Smurf1-mediated axin ubiquitination requires Smurf1 C2 domain and is cell cycle-dependent.
Previously, Smad ubiquitination regulatory factor 1 (Smurf1)-mediated Lys29 (K29)-linked poly-ubiquitination of Axin has been identified as a novel regulatory process in Wnt/β-catenin signaling. In this work, we discovered that the C2 domain of Smurf1 is critical for targeting Axin for ubiquitination. We found that the C2 domain-mediated plasma membrane localization of Smurf1 is required for Axin ubiquitination, and interfering with that disturbs the co-localization of Smurf1 and Axin around the plasma membrane. Moreover, the C2 domain of Smurf1, rather than its WW domains, is involved in Smurf1's interaction with Axin; and the putative PPXY motifs (PY motif) of Axin are not essential for such an interaction, indicating that Smurf1 binds to Axin in a non-canonical way independent of WW-PY interaction. Further, we found that Smurf1-Axin interaction and Axin ubiquitination are attenuated in the G2/M phase of cell cycle, contributing to an increased cell response to Wnt stimulation at that stage. Collectively, we uncovered a dual role of Smurf1 C2 domain, recruiting Smurf1 to membrane for accessing Axin and mediating its interaction with Axin, and that Smurf1-mediated Axin ubiquitination is subjected to the regulation of cell cycle.
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China cfei@sibcb.ac.cn.
Cong
C
Fei
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Xiaoli
X
He
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Sichun
S
Xie
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Haofei
H
Miao
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Zhilei
Z
Zhou
From the State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China lli@sibs.ac.cn.
Lin
L
Li
D000818:Animals; D060466:Axin Protein / Q000378:metabolism*; D002453:Cell Cycle; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*; D054875:Ubiquitination; D060449:Wnt Signaling Pathway; D051176:beta Catenin / Q000378:metabolism
D060466:Axin Protein; D051176:beta Catenin; C498342:SMURF1 protein, human; D044767:Ubiquitin-Protein Ligases
Beta-catenin; Cell Cycle; Protein-Protein Interactions; Ubiquitination; Wnt Signaling