Journal of Cell Science, Vol 49, Issue 1 283-297, Copyright © 1981 by Company of Biologists

JOURNAL ARTICLES

Modification of fibroblast surface amines alters receptor-mediated cell spreading on protein-coated substrata but not adsorptive endocytosis

JD Aplin and RC Hughes

Fluorescein isothiocyanate (FITC) and other anionic reagents specific for amine groups have previously been shown to inhibit the adhesion and spreading of cultured fibroblasts to fibronectin-coated surfaces (Butters, Devalia, Aplin & Hughes, 1980). Here it is demonstrated that a population of FITC-labelled cells can be separated using flow cytometry into fractions displaying greater and lesser adhesivity at lower and higher fluorescence, respectively, demonstrating that the inhibition is dose-dependent. Glass coverslips covalently derivatized with the lectins ricin and concanavalin A are used to show that the inhibition also occurs in lectinmediated cell adhesion as well as in adhesion to collagen coated with fibronectin and plastic coated with serum or antibody, suggesting that all of these responses share a common, FITC-sensitive component. Simple primary amine compounds inhibit adhesion to fibronectin, but specific inhibitors of transglutaminases do not affect the process. Transglutaminase activity of cell surfaces has been implicated in protein endocytosis and receptor recycling (Davies et al. 1980). FITC modification of cells appears to affect specifically adhesive interaction, since ricin cytotoxicity and infection of cells with influenza and Sendai viruses (phenomena thought to proceed by means of receptor-mediated endocytosis) are unaffected. Evidently, receptor-mediated cell attachment, spreading on protein-coated surfaces and protein endocytosis are functionally separate events requiring different cell-surface membrane components, even when the same protein (ricin) is used to trigger these 2 processes.