Development of a Testing Funnel for Identification of Small-Molecule Modulators Targeting Secretin Receptors.

Area of Science:

• Pharmacology
• Biochemistry
• Drug Discovery

Background:

• The secretin receptor (SCTR), a class B G protein-coupled receptor (GPCR), plays a role in various physiological processes and diseases like heart failure, obesity, and diabetes.
• Discovering non-peptide ligands for SCTR is challenging, limiting therapeutic interventions.

Purpose of the Study:

• To establish a high-throughput screening (HTS) platform for identifying small-molecule positive allosteric modulators (PAMs) of the SCTR.
• To validate and characterize novel SCTR-targeting small molecules.

Main Methods:

• Development of a unique primary screening assay using a mixture of orthosteric stimulators to test 12,000 small molecules.
• Implementation of secondary assays, including radiolabel-free target engagement and NanoBiT-based β-arrestin-2 recruitment assays for high-throughput profiling.
• Validation and characterization of identified hit compounds for allosteric activity.

Main Results:

• A testing funnel was created, enabling the targeted detection of SCTR small-molecule activators.
• Five promising molecular scaffolds were discovered, with four validated for their allosteric modulatory effects on SCTR.
• The developed assays are suitable for high-throughput screening and ligand profiling.

Conclusions:

• The study presents a successful strategy for discovering small-molecule SCTR PAMs, overcoming challenges in class B GPCR drug discovery.
• The identified scaffolds represent potential starting points for developing novel therapeutics targeting SCTR for various diseases.
• This work lays the foundation for the development of the first in vivo active small molecules targeting SCTRs.