ADHESIVE ACTIVITY OF GICERIN, A CELL-ADHESION MOLECULE, IN KIDNEYS AND NEPHROBLASTOMAS OF CHICKENS

Gicerin, a cell-adhesion molecule belonging to the immunoglobulin supe rfamily, has both hemophilic and heterophilic binding activities to ne urite outgrowth factor, an extracellular matrix molecule in the lamini n family. Gicerin is thought to play a role in the normal development of chicken kidney, because it is expressed abundantly in the embryonic organ and only slightly in the mature organ. In this study, we have e xamined the adhesive activity of gicerin in the kidney to characterize its function in organogenesis. We have also examined the function of gicerin in chicken nephroblastomas (''embryonic nephromas''), which sh ow various structures resembling those in embryonic kidneys. Immunohis tochemically, the expression patterns of gicerin and neurite outgrowth factor in nephroblastomas are similar to those of embryonic kidneys. Cell-aggregation assays have shown that primary culture cells from bot h embryonic kidneys and nephroblastomas have strong aggregation activi ties, and that each aggregation is partially inhibited by gicerin anti body, In contrast, cells from adult kidney exhibit weak aggregation ac tivity that is not inhibited by the antibody. In addition, ligand blot analysis has revealed that gicerins in embryonic kidney and nephrobla stoma bind to purified neurite outgrowth factor, whereas extracts from adult kidney show no positive reaction. These findings suggest that t he hemophilic and heterophilic adhesive activities of gicerin are invo lved in the formation of both normal kidney and nephroblastoma.