirus (HPV) 16 E7 Protein in Cervical Cancer Cells and Its Perturbation by RNA Aptamers.
abstract: Human papillomavirus (HPV) is the most common viral infection of the reproductive tract, affecting both men and women. High-risk oncogenic types are responsible for almost 90% of anogenital and oropharyngeal cancers including cervical cancer. Some of the HPV "early" genes, particularly E6 and E7, are known to act as oncogenes that promote tumour growth and malignant transformation. Most notably, HPV-16 E7 interacts with the tumour suppressor protein pRb, promoting its degradation, leading to cell cycle dysregulation in infected cells. We have previously shown that an RNA aptamer (termed A2) selectively binds to HPV16 E7 and is able to induce apoptosis in HPV16-transformed cervical carcinoma cell lines (SiHa) through reduction of E7 levels. In this study, we investigated the effects of the A2 aptamer on E7 localisation in order to define its effects on E7 activity. We demonstrate for the first time that E7 localised to the plasma membrane. In addition, we show that A2 enhanced E7 localisation in the ER and that the A2-mediated reduction of E7 was not associated with proteasomal degradation. These data suggest that A2 perturbs normal E7 trafficking through promoting E7 ER retention.
authors.affiliation: School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. bs09oc@leeds.ac.uk.
authors.forename: Özlem
authors.initials: Ö
authors.lastname: Cesur
authors.affiliation: School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. c.nicol@leeds.ac.uk.
authors.forename: Clare
authors.initials: C
authors.lastname: Nicol
authors.affiliation: School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. h.groves14@imperial.ac.uk.
authors.forename: Helen
authors.initials: H
authors.lastname: Groves
authors.affiliation: School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. j.mankouri@leeds.ac.uk.
authors.forename: Jamel
authors.initials: J
authors.lastname: Mankouri
authors.affiliation: School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. g.e.blair@leeds.ac.uk.
authors.forename: George Eric
authors.initials: GE
authors.lastname: Blair
authors.affiliation: School of Molecular and Cellular Biology, Faculty of Biological Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK. n.j.stonehouse@leeds.ac.uk.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Stonehouse
mesh_terms: D052157:Aptamers, Nucleotide / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000821:virology; D005260:Female; D015967:Gene Expression Regulation, Viral; D052162:Human papillomavirus 16 / Q000235:genetics* / Q000378:metabolism*; D006801:Humans; D050725:Papillomavirus E7 Proteins / Q000235:genetics / Q000378:metabolism*; D030361:Papillomavirus Infections / Q000821:virology*; D021381:Protein Transport; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000821:virology*
chemical_list: D052157:Aptamers, Nucleotide; D050725:Papillomavirus E7 Proteins; D012367:RNA, Viral; C059731:oncogene protein E7, Human papillomavirus type 16
keywords: ER retention; HPV16 E7; RNA aptamers; SELEX; cell surface localisation