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Critical Role of RPS4X in Modulating SCF Complex Formation and Cell Survival
Satsuki Ryu1, Min Ji Kim1, Shuya Bando2
1Faculty of Pharmaceutical Science at Kagawa Campus, Tokushima Bunri University, Takamatsu 760-8542, Kagawa, Japan.
Biomolecules
|October 29, 2025
Summary
The ribosomal protein S4 X-linked (RPS4X) disrupts the SCF ubiquitin ligase complex, stabilizing anti-apoptotic proteins and increasing cell resistance to doxorubicin-induced apoptosis. This highlights RPS4X
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Ribosomal proteins are primarily known for their role in protein synthesis.
- Emerging research reveals extraribosomal functions for some ribosomal proteins.
- The Skp1-Cullin1-F-box (SCF) ubiquitin ligase complex regulates protein degradation and cellular processes.
Purpose of the Study:
- To investigate the extraribosomal role of ribosomal protein S4 X-linked (RPS4X).
- To determine RPS4X's effect on the SCF ubiquitin ligase complex and apoptosis.
- To elucidate the mechanism by which RPS4X influences cellular responses to stress.
Main Methods:
- Cell culture (HeLa cells)
- Western blotting to assess protein levels and interactions
- Ubiquitination assays
- Apoptosis assays (e.g., doxorubicin-induced)
Main Results:
- RPS4X expression interfered with SCF complex formation by disrupting Cullin1-Skp1 interaction.
- Ubiquitination of SCF substrates, including anti-apoptotic proteins MCL1 and HAX1, was suppressed.
- Stabilization of MCL1 and HAX1 by RPS4X conferred resistance to doxorubicin-induced apoptosis in HeLa cells.
Conclusions:
- RPS4X modulates SCF complex activity, impacting protein homeostasis and apoptotic pathways.
- These findings reveal a novel extraribosomal function for RPS4X in regulating cellular survival.
- RPS4X's role in SCF complex regulation offers new therapeutic targets for apoptosis-related diseases.
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