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Olfaction

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Related Experiment Video

Updated: Jun 29, 2026

Live-cell Measurement of Odorant Receptor Activation Using a Real-time cAMP Assay

Live-cell Measurement of Odorant Receptor Activation Using a Real-time cAMP Assay

Published on: October 2, 2017

Emx2 stimulates odorant receptor gene expression.

Jeremy C McIntyre¹, Soma C Bose, Arnold J Stromberg

¹Department of Physiology, University of Kentucky, Lexington, KY 40536-0298, USA.

Chemical Senses

|October 16, 2008

Summary

The homeobox transcription factor Emx2 is crucial for olfactory sensory neuron (OSN) gene expression, regulating many odorant receptors (ORs). Emx2 deficiency significantly reduces OR expression, impacting odor discrimination.

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Assaying Surface Expression of Chemosensory Receptors in Heterologous Cells

Assaying Surface Expression of Chemosensory Receptors in Heterologous Cells

Published on: February 23, 2011

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Last Updated: Jun 29, 2026

Live-cell Measurement of Odorant Receptor Activation Using a Real-time cAMP Assay

Live-cell Measurement of Odorant Receptor Activation Using a Real-time cAMP Assay

Published on: October 2, 2017

Assaying Surface Expression of Chemosensory Receptors in Heterologous Cells

Assaying Surface Expression of Chemosensory Receptors in Heterologous Cells

Published on: February 23, 2011

Area of Science:

Neuroscience
Genetics
Molecular Biology

Background:

Olfactory sensory neurons (OSNs) express a single odorant receptor (OR) gene, forming a pattern essential for odor discrimination.
The mechanisms governing this OR gene selection remain largely unknown.
Homeobox transcription factors, like Emx2, are implicated due to homeodomain-like sites in OR promoters.

Purpose of the Study:

To investigate the role of the homeobox transcription factor Emx2 in regulating odorant receptor (OR) gene expression in olfactory sensory neurons (OSNs).
To determine if Emx2 influences the selection and expression levels of specific OR genes.

Main Methods:

Analysis of OR gene expression in Emx2-deficient (Emx2(-/-)) mice at embryonic day 18.5.
Quantification of OSNs expressing individual ORs using specific metrics.
Assessment of changes in both Class I and Class II ORs, as well as other neuron-enriched mRNAs.

Main Results:

Emx2 deficiency led to a significant decrease (49-76%) in the expression of many ORs, primarily due to fewer OSNs expressing each OR.
Affected ORs showed disproportionately greater decreases than the overall reduction in mature neurons.
While most ORs were downregulated, a small percentage of Class II ORs showed increased expression, suggesting Emx2-independent regulation for some genes.

Conclusions:

Emx2 plays a vital role in stimulating the transcription of a broad range of OR genes, likely through direct promoter interaction.
Emx2 does not appear to regulate other critical aspects of OR gene expression, such as zonal patterning or the singularity of gene choice.
These findings highlight Emx2 as a key regulator of OR expression necessary for olfactory sensory neuron function.