Dlg1-PTEN Interaction Regulates Myelin Thickness to Prevent Damaging Peripheral Nerve Overmyelination

Abstract

Too Much of a Good Thing: In peripheral nerves, the insulating myelin sheath speeds up electrical conductivity by allowing impulses to skip down the axon from node to node. Axons signal using neuregulin to get the Schwann cells to begin their wrap-around insulation project. But when is enough myelin too much? Cotter et al. (p. 1415 , published online 6 May) have now found the signal that stops further rounds of myelin insulation. In developing mice, the proteins Dlg1 (mammalian disc large 1) and PTEN (phosphatase and tensin homolog) were involved in calling a halt to insulation during early development. The balance between not enough and too much myelin insulation is controlled by opposing signals, which together optimize both the myelination and the velocity of nerve conduction.