An ageing view of myelin repair

摘要

When the myelin layer that covers neuronal processes is lost through disease, neural stem cells recapitulate the developmental program of 'myelinatton'. The underlying molecular mechanisms often fail in the ageing brain. In the brain, the function of neurons and their long axonal processes depends on neighbouring support cells called glia. For example, one class of glia, called oligodendrocytes, wrap the neurons' axons in a multilayered spiral extension of their own cell membrane - the myelin sheath. This insulating layer is required not only for fast nerve-impulse conduction along a neuron, and so for virtually all motor, sensory and higher functions of the brain, but also for the integrity and long-term survival of the axons. Myelin can be damaged in various diseases, including multiple sclerosis, but the mammalian brain has a remarkable ability to repair itself. With age, however, the efficiency of this remyeli-nation declines or is lost completely. Writing in Nature Neuroscience, Shen et aV provide insights into how this failure of remyelination can be explained at a molecular level.