DIFFERENTIAL EXPRESSION OF THE HMG BOX TRANSCRIPTION FACTORS XTCF-3 AND XLEF-1 DURING EARLY XENOPUS DEVELOPMENT

The recent discovery that the HMG box transcription factor XTCF-3 is i nvolved in early axis specification in Xenopus laevis (Molenaar, M., v an de Wetering, M., Oosterwegel, M., Peterson-Maduro, J. Godsave, S., Korinek, V., Roose, J., Destree, O., Clevers, H., 1996. XTcf-3 transcr iption factor mediates beta-catenin-induced axis formation in Xenopus embryos. Cell 86, 391-399) led us to search for other members of the T CF/LEF family in this species. A newly identified HMG box factor was c loned with highest homology to human LEF-1, called XLEF-1. Unlike XTcf -3, XLef-1 is not expressed maternally, but its transcripts become det ectable directly after the mid blastula transition (MBT). At later sta ges, both genes are expressed in the central nervous system (CNS), eye s, otic vesicles, head mesenchyme, neural crest and derivatives, branc hial arches, developing heart, tailbud and limb buds. The expression p attern of Lef-1 during later stages of development is evolutionarily c onserved. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.