Identification and gene expression of Versican during early development of Xenopus.

The chondroitin sulfate proteoglycan (PG) PG-M/versican is known to be a primary component of the vertebrate embryonic extracellular matrix and, in the mouse, functional abrogation of the versican gene leads to severe cardiovascular malformations and embryonic lethality. In order to provide a means for approaching the study of the role of versican during embryogenesis, we have cloned the Xenopus versican cDNA and we have performed in situ hybridization on embryos at different stages of development. We showed maternal Xversican transcription, as well as a previously undocumented early expression of the PG during gastrulation and neurulation. At later stages of development, spatial transcription of Xversican correlates with the patterns of migrating neural crest cells (NCC) and it is expressed in embryonic regions representing the final sites of arrest of NCC. Xversican mRNA was also detected in a subpopulation of trunk NCC migrating into the fin, in tissues flanking the trunk NCC ventral migratory pathway and in post-migratory cranial skeletogenic NCC. Further embryonic sites expressing Xversican were the pronephros, pronephric ducts, heart anlage and branchial pouches. These findings constitute the basis for future studies aimed at clarifying unresolved aspects of versican function during embryogenesis.