Role of Fox Genes During Xenopus Embryogenesis

Fox genes encode a remarkably conserved family of nuclear proteins that can act as transcriptional activators or repressors. Their high level of conservation is probably due to the critical roles they play in embryonic pattern formation and tissue-specific gene expression (Dirksen and Jamrich 1992; Sasaki and Hogan 1993; Hatini et al. 1994; Dirksen and Jamrich 1995; Kaufmann and Knochel 1996; Martinez et al. 1997; Kenyon et al. 1999; Brownell et al. 2000; Carlsson and Mahlapuu 2002). Fox genes encode proteins that contain a highly conserved 110 amino acid long DNA-binding domain that was originally described in the Drosophila mutant fork head (Lai et al. 1990; Weigel and Jackie 1990). Because of this, they were called the forkhead genes. The structure of these proteins resembles a winged helix, and because of their structure, they are also referred to as winged helix proteins (Clark et al. 1993). Eventually, a unified nomenclature was established, and currently these genes are called Fox genes (Kaestner et al. 2000).