The Regulation and Function of NGF Receptors in Normal and Immortalized Sympathoadrenal Progenitor Cells

The generation of neurons from progenitor cells is regulated at several steps, including proliferation, lineage commitment, overt differentiation and survival. Much of our current understanding of the molecular control of early stages in neurogenesis derives from experiments in invertebrate systems where mutational genetics is feasible, such as Drosophila and C. elegans (for a review, see Campos-Ortega and Jan (1)). Such studies appear to be directly extendible to vertebrate neurogenesis due to the remarkable evolutionary conservation of structure and expression pattern for many of the genes important in invertebrate neurogenesis (2-6). However, one fundamentally important aspect of vertebrate neurogenesis that is not yet adequately modeled by invertebrate genetic systems is the control of neurotrophic factor responsiveness.