L-DOPA Receptor GPR143 Functionally Couples with Adrenergic α_1B Receptor at the Second Transmembrane Interface

Area of Science:

• Neuropharmacology
• G protein-coupled receptor research
• Cell signaling

Background:

• Adrenergic receptors (ADRs) are vital in the nervous system.
• L-3,4-dihydroxyphenylalanine (L-DOPA) sensitizes adrenergic α1 receptor (ADRA1) through GPR143.
• Previous studies highlighted the role of GPR143 in ADR signaling.

Purpose of the Study:

• To elucidate the specific domains of GPR143 involved in ADRA1 sensitization.
• To investigate the molecular mechanism underlying the interaction between GPR143 and ADRA1B.
• To identify key regions for functional coupling between these receptors.

Main Methods:

• Chimeric receptor analysis swapping transmembrane domains between GPR143 and GPR37.
• HEK293T cell co-expression systems for ADRA1B and GPR143.
• Extracellular signal-regulated kinase (ERK) phosphorylation assays.
• Immunoprecipitation using a synthetic peptide targeting GPR143 TM2.

Main Results:

• The second transmembrane (TM2) domain of GPR143 is essential for potentiating phenylephrine-induced ERK phosphorylation.
• GPR143 co-expression augmented phenylephrine-induced ERK phosphorylation in ADRA1B-expressing cells.
• A synthetic peptide targeting GPR143 TM2 disrupted GPR143-ADRA1B interaction and suppressed signaling potentiation.

Conclusions:

• The interaction between GPR143 and ADRA1B is necessary for GPR143-mediated potentiation of ADRA1B signaling.
• GPR143's TM2 region serves as a critical dimeric interface for functional coupling.
• This interaction is key for understanding ADR signaling modulation by GPR143.