XIPOU 2, A NOGGIN-INDUCIBLE GENE, HAS DIRECT NEURALIZING ACTIVITY

XlPOU2, a member of the class III POU domain family, is expressed init ially in Spemann's organizer, and later, in discrete regions of the de veloping nervous system in Xenopus laevis, XlPOU 2 may act downstream from initial neural induction events, since it is activated by the neu ral inducer, noggin. To determine if XlPOU 2 participates in the early events of neurogenesis, synthetic mRNA was microinjected into specifi c blastomeres of the 32-cell stage embryo, Misexpression of XlPOU 2 in the epidermis causes a direct switch in cell fate from an epidermal t o a neuronal phenotype, In the absence of mesoderm induction, XlPOU 2 has the ability to induce a neuronal phenotype in uncommitted ectoderm . These data demonstrate the potential of XlPOU 2 to act as a master r egulator of neurogenesis.