Purification, Visualization, and Molecular Signature of Neural Stem Cells.

Neural stem cells (NSCs) are isolated from primary brain tissue and propagated as a heterogeneous mix of cells, including neural progenitors. To date, NSCs have not been purified in vitro to allow study of their biology and utility in regenerative medicine. In this study, we identify C1qR1 as a novel marker for NSCs and show that it can be used along with Lewis-X (LeX) to yield a highly purified population of NSCs. Using time-lapse microscopy, we are able to follow NSCs forming neurospheres, allowing their visualization. Finally, using single-cell polymerase chain reaction (PCR), we determine the molecular signature of NSCs. The single-cell PCR data suggest that along with the Notch and Shh pathways, the Hippo pathway plays an important role in NSC activity.

NogoR1 and PirB signaling stimulates neural stem cell survival and proliferation.

Neural stem cells (NSCs) and neural progenitors (NPs) in the mammalian neocortex give rise to the main cell types of the nervous system. The biological behavior of these NSCs and NPs is regulated by extracellular niche derived autocrine-paracrine signaling factors on a developmental timeline. Our previous reports [Plos One 2010;5:e15341; J Neurochem 2011;117:565-578] have shown that chondroitin sulfate proteoglycan and ApolipoproteinE are autocrine-paracrine survival factors for NSCs. NogoA, a myelin related protein, is expressed in the cortical ventricular zones where NSCs reside. However, the functional role of Nogo signaling proteins in NSC behavior is not completely understood. In this study, we show that NogoA receptors, NogoR1 and PirB, are expressed in the ventricular zone where NSCs reside between E10.5 and 14.5 but not at E15.5. Nogo ligands stimulate NSC survival and proliferation in a dosage-dependent manner in vitro. NogoR1 and PirB are low and high affinity Nogo receptors, respectively and are responsible for the effects of Nogo ligands on NSC behavior. Inhibition of autocrine-paracrine Nogo signaling blocks NSC survival and proliferation. In NSCs, NogoR1 functions through Rho whereas PirB uses Shp1/2 signaling pathways to control NSC behavior. Taken together, this work suggests that Nogo signaling is an important pathway for survival of NSCs.