Bambi is coexpressed with Bmp-4 during mouse embryogenesis

Signaling of TGF-beta superfamily members is tightly controlled by an elabo rate network of regulators (for recent review see Trends Genet. 15 (1999) 3 ; Genes Dev. 14 (2000) 627). Recently, the transmembrane protein BAMBI (BMP and activin membrane-bound inhibitor) has been shown to interfere with Bmp and activin-like signaling by inhibiting Tgf-beta type I receptor activati on (Nature 401 (1999) 480). In striking contrast to other Bmp antagonists l ike noggin (Cell 86 (1996) 599) or chordin (Cell 86 (1996) 589), BAMBI is s trictly coexpressed with Bmp-4 during early Xenopus embryogenesis. The grou ping of genes according to their shared complex spatial expression pattern and their involvement in the same biological signaling pathway has been ref erred to as synexpression group. This concept facilitates prognoses about t he roles of a group member with unknown function. Apparently, only a minori ty of genes is organized in synexpression groups and up to now they have ma inly been described in yeast and Xenopus (for review see Nature 402 (1999) 483). In the frog, BAMBI is a member of the Bmp-4 synexpression group (Natu re 401 (1999) 480). We identified two murine homologues of BAMBI one of whi ch, named Bambi-psi, is a pseudogene. We show that the spatiotemporal expre ssion pattern of Bambi closely matches that of Bmp-4 during mouse embryonic development, Moreover, we show that Bambi expression is induced in mouse e mbryonic fibroblasts by Bmp-4. Hence, we provide first evidence for the exi stence of an evolutionarily conserved Bmp-4 synexpression group in mammals. (C) 2001 Elsevier Science Inland Ltd. All rights reserved.