Mapping and expression analysis of the mouse ortholog of Xenopus Eomesodermin

The T-box gene family has been conserved throughout metazoan evolution. The genes code for putative transcription factors which share a uniquely defin ing DNA binding domain, known as the T-box (Bollag et al., 1994). They are implicated in the control of diverse developmental processes by their highl y specific expression patterns throughout gastrulation and organogenesis in mouse and other species (Chapman et al., 1996) (Gibson-Brown et al., 1998) , and by mutations in T-box genes that have profound developmental effects (Papaioannou, 1997; Chapman and Papaioannou, 1998; Papaioannou and Silver, 1998). In this report, we describe the mapping and expression pattern of th e mouse ortholog of a gene, Eomesodermin, first identified in Xenopus (Ryan et al., 1996). The mouse gene was previously reported (Wattler et al., 199 8) under the name MmEomes. The gene maps to mouse chromosome 9 in a region syntenic with human chromosome 3p. Mouse eomesodermin is expressed in the t rophoblast of the blastocyst and in its derivative, the chorionic ectoderm. At gastrulation, eomesodermin is expressed in the primitive streak and emb ryonic mesoderm as well, but this expression disappears prior to the end of gastrulation. Later, eomesodermin is expressed in the developing forebrain , in a pattern largely overlapping a closely related T-box gene, Tbr1 (Bulf one et al,, 1995), and is also seen in a localized area of each limb. (C) 1 999 Elsevier Science Ireland Ltd. All rights reserved.