Journal article
Mutation of Putative GRK Phosphorylation Sites in the Cannabinoid Receptor 1 (CB1R) Confers Resistance to Cannabinoid Tolerance and Hypersensitivity to Cannabinoids in Mice
The Journal of neuroscience, Vol.34(15), pp.5152-5163
04/09/2014
DOI: 10.1523/JNEUROSCI.3445-12.2014
PMCID: PMC3983798
PMID: 24719095
Abstract
For many G-protein-coupled receptors (GPCRs), including cannabinoid receptor 1 (CB1R), desensitization has been proposed as a principal mechanism driving initial tolerance to agonists. GPCR desensitization typically requires phosphorylation by a G-protein-coupled receptor kinase (GRK) and interaction of the phosphorylated receptor with an arrestin. In simple model systems, CB1R is desensitized by GRK phosphorylation at two serine residues (S426 and S430). However, the role of these serine residues in tolerance and dependence for cannabinoids in vivo was unclear. Therefore, we generated mice where S426 and S430 were mutated to nonphosphorylatable alanines (S426A/S430A). S426A/S430A mutant mice were more sensitive to acutely administered delta-9-tetrahydrocannabinol (Delta(9)-THC), have delayed tolerance to Delta(9)-THC, and showed increased dependence for Delta(9)-THC. S426A/S430A mutants also showed increased responses to elevated levels of endogenous cannabinoids. CB1R desensitization in the periaqueductal gray and spinal cord following 7d of treatment with Delta(9)-THC was absent in S426A/S430A mutants. Delta(9)-THC-induced downregulation of CB1R in the spinal cord was also absent in S426A/S430A mutants. Cultured autaptic hippocampal neurons from S426A/S430A mice showed enhanced endocannabinoid-mediated depolarization-induced suppression of excitation (DSE) and reduced agonist-mediated desensitization of DSE. These results indicate that S426 and S430 play major roles in the acute response to, tolerance to, and dependence on cannabinoids. Additionally, S426A/S430A mice are a novel model for studying pathophysiological processes thought to involve excessive endocannabinoid signaling such as drug addiction and metabolic disease. These mice also validate the approach of mutating GRK phosphorylation sites involved in desensitization as a general means to confer exaggerated signaling to GPCRs in vivo.
Details
- Title: Subtitle
- Mutation of Putative GRK Phosphorylation Sites in the Cannabinoid Receptor 1 (CB1R) Confers Resistance to Cannabinoid Tolerance and Hypersensitivity to Cannabinoids in Mice
- Creators
- Daniel J. Morgan - Indiana University BloomingtonBrian J. Davis - Indiana University BloomingtonChris S. Kearn - University of WashingtonDavid Marcus - Indiana University BloomingtonAlex J. Cook - Indiana University BloomingtonJim Wager-Miller - Indiana UniversityAlex Straiker - Indiana University BloomingtonMichael H. Myoga - University of WashingtonJeffrey Karduck - Indiana University BloomingtonEmma Leishman - Indiana University BloomingtonLaura J. Sim-Selley - Virginia Commonwealth UniversityTraci A. Czyzyk - Indiana University BloomingtonHeather B. Bradshaw - Indiana University BloomingtonDana E. Selley - Virginia Commonwealth UniversityKen Mackie - Indiana University Bloomington
- Resource Type
- Journal article
- Publication Details
- The Journal of neuroscience, Vol.34(15), pp.5152-5163
- DOI
- 10.1523/JNEUROSCI.3445-12.2014
- PMID
- 24719095
- PMCID
- PMC3983798
- NLM abbreviation
- J Neurosci
- ISSN
- 0270-6474
- eISSN
- 1529-2401
- Publisher
- Soc Neuroscience
- Number of pages
- 12
- Grant note
- R01DA014277 / NATIONAL INSTITUTE ON DRUG ABUSE; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute on Drug Abuse (NIDA); European Commission DA011322; DA021696; DA014277; DA036385; DA015916 / National Institutes of Health; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA Lilly Foundation
- Language
- English
- Date published
- 04/09/2014
- Academic Unit
- Neurology
- Record Identifier
- 9984695678402771
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