Scientists have identified a gene that helps regulate how well nerves of the central nervous system are insulated, a finding that may have implications for human diseases such as multiple sclerosis.
Healthy insulation is vital for the speedy propagation of nerve cell signals.
Nerve cells send electrical signals along lengthy projections called axons. These signals travel much faster when the axon is wrapped in myelin, an insulating layer of fats and proteins.
In the central nervous system, the cells responsible for insulating axons are called oligodendrocytes.
The research, in zebrafish and mice, focused on a gene called Gpr56, which manufactures a protein of the same name.
Researchers at Washington University School of Medicine in St Louis found that when the protein Gpr56 is disabled, there are too few oligodendrocytes to provide insulation for all of the axons. Still, the axons looked normal.
And in the relatively few axons that were insulated, the myelin also looked normal. But the researchers observed many axons that were simply bare, not wrapped in any myelin at all.
Without Gpr56, the cells responsible for applying the insulation failed to reproduce themselves sufficiently, according to the study's senior author, Kelly R Monk.
These cells actually matured too early instead of continuing to replicate as they should have. Consequently, in adulthood, there were not enough mature cells, leaving many axons without insulation.
"We first saw this defect in the developing zebrafish embryo," said first author Sarah D Ackerman, a graduate student in Monk's lab.
Senior author Xianhua Piao, of Harvard University, and her co-authors, including Monk, showed similar defects in mice without Gpr56.
In past work, Piao also has shown evidence that human defects in Gpr56 lead to brain malformations related to a lack of myelin.
"Dr Piao's research in human patients suggests that similar mechanisms are at work in people," Monk said.
Monk also said that Gpr56 belongs to a large class of cell receptors that are common targets for many commercially available drugs, making the protein attractive for further research.
The investigators pointed out its possible relevance in treating diseases associated with a lack of myelin, with particular interest in multiple sclerosis.
"In the case of MS, there are areas where the central nervous system has lost its myelin," Monk said.
The study appears in the journal Nature Communications.
