UC San Diego

The role of non-sulfated chondroitin in developmental events of the nematode Caenorhabditis elegans has been investigated. This work took advantage of a class of mutants defective in glycosaminoglycan biosynthesis that show perturbations in vulval invagnation and early embryogenesis. It was demonstrated that all components of the mammalian chondroitin biosynthetic machinery are conserved in C. elegans, and that the phenotypic defects observed in the mutants result from loss of chondroitin, not heparan sulfate. A biochemical screen identified nine novel chondroitin core proteins that carry chondroitin chains, none of them common to mammalian chondroitin sulfate core proteins. Two of these, chondroitin proteoglycans-1 and -2, are functionally redundant and required for the same set of early embryonic events affected in mutants lacking chondroitin biosynthetic enzymes. We hypothesize that the chondroitin proteoglycans play biophysical or structural roles that direct vulval invagination and embryogenesis in the worm