Fbxw7 acts as an E3 ubiquitin ligase that targets c-Myb for Nemo-like kinase (NLK)-induced degradation

Chie Kanei-Ishii, Teruaki Nomura, Tsuyoshi Takagi, Nobumoto Watanabe, Keiichi I. Nakayama, Shunsuke Ishii

研究成果: ジャーナルへの寄稿学術誌査読

51 被引用数 (Scopus)


The c-myb proto-oncogene product (c-Myb) is degraded in response to Wnt-1 signaling via a pathway involving TAK1 (transforming growth factor-β- activated kinase 1), HIPK2 (homeodomain-interacting protein kinase 2), and NLK (Nemo-like kinase). NLK directly binds to c-Myb, which results in the phosphorylation of c-Myb at multiple sites, and induces its ubiquitination and proteasome-dependent degradation. Here, we report that Fbxw7, the F-box protein of an SCF complex, targets c-Myb for degradation in a Wnt-1- and NLK-dependent manner. Fbxw7α directly binds to c-Myb via its C-terminal WD40 domain and induces the ubiquitination of c-Myb in the presence of NLK in vivo and in vitro. The c-Myb phosphorylation site mutant failed to interact with Fbxw7α, suggesting that the c-Myb/Fbxw7α interaction is enhanced by NLK phosphorylation of c-Myb. Treatment of M1 cells with Fbxw7 small interfering RNA (siRNA) rescued the Wnt-induced c-Myb degradation and also the Wnt-induced inhibition of cell proliferation. NLK bound to Cul1, a component of the SCF complex, while HIPK2 interacted with both Fbxw7α and Cul1, suggesting that both kinases enhance the c-Myb/SCF interaction. In contrast to c-Myb, the v-myb gene product (v-Myb) encoded by the avian myeloblastosis virus was resistant to NLK/Fbxw7α-induced degradation. Thus, Fbxw7 is an E3 ubiquitin ligase of c-Myb, and the increased c-Myb levels may contribute, at least partly, to transformation induced by mutation of Fbxw7.

ジャーナルJournal of Biological Chemistry
出版ステータス出版済み - 11月 7 2008

!!!All Science Journal Classification (ASJC) codes

  • 生化学
  • 分子生物学
  • 細胞生物学


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