Development/Plasticity/Repair Purification of Neural Precursor Cells Reveals the Presence of Distinct, Stimulus-Specific Subpopulations of Quiescent Precursors in the Adult Mouse Hippocampus

The activity of neural precursor cells in the adult hippocampus is regulated by various stimuli; however, whether these stimuli regulate the same or different precursor populations remains unknown. Here, we developed a novel cell-sorting protocol that allows the purifi-cation to homogeneity of neurosphere-forming neural precursors from the adultmouse hippocampus and examined the responsiveness of individual precursors to various stimuli using a clonal assay.We show that within the Hes5-GFP/Nestin-GFP/EGFR cell popula-tion, which comprises the majority of neurosphere-forming precursors, there are two distinct subpopulations of quiescent precursor cells, one directly activated by high-KCl depolarization, and the other activated by norepinephrine (NE).We then demonstrate that these two populations are differentially distributed along the septotemporal axis of the hippocampus, and show that the NE-responsive precursors are selectively regulated by GABA, whereas the KCl-responsive precursors are selectively modulated by corticosterone. Finally, based on RNAseq analysis by deep sequencing, we show that the progeny generated by activating NE-responsive versus KCl-responsive quiescent precursors are molecularly different. These results demonstrate that the adult hippocampus contains phenotypi-cally similar but stimulus-specific populations of quiescent precursors, which may give rise to neural progeny with different functional capacity. Key words: adult neurogenesis; hippocampus; neural precursor cells; neural stem cells; norepinephrine; quiescen