FUNCTIONAL IDENTIFICATION OF INTEGRIN LAMININ RECEPTORS THAT MEDIATE PROCESS OUTGROWTH BY HUMAN SY5Y NEUROBLASTOMA-CELLS

Treatment of the human neuroblastoma cell line SY5Y with nerve growth factor (NGF) induces terminal neuronal differentiation of a subpopulat ion of cells which can be selected by treatment with a DNA synthesis i nhibitor. We have examined the interactions of naive (untreated) and N GF-differentiated SY5Y cells with laminin, and identified integrin rec eptors that mediate laminin-induced process outgrowth. Differentiated cells displayed a greater capacity for process extension, which correl ated with increased expression of integrin laminin receptors. Both nai ve and differentiated cells expressed integrins alpha 1/beta 1, alpha 2/beta 1, and alpha 3/beta 1 but the differentiated population express ed about 5-fold higher levels of alpha 1/beta 1 and about 2-fold more alpha 2/beta 1 and alpha 3/beta 1 on their surface. Function blocking monoclonal antibodies were used to identify integrin receptors mediati ng process outgrowth. The anti-alpha 1 monoclonal antibody SR84 was sh own to block alpha 1 function and inhibit process outgrowth on laminin . Despite the presence of multiple integrins which have been shown to bind laminin in other cell types, alpha 1/beta 1 mediated the majority of process outgrowth in both naive and differentiated cells, with a m inor role played by alpha 3/beta 1. These data indicate that alpha 1/b eta 1 function is required for process outgrowth on laminin by SY5Y ce lls and suggest that increased expression may be a crucial aspect of n euronal differentiation. (C) 1994 Wiley-Liss, Inc.