Cytoskeletal organization of the developing mouse olfactory nerve layer.

Area of Science:

• Neuroscience
• Developmental Biology
• Cell Biology

Background:

• Olfactory sensory neuron (OSN) axons navigate the olfactory nerve layer (ONL) to target the olfactory bulb (OB).
• The ONL has distinct sublaminae (outer ONLo and inner ONLi) with differing axon organization.
• Cadherin-2 and gamma-catenin are differentially expressed in OSN axons within the ONL during development.

Purpose of the Study:

• To investigate the differential expression and organization of cytoskeletal elements in OSN axons across the ONL.
• To test the hypothesis that cytoskeletal proteins are unevenly distributed within the ONL during perinatal development.

Main Methods:

• Immunofluorescence staining of OSN axons in the olfactory nerve layer (ONL) at postnatal day 0 (P0).
• Analysis of cytoskeletal components including microfilaments, microtubules, vimentin, peripherin, and alpha-internexin.
• Measurement of OSN axon diameter in the outer (ONLo) and inner (ONLi) sublaminae.

Main Results:

• Microfilaments, microtubules, and vimentin showed homogeneous expression across the ONL.
• Peripherin and alpha-internexin were preferentially localized to the ONLo, with alpha-internexin in a subset of OSNs.
• OSN axons in the ONLo were significantly smaller than those in the ONLi.

Conclusions:

• Cytoskeletal proteins, specifically intermediate filaments peripherin and alpha-internexin, are differentially regulated across the ONL.
• Down-regulation of certain cytoskeletal elements and adhesion molecules occurs as axons exit the ONLo for targeting.
• Changes in axon diameter and cytoskeletal composition may facilitate glomerular targeting and terminal bouton formation.