Alcohol inhibition of cell adhesion in BMP-treated NG108-15 cells

The L1 cell adhesion molecule is expressed as alternatively spliced neuronal and nonneuronal isoforms. We have reported that in transfected fibroblasts, ethanol variably inhibits cell-cell adhesion mediated by the nonneuronal isoform of human L1. In contrast, ethanol consistently inhibits morphogenetic changes and cell-cell adhesion in NG108-15 cells treated with OP-1 (BMP-7), a powerful inducer of L1 and N-CAM gene expression.

All studies were performed by using NG108-15 cells cultured in serum-free medium. Cell morphology was assessed by a quantitative assay of cell clustering. Cell adhesion was measured by a short-term re-aggregation assay, and isoforms of L1 were characterized by RT-PCR and sequencing.

We show that ethanol inhibits the morphogenetic effects of BMP-2, BMP-4, BMP-5, and BMP-6, each of which increases the expression of L1 and N-CAM. Pretreatment of NG108-15 cells with 25-100 mM ethanol did not induce tolerance to ethanol's inhibition of OP-1 morphogenesis or cell-cell adhesion. Ethanol or anti-L1 Fab fragments partially inhibited cell-cell adhesion in OP-1-treated NG108-15 cells. The combination of ethanol and Fab fragments did not inhibit cell-cell adhesion more than Fab fragments alone. As in L1-transfected fibroblasts, a series of n-alcohols displayed a cutoff between butanol and pentanol for inhibition of cell-cell adhesion in OP-1-treated NG108-15 cells. RT-PCR and direct sequencing revealed that the neuronal isoform was the sole or predominant L1 isoform in OP-1-treated NG108-15 cells.

These data suggest that ethanol inhibits cell-cell adhesion in OP-1-treated NG108-15 cells by interacting directly or indirectly with the neuronal isoform of L1.