USC Researchers Closer To Cure Myelin-related Diseases

[Guest guest]

Researchers Closer To Cure For Multiple Sclerosis And Other Myelin-

related Diseases

(NOTE: THIS MENTIONS PERIPHERAL NEUROPATHIES)

http://www.sciencedaily.com/releases/2006/11/061103083630.htm

A breakthrough finding on the mechanism of myelin formation by Jonah

Chan, assistant professor of cell and neurobiology at the Keck

School of Medicine of the University of Southern California, could

have a major impact on the treatment of diseases such as multiple

sclerosis and demyelination as a result of spinal cord injuries.

Myelin, the white matter that coats all nerves, allows long-distance

communication in the nervous system. " It plays a vital role in the

overall health and function of the nervous system, and its

degeneration plays a role in a number of diseases, such as multiple

sclerosis, peripheral neuropathies, and even in spinal cord injury, "

Chan explained.

The study, " The Polarity Protein Par-3 Directly Interacts with

p75NTR to Regulate Myelination " , appears in the Nov. 3 issue of

Science. Chan, who works at the Zilkha Neurogenetic Institute at the

Keck School of Medicine of USC, collaborated on the study with

Michel Cayouette and researchers at the Institut de Recherches

Cliniques de Montreal in Canada.

At a basic level, the nervous system functions like a collection of

wires that transmit electrical signals encoding our thoughts,

feelings, and actions. Just as an electrical wire needs insulation,

myelin is wrapped around axons - the wire-like extensions of neurons

that make up nerve fibers. The sheath helps to propagate the

electrical signal and maximize the efficiency and velocity of these

signals in our brain and body.

Diseases and injuries that compromise the integrity of myelin, such

as multiple sclerosis or peripheral neuropathies, have dramatic

consequences like paralysis, uncoordinated movements, and

neuropathic pain.

Chan's study sheds light on the mechanisms that control how myelin

is formed during development of the nerves. The article constitutes

an important step forward in understanding the process of

myelination and opens the way to new research in this field.

Chan showed that a protein, Par-3, is at the base of the myelination

process. This protein becomes localized to one side of the myelin-

forming cells, known as Schwann cells, upon contact with the axon

that is to be myelinated. Par-3 acts almost as a molecular scaffold

to set-up an " organizing centre " , which brings together key proteins

essential for myelination, in particular a receptor for a molecule

secreted by the neurons.

The researchers found that when they disrupted this organizing

centre, cells could not form myelin normally. Importantly, their

discovery demonstrates that Schwann cells need to become polarized

so that they know which side is in contact with the axon to initiate

wrapping and to bring essential molecules to this critical interface.

These studies open the way to new research, said Chan, which should

help to identify other components that are recruited at the

organizing center set-up by Par-3. In multiple sclerosis, or after

injury, Schwann cells can re-myelinate axons of the central nervous

system to some degree. Therefore, these experiments bring about the

possibility that manipulating the Par-3 pathway might allow for more

efficient re-myelination of damaged or diseased nerves.

This work was supported by the National Multiple Sclerosis Society

Career Transition Award and the E. and Delia B. Baxter

Foundation Award to Jonah Chan, and the Canadian Institute of Health

Research to Michel Cayouette.

Chan, J. R., Jolicoeur, C., Yamauchi, J, Elliott, J, Fawcett, J. P.,

Ng, B. K., and Cayouette, M. , " The Polarity Protein Par-3 Directly

Interacts with p75NTR to Regulate Myelination, " Science, Nov. 3,

2006.