Genetic discovery offers clues for repairing damaged neural connections
· News-MedicalA new discovery by neuroscientists at Brown University's Carney Institute for Brain Science challenges long-held beliefs in neurobiology about how neurons extend axons to reach their targets.
Published in PNAS, the findings provide what the authors call a "genetic atlas" of neuronal development as well as a potential step forward for understanding how to repair broken neural connections in conditions such as stroke and spinal cord injury.
Axons are critical components of neural wiring. During embryonic development, they shoot out from neurons like plant tendrils searching for light, traveling along intricate and sometimes long pathways to reach target cells. For example, the axon of a motor neuron that enables foot movement extends all the way to the foot from the base of the spine.
A team of researchers in Jaworski's lab discovered a new twist: Axons are actually controlled by a genetic switch in the cell body of the neuron.
Prior to this study, researchers knew that part of the secret to an axon's long-distance travel is that they stop at intermediate waystations en route to their destination. As they pass through a waystation, axons pivot as needed to aim for the next one - a process called axon pathfinding.
To understand this process in more depth, the researchers focused on commissural neurons, which connect the left and right sides of the central nervous system. This specific neuron type is particularly useful to study because its axon makes a distinct, sharp change in direction as it crosses the spinal cord midline.
"Now that we know about this genetic switch in the neuron, we might be one step closer to finding a way to actually turn on the specific genes that allow axons to grow back to their correct targets," Jaworski said.
"We're beginning to perceive the bigger picture of axon pathfinding, moving beyond the actions of individual molecules," Jaworski said. "How entire groups of genes collaborate to shape axon pathfinding decisions is an exciting research question the field doesn't yet fully understand."
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