title: HPV16 E6 augments Wnt signaling in an E6AP-dependent manner.
abstract: In this study we investigated the effect of HPV16 E6 on the Wnt/beta-catenin oncogenic signaling pathway. Luciferase reporter assays indicated that ectopically expressed E6 significantly augmented the Wnt/beta-catenin/TCF-dependent signaling response in a dose-dependent manner. This activity was independent of the ability of E6 to target p53 for degradation or bind to the PDZ-containing E6 targets. Epistasis experiments suggested that the stimulatory effect is independent of GSK3beta or APC. Coexpression, half-life determination, cell fractionation and immunofluorescence analyses indicated that E6 did not alter the expression levels, stability or cellular distribution of beta-catenin. Further experiments using E6 mutants defective for E6AP binding and E6AP knockdown cells indicated the absolute requirement of the ubiquitin ligase E6AP for enhancement of the Wnt signal by E6. Thus, this study suggests a role for the E6/E6AP complex in augmentation of the Wnt signaling pathway which may contribute to HPV induced carcinogenesis.
authors.affiliation: Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel.
authors.forename: Hava
authors.initials: H
authors.lastname: Lichtig
authors.forename: Daniella Avital
authors.initials: DA
authors.lastname: Gilboa
authors.forename: Anna
authors.initials: A
authors.lastname: Jackman
authors.forename: Pinhas
authors.initials: P
authors.lastname: Gonen
authors.forename: Yaara
authors.initials: Y
authors.lastname: Levav-Cohen
authors.forename: Ygal
authors.initials: Y
authors.lastname: Haupt
authors.forename: Levana
authors.initials: L
authors.lastname: Sherman
mesh_terms: D002478:Cells, Cultured; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D009856:Oncogene Proteins, Viral / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000502:physiology; D012097:Repressor Proteins / Q000502:physiology*; D015398:Signal Transduction; D051820:TCF Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*; D051153:Wnt Proteins / Q000502:physiology*; D051176:beta Catenin / Q000502:physiology
chemical_list: C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D051820:TCF Transcription Factors; D016159:Tumor Suppressor Protein p53; D051153:Wnt Proteins; D051176:beta Catenin; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3; D046988:Proteasome Endopeptidase Complex