St. Louis, July 22, 1999 -- When nerve cells migrate from their birthplace to their permanent home in the brain, how do they find their way? Researchers have discovered the first molecular guide, a known protein called Slit. This protein doesn't attract young cells to where they need to go. It repels them, like a dog herding a flock of sheep.
"This is the first demonstration of a diffusible molecule that directs migrating neurons," says Yi Rao, Ph.D., assistant professor of neurobiology at Washington University School of Medicine in St. Louis. "Such a repulsive molecule might be useful for controlling the unwanted migration of tumor cells or for delivering therapeutic cells to specific regions of the brain in patients with Parkinson?s disease or Alzheimer?s."
Rao and Jane Y. Wu, M.B., Ph.D., assistant professor of pediatrics and of molecular biology and pharmacology, directed the research. Visiting research technician Wei Wu, from the Chinese Academy of Sciences in Shanghai, was first author of the paper, which appears in the July 22 issue of Nature.
"This finding has important conceptual implications," says Pasko Rakic, M.D., Ph.D., professor and chair of neurobiology at Yale University School of Medicine. "Although it previously has been suggested that some brain structures may release factors that repulse neurons, Rao and his colleagues are the first to identify specific genes whose products perform this function."
In the early 1970s, Rakic obtained the first definitive electron microscopic evidence of neuronal migration and proposed that interactions among different types of cells help direct it. In the past decade, he and others have identified several families of genes and molecules that recognize the "highways" for cell movement. "The novelty of the finding by the St. Louis group is that their molecules are diffusible and are distributed as concentration gradients that migrating cells can read," Rakic says.