Carbohydrate-mediated sorting in aggregating embryonal carcinoma cells

The oligosaccharide structure carried by embryoglycan, Lex hapten, as well as E-cadherin, has been described to mediate Ca(2+)-dependent cell-cell adhesions in embryonal carcinoma cells. To examine the contribution of these two systems to intercellular adhesion, we analyzed aggregation properties of previously isolated embryoglycan-defective mutants of P19 embryonal carcinoma cells. Our data indicate that the absence of Lex and embryoglycan has no effect on homotypic cell aggregation. Pretreatment of the cells with E-cadherin-specific antibody reduced homotypic aggregation of both parental and mutant cells, suggesting that E-cadherin plays a major role in this system. When parental cells were mixed with mutant cells, the aggregates contained either parental or mutant cells; no heterotypic aggregation was observed. The absence of mixed aggregates formed between parental and Lex-or embryoglycan-negative mutant P19 cells suggests that carbohydrates are involved in cadherin-mediated cell sorting.