NELL2 promotes motor and sensory neuron differentiation and stimulates mitogenesis in DRG in vivo

We previously identified a secreted glycoprotein, neural epidermal growth factor- like like 2 (NELL2), in a subtraction screen designed to identify molecules regulating sensory neurogenesis and differentiation in the chick dorsal root ganglion (DRG). Characterization of NELL2 expression during embryogenesis revealed that NELL2 was specifically expressed during the peak periods of both sensory and motor neuron differentiation, and within the neural crest was restricted to the sensory lineage. We now provide evidence for a function for NELL2 during neuronal development. We report here that NELL2 acts cell autonomously within CNS and PNS progenitors, in vivo, to promote their differentiation into neurons. Additionally, neuron-secreted NELL2 acts paracrinely to stimulate the mitogenesis of adjacent cells within the nascent DRG. These studies implicate dual functions for NELL2 in both the cell autonomous differentiation of neural progenitor cells while simultaneously exerting paracrine proliferative activity.