Reeler

Reeler refers to a gene and the resulting protein that plays a crucial role in neuronal migration during brain development. Discovered in mice, the reelin gene is essential for the proper positioning of neurons within the cerebral cortex and other brain structures. When the reelin gene is mutated, neurons fail to migrate correctly, leading to a disorganized brain architecture. This disorganized structure is often characterized by an inversion of the cortical layers, where neurons that should be on the surface are found deeper within the brain.

The reelin protein is a secreted extracellular matrix glycoprotein. It acts as a signaling molecule, interacting with receptors on migrating neurons and influencing their movement. This signaling pathway is critical for guiding neurons to their final destinations. Without functional reelin, the "stop" signal that normally halts neuronal migration at the correct layer is absent or weakened, causing neurons to overshoot their intended locations.

Mutations in the reelin gene or related signaling pathway components are associated with neurological disorders. In mice, reeler mutations result in a distinct phenotype characterized by ataxia and tremors, reflecting the severe disruption of brain circuitry. While the reelin gene is highly conserved across species, suggesting its fundamental importance, the specific consequences of reelin dysfunction in humans are complex and can vary depending on the mutation. Research into reelin continues to provide insights into the intricate mechanisms of brain development and the origins of neurological abnormalities.