Two murine and human homologs of mab-21, a cell fate determination gene involved in Caenorhabditis elegans neural development

We report the cloning and genetic characterization of one human and two mur ine homologs of the mab-21 cell fate specification gene. mab-21 participate s in the formation of sensory organs in the male nematode tail, and is esse ntial for other developmental functions elsewhere in the Caenorhabditis ele gans embryo. The expanding mab-21 gene family, which is strikingly conserve d in evolution, includes two putative Drosophila members. The two mammalian genes, encoding 41 kDa nuclear basic proteins, are expressed in partially overlapping territories in the embryonic brain, eye and limbs, as well as i n neural crest derivatives. Recent genetic data implicating mab-21 as a dow nstream target of TGF-beta signaling, together with the distribution of mab -21 transcripts in the mouse embryo, propose these novel genes as relevant factors in various aspects of vertebrate neural development.