ETHANOL DOES NOT INHIBIT THE ADHESIVE ACTIVITY OF DROSOPHILA NEUROGLIAN OR HUMAN L1 IN DROSOPHILA S2 TISSUE-CULTURE CELLS

Members of the L1 family of hemophilic neural cell adhesion molecules are thought to play an important role in nervous system development an d function. It is also suggested that L1 is a direct target of ethanol in fetal alcohol syndrome, since ethanol inhibits the aggregation of cultured cells expressing L1 (Ramanathan, R., Wilkemeyer, M. F., Mitte l, B., Perides, G., and Charness, M. E. (1996) J. Cell Biol. 133, 381- 390). If ethanol acts directly on the hemophilic adhesive function of the L1 molecule, then inhibition of aggregation by ethanol should be o bserved in any cell type that expresses L1. Here we examined the effec t of physiologically relevant concentrations of ethanol on the aggrega tion of Drosophila S2 cells that expressed either neuroglian (the Dros ophila homolog of L1) or human L1. The aggregation of these S2 cells i s known to be solely dependent on the hemophilic interactions between L1 or neuroglian molecules. Neither cell adhesion molecule was affecte d when cell aggregation assays were carried out in the presence of gre ater than or equal to 38 mM ethanol. The recruitment of membrane skele ton assembly at sites of cell cell contact (a transmembrane signaling function of human L1) was also unaffected by the presence of ethanol. Thus the previously described inhibition of cell adhesion by ethanol i n L1-expressing cells cannot be explained by a simple direct effect on the adhesive activity of L1 family members.