Iazarus is a novel pbx gene that globally mediates Hox gene function in zebrafish

Individual vertebrate Hox genes specify aspects of segment identity along t he anterior-posterior axis. The exquisite in vivo specificity of Hox protei ns is thought to result from their interactions with members of the Pbx/Exd family of homeodomain proteins. Here, we report the identification and clo ning of a zebrafish gene, lazarus, which is required globally for segmental patterning in the hindbrain and anterior trunk. We show that lazarus is a novel pbx gene and provide evidence that it is the primary pbx gene require d for the functions of multiple hox genes during zebrafish development, laz arus plays a critical role in orchestrating the corresponding segmentation of the hindbrain and the pharyngeal arches, a key step in the development o f the vertebrate body plan.