MULTIPLE MECHANISMS OF N2A AND CHO CELL-ADHESION TO NCAM PURIFIED FROM CHICK EMBRYONIC BRAIN AND RETINA

The neural cell adhesion molecule (NCAM) is thought to have an importa nt role in cell-cell interactions during development. To better unders tand NCAM function, we studied the adhesion of mouse N2A neuroblastoma cells and Chinese hamster ovary cells to different forms of NCAM usin g a quantitative centrifugal cell adhesion assay that measures the rat e of cell removal from experimental substrates. Embryonic brain NCAM i s highly polysialylated and contains both 180- and 140-kDa polypeptide isoforms, whereas embryonic retinal NCAM is less highly polysialylate d and contains primarily the 110-kDa isoform. For both forms, cell adh esion to substrate-immobilized NCAM was temperature dependent, cation independent, and time dependent. Cell adhesion to NCAM substrates was not directly affected by drugs inhibiting cytoskeletal function or cel lular metabolism, suggesting that NCAM function does not depend critic ally on cytoskeletal function or metabolic activity. Cell adhesion to retinal NCAM was blocked by anti-NCAM antibodies, and adhesion was inc reased by neuraminidase treatment of both types of NCAM. Adhesion to b rain NCAM was effectively blocked by anti-NCAM antibodies only after n euraminidase treatment, suggesting that these cells adhere to highly s ialylated and less-sialylated NCAM by different mechanisms. We propose that multiple mechanisms of cell adhesion involving NCAM may exist in different tissues during development and that the state of polysialyl ation of NCAM is important in regulating the relative importance of th ese mechanisms. (C) 1994 Academic Press. Inc.