Expression of the polysialyltransferase ST8SiaIV: Polysialylation interferes with adhesion of PC12 cells in vitro

Addition of polysialic acid (PSA) to the neural cell adhesion molecule, NCA M, represents a unique posttranslational modification. Polysialylation of N CAM is developmentally regulated and associated with neural regeneration an d plastic processes, as well as learning and memory. Two enzymes, the polys ialyltransferases ST8SiaII and ST8SiaIV, are known to be involved in the po lysialylation of NCAM. Both enzymes are individually capable of catalyzing polysialylation of NCAM, but their time of occurrence and their tissue expr ession are different. In this study the influence of polysialylation on the nerve growth factor-induced differentiation of PC12 cells was investigated . For this purpose, PC12 cells, which endogenously express NCAM, were trans fected with ST8SiaIV to produce, for the first time, a stable polysialylate d PC12 cell. We demonstrate that integrin-dependent adhesion to collagen I is reduced in PSA-expressing PC12 cells. Furthermore, polysialylated cell m embranes as matrix are a poor substrate for the adhesion and differentiatio n of PC12 cells, compared with normal cell membranes. (C) 1999 Academic Pre ss.