SENP1 Decreases RNF168 Phase Separation to Promote DNA Damage Repair and Drug Resistance in Colon Cancer

Area of Science:

• Molecular Biology
• Genomic Stability
• Cancer Research

Background:

• The DNA damage response (DDR) is crucial for maintaining genomic stability.
• Protein posttranslational modifications, such as SUMOylation, regulate DDR.
• RNF168 is a key E3 ubiquitin ligase involved in DNA repair pathways.

Purpose of the Study:

• To investigate the role of RNF168 SUMOylation in the DNA damage response.
• To identify the deSUMOylase of RNF168 and its function in DNA repair.
• To explore the therapeutic potential of targeting the RNF168-SENP1 axis in cancer.

Main Methods:

• Western blotting to detect SUMOylated RNF168.
• Immunofluorescence microscopy to visualize RNF168 and 53BP1 localization.
• Cell-based assays to assess DNA repair efficiency and chemosensitivity.
• Analysis of patient data to correlate SENP1 expression with prognosis.

Main Results:

• SUMOylated RNF168 undergoes liquid-liquid phase separation (LLPS), impairing its recruitment to DNA damage sites.
• RNF168-catalyzed H2A ubiquitination and 53BP1 recruitment are reduced by RNF168 LLPS.
• Sentrin/SUMO-specific protease 1 (SENP1) deSUMOylates RNF168, preventing LLPS and promoting DNA repair.
• High SENP1 expression in colorectal adenocarcinoma correlates with poor prognosis and chemotherapy resistance.

Conclusions:

• SUMOylation-induced LLPS of RNF168 suppresses the DNA damage response.
• SENP1 promotes DNA repair and cancer cell resistance to DNA damaging agents by inhibiting RNF168 LLPS.
• SENP1 is a potential therapeutic target for enhancing chemotherapy efficacy in cancer patients.