EMBRYONIC EXPRESSION PATTERNS OF XENOPUS SYNDECANS

Syndecans are a family of heparan sulfate proteoglycaus implicated in cell-cell and cell-matrix interactions. To investigate the roles of sy ndecans in early development, we identified three syndecan family memb ers in Xenopus laevis: Xsyn-1, Xsyn-2, and Xsyn-3. Xsyn-1 and Xsyn-2 a re maternal mRNAs localized to the animal pole in blastulae, and are e xpressed in the ectoderm of gastrulae. In neurulae, Xsyn-1 is restrict ed to non-neural ectoderm and Xsyn-2 is restricted to neural ectoderm. In tailbud embryos, the three syndecans are expressed in adjacent, no n-overlapping patterns. Xsyn-2 is expressed in the heart while Xsyn-1 is expressed in the underlying anterior endoderm. Xsyn-3 is expressed in the hindbrain, midbrain, and forebrain, while Xsyn-2 is expressed i n the intervening regions. These results suggest that different member s of the syndecan family have distinct developmental roles, perhaps ac ting as barriers to define tissue boundaries.