Molecular fats prevent nerve sheath a...( CHAPEL HILL - A study led by scientis...)

CHAPEL HILL - A study led by scientists at the University of North Carolina at Chapel Hill points to a group of lipids (fats) that are crucial to proper formation of the myelin sheath surrounding nerve fibers.

Although without direct clinical implications for human disease, the new findings help solve a scientific puzzle while adding important new knowledge to the molecular biology of myelin and diseases of myelin loss, particularly multiple sclerosis.

A report of the research appears in the December 13 issue of the Journal of Cell Biology.

Myelin, which is 30% protein and 70% lipid, forms the multi-membrane shield that surrounds nerve axons, hair-like extensions of nerve cells that snake off and make connections with other nerve cells. These myelinated connections form the wiring circuitry of both the central (brain and spinal cord) and peripheral nervous systems.

In his laboratory in the UNC Neuroscience Center, Dr. Brian J. Popko, associate professor of biochemistry, studies myelin on two overlapping levels. "We're interested in the basic molecular biology and biochemistry of myelin formation, maintenance and function - a very basic approach to what myelin is, how it's formed and what it does," he said. "We're also interested in the disease MS, an auto-immune response to the person's own myelin that results in its loss. Specifically, we're interested in the effect of the immune response on the myelin sheath and on the myelinating cell."

Popko noted that the myelin sheath is actually segmental, containing regularly spaced unmyelinated gaps known as nodes of Ranvier. These gaps enable electrical impulses to travel down the axon rapidly by jumping from one unmyelinated region to the next. Thus, for a higher nervous system containing millions of neurons, myelin increases the speed at which electrical impulses travel down axons without having to increase axon size.

"In MS, the myelin sheath is stripped away leaving entire segments u
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Contact: Karen Stinneford
kstinnef@unch.unc.edu
919-966-6047
University of North Carolina School of Medicine
12-Dec-1999