Microvillous cells expressing IP3 receptor type 3 in the olfactory epithelium of mice

Area of Science:

• Neuroscience
• Cell Biology
• Sensory Biology

Background:

• Microvillous cells in the main olfactory epithelium have ambiguous classifications, including primary olfactory neurons, secondary chemosensory cells, or non-sensory cells.
• The precise function and identity of these cells remain unclear, leading to varied descriptions in scientific literature.

Purpose of the Study:

• To characterize the cells expressing inositol trisphosphate receptor type 3 (IP3R3) within the olfactory epithelium.
• To determine if these IP3R3-expressing cells are olfactory sensory neurons or a distinct cell type.

Main Methods:

• Generated a transgenic mouse model (IP3R3(tm1(tauGFP))) to specifically label IP3R3-expressing cells.
• Utilized immunohistochemistry, retrograde labeling, unilateral bulbectomy, and intracellular calcium recordings.
• Assessed cellular responses to various stimuli, including odors, ATP, and substance P.

Main Results:

• Identified and termed IP3R3 MV cells based on their microvilli and IP3R3 expression.
• Demonstrated that IP3R3 MV cells lack axonal projections to the olfactory bulb, confirming they are not olfactory sensory neurons.
• Observed varied immunohistochemical features and functional responses, suggesting developmental heterogeneity or distinct subsets.
• Confirmed chemoresponsiveness to odors, ATP, and substance P in IP3R3 MV cells.

Conclusions:

• IP3R3 MV cells are non-neuronal, chemoresponsive cells within the olfactory epithelium.
• These findings resolve the ambiguity surrounding microvillous cell classification and contribute to understanding olfactory epithelium function.