Jagged1 is Essential for Radial Glial Maintenance in the Cortical Proliferative Zone

Radial glial maintenance is essential for the proper development of the cortex. It is known that the evolutionarily conserved Notch signaling pathway is required for maintaining the pool of radial glial stem cells although the mechanisms involved are not entirely understood. Here, we study the Notch ligand, Jagged1, in the mouse ventricular zone at a late stage of embryonic development. We use a conditional loss of function allele to show that Jagged1 is required for maintaining radial glial cells and when absent, leads to defects in the cortical proliferation zone and expression of intermediate progenitor cells. Using in vitro approaches, we found that depletion of Jagged1 reduced the size of primary neurospheres and their capacity to self-renewal. Finally, Jagged1 mutants also showed precocious neuronal differentiation and cortical defects. Together, these data support a role for Jagged1 in radial glia maintenance in the neocortex.