University of Missouri researchers have determined that the proteins previously thought to play a significant role in the development of the nervous system are not in fact an essential part of the process.
For the last 15 years, the proposed underlying mechanism for an axon’s diameter growth, which is part of the myelination process, had focused on myelin-dependent modification of regions of neurofilaments that are located within the heavy and medium subunits. In a previous study, genetically removing the region of the medium subunit that is modified impaired growth and slowed nerve conduction.
This did not, however, directly test if the proposed modification was required, as a much larger region was genetically removed. The scientists thus genetically altered neurofilament medium subunits such that they could no longer be modified in response to myelination.
To their surprise, the team found that prevention of that modification did not influence axonal diameter. “It is now clear that the basic mechanism for how neurofilaments affect axonal diameters remains unanswered,” says Michael Garcia, Ph.D., assistant professor of biological sciences in the University of Missouri College of Arts and Science.
These results appear in the The Journal of Neuroscience.