Signal Transduction of Bioactive Carbohydrate Chains and Their Genetic Expression

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During the period of investigation on the mechanism of signal transduction through carbohydrate chain and of the gene-expression, the following findings were obtained ;1 Membrane-associated glycoproteins which were characteristically phoshporylated in response with GQlb ganglioside were found in human neuroblastoma cells, whose neurite was extended with GQlb ganglioside. These kinases were inhibited with an impermeable inhibitor for protein kinase, which was also inhibited the activity of GQlb-mediated neurite outgrowth of the cells. The results indicate an occurrence of carbohydrate chain dependent signal transduction system.2 By gene-transfection technique, the characteristic expression of glycosphingolipids, such as GD3 by adenovirus ElA and myc, and lacto-and ganglio-series glycolipids by src, fes, fps and ras oncogenes, were observed in rat 3Yl cells, indicating that the different oncogene products modify the glycolipid metabolism in their own manners.3 When compared the proliferative and the secretory phases of human uterine endometrium, a characteristic induction of sulfatide was observed in the secretory phase. Since the ganglioside contents in both phases were identical each other, a ngative charge due to the sulfate group was added in the secretory phase, in which the fertilized egg was trapped and embedded. Probably, the sulfotransferase activity for the synthesis of sulfatide is induced by progesterone.4 N-(O-linoleoyl) hydroxy fatty acyl sphingosyl glucose was found to be characteristically contained in mammalian epidermis and showed an activity enhancing the kerachinization process of kerachinocytes established from fetal rat skin. The activity involved the stimulation of cornified envelops-formation and the activation of glutamyl peptide transglutaminase and was found to be the same activity as that induced by phorbol ester.