POU transcription factors have been shown to be important in the regulation of cell fate decisions during development. We have focused on understanding the function of one POU domain gene, XlPOU 2, in early neural development. We generated a """"""""knockout"""""""" of function in Xenopus, utilizing a construct consisting of the engrailed repressor fused to the POU domain of XlPOU 2. This construct was under the regulation of the hormone, dexamethasone, and mRNA obtained from this construct was overexpressed in the lineage that will become the future brain. Thus, both temporal and spatial expression of the """"""""dominant-inhibitory"""""""" POU construct showed that XlPOU 2 is required for proper formation of the brain, specifically the mid-brain hindbrain boundary region. XlPOU 2 induces a host of regulatory genes in the early neurogenesis, and is likely to play a pivotal role in this process. In order to understand the cascade of events that follow neural induction, a subtraction scheme to clone genes that up-regulated by the neural induction factor noggin was undertaken. Two novel candidate genes have been identified and are being characterized: one of these genes is a Kruppel-like zinc finger gene, and the other a homeobox gene. We have also cloned and characterized a novel Brain-1-related POU gene in zebrafish, tai-ji. Taiji is a hallmark of proliferating, non- differentiated cells of the adult teleost nervous system. The characterization of mouse tai-ji and its role in neural stem cells will be examined using primary progenitor cultures of neurons and gene ablation in the mouse.
