Profiling identifies precursor suspects: notch family again!

Abstract

Newborn neurons in the adult dentate gyrus pass through several distinct precursor and progenitor classes prior to differentiation. In this issue of Cell Stem Cell, Lugert et al. (2010) characterized their strikingly different proliferative behaviors after neurogenic stimuli or aging.

Figure 1. Current View of the Sequence of Neurogenesis from Precursor/Progenitor Cells in the Adult Dentate Gyrus

GFAP⁺ Type 1 neural stem/precursor cells are believed to divide asymmetrically to give rise to more committed daughter cell types. However, some doubt exists as to the precise lineage relationships between radial and horizontal Type 1 cells. Type 2a cells express Sox2 and Ascl1 but not GFAP⁺. Type 2b cells begin to express mature neuronal markers such as Dcx. These cell types are believed to undergo symmetric neurogenic divisions. Type 3 cells are migrating neurons that will integrate into the granule cell layer over the course of several weeks in the rodent. Lugert et al. use a surrogate marker of Notch signaling (Hes5::GFP) to label Type 1 cells and show that running, aging, and seizure activity have varied effects on proliferation and expansion of radial and horizontal progenitor populations.