Development of Degraders and 2-pyridinecarboxyaldehyde (2-PCA) as a recruitment Ligand for FBXO22

Area of Science:

• Biochemistry
• Molecular Biology
• Chemical Biology

Background:

• Targeted protein degradation (TPD) is a therapeutic strategy utilizing small molecules to link E3 ligases with target proteins.
• FBXO22, an E3 ligase overexpressed in cancers, has potential for TPD but requires optimized recruitment ligands.
• Previous studies showed FBXO22 recognizes ligands with primary amine degrons, necessitating further development.

Purpose of the Study:

• To discover and characterize chemical probes for FBXO22-targeted protein degradation.
• To develop tools for studying FBXO22 biology and its role in cancer.
• To expand the utility of FBXO22 in therapeutic applications.

Main Methods:

• Synthesis and evaluation of FBXO22 degraders, including AHPC(Me)-C6-NH2.
• Investigation of diamine analogs (hexane-1,6-diamine, putrescine, cadaverine) for FBXO22 self-degradation.
• Identification of 2-pyridinecarboxaldehyde (2-PCA) as a novel electrophilic degron for FBXO22 recruitment.
• Conjugation of 2-PCA to ligands to induce degradation of target proteins like BRD4 and CDK12.

Main Results:

• AHPC(Me)-C6-NH2 demonstrated potent and selective FBXO22 degradation (DC50 = 77 nM, Dmax = 99%).
• Hexane-1,6-diamine was identified as a minimal FBXO22 self-degrader, unlike shorter analogs.
• 2-PCA formed a reversible thioketal with Cys326, enabling FBXO22 recruitment.
• FBXO22-dependent degradation of BRD4 and CDK12 was achieved using 2-PCA-conjugated ligands.

Conclusions:

• Novel chemical probes were developed for selective FBXO22 degradation and recruitment.
• These probes enhance the study of FBXO22 function and its role in cancer.
• The findings broaden the application of FBXO22 in targeted protein degradation therapies.