1. Academic Validation
  2. USP2 is an SKP2 deubiquitylase that stabilizes both SKP2 and its substrates

USP2 is an SKP2 deubiquitylase that stabilizes both SKP2 and its substrates

  • J Biol Chem. 2021 Oct;297(4):101109. doi: 10.1016/j.jbc.2021.101109.
Fengwu Zhang 1 Yongchao Zhao 2 Yi Sun 3
Affiliations

Affiliations

  • 1 Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China.
  • 2 Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China; Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Cancer Center, Zhejiang University, Hangzhou, China. Electronic address: yongchao@zju.edu.cn.
  • 3 Cancer Institute of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China; Institute of Translational Medicine, Zhejiang University School of Medicine, Hangzhou, China; Cancer Center, Zhejiang University, Hangzhou, China. Electronic address: yisun@zju.edu.cn.
Abstract

The stability of a protein is regulated by a balance between its ubiquitylation and deubiquitylation. S-phase kinase-associated protein 2 (SKP2) is an oncogenic F-box protein that recognizes tumor suppressor substrates for targeted ubiquitylation by the E3 ligase SKP1-Cullin1-F-box and degradation by Proteasome. SKP2 is itself ubiquitylated by the E3 Ligases APC/CCDH1 and SCFFBXW2, and deubiquitylated by deubiquitylases (DUBs) USP10 and USP13. Given the biological significance of SKP2, it is likely that the other E3s or DUBs may also regulate its stability. Here, we report the identification and characterization of USP2 as a new DUB. We first screened a panel of DUBs and found that both USP2 and USP21 bound to endogenous SKP2, but only USP2 deubiquitylated and stabilized SKP2 protein. USP2 inactivation via siRNA knockdown or small-molecule inhibitor treatment remarkably shortened SKP2 protein half-life by enhancing its ubiquitylation and subsequent degradation. Unexpectedly, USP2-stabilized SKP2 did not destabilize its substrates p21 and p27. Mechanistically, USP2 bound to SKP2 via the leucine-rich repeat substrate-binding domain on SKP2 to disrupt the SKP2-substrate binding, leading to stabilization of both SKP2 and these substrates. Biologically, growth suppression induced by USP2 knockdown or USP2 inhibitor is partially mediated via modulation of SKP2 and its substrates. Our study revealed a new mechanism of the cross-talk among the E3-DUB substrates and its potential implication in targeting the USP2-SKP2 axis for Cancer therapy.

Keywords

SKP1-Cullin1-F-box E3 (SCF E3); SKP2; USP2; deubiquitylation; ubiquitylation.

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