A genomic screen for Zic1 target genes in neural development
The transcription factor Zic1 plays important roles in patterning the neural plate in early vertebrate development. A crucial step toward understanding the mechanisms of Zic1 function is to identify the downstream target genes. We misexpressed Zic1 in animal caps from Xenopus embryos, and screened for differential gene expression with DNA microarrays. Candidate genes from these microarray data were further validated by quantitative PCR. Through this study, eleven genes have been shown to be directly upregulated by Zic1. One of the direct targets of Zic1 is a novel gene that we have named Xfeb. Xfeb is expressed in the presumptive hindbrain region during neurula stages and in somite tissues later in development. Xfeb represses the hindbrain gene hoxB1 and the anterior neural gene otx2, suggesting that Xfeb is involved in regionalizing the neural plate, possibly by ensuring a posterior expression limit for otx2.