miR-17~92 exerts stage-specific effects in adult V-SVZ neural stem cell lineages

In the adult mouse brain, neural stem cells (NSCs) in the ventricular-subventricular zone (V-SVZ) generate neurons and glia throughout life. microRNAs are important regulators of cell states, frequently acting in a stage- or context-dependent manner. Here, miRNA profiling of FACS-purified populations identified miR-17[~]92 as highly upregulated in activated NSCs and transit amplifying cells (TACs) in comparison to quiescent NSCs. Conditional deletion of miR-17[~]92 in NSCs reduced stem cell proliferation both in vitro and in vivo. In contrast, in TACs, miR-17[~]92 deletion caused a selective shift from neurogenic DLX2+ TACs towards oligodendrogenic OLIG2+ TACs, resulting in increased oligodendrogenesis to the corpus callosum. miR-17[~]92 deletion also decreased proliferation and maturation of intraventricular oligodendrocyte progenitor cells. Together, these findings reveal stage- and cell-type-specific functions of the miR-17[~]92 cluster within adult V-SVZ neural stem cell lineages.