Scientists Uncover New Clues to Regenerating Damaged Nerve Cells

Rebecca Lewis November 12, 2013

American researchers have recently identified a chain reaction that triggers the regeneration of some damaged nerve cell branches, a groundbreaking discovery that can help improve treatments for nerve injuries.

Scientists knew all along that several genes contribute to the re-growth of damaged axons – nerve cell branches that send signals or electrical impulses to different neurons, muscles and glands throughout the body. They are much longer and more vulnerable to injury than dendrites (cells that receive messages). But until now, it is unknown what activates the expression of these genes, and hence, the repair process. The new study found that activating a protein called HDAC5 in the central nervous system may turn on the regeneration of nerve cell branches in the central nervous system where injuries often cause lasting paralysis.

In the peripheral nervous system – the network of nerve cells outside the brain and spinal column, cells naturally regenerate damaged axons. However, in the central nervous system which is comprised of the brain and the spinal cord, injured nerve cells do not replace lost axons. The researchers found that the central nervous system is missing the HDAC5 protein in the chain reaction.

The researchers learned that after leaving the nucleus, the HDAC5 stimulates a number of genes to initiate the regeneration of nerve cells. What’s more, in the peripheral nervous system, it travels to the site of injury to assist in the production of microtubules – the rigid tubes that act as support structures for the cell and help establish the structure of the replacement axon. In the central nervous system however, they found that the HDAC5 did not travel to the site of injury. They conclude that the failure of this essential protein to get out of the nucleus may be one of the key reasons why cells in the brain and spinal cord do not regenerate axons.

“This gives us the hope that if we can find ways to manipulate this system in brain and spinal cord neurons, we can help the cells of the central nervous system regrow lost branches," says senior author Valeria Cavalli, PhD, assistant professor of neurobiology at Washington University School of Medicine. "This puts us a step closer to one day being able to develop treatments that enhance axon regrowth."

Their findings were published in the journal Cell.

Source of this article:

Injury-induced HDAC5 nuclear export is essential for axon regeneration