University of South Carolina neuroscientists have discovered how one common protein helps damaged nerves to heal. 

Coincidentally, it’s the same protein best known for breaking down nerve cells. 

Ashley Kalinski, assistant professor in the McCausland College of Arts and Sciences, found that the protein SARM1 is required for effective nerve healing. The research, published in Science Translational Medicine, reveals that SARM1 helps to create the cellular environment necessary for nerves to regrow, in addition to its role in degeneration. 

“Approximately 20 million Americans suffer nerve damage from physical injuries or disease," Kalinski says. “This work highlights the complexity of the nervous system and how hard it is to fix it when its damaged. Importantly, we realized that even if a protein (SARM1) has a major function, degeneration, its minor function, preparing the microenvironment for regrowth, is equally as important.” 

The protein SARM1 is found in many species “from flies to humans,” Kalinski says, allowing scientists many ways to study how the protein functions. In experiments with mice, Kalinski’s team found that deleting SARM1 delayed the clearance of damaged nerve fibers, as expected.  

"Without SARM1, the immune response is delayed,” Kalinski says. “This delay prevents the clearance of all the ‘gunk’ that is left when axons, or nerve cells, no longer connected to the cell body die. Regenerating axons don’t like that gunk.” 

Kalinski also found that SARM1 is required to activate Schwann cells ― part of the nervous system ― for working on nerve repair. "This reprogramming is essential because the repair Schwann cells secrete growth factors and provide the laminin tubes for regenerating axons to grow through,” Kalinski says. Without SARM1, the Schwann cells’ activity lagged, impairing nerve regrowth.

These findings highlight the protein’s dual function, both as a factor in degeneration and as a catalyst for regeneration. 

Kalinski noted that clinical studies are underway to test drugs that suppress SARM1 activity in humans to prevent nerve degeneration. “While that is obviously a great thing, our work highlights that SARM1 is not just a destroyer of axons,” she says. “We still do not fully understand the implications of what SARM1 inhibition could do to other cells.” 

Kalinski’s lab is already working on more research with SARM1 to explore why it is required in the immune response that clears old nerve cells. 

Kalinski’s lab is one of many at the University of South Carolina studying neurodevelopment and nerve repair. Scientists explore how the nervous system develops, how nerves get injured and break down, and how they can be repaired. 

"A healthy nervous system is critical to overall health and wellbeing, making this an important research area for many of us at the University of South Carolina," says Jeff Twiss, SmartState Chair in Childhood Neurotherapeutics and associate dean for research in the McCausland College of Arts and Sciences. "The work we are doing now sets the stage for new therapies to improve life years in the future."