title: Downregulation of active IKK beta by Ro52-mediated autophagy.
abstract: Upon activation, NF-kappaB translocates into the nucleus and initiates many biological events. This NF-kappaB signaling is mainly induced by the protein kinase IKK beta. Early in this signaling pathway, IKK beta is phosphorylated for activation by several factors, such as pro-inflammatory cytokines and the Tax oncoprotein of human T-cell leukemia virus type 1 (HTLV-1). In cells expressing Tax protein, IKK beta is persistently phosphorylated, which chronically activates NF-kappaB signaling. But the active IKK beta is conjugated with a monoubiquitin by the E3 ubiquitin ligase Ro52, and the IKK beta-induced NF-kappaB signaling is downregulated. However, the mechanism of the downregulation has been unknown. Here, we show that Ro52-mediated monoubiquitination is involved in the subcellular translocation of active IKK beta to autophagosomes. Furthermore, using reporter assays, we show that Ro52 suppresses IKK beta-induced NF-kappaB signaling and that this suppression is blocked by an autophagy inhibitor. These results suggest that Ro52-mediated monoubiquitination plays a critical role in the downregulation of active IKK beta through autophagy.
authors.affiliation: Department of Cardiology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Motoko
authors.initials: M
authors.lastname: Niida
authors.forename: Makoto
authors.initials: M
authors.lastname: Tanaka
authors.forename: Tetsu
authors.initials: T
authors.lastname: Kamitani
mesh_terms: D019943:Amino Acid Substitution; D001343:Autophagy / Q000502:physiology*; D001693:Biological Transport, Active; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000737:chemistry / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism; D010766:Phosphorylation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination; D000097573:Red Fluorescent Protein; D000099207:SS-A Antigen
chemical_list: D004268:DNA-Binding Proteins; D049452:Green Fluorescent Proteins; D051550:I-kappa B Kinase; D008164:Luminescent Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012261:Ribonucleoproteins; D044767:Ubiquitin-Protein Ligases; D000097573:Red Fluorescent Protein; D000099207:SS-A Antigen; C485184:enhanced green fluorescent protein