UBE2O and USP7 co-regulate RECQL4 ubiquitinylation and homologous recombination-mediated DNA repair

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• RECQL4 is crucial for genomic stability and DNA repair.
• Its post-translational modifications, key to its regulation, are not fully understood.

Purpose of the Study:

• To elucidate the regulatory mechanisms of RECQL4, focusing on its post-translational modifications.
• To investigate the role of the ubiquitin-conjugating enzyme UBE2O in RECQL4 regulation and DNA repair.

Main Methods:

• Co-immunoprecipitation to confirm physical interaction between UBE2O and RECQL4.
• Western blotting to detect multi-monoubiquitinylation and proteasomal degradation of RECQL4.
• Assays to evaluate homologous recombination (HR)-mediated DNA double-strand breaks (DSBs) repair.
• Analysis of protein-protein interactions involving RECQL4, UBE2O, and USP7.

Main Results:

• UBE2O directly interacts with RECQL4 and mediates its multi-monoubiquitinylation, leading to proteasomal degradation.
• UBE2O inhibits HR-mediated DSBs repair in a manner dependent on its catalytic activity and RECQL4.
• UBE2O disrupts the interaction between RECQL4 and key DNA repair proteins (MRE11-RAD50-NBS1 complex and CtIP).
• Deubiquitinylase USP7 interacts with both UBE2O and RECQL4, antagonizing UBE2O's regulatory effects on RECQL4.

Conclusions:

• UBE2O acts as a negative regulator of RECQL4 stability and function.
• A novel ubiquitin-mediated pathway involving UBE2O and USP7 regulates RECQL4 in HR-mediated DSBs repair.
• This discovery sheds light on the intricate mechanisms governing genomic stability and DNA repair.