Discovery of a 53BP1 Small Molecule Antagonist Using a Focused DNA-Encoded Library Screen
Devan J Shell1, Caroline A Foley1, Qinhong Wang2
1UNC Eshelman School of Pharmacy, Center for Integrative Chemical Biology and Drug Discovery, Chemical Biology and Medicinal Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Abstract:
Methyl-lysine reader p53 binding protein 1 (53BP1) is a central mediator of DNA break repair and is associated with various human diseases, including cancer. Thus, high-quality 53BP1 chemical probes can aid in further understanding the role of 53BP1 in genome repair pathways. Herein, we utilized focused DNA-encoded library screening to identify the novel hit compound UNC8531, which binds the 53BP1 tandem Tudor domain (TTD) with an IC50 of 0.47 ± 0.09 μM in a TR-FRET assay and Kd values of 0.85 ± 0.17 and 0.79 ± 0.52 μM in ITC and SPR, respectively. UNC8531 was cocrystallized with the 53BP1 TTD to guide further optimization efforts, leading to UNC9512. NanoBRET and 53BP1-dependent foci formation experiments confirmed cellular target engagement. These results show that UNC9512 is a best-in-class small molecule 53BP1 antagonist that can aid further studies investigating the role of 53BP1 in DNA repair, gene editing, and oncogenesis.
Insights
Researchers developed UNC9512, a potent small molecule antagonist targeting p53 binding protein 1 (53BP1). This chemical probe aids in studying 53BP1
Area of Science:
- Molecular Biology
- Biochemistry
- Chemical Biology
Background:
- p53 binding protein 1 (53BP1) is crucial for DNA damage repair.
- Dysregulation of 53BP1 is implicated in cancer and other diseases.
- High-quality chemical probes are needed to study 53BP1's function.
Purpose of the Study:
- To identify and develop novel small molecule inhibitors of 53BP1.
- To characterize the binding affinity and cellular activity of identified compounds.
- To provide tools for investigating 53BP1's role in genome stability and disease.
Main Methods:
- DNA-encoded library screening for 53BP1 inhibitors.
- Biophysical assays (TR-FRET, ITC, SPR) for binding characterization.
- Cellular assays (NanoBRET, foci formation) for target engagement.
Main Results:
- Identified UNC8531, a novel 53BP1 tandem Tudor domain (TTD) binder.
- Optimized UNC8531 to UNC9512, a best-in-class 53BP1 antagonist.
- Confirmed cellular target engagement and activity of UNC9512.
Conclusions:
- UNC9512 is a validated chemical probe for 53BP1.
- This antagonist can advance research in DNA repair, gene editing, and cancer biology.
- The developed probes facilitate understanding of 53BP1's role in human diseases.
