commissural neuron axon guidance

Definition

Target type: biologicalprocess

The process in which the migration of an axon growth cone of a commissural neuron is directed to its target in the brain in response to a combination of attractive and repulsive cues. [GOC:BHF, GOC:mah]

Commissural neurons are a type of neuron that project axons across the midline of the nervous system. This process, known as commissural axon guidance, is essential for the formation of proper neural circuits. The guidance of commissural axons involves a complex interplay of signaling molecules, cell surface receptors, and cytoskeletal dynamics.

One key signaling molecule involved in commissural axon guidance is Netrin-1, a chemoattractant secreted from the floor plate, a specialized region of the ventral midline of the spinal cord. Netrin-1 binds to receptors on the surface of commissural axons, including DCC (Deleted in Colorectal Cancer) and Unc5, triggering downstream signaling cascades that promote axon growth towards the midline.

As commissural axons approach the midline, they encounter another key signaling molecule, Slit, a chemorepellent secreted from cells along the midline. Slit binds to Robo receptors on the surface of commissural axons. This interaction activates a signaling pathway that repels the axons from crossing the midline, preventing them from forming aberrant connections.

The guidance of commissural axons is also regulated by cell adhesion molecules, such as N-cadherin and Ephrins, which mediate cell-cell interactions and contribute to axon fasciculation and targeting. N-cadherin is expressed on both commissural axons and cells along the midline, promoting adhesion and facilitating axon crossing. Ephrins, on the other hand, are expressed in a gradient along the midline, providing positional cues for axon targeting.

In addition to these signaling molecules, cytoskeletal dynamics play a crucial role in commissural axon guidance. The growth cone, the tip of a growing axon, undergoes dynamic rearrangements of its microtubules and actin filaments in response to guidance cues. These rearrangements allow the axon to navigate towards attractive signals and away from repulsive signals.

In summary, the guidance of commissural axons is a complex and tightly regulated process involving multiple signaling molecules, cell adhesion molecules, and cytoskeletal dynamics. This intricate interplay of cues ensures that commissural axons reach their appropriate targets, contributing to the formation of functional neural circuits.'
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Compounds (807)