Development and Characterization of Potent Succinate Receptor Fluorescent Tracers.

Area of Science:

• Pharmacology and Medicinal Chemistry
• Molecular Biology and Biochemistry

Background:

• The succinate receptor (SUCNR1) is a therapeutic target for metabolic and inflammatory diseases like hypertension and arthritis.
• Species-specific differences in SUCNR1 pharmacology between humans and rodents hinder drug development and validation.

Purpose of the Study:

• To develop novel fluorescent tool compounds for SUCNR1 research.
• To investigate and define species-specific differences in ligand binding to human and mouse SUCNR1.

Main Methods:

• Development of fluorescent agonist and antagonist tool compounds based on known SUCNR1 ligand scaffolds.
• Characterization of ligand binding affinities for human and mouse SUCNR1 orthologs.
• Introduction of specific humanizing mutations into mouse SUCNR1 to assess their impact on antagonist binding.

Main Results:

• A potent fluorescent agonist tracer (TUG-2384) was developed, binding to both human and mouse SUCNR1.
• A novel fluorescent antagonist tracer (TUG-2465) with high affinity for human SUCNR1 was synthesized.
• Three specific mutations in mouse SUCNR1 (N18^1.31E, K269^7.32N, G84^EL1W) were found to restore high-affinity antagonist binding.

Conclusions:

• Novel fluorescent SUCNR1 ligands provide valuable tools for studying receptor pharmacology.
• Key amino acid differences in SUCNR1 explain species-specific antagonist binding.
• Humanizing mutations can bridge the pharmacological gap, facilitating the development of SUCNR1-targeted therapeutics.