Bioinspired Material Having Nucleoside and Carbohydrate
	It is well known that glycosyltransferase exists in endoplasmic reticulum or Golgi apparatus, and catalyzes the glycosyl transfer reaction from a glycosyl donor (sugar nucleotide) onto a glycosyl acceptor (alcohol such as carbohydrate). Therefore, a glycosyltransferase has three kinds of substrate specificity. One for the sugar unit which is transferred, one for the alcohol which accepts the sugar unit, and one for the nucleotide residue of the glycosyl donor. Recently, it was reported that a glycosyltransferase exists not only in the organelle of the cell but also on the cell surface, and the function of the cell surface enzyme is of interest. On the cell surface, there are many kinds of molecular recognition sites which work in cell adhesion, cell proliferation, cell movement, and so on. A kind of receptor on the cell surface recognizes the carbohydrate chain. In this article, cell adhesion through specific recognition of cell surface glycosyltransferase is reported. In the case of cell adhesion through a recognition site, molecular clustering on the cell surface and the resulting multiple interactions are quite important. Therefore,clustering of the adhesive molecule which is recognized by glycosyltransferase is necessary for the specific cell adhesion through glycosyltransferase. Clusters of adhesive molecules are a kind of bioinspired material. Among the aggregated materials such as micelles, liposomes, and dendrimers, the random polymer is the most suitable substrate for cell adhesion because of its ease of preparation, ease of immobilization on the solid surface, diversity of shape, and difficulty of phase separation. 3T3-L1 fibroblast has galactosyltransferase on the cell surface which recognizes D-galactose, N-acetyl-D-glucosamine, and uridine. As the bioinspired material, the polystyrene dish was coated with the substituted polystyrene having D-galactose, N-acetyl-D-glucosamine, and uridine1). By seeding 3T3-L1 fibroblast on the polymer-coated dish, specific interaction between the cell and the glycopolymer can be observed (Figure).
	Among the three kinds of recognition molecules, uridine is the most strongly related to cell adhesion2). 3T3-L1 fibroblast is a good adhesive specifically on the dish coated with a uridine-containing polymer. On the other hand, it does not attach to the surface of polymers having galactose or glucosamine. However, it dose attach to a glucosamine-containing polymer in the presence of a soluble uridine derivative. Thus, cell adhesion through cell-surface glycosyltransferase is controlled by three kinds of different recognition molecules. In the future, the control of the spatial arrangement of the three kinds of biofunctional groups (two kinds of sugars and one kind of nucleoside), will enable the cells to show the maximum function, and its related gel may work as an artificial extracellular matrix and/or the basement of a biosystem construction.
	Kenichi Hatanaka (Institute of Industrial Science, University of Tokyo)
	References (1) K. Hatanaka, H. Takeshige, and T. Akaike, J. Carbohydr. Chem., 13, 603-610 (1994). (2) K. Hatanaka, J. Oishi, A. Tsuda, S. Matsunaga, M. Kunou, Y. Yachi, M. C. Kasuya, and T. Okinaga, Macromol. Biosci., 1, 397-400 (2001).
Apr. 1, 2003