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Updated: Feb 6, 2026
Evaluation of Substrate Ubiquitylation by E3 Ubiquitin-ligase in Mammalian Cell Lysates
Published on: May 10, 2022
Chemical probes of Skp2-mediated p27 ubiquitylation and degradation
Lea Lough1, Dan Sherman1, Eric Ni1
1Department of Biochemistry and Molecular Pharmacology , New York University School of Medicine , New York , NY 10016 , USA . Email: cardot01@nyumc.org ; ; Tel: +1 212 263 6337.
Abstract:
Skp2 is a member of the F-box family of proteins that serve as substrate-specific adaptors in Skp1-CUL1-ROC1-F-box (SCF) E3 ubiquitin ligases. Skp2 (Fbxl1) directly binds to the tumor suppressor p27 in the context of the SCFSkp2 E3 ubiquitin ligase to ubiquitylate and target-phosphorylated p27 for proteasomal degradation. As p27 is a powerful suppressor of growth in a variety of cells, and as Skp2 is also overexpressed in many human cancers, Skp2 is considered an oncogene and an intriguing drug target. However, despite 20 years of investigation, a valid chemical inhibitor of Skp2-mediated degradation of p27 has not been identified. Recently, an increasing number of compounds designed to have this bioactivity have been reported. Here, we conduct a meta-analysis of the evidence regarding bioactivity, structure, and medicinal chemistry in order to evaluate and compare these Skp2 inhibitor compounds. Despite chemically diverse compounds with a wide array of Skp2-mediated p27 ubiquitylation inhibition properties reported by several independent groups, no current chemical probe formally qualifies as a validated pharmaceutical hit compound. This finding suggests that our knowledge of the structural biochemistry of the Skp2-p27 complex remains incomplete and highlights the need for novel modes of inquiry.
Insights
Despite extensive research, no validated chemical inhibitors targeting Skp2 (F-box protein) and its role in cancer have been identified. This meta-analysis highlights gaps in understanding the Skp2-p27 complex for drug development.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Skp2 is an F-box protein crucial for SCF E3 ubiquitin ligase complex formation.
- Skp2 targets the tumor suppressor p27 for proteasomal degradation, promoting cell growth.
- Overexpression of Skp2 is linked to various human cancers, making it a significant drug target.
Purpose of the Study:
- To conduct a meta-analysis of reported Skp2 inhibitor compounds.
- To evaluate and compare the bioactivity, structure, and medicinal chemistry of these compounds.
- To assess their potential as validated pharmaceutical hit compounds.
Main Methods:
- Meta-analysis of existing scientific literature.
- Evaluation of reported bioactivity data for Skp2 inhibitors.
- Assessment of structure-activity relationships and medicinal chemistry properties.
Main Results:
- Diverse chemical compounds with varying Skp2-p27 ubiquitylation inhibition properties were reported.
- No current chemical probe meets the criteria for a validated pharmaceutical hit compound.
- Significant variability exists in reported inhibitory activities and compound characteristics.
Conclusions:
- Current Skp2 inhibitor compounds lack validation as pharmaceutical hits.
- Incomplete understanding of the Skp2-p27 complex's structural biochemistry hinders drug development.
- Novel research approaches are needed to advance Skp2-targeted cancer therapies.
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