Affinity electrophoresis for studies of mechanisms regulating glycosylation of plasma proteins.

A model system for studies of mechanisms governing the alterations of glycosylation of plasma glycoproteins was developed. The system employs two human hepatoma cell lines, Hep 3B and Hep G2, as target cells and agarose affinity electrophoresis with lectins for studies of microheterogeneity of alpha 1-protease inhibitor (PI), a model glycoprotein synthesized by hepatocytes. As an example for the application of the system, the effect of cytokines on major microheterogeneity of plasma proteins is demonstrated. The results indicate that interleukin 6, transforming growth factor beta 1 and, to some extent, tumor necrosis factor alpha are directly involved in regulating the pattern of glycosylation of plasma proteins in vitro, but the major effect is obtained by using combinations of interleukin 6, transforming growth factor beta 1, tumor necrosis factor alpha and interleukin 1. In addition, the results underline the dissociation between alteration of gene expression and the changes in the pattern of plasma protein glycosylation.