Nav2 hypomorphic mutant mice are ataxic and exhibit abnormalities in cerebellar development

Area of Science:

• Neuroscience
• Developmental Biology
• Molecular Biology

Background:

• Cerebellar development is critical for motor function, involving precise neuronal migration and outgrowth.
• Neuron navigator 2 (Nav2) is a cytoskeletal protein known to regulate neurite outgrowth and axonal elongation.

Purpose of the Study:

• To investigate the role of full-length Nav2 in cerebellar development and function.
• To elucidate the impact of Nav2 deficiency on neuronal migration and process outgrowth in the cerebellum.

Main Methods:

• Utilized hypomorphic mutant mice lacking full-length Nav2 transcript.
• Analyzed cerebellar development at embryonic day (E)17.5, including size, foliation, and cell proliferation (BrdU labeling).
• Examined granule cell migration and neurite outgrowth using cerebellar explants and isolated cell cultures.

Main Results:

• Nav2 hypomorphic mice exhibited ataxia and cerebellar developmental defects, including reduced size and abnormal foliation at E17.5.
• Reduced cell proliferation was observed at early developmental stages (E12.5, E14.5) in mutants.
• Granule cells in Nav2 mutants showed impaired migration from the external granule layer (EGL) and reduced neurite outgrowth.

Conclusions:

• Full-length Nav2 plays an essential role in cerebellar development.
• Nav2 is critical for axonal elongation and migration of external granule layer neurons.
• Disruption of Nav2 function leads to defects in parallel fiber formation and cerebellar motor function.