Sugar chains in cell adhesion and cell division-comparative glycomics throwing light on glycobiology

Blood-group-ABH antigens have been attributed no physiological roles. While studying Ca²⁺ dependent cell-cell adhesion of Xenopus laevis, we found that blood-group-B active GPI-anchored lectin and blood-group-B active glycoconjugates are mediating cell adhesion of early embryonic cells. In mouse embryonic cells, not the blood-group-B antigens but the Lewis x blood-group-active molecules are playing similar roles in compaction. How did the surface glycomes playing roles in cell-cell adhesion evolve in these two species? In the nematode Caenorhabditis elegans, sugar chains of chondroitin proteoglycan play indispensable roles in completion of cell division. A decrease of chondroitin on the embryonic cell surfaces results in apparent reversion of cell division. Cytokinesis and chromosome partition becomes abnormal, and the embryonic cells die. Are chondroitin in the higher organisms playing similar roles in cell division, or are the roles of chondroitin replaced with different sugar chains? As seen in the two examples, comparison of glycomes between various organisms could be very powerful hypothesis generating tools in glycobiology. With the completion of genome DNA sequencing, it seems to be high time to study the evolution of glycomes with bioinformatics and functional glycomics.