Asymmetric expression of Syndecan-2 in early chick embryogenesis

Chicken Syndecan-2 (cSyndecan-2) is the homologue of Xenopus Syndecan-2, a member of the heparan sulfate proteoglycan family with an important role in left-right patterning in frog embryos. A relationship to LR asymmetry in other species has not been reported. We show that cSyndecan-2 is expressed throughout the primitive streak between st. 1 and 3 in the chick embryo, and is restricted to the rostral and caudal tips of the primitive streak at st. 4. It displays distinct left-right asymmetry, being expressed in the right side of Hensen's node at st. 5. The asymmetric expression of cSyndecan-2 is maintained around the node between st. 5 and 7. At early somite stages, somites and neural folds express cSyndecan-2. The somite expression disappears by st. 11, but strong expression in the neural tube continues. Our data reveal a new asymmetric transcript in the chick embryo and indicate that in contrast to protein-level asymmetries, which underlie syndecan-2 function in Xenopus, chick syndecan-2 exhibits asymmetry at the mRNA level.