Kheper, a novel ZFH/delta EF1 family member, regulates the development of the neuroectoderm of zebrafish (Danio rerio)

Kheper is a novel member of the ZFH (zinc-finger and homeodomain protein)/d elta EF1 family in zebrafish. kheper transcripts are first detected in the epiblast of the dorsal blastoderm margin at the early gastrula stage and kh eper is expressed in nearly all the neuroectoderm at later stages. kheper e xpression was expanded in noggin RNA-injected embryos and also in swirl mut ant embryos and was reduced in bmp4 RNA-injected embryos and chordino mutan t embryos, suggesting that kheper acts downstream of the neural inducers No ggin and Chordino. Overexpression of Kheper elicited ectopic expansion of t he neuroectoderm-specific genes fkd3, hoxa-1, and eng3, and the ectopic exp ression of hoxa-1 was not inhibited by BMP4 overexpression. Kheper interact ed with the transcriptional corepressors CtBP1 and CtBP2. Overexpression of a Kheper mutant lacking the homeodomain or of a VP16-Kheper fusion protein disturbed the development of the neuroectoderm and head structures. These data underscore the role of Kheper in the development of the neuroectoderm and indicate that Kheper acts as a transcriptional repressor. (C) 2000 Acad emic Press.