The functions of exogenous and endogenous laminin-5 on corneal epithelial cells

In this study, the authors investigated the functions of laminin-332 on SV-40 transfected human corneal epithelial cells (HCE cells). We also revealed different functions between exogenous and endogenous laminin-332 on HCE cells. HCE cells themselves secreted laminin-5 endogenously. Exogenously added laminin-5 strongly promoted cell adhesion via a3b1 integrin, cell spreading, assembly of hemidesmosomes, and mildly inhibited cell migration. Using an anti-laminin-5 monoclonal antibody (mAb) or anti-integrin a3b1 mAbs, the blocking of the interaction between endogenously secreted laminin-5 and HCE cells caused strong inhibition of cell migration. Integrin a3b1 and a6b4 were expressed in HCE cells. These results indicated that endogenous (unprocessed) laminin-5 has a crucial role in cell migration on HCE cells via a3b1 integrin. In conclusion, structural differences between exogenous and endogenous laminin-5 regulated their functions on HCE cells. Exogenously added laminin-5 strongly promoted cell adhesion, cell spreading, and assembly of hemidesmosomes. Endogenously secreted laminin-5 had a crucial role in cell migration.