Glycoprotein Inhibits Regeneration of Nerve Cells.

Data from a new study implicates the nerve cell surface gangliosides GD1a and GT1b as functional ligands of a myelin-associated glycoprotein (MAG), which contributes to the inability of injured nerve tissue to regenerate.

Researchers from The Johns Hopkins University School of Medicine (Baltimore, MD, USA) and the University of Hamburg (Germany) studied brain cells from rats to determine what factors prevent the regeneration of cells in nerve tissue. MAG, which is part of the myelin wrapping that insulates nerve cells, was one of the main targets of the investigation. In the rat model it was found that two gangliosides on the surface of nerve cells specifically bind to MAG.

The study, published in the June 11, 2002, issue of the Proceedings of the National Academy of Sciences, describes four different methods that were tested for their ability to reverse MAG's inhibitory effect. The investigators used neuraminidase to treat the neurons and chemically modify the cell surface gangliosides. Then they used drugs to block neuronal ganglioside biosynthesis. They also tried genetic engineering to modify the terminal structures of nerve cell surface gangliosides. In addition, they used highly specific IgG-class anti-ganglioside monoclonal antibodies to block binding of the gangliosides to MAG.

"In the central nervous system, once an axon is interrupted in some way, through disease or injury, generally it is stopped dead in its tracks, but in the rest of the body, damaged axons can regrow,” explained Dr. Ronald Schnaa, of the departments of pharmacology and neuroscience at Johns Hopkins. "To make headway in treating brain and spinal cord injury, we need to attack this problem from a number of angles, and our studies have provided an additional target for intervention.”




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