Olfactory receptor surface expression is driven by association with the beta2-adrenergic receptor

Area of Science:

• Biochemistry
• Neuroscience
• Molecular Biology

Background:

• Olfactory receptors (ORs) are a major class of G protein-coupled receptors (GPCRs).
• Wild-type ORs exhibit poor cell surface expression in heterologous systems, hindering functional studies.
• Receptor-receptor interactions are known to influence GPCR trafficking.

Purpose of the Study:

• To investigate if interactions with other GPCRs can enhance olfactory receptor surface expression.
• To determine the role of beta-adrenergic receptor (AR) subtypes in OR trafficking.
• To demonstrate functional expression of a wild-type OR in a heterologous system.

Main Methods:

• Coexpression of mouse 71 (M71) OR with various beta-AR subtypes in HEK293 cells.
• Coimmunoprecipitation and cointernalization assays to assess receptor interaction.
• Ligand-induced cAMP assays to measure functional activity.
• In situ hybridization to examine receptor colocalization in olfactory epithelium.

Main Results:

• Coexpression with beta(2)-ARs, but not other AR subtypes, dramatically increased M71 OR surface expression.
• A persistent physical association between M71 OR and beta(2)-AR was confirmed.
• Coexpression enabled functional cAMP responses to the M71 ligand, acetophenone.
• Extensive colocalization of M71 OR and beta(2)-AR was observed in mouse olfactory epithelium.

Conclusions:

• Successful heterologous surface expression of a functional wild-type OR is achieved.
• Persistent physical association with beta(2)-ARs controls OR surface expression.
• This interaction provides a novel strategy for studying olfactory receptor function.