Cannabinoid Receptor Signaling is Dependent on Sub-Cellular Location

Area of Science:

• Cellular Biology
• Molecular Pharmacology
• Neuroscience

Background:

• G protein-coupled receptors (GPCRs) are crucial for human physiology, with signaling occurring at both cell surface and internal membranes.
• Cannabinoid receptor 1 (CB1) signaling is increasingly recognized to be influenced by its subcellular localization.
• Understanding CB1's location-dependent signaling is key to deciphering its complex physiological roles.

Approach:

• Investigated the impact of promoter choice and genetic tags on CB1 receptor subcellular localization and downstream signaling.
• Utilized genetically encodable non-canonical amino acids (ncAA) and copper-free click chemistry for live-cell fluorophore tagging of CB1 and CB2 receptors.
• Examined the coupling of CB1 receptors to Gαi and Gαs proteins based on their localization.

Key Points:

• CB1 receptors predominantly signal through Gαi when localized to internal membranes, often driven by low-expressing promoters and lacking N-terminal tags.
• CB1 receptors predominantly signal through Gαs when localized to the plasma membrane, typically resulting from strong promoters or N-terminal tags.
• Non-canonical amino acid tagging provides a method to tag receptors with fluorophores without disrupting CB1 signaling or trafficking.

Conclusions:

• Subcellular localization critically dictates CB1 receptor signaling pathways (Gαi vs. Gαs).
• Experimental control over CB1 localization and signaling is achievable through strategic promoter selection and genetic tagging.
• Novel ncAA-based tagging strategies enable precise tracking of cannabinoid receptor dynamics in living cells.