THE UNIVIN GENE ENCODES A MEMBER OF THE TRANSFORMING GROWTH-FACTOR-BETA SUPERFAMILY WITH RESTRICTED EXPRESSION IN THE SEA-URCHIN EMBRYO

We have identified a gene in the sea urchin Strongylocentrotus purpura tus that encodes a member of the transforming growth factor beta (TGF- beta) gene superfamily. We have named the gene univin, and it is the f irst member of this superfamily to be reported in echinoderms. The cDN A sequence predicts a 383-amino-acid residue protein with 7 cysteine r esidues characteristic of members of this superfamily and with a clust er of basic residues appropriately situated to signal proteolytic clea vage. Sequence comparisons place univin in the bone morphogenetic prot ein (BMP) group of the TGF-beta superfamily along with the vertebrate BMPs, decapentaplegic protein from Drosophila, and Vg-1 from Xenopus. Analyses of univin expression in early embryos by RNA blots and in sit u hybridization revealed the highest levels of expression in the egg a nd prehatching blastula. During late cleavage stages, univin mRNA accu mulation is progressively restricted to a circumequatorial band. Expre ssion is further restricted during gastrulation when univin transcript s are detected primarily in the presumptive foregut and ciliated band. By pluteus stage, signals are detectable only in these cell types. Th e restricted temporal and spatial patterns of expression of univin dur ing early blastula stages parallel those of SpAN, which encodes an ast acin-like protease related to tolloid and BMP-1 (Reynolds et al., 1992 ). The fact that these proteases are thought to function in the proteo lytic activation of TGF-beta-related proteins that, respectively, regu late Drosophila embryonic dorsal-ventral patterning and vertebrate bon e development suggests that SpAN and univin could also have critical r oles in early developmental decisions in the sea urchin embryo. (C) 19 94 Academic Press, Inc.