The tight temporal and spatial regulation of signalling by the secreted bone morphogenetic proteins (BMPs) is essential for patterning the dorsal-ventral axis of vertebrate embryos. Now Blitz et al. provide further details of how BMP activity is regulated during early Xenopusembryogenesis and, in particular, show that the secreted protein twisted gastrulation (TSG) is a BMP inhibitor (see p. 4975). In their experiments, reducing TSG expression with antisense morpholino oligonucleotides caused moderate head defects that could be rescued by chordin, a BMP antagonist that is produced by the Spemann's organiser. The simultaneous downregulation of TSG and chordin produced stronger BMP inhibition than did downregulating either TSG or chordin alone. Blitz and co-workers conclude that, by acting together to inhibit BMP signalling, TSG and chordin cooperate to regulate dorsal cell fates during early frog development.

© 2003.
2003