Regenerate Nerves: Protein Discovered That Helps Neurons Heal

Scientists have identified a protein that tells peripheral nerve cells when they are damaged, and when they should regenerate. The findings could help establish a procedure for helping regulate the regeneration of nerve cells.

Peripheral nerve cells are the ones that drive muscles and provide a sense of touch. After they are cut or crushed, they do have the ability to regenerate, although the process has largely been shrouded in mystery, until now.

The team of researchers from the Washington University School of Medicine in St. Louis identified dual leucine zipper kinase (DLK) as a protein that regulates the signals telling a peripheral nerve to regenerate or not. It can do this over distances as large as several feet. 

They published their findings in the journal Neuron.

"DLK is a key molecule linking an injury to the nerve's response to that injury, allowing the nerve to regenerate," says Aaron DiAntonio, M.D., PhD, professor of developmental biology. "How does an injured nerve know that it is injured? How does it take that information and turn on a regenerative program and regrow connections? And why does only the peripheral nervous system respond this way, while the central nervous system does not? We think DLK is part of the answer."

The central nervous system is more rigid, and does not have the ability like the peripheral nervous system to regenerate as well. The scientists think this may have to do with the presence of DLK.

"Since this sort of signaling doesn't appear to happen in the central nervous system, it's possible these nerves don't 'know' when they are injured," DiAntonio said. "It's an exciting idea - but not at all proven - that activating DLK in the central nervous system could promote its regeneration."

The main body, or nucleus, or peripheral nerves lie in the spinal cord. From there, they extend long, spindly branches known as axons that reach out to muscles and the tips of fingers and toes. If the axon is severed or damaged, DLK helps the separated part disintegrate and tells the part of the axon still connected to the spinal cord to regrow or extend.

It has also been proven that axons injured more than once regrow faster than axons that receive a first-time injury. This may be due to the presence of DLK left over from the first injury, which expedites regeneration.