Mutation at the Lmx1a locus provokes aberrant brain development in the rat

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• A spontaneous rat mutation,
• queue courte
• (qc), exhibits neurological defects.
• These abnormalities resemble those in the mouse
• dreher
• (dr) mutation affecting the LMX1A gene.

Purpose of the Study:

• To characterize the neurological defects and underlying genetic basis of the
• queue courte
• rat mutation.
• To investigate the mutation's impact on brain development, particularly the ventricular system and neuronal migration.

Main Methods:

• Histopathological examination of adult qc/qc rats.
• Genetic mapping of the qc mutation to rat chromosome 13.
• Northern blot analysis to assess Lmx1a expression.
• BrdU immunohistochemistry for neuronal migration analysis.

Main Results:

• qc/qc rats display cerebellar and hippocampal hypoplasia, choroid plexus and corpus callosum maldevelopment.
• Ventricular narrowing, distortion, neuroepithelial fusion, and rosettes observed from embryonic day 17.
• Disrupted radial glial processes and defective neuronal migration from the neuroepithelium were evident.
• Lmx1a expression was absent in qc/qc rats, suggesting allelism with the
• dreher
• mutation.

Conclusions:

• The
• queue courte
• mutation in rats is an autosomal recessive disorder affecting Lmx1a.
• The mutation impairs the development of the brain's ventricular system and disrupts dorsal neuronal migration.
• This provides a new model for studying neurodevelopmental disorders linked to LMX1A function.