Scientists at the University College London, London, UK, have solved the mystery behind the miraculous age-reversing abilities of myelin-making Schwann cells, by identifying the protein that turns back the clock for the cells, returning them to their youthful state.
The researchers said that the finding might help researchers understand why myelin production falters in some diseases.
The cells have the ability to "dedifferentiate," or revert back to an immature state in which they can no longer manufacture myelin, in order to speed the healing of injured nerves.
Though it's known that the protein Krox-20 causes immature Schwann cells to grow up fast and start myelin production, no one has discovered what exactly caused them to reverse the process and return to youth until now.
One suspect was a protein called c-Jun, which youthful Schwann cells make but Krox-20 blocks.
For the study, David B. Parkinson and colleagues cultured neurons with Schwann cells whose c-Jun gene they could activate.
Turning on the gene curbed myelination, suggesting that c-Jun prevents young Schwann cells from growing up. c-Jun also prodded mature Schwann cells to become youthful again, the researchers discovered.
Schwann cells that are separated from neurons normally dedifferentiate, but the team found that the cells remained specialized if c-Jun was missing. They suspect that c-Jun works in part by activating Sox-2, as this protein also inhibits myelination.
The researchers now want to investigate whether c-Jun is involved in illnesses where myelin dwindles, such as Charcot-Marie Tooth disease and Guillain-Barre syndrome.
The results might also provide clues about multiple sclerosis, in which immune attacks destroy myelin in the central nervous system.
Unlike Schwann cells, oligodendrocytes, the myelin makers in the central nervous system, can't revert to an immature state. Whether c-Jun affects oligodendrocyte differentiation isn't known.
The study appears in the May 19 issue of the Journal of Cell Biology.