XATH-1,a Vertebrate Homolog ofDrosophila atonal,Induces Neuronal Differentiation within Ectodermal Progenitors

AbstractXATH-1,a basic/helix-loop-helix transcription factor and a homolog ofDrosophila atonaland mammalianMATH-1,is expressed specifically in the dorsal hindbrain duringXenopusneural development. In order to investigate the role ofXATH-1in the neuronal differentiation process, we have examined the effects ofXATH-1overexpression duringXenopusdevelopment.XATH-1induces the expression of neuronal differentiation markers, such asN-tubulin,within the neural plate as well as within nonneural ectodermal progenitor populations, resulting in the appearance of process-bearing neurons within the epidermis. The related basic/helix-loop-helix genesneurogenin-related-1andneuroDare not induced in response toXATH-1overexpression within the embryo, suggesting thatXATH-1may activate an alternate pathway of neuronal differentiation. In further contrast toneurogenin-related-1andneuroD,high-level expression of general neural markers expressed earlier in development, such asN-CAM,is not induced byXATH-1overexpression. Competent ectodermal progenitors therefore respond to ectopicXATH-1expression by initiating a distinct program of neuronal differentiation