和田　圭司    Department   Other, Other    Position
Article types	Original article
Language	English
Peer review	Peer reviewed
Title	Ro52-mediated monoubiquitination of IKK{beta} down-regulates NF-{kappa}B signalling.
Journal	Formal name：Journal of biochemistry Abbreviation：J Biochem ISSN code：(1756-2651)0021-924X(Linking)
Domestic / Foregin	Foregin
Volume, Issue, Page	146(6),pp.821-32
Author and coauthor	Wada Keiji, Niida Motoko, Tanaka Makoto, Kamitani Tetsu
Publication date	2009/12
Summary	Upon activation, NF-kappaB translocates into the nucleus and initiates biological events. This NF-kappaB signalling is mainly regulated by the protein kinase IKKbeta. Early in this signalling pathway, IKKbeta is phosphorylated for activation by several factors, such as pro-inflammatory cytokines and the Tax oncoprotein of HTLV-1. In cells infected by HTLV-1, IKKbeta is persistently phosphorylated and conjugated with monoubiquitin due to Tax expression. Although this Tax-induced monoubiquitination appears to be an important regulation system for IKKbeta, how the monoubiquitination occurs is unknown and its role in NF-kappaB signalling is still unclear. Here, we show that an E3-ubiquitin ligase Ro52 interacts weakly with wild-type IKKbeta but strongly with a phosphomimetic mutant IKKbeta to conjugate monoubiquitin in cooperation with an E2-ubiquitin-conjugating enzyme UbcH5B. These results suggest that the Tax-induced phosphorylation of IKKbeta causes an interaction with Ro52 for the subsequent monoubiquitination. NF-kappaB reporter assays have shown that the IKKbeta activity is suppressed by wild-type Ro52, but not by its inactive mutant. In addition, monoubiquitin fusion of IKKbeta reduced its activity for NF-kappaB signalling. We also found that Ro52 dramatically reduces the level of Tax. These results suggest that Ro52 down-regulates Tax-induced NF-kappaB signalling by monoubiquitinating IKKbeta and by reducing the level of Tax.
DOI	10.1093/jb/mvp127
PMID	19675099