Lineage Commitment and Fate of Neural Crest- Derived Neurogenic Cells

Abstract

Publisher Summary The differentiation of neural crest derivatives in distinct embryonic locations in the vertebrate embryo has stimulated many attempts to understand the underlying mechanism of specific pathway choices made by migrating neural crest cells. It is known that evelopmentally distinct subpopulations of crest-derived cells arise from crest cell precursors prior to their dispersal from a “migration staging area” (MSA). These include both neurogenic and nonneurogenic cells that express characteristic receptor tyrosine kinases (RTKs) and other early cell type-specific markers. The MSA would, therefore, be the embyronic location where neural crest cells make their first specific pathway choices. In vivo , after most of the crest cells have departed on the medial migration pathway, some of the cells remaining in the MSA begin to express mRNAs encoding c-kit and tyrosinase-related protein-2 (TRP-2) characteristic of melanocyte precursors. It has been suggested that the expression of specific receptors (RTKs) in developmentally distinct subpopulati ns allows them to respond to differentially localized ligands in the embyro. And the responses to specific growth-factor activities mediate the onset of dispersal and subsequent survival of crest-derived subpopulations in specific embryonic locations. In vivo , at least a subpopulation of neurogenic neural crest-derived cells expresses functional trkC receptors and requires the timely availability of neurotrophin-3 (NT-3) for normal gangliogenesis. NT-3 is produced by the neural tube and possibly by other embryonic tissues and is presumed to be present in somitic tissues and, therefore, available on both the medial and lateral crest migration pathways.