INVOLVEMENT OF GICERIN, A CELL-ADHESION MOLECULE, IN TRACHEAL DEVELOPMENT AND REGENERATION

Gicerin is a novel cell adhesion protein that belongs to the immunoglo bulin superfamily. Gicerin protein adheres to neurite outgrowth factor , an extracellular matrix protein in the laminin family, and also exhi bits hemophilic adhesion. in the present study, we investigated the in volvement of gicerin and neurite outgrowth factor in tracheal developm ent and regeneration. In an early embryonic stage, gicerin protein was highly expressed in tracheal epithelial cells, but not in loosely arr anged mesenchymal cells. During development, mesenchymal cells become condensed around the tracheal epithelium and then differentiate into m uscle and cartilage; high levels of gicerin expression were observed i n these cells. In the later embryonic and posthatching stages, no gice rin expression was detected in tracheal epithelium or cartilage. In ad dition, expression of gicerin increased transiently in the tracheal ep ithelium during the regeneration after tracheitis induced by the infec tious bronchitis virus. Furthermore, a polyclonal antibody against gic erin inhibited the epithelial regeneration in tracheal organ cultures. These findings suggest that gicerin plays an important role in both t racheal development and regeneration.