The role of gicerin, a novel cell adhesion molecule, in development, regeneration and neoplasia

Neurite outgrowth factor (NOF) is an extracellular matrix (ECM) protein in the laminin family and its ligand, gicerin, is a novel cell adhesion molecu le in the immunoglobulin superfamily. Gicerin has a homophilic adhesive act ivity as well as a heterotypic manner to NOF. In the nervous systems, gicer in is expressed during developmental stage when neurons migrate or extend n eurites to form a neural network. Gicerin promotes neurite extension and mi gration of embryonic neurons in vitro by its homophilic and heterophilic ad hesion activities. Introduction of anti-gicerin antibody into early develop ing eyes perturbs the layer formation of neural retina. These data suggest that gicerin participates in the formation of neural tissues. Gicerin is al so expressed in other non-neural tissues; in epithelia of trachea, kidney a nd oviduct, gicerin expression is restricted in the developmental period. I n contrast, muscular tissues and endothelial cells express gicerin continuo usly even after maturation. Interestingly, gicerin re-appears strongly in t he regenerating epithelia of trachea, kidney and oviduct, and also anti-gic erin antibody disrupts the healing process of trachea. Furthermore, gicerin and NOF are overexpressed in the chicken nephroblastomas (Wilm's tumor) an d oviductal adenocarcinomas. lit vitro analyses show that gicerin adhesive activities can promote binding among tumor cells and adhesion of tumor cell s to NOF. A polyclonal antibody against gicerin also perturbs the re-attach ment of cancer cells onto metastasizing sites. It is clear from these studi es that gicerin is a potential effector for pathological tissue formation a s well as for normal development.