Functional identification of integrin laminin receptors that mediate process outgrowth by human SY5Y neuroblastoma cells

Abstract

Treatment of the human neuroblastoma cell line SY5Y with nerve growth factor (NGF) induces terminal neuronal differentiation of a subpopulation of cells which can be selected by treatment with a DNA synthesis inhibitor. We have examined the interactions of navie (untreated) and NGF‐differentiated SY5Y cells with laminin, and identifid integrin receptors that mediate laminin‐induced process outgrowth. Differentiated cells displayed a greater capacity for process extension, which correlated with increased expression of integrin laminin receptors. Both naive and differentiated cells expressed integrins α1/β1, α2/β1, and α3/β1 but the differentiated population expressed about 5‐fold higher levels of α1/β1 and about 2‐fold nore α2/β1 and α3/β1 on their surface. Function blocking monoclonal antibodies were used to identify integrin receptors mediating process outgrowth. The anti‐α1 monoclonal antibodies were used to identify intergrin receptors mediating process outgrowth. The anti‐α1 moniclonal antibody SR84 was shown to block α1 function and inhibit process outgrowth on laminin. Despite the presence of multiple integrins which have been shown to bind laminin in other cell types, α1/β1 mediated the majority of process outgrowth in both naive and differentiated cells, with a minor role played by α3/β1. These data indicate that α1/β1 function is requried for process outgrowth on laminin by SY5Y cells and suggest that increased expression may be a crucial aspect of neuronal differentiation.