In the adult brain, neural stem cells continuously generate new neurons. The stem cells are a subset of glial cells, classically associated with support functions in the brain. This raises the possibility that glial cells elsewhere in the brain are also latent stem cells. Neural stem cells are predominantly found in a quiescent state, and occasionally become activated to divide. However the molecular mechanisms that control the dormant state are largely unknown. MicroRNAs are small, non-coding RNAs that are capable of rapidly suppressing translation of hundreds of transcripts, making them attractive mediators of rapid changes in cell state. We have found that different cohorts of microRNAs are expressed in quiescent and activated adult neural stem cells, and are important regulators of the transition of stem cells from quiescence to activation. We will define 1) the role of the miR-17~92 cluster and 2) its targets in adult neural stem cell regulation. Elucidating the regulatory networks that control stem cells in the adult mammalian brain will provide insight into the possibility of harnessing endogenous stem cells, as well as activating other cells in non-neurogenic regions, for brain repair.
