文章基本信息

标题：M-phase kinases induce phospho-dependent ubiquitination of somatic Wee1 by SCFβ-TrCP
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作者：Nobumoto Watanabe ; Harumi Arai ; Yoshifumi Nishihara 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：13
页码：4419-4424
DOI：10.1073/pnas.0307700101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Wee1, the Cdc2 inhibitory kinase, needs to be down-regulated at the onset of mitosis to ensure rapid activation of Cdc2. Previously, we have shown that human somatic Wee1 (Wee1A) is down-regulated both by protein phosphorylation and degradation, but the underlying mechanisms had not been elucidated. In the present study, we have identified the {beta}-transducin repeat-containing protein 1/2 ({beta}-TrCP1/2) F-box protein-containing SKP1/Cul1/F-box protein (SCF) complex (SCF{beta}-TrCP1/2) as an E3 ubiquitin ligase for Wee1A ubiquitination. Although Wee1A lacks a consensus DS(p)GXXS(p) phospho-dependent binding motif for {beta}-TrCP, recognition of Wee1A by {beta}-TrCP depended on phosphorylation, and two serine residues in Wee1A, S53 and S123, were found to be the most important phosphorylation sites for {beta}-TrCP recognition. We have found also that the major M-phase kinases polo-like kinase 1 (Plk1) and Cdc2 are responsible for the phosphorylation of S53 and S123, respectively, and that in each case phosphorylation generates an unconventional phospho-degron (signal for degradation) that can be recognized by {beta}-TrCP. Phosphorylation of Wee1A by these kinases cooperatively stimulated the recognition and ubiquitination of Wee1A by SCF{beta}-TrCP1/2 in vitro. Mutation of these residues or depletion of {beta}-TrCP by small-interfering RNA treatment increased the stability of Wee1A in HeLa cells. Moreover, our analysis indicates that {beta}-TrCP-dependent degradation of Wee1A is important for the normal onset of M-phase in vivo. These results also establish the existence of a feedback loop between Cdc2 and Wee1A in somatic cells that depends on ubiquitination and protein degradation and ensures the rapid activation of Cdc2 when cells are ready to divide.