title: Ubiquitin-dependent proteolysis of trihydrophobin 1 (TH1) by the human papilloma virus E6-associated protein (E6-AP).
abstract: Human Papilloma virus E6-associated protein (E6-AP), which is known as an E3 ubiquitin ligase, mediates ubiquitination and subsequent degradation of a series of cellular proteins. In this paper, we identify here trihydrophobin 1 (TH1), an integral subunit of the human negative transcription elongation factor (NELF) complex, as a novel E6-AP interaction protein and a target of E6-AP-mediated degradation. Overexpression of E6-AP results in degradation of TH1 in a dose-dependent manner, whereas knock-down of endogenous E6-AP elevates the TH1 protein level. TH1 protein turnover is substantially faster, compared to controls, in cells that overexpressed E6-AP. Wild-type E6-AP promotes the ubiquitination of TH1, while a catalytically inactive point mutant of E6-AP abolishes its ubiquitination. Furthermore, in vitro ubiquitination assay also demonstrates that TH1 can be ubiquitinated by E6-AP. The degradation is blocked by treatment with proteasome inhibitor MG132. Herein, we provide strong evidence that TH1 is a specific substrate that is targeted for degradation through E6-AP-catalyzed polyubiquitination.
authors.affiliation: Key Laboratory of Medical Molecular Virology Ministry of Education and Health, Gene Research Center, Shanghai Medical College and Institutes of Biomedical Science of Fudan University, Shanghai 200032, P.R. China.
authors.forename: Yanzhong
authors.initials: Y
authors.lastname: Yang
authors.forename: Weicheng
authors.initials: W
authors.lastname: Liu
authors.forename: Weiying
authors.initials: W
authors.lastname: Zou
authors.forename: Hanzhou
authors.initials: H
authors.lastname: Wang
authors.forename: Hongliang
authors.initials: H
authors.lastname: Zong
authors.forename: Jianhai
authors.initials: J
authors.lastname: Jiang
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Wang
authors.forename: Jianxin
authors.initials: J
authors.lastname: Gu
mesh_terms: D006528:Carcinoma, Hepatocellular / Q000473:pathology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D015723:Gene Library; D005982:Glutathione Transferase / Q000378:metabolism; D006207:Half-Life; D006367:HeLa Cells; D052163:Human papillomavirus 6 / Q000201:enzymology*; D006801:Humans; D006868:Hydrolysis; D008113:Liver Neoplasms / Q000473:pathology; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids; D017354:Point Mutation; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D014157:Transcription Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D009856:Oncogene Proteins, Viral; D011994:Recombinant Proteins; D014157:Transcription Factors; D014452:Ubiquitins; C118437:negative elongation factor; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases; D005982:Glutathione Transferase