Régulation du récepteur aux opioïdes de type delta par les protéines Homer1

Compared to other opioid receptors, the delta opioid receptor (DOP), a G proteincoupled receptor (GPCR), is considered a promising therapeutic target for chronic pain management. However, DOP mainly localizes to intracellular compartments whereas its analgesic effects occur when translocated to the plasma membrane. The mechanisms involved in its trafficking remain also poorly known. Recently, liquid chromatographytandem mass spectrometry (LC-MS/MS) analyses established the DOP interactome, which included Homer Protein Homolog 1 (Homer1). Interestingly, it was reported that its short and long isoforms, namely Homer1a and Homer1b, regulate the cell-surface expression of various GPCR. Furthermore, neuropathic and inflammatory models demonstrated pain modulation by Homer1. We thus hypothesized that Homer1 isoforms regulate DOP. Resuming preliminary work on this project (Degrandmaison, 2023) with DOP and Homer1 human orthologs (hDOP, Homer1a and Homer1b), we first determined that Homer1b interacts with the hDOP C-terminal (CT) and third intracellular loop (ICL3) in GSTPulldowns binding assays. We then generated truncated, alanine and phosphomimetic GSThDOP-CT mutants to investigate a potential Homer1 consensus binding motif. Whereas amino acids 339 to 354 of hDOP-CT were important to Homer1 binding, individual residues within this sequence were not identified as essential for this interaction. Indirect ELISA assays in HEK 293 cells resulted in a decrease in hDOP cell-surface expression with transient overexpression of Homer1b; preliminary results showed also a decrease of hDOP cellsurface expression with CT 339 and 354 deletions. Furthermore, endogenous Homer1b colocalization with stably expressed hDOP in HEK 293 cells was observed at the plasma membrane and in intracellular compartments by confocal fluorescence microscopy. Lastly, stimulation of hDOP with SNC80 and [D-Ala2] Deltorphine II did not show any significant Homer1 regulatory effect on ERK1/2 signaling pathway. Altogether, these results will further our understanding of the role and pharmacological potential of Homer1 interaction with DOP.

Name thesis:degree_name

M. Sc.

Level thesis:degree_level

Maîtrise

Discipline thesis:degree_discipline

Pharmacologie

Grantor dc:publisher

Université de Sherbrooke

Year dc:date.issued

2025

Author dc:creator

• Grisé, Olivier

Advisors dc:contributor.advisor

• Parent, Jean-Luc
• Gendron, Louis

• Récepteur couplé aux protéines G (RCPG)
• Récepteur aux opioïdes de type delta (DOP)
• Homer1
• Douleur
• G protein-coupled receptors (GPCR)
• Delta-opioid receptor (DOP)
• Pain

Language dc:language.iso

fr

Handle dc:identifier.uri

http://hdl.handle.net/11143/22548

OAI identifier oai:identifier

oai:usherbrooke.scholaris.ca:11143/22548