Visualization and ligand-induced modulation of dopamine receptor dimerization at the single molecule level

Area of Science:

• Pharmacology
• Neuroscience
• Cell Biology

Background:

• G protein-coupled receptors (GPCRs), including dopamine receptors, are key drug targets.
• Increased dopamine receptor D2 homodimerization is implicated in schizophrenia pathophysiology.
• Investigating these dimers can elucidate their role in disease.

Purpose of the Study:

• To investigate the formation and modulation of dopamine receptor D2 homodimers.
• To explore the potential of targeting receptor dimerization for therapeutic insights.

Main Methods:

• Single-molecule TIRF microscopy to observe transient homodimer formation.
• Cryogenic localization microscopy to confirm physical interaction and measure protomer distance.
• Utilizing stably transfected CHO cells expressing dopamine receptors.

Main Results:

• Observed transient homodimer formation of dopamine receptors at the single-molecule level.
• Ligand binding modulated the dimer-monomer equilibrium: agonists increased dimerization, while antagonists did not.
• Bivalent D2 ligands significantly enhanced D2 receptor dimer formation.
• Confirmed physical interaction between protomers with centers of mass approximately 9 nm apart.

Conclusions:

• Dopamine receptor D2 homodimerization is ligand-dependent, with agonists promoting dimer formation.
• These findings provide a molecular basis for the role of dopamine receptor D2 dimers in schizophrenia.
• Targeting receptor dimerization represents a potential therapeutic strategy for neurological disorders.