Fluorescent Human EP3 Receptor Antagonists | JoVE Visualize

Area of Science:

Medicinal Chemistry
Pharmacology
Molecular Imaging

Background:

The human Prostaglandin E receptor 3 (hEP3R) is a G protein-coupled receptor implicated in various physiological processes.
Development of specific ligands for hEP3R is crucial for understanding its function and for therapeutic applications.
Fluorescent probes offer valuable tools for visualizing and characterizing receptor distribution and activity in biological systems.

Purpose of the Study:

To synthesize and characterize novel fluorescent ligands targeting hEP3R.
To evaluate the potential of these ligands as pharmacological tools for hEP3R visualization and functional antagonism.
To investigate the inhibitory effects of these ligands on platelet aggregation.

Main Methods:

Synthesis of ortho-substituted cinnamic acid derivatives functionalized with various fluorophores via a dimethylene spacer.
Determination of ligand affinity for hEP3R using binding assays.
Visualization of hEP3Rs in HT-29 cells, murine kidney, and human brain tissues using confocal laser scanning microscopy.
Functional characterization as antagonists on human platelets, measuring inhibition of prostaglandin E2 (PGE2) and collagen-induced aggregation.

Main Results:

Novel hEP3R ligands with nanomolar affinities were successfully synthesized.
The synthesized compounds exhibited fluorescence across the blue, green, and red spectrum.
hEP3Rs were successfully visualized in various tissue types, and the ligands demonstrated antagonist activity on human platelets, inhibiting aggregation.
Pyryllium-labeled ligand 8 showed particularly promising fluorescence properties and high affinity for hEP3R antagonism.

Conclusions:

The developed fluorescent ligands are potent and selective hEP3R antagonists.
These ligands serve as effective tools for visualizing hEP3R distribution in cellular and tissue contexts.
The findings highlight the potential of these novel compounds as pharmacological agents for studying hEP3R-related pathways and conditions, particularly those involving platelet function.