Molecules That Tell Brain Cells to Grow Up

Stanford University School of Medicine's Ben Barres and his colleagues identified a molecular on-switch that catalyzes the transformation of immature brain cells into myelin-producing oligodendrocytes. In a study to be published in today's Neuron, the scientists found that the microRNA molecule miR-219 is found at high levels only in oligodendrocytes and that it's necessary to induce these brain cells' precursors to mature. The scientists blocked all microRNA production in the oligodendrocytes of live mice, producing both behavioral and anatomical defects in their brains, due to their lack of proper myelination. Then, the scientists induced a transformation of the oligodendrocyte precursors to mature cells, and found that the levels of miR-219 increased by 100-fold.