EXPRESSION OF THE MOUSE CERBERUS-RELATED GENE, CERR1, SUGGESTS A ROLEIN ANTERIOR NEURAL INDUCTION AND SOMITOGENESIS

The Xenopus cerberus gene encodes a secreted factor that is expressed in the anterior endomesoderm of gastrula stage embryos and can induce the formation of ectopic heads when its mRNA is injected into Xenopus embryos [Bouwmeester, T., Kim, S., Lu, B. & De Robertis, E. M. (1996) Nature (London) 382, 595-601]. Here we describe the existence of a cer berus-related gene, Cerr1, in the mouse. Cerr1 encodes a putative secr eted protein that is 48% identical to cerberus over a 110-amino acid r egion. Analysis of a mouse interspecific backcross panel demonstrated that Cerr1 mapped to the central portion of mouse chromosome 4. In ear ly gastrula stage mouse embryos, Cerr1 is expressed in the anterior vi sceral endoderm and in the anterior definitive endoderm. In somite sta ge embryos, Cerr1 expression is restricted to the most recently formed somites and in the anterior presomitic mesoderm. Germ layer explant r ecombination assays demonstrated that Cerr1-expressing somitic-presomi tic mesoderm, but not older Cerr1-nonexpressing semitic mesoderm, was able to mimic the anterior neuralizing ability of anterior mesendoderm and maintain Otx2 expression in competent ectoderm. In most Lim1 -/- headless embryos, Cerr1 expression in the anterior endoderm was weak o r absent. These results suggest that Cerr1 may play a role in anterior neural induction and somite formation during mouse development.