Neurons need miRNA to survive

miRNA—small pieces of RNA generated by the RNA-chopping enzyme called Dicer—strategically shut off genes to allow embryonic cells to differentiate. Because mice that lack Dicer die as embryos, the role of miRNA in vivo has been studied by deleting Dicer only in specific cell types. These studies showed that Dicer—and thus miRNA—is required for both cell differentiation and the survival of some cells. Neurons need miRNA for differentiation, but whether they also need them for survival later was unknown.

Schaefer et al. now find that inactivating Dicer in postmitotic neurons of adult mice eventually kills these cells. The neurons maintained some of their miRNA...