title: E6AP ubiquitin ligase mediates ubiquitin-dependent degradation of peroxiredoxin 1.
abstract: E6-associated protein (E6AP) is a cellular ubiquitin protein ligase that mediates ubiquitylation and degradation of tumor suppressor p53 in conjunction with the high-risk human papillomavirus E6 protein. We previously reported that E6AP targets annexin A1 protein for ubiquitin-dependent proteasomal degradation. To gain a better understanding of the physiological function of E6AP, we have been seeking to identify novel substrates of E6AP. Here, we identified peroxiredoxin 1 (Prx1) as a novel E6AP-binding protein using a tandem affinity purification procedure coupled with mass spectrometry. Prx1 is a 25-kDa member of the Prx family, a ubiquitous family of antioxidant peroxidases that regulate many cellular processes through intracellular oxidative signal transduction pathways. Immunoprecipitation analysis showed that E6AP binds Prx1 in vivo. Pull-down experiments showed that E6AP binds Prx1 in vitro. Ectopic expression of E6AP enhanced the degradation of Prx1 in vivo. In vivo and in vitro ubiquitylation assays revealed that E6AP promoted polyubiquitylation of Prx1. RNAi-mediated downregulation of endogenous E6AP increased the level of endogenous Prx1 protein. Taken together, our data suggest that E6AP mediates the ubiquitin-dependent proteasomal degradation of Prx1. Our findings raise a possibility that E6AP may play a role in regulating Prx1-dependent intracellular oxidative signal transduction pathways.
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.
authors.forename: Junichi
authors.initials: J
authors.lastname: Nasu
authors.forename: Kyoko
authors.initials: K
authors.lastname: Murakami
authors.forename: Shoji
authors.initials: S
authors.lastname: Miyagawa
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Yamashita
authors.forename: Tohru
authors.initials: T
authors.lastname: Ichimura
authors.forename: Takaji
authors.initials: T
authors.lastname: Wakita
authors.forename: Hak
authors.initials: H
authors.lastname: Hotta
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Miyamura
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Suzuki
authors.forename: Tazuko
authors.initials: T
authors.lastname: Satoh
authors.forename: Ikuo
authors.initials: I
authors.lastname: Shoji
mesh_terms: D000975:Antioxidants; D002460:Cell Line; D006801:Humans; D010084:Oxidation-Reduction; D054464:Peroxiredoxins / Q000378:metabolism*; D011485:Protein Binding; D015398:Signal Transduction; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D025801:Ubiquitin; D054464:Peroxiredoxins; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases