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Published on: July 3, 2015
Facilitation of μ-opioid receptor activity by preventing δ-opioid receptor-mediated codegradation
Shao-Qiu He1, Zhen-Ning Zhang, Ji-Song Guan
1Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China.
Abstract:
δ-opioid receptors (DORs) form heteromers with μ-opioid receptors (MORs) and negatively regulate MOR-mediated spinal analgesia. However, the underlying mechanism remains largely unclear. The present study shows that the activity of MORs can be enhanced by preventing MORs from DOR-mediated codegradation. Treatment with DOR-specific agonists led to endocytosis of both DORs and MORs. These receptors were further processed for ubiquitination and lysosomal degradation, resulting in a reduction of surface MORs. Such effects were attenuated by treatment with an interfering peptide containing the first transmembrane domain of MOR (MOR(TM1)), which interacted with DORs and disrupted the MOR/DOR interaction. Furthermore, the systemically applied fusion protein consisting of MOR(TM1) and TAT at the C terminus could disrupt the MOR/DOR interaction in the mouse spinal cord, enhance the morphine analgesia, and reduce the antinociceptive tolerance to morphine. Thus, dissociation of MORs from DORs in the cell membrane is a potential strategy to improve opioid analgesic therapies.
Insights
Dissociating delta-opioid receptors (DORs) from mu-opioid receptors (MORs) prevents MOR degradation, enhancing morphine
Area of Science:
- Neuroscience
- Pharmacology
- Molecular Biology
Background:
- Delta-opioid receptors (DORs) form heteromers with mu-opioid receptors (MORs).
- DORs negatively regulate MOR-mediated spinal analgesia through unclear mechanisms.
- Understanding MOR/DOR interactions is crucial for improving opioid therapies.
Purpose of the Study:
- To elucidate the mechanism by which DORs regulate MOR activity.
- To investigate strategies for enhancing MOR-mediated analgesia and reducing tolerance.
- To explore the therapeutic potential of disrupting MOR/DOR interactions.
Main Methods:
- Treatment with DOR-specific agonists and an interfering peptide (MOR(TM1)).
- Analysis of receptor endocytosis, ubiquitination, and lysosomal degradation.
- In vivo studies in mice using a MOR(TM1)-TAT fusion protein.
Main Results:
- DOR activation promotes MOR/DOR heteromer endocytosis and subsequent lysosomal degradation.
- The MOR(TM1) peptide disrupts MOR/DOR interactions and prevents MOR degradation.
- Systemic administration of MOR(TM1)-TAT enhances morphine analgesia and reduces antinociceptive tolerance in mice.
Conclusions:
- Preventing MOR/DOR codegradation enhances MOR activity and analgesic efficacy.
- Disrupting MOR/DOR interactions is a promising strategy for improving opioid therapies.
- Targeting MOR/DOR dissociation may offer a novel approach to pain management.
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